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Salt Kilns and Landscape Change in the Sundarbans

Geohazards in Bangladesh - Sat, 03/21/2015 - 06:58
Rabi, Diana, Khris, Joelle, Dan and Alamgir watching the landscape as we sail through the Sundarbans

Rabi, Diana, Khris, Joelle, Dan and Alamgir watching the landscape as we sail through the Sundarbans

We left Hiron Point with the high tide and sailed through small channels of the Sundarbans Mangrove Forest. As a tidal marsh, the Sundarbans is crisscrossed by channels with sizes that range from 10 km across to less than a foot. The tides rise and fall periodically inundating all of the land. Mangroves are trees that are adapted to living in brackish water. Different tree species are found in different parts of the Sundarbans, adapted to different levels of saltiness.

We arrived at Kotka in the afternoon. Most of the group went on a forest walk with Tanzeel, our guide. A smaller group of us split off to visit thee remains of 300-year old salt kilns. We passed Chital deer and a wild boar on the way. A stag was silhouetted at the coast before it ran off. The

A boat harvests leaves for thatching roofs in the Sundarbans.

A boat harvests leaves for thatching roofs in the Sundarbans.

people that built the kilns used to allow seawater to flow into evaporation pans at Spring high tide. Before the next Spring tide they would bake the concentrated brine in clay pots to produce salt. The kilns are surrounded by innumerable potsherds, and quite a few intact clay pots. It is thought that the operation was suddenly destroyed, abandoned and buried, perhaps by a 1699 cyclone that killed 50,000 people. Recent erosion, include the destruction by Cyclone Sidr in 2007 have unearthed them.

Since the age of the kilns is known, it is a good site for Liz to use OSL dating to determine the sedimentation rate. We drilled several auger hole to determine the stratigraphy, the deepest one was 5.8 meters. Liz drilled assisted by two crew from

Remains of trees destroyed by Cyclone Sidr along the coast at Kotka

Remains of trees destroyed by Cyclone Sidr along the coast at Kotka

the Kokilmoni while I took notes and photos. The kiln site is now in the intertidal zone – exposed at low tide and covered at high tide. This means that they have subsided since they were last used. The rate is estimated as 4.1 mm/yr by a German group that worked here. We completed 3 holes, but ran out of daylight before we could take the OSL samples. We returned to the ship, walking past buildings destroyed by Sidr with our larger group who ended their forest walk at the kiln site.

We returned at dawn the next morning – with a guard to protect against tigers – while the remainder of the group went on a silent ride up a tidal creek. We collected 3 OSL samples from different depths, the last one completed as the rising tide reached over our knees. Whenever the

Liz standing by the remains of 300-year old kilns used for salt making surrounded by shards of the pots used for holding the salt

Liz standing by the remains of 300-year old kilns used for salt making surrounded by shards of the pots used for holding the salt

sampler was removed from the hole, one of us had to keep our hand in the hole, usually Matt, so we could find it again. Happy with our successful sampling, we returned to the ship for breakfast.

Back with the others, we set out for a forest walk to Kotka Beach. Climbing an observation tower, we got an overview of the region. There are old shoreline deposits here that are above the high water level. These sediments provide evidence of the seaward progradation of delta. As a result there is a meadow and many non-mangrove species as the area doesn’t regularly flood. This attracts a lot of deer and, as a result, tigers. However, we only deer. We also walked through the muddy mangrove forest and finally emerged at Kotka Beach where we went swimming in the Bay

We finish collecting our last sample as the tide came in and water covered the site.  We had to pound the last bit of the sampler through the water.

We finish collecting our last sample as the tide came in and water covered the site. We had to pound the last bit of the sampler through the water.

of Bengal. We continued along the beach for a few kilometers passing hordes of scurrying crabs. Finally, we rejoined the Kokilmoni for a late lunch.

In this area, plans always have to be adjusted according to the tides and weather. As a result, we switched our visit to Bird and Egg Islands to later in the afternoon instead of the following morning. These two islands emerged from the sea about 20-25 years ago and have grown and merged. In answer to the age old question, the Egg came first. While a few people skipped the walk after the morning’s trek, most of us went along. It is a great place to see the biological succession that develops on a new island. The coast is bare sand with the high water mark littered with plant debris. Beyond the wind-blown coastal dunes, grasses

View from the observation tower at Kotka.  The sandy paleo-shoreline separates the meadow on the left from the mangroves on the right

View from the observation tower at Kotka. The sandy paleo-shoreline separates the meadow on the left from the mangroves on the right

have taken hold. Then tall grasses and a scattering of shrubs and then trees in a muddy salt marsh. Finally in the distance is a full-fledged mangrove forest. We saw tracks and spoor of deer and monkeys, but as of yet there are no tigers on the island.

An unsuspected bonus was a tidal channel near the beach. Here at small scale, we could see all the features of river systems that we discussed in class: cut banks and point bars, meanders and avulsions, small deltas and chars. All at a scale that brought the geology to life for the students far better than any lecture or photos. It was a long and very successful day in the Sundarbans.

Group photo on Egg Island.  We stand at the transition from sand to grass while behind us the entire succession to mangroves is visible

Group photo on Egg Island. We stand at the transition from sand to grass while behind us the entire succession to mangroves is visible

As the sun sets, we climb into the launch to leave the island and return to the Kokilmoni

As the sun sets, we climb into the launch to leave the island and return to the Kokilmoni

Polder 32 and Hiron Point

Geohazards in Bangladesh - Fri, 03/20/2015 - 12:48
Mimi, Matt and Yassamin sitting in the bridge of the Kokilmoni

Mimi, Matt and Yassamin sitting in the bridge of the Kokilmoni

We sailed downstream to join the M/V Bawali with the Vanderbilt-Dhaka-Khulna group working on Bangladesh late at night and awoke to greet old friend and meet new ones. After breakfast, we all headed to Polder 32. Polder 32 is one of the islands that had embankments constructed around them to prevent flooding and improve agriculture. They use the Dutch term polder for the embankments. Polder 32 was one in which the polders failed during Cyclone Aila in 2009. As it turned out, while the polders improved agriculture as planned, it also led to subsidence of the island. It is now over 4 feet lower than land outside the island. This led to widespread flooding of the island after the cyclone that lasted for almost 2 years. We have been studying the causes and impact for the last few years. The subsidence inside the polders put everyone at risk as an unintended consequence of keeping out the natural flooding and sedimentation to improve agriculture. How to manage this system now is a difficult problem.

Kazi Matin explains his MAR site on Polder 32

Kazi Matin explains his MAR site on Polder 32

 

We also learned about the water problems at Polder 32. The groundwater is saline and not usable for either drinking or irrigation. They can only grow one crop a year, so the fields are all fallow except for some vegetable gardens by the homes. In other parts of Bangladesh 2 and even 3 crops a year are possible. We saw the abandoned tube wells installed by a wealthy donor after Cyclone Aila. They are all saline. Kazi Matin showed us his MAR site – managed aquifer recharge. They are attempting to create a pool of fresh groundwater over the heavier salt water providing a source of sweet water. Nearby, the Vanderbilt team is

Shrimp farm we visited at Polder 33

Shrimp farm we visited at Polder 33

installing equipment to measure water levels and flow at different depths, trying to better understand the groundwater system.

While the students fanned out to discuss agriculture with the farmers and test what few tube wells they could find, a small group of us took a speed boat to a large industrial shrimp farm on Polder 33. We found the site to be surrounded by a barbed wire fence. We found out later that it is to protect the site from tigers as it is on a peninsula surrounded on 3 sides by the Sundarbans. There was a rumor that the shrimp farm had closed and could be used to calibrate remote sensing data, but it was fully running. They grow 2 crops of jumbo shrimp a year over 9 months and spend the

With limited tube wells to test, the group returned to the ship early and had a swim break.

With limited tube wells to test, the group returned to the ship early and had a swim break.

remaining 3 months cleaning the ponds and preparing for the next season’s crop. They were one of the first large-scale shrimp operations in Bangladesh.

We sped back to the ship to find that the others had all returned and were having a swim break. I barely managed to change into my swimsuit and jump in before we all had to return to the ship to sail to Hiron Point. The strong tides in southern Bangladesh set our schedule as we try to catch tides going our way and avoid sailing against the tide. We sailed down channel between Polder 32 and the Sundarbans to the Shibsa River. At the end we passed Kalibogi. It is a peninsula at the end of Polder 32 that has had about a kilometer of erosion. It is now very narrow and the

Homes on the edge of the eroding peninsula at Kalibogi

Homes on the edge of the eroding peninsula at Kalibogi

embankment has been moved north of the peninsula, abandoning it. The shrimp farms that were once here are gone. There are only homes poorly protected from the elements and fishing is their only livelihood.

We sailed down the Shibsa to the Pusur River and overnighted in a narrow channel across from Hiron Point. In the morning we crossed. This stop is manly for me to service our GPS installation. We are using the precise measurements to determine the subsidence rate of this part of the delta. There is a tide gauge here that monitors the relative level between the sea and the land. While intended for navigation, over time it records the combined effect of land subsidence and sea level rise. With the GPS, we will be able to separate the two rates.

On the wooden launch sailing to Hiron Point forest station

On the wooden launch sailing to Hiron Point forest station

We all took the small wooden launch into the channel to the Forest Station. The Kokilmoni stayed outside lest it get trapped behind the mouth bar when the tide goes out. Hasnat and I, with Sabrina filming went to service the GPS while Liz demonstrated how to auger to get stratigraphy and sample for OSL dating. Small groups also took turns going up the observation tower. I discovered that I did not have my internet adapter – Apple have eliminated them from the newest Mac. I was stuck. Hasnat rushed back to the ship with the launch to get his computer. I could only wander around. I was shown the small spring with natural gas bubbling up. It could even be lit on fire. Finally Hasnat returned and we were able to download all the data since my last visit and upgrade the firmware of the receiver. We finished right at high time and rushed back to the ship to sail to our next stop. Thanks to Hasnat, we were able to accomplish our goals here.

Group photo at Hiron Point in the Sundarbans Mangrove Forest - a world heritage site.

Group photo at Hiron Point in the Sundarbans Mangrove Forest – a world heritage site.

Working in the Bangladeshi Countryside

Geohazards in Bangladesh - Fri, 03/20/2015 - 06:08
Sailing through the Sundarban Mangrove Forest

Sailing through the Sundarban Mangrove Forest

The shortest route to where we are headed has silted up and is no longer passable. Farmers have moved in and started shrimp farming there. As a result, we and others have to take a longer route through the Sundarbans Mangrove Forest. Our first tantalizing sight of the forest we will return to later. Will lots of ship traffic on this route, the inevitable happened. Last December a ship collision resulted in an oil spill. With initial inaction by the government not wanting to face it, the local people went in and cleaned up the oil themselves by hand. Without any protective gear from the toxic oil, they saved the situation. Now only a slight oily film is visible at low tide. We started at 2 am to travel through the passage with the rising tide.

The team studying agriculture changes in Bangladesh meet with Chris Small to plan for interviewing farmers

The team studying agriculture changes in Bangladesh meet with Chris Small to plan for interviewing farmers

By 10 am we had passed through the Sundarbans to the Pusur River and stopped to pick up Carol Wilson and Saddam Hosain. They will join us for a few days from another boat that a Vanderbilt-Dhaka University team is using for research work at Polder 32. We continued up to Khulna ghat (dock). We had lunch and transferred to land by launch. In three vans we drove for and hour to asite where we installed instruments to measure the compaction and subsidence of the sediments. In 2011 we drilled 6 wells with depths from 20 to 300 meters installed optical fiber strainmeters. The fibers are stretched like a rubber band and every week one of the sons from the Islam family uses a device to measure its length, watching to see the change as the sediments compact.

Tanner and Yassamin in a discussion at sunset.

Tanzir and Yassamin in a discussion at sunset.

While I service the equipment, my students spread out in several groups. Four of my students, each with a Bangladeshi partner spread out over the area with Chris Small to interview farmers about their farming practices, what crops they grow and changes through time. The information the agriculture team collects will help calibrate remote sensing observations. The other 6 students work with Kazi Matin Ahmed of Dhaka University form 5 teams to measure arsenic levels in the wells that provide drinking water. Finally, Liz Chamberlain and Carol use an augur to drill into the sediments. They will look at the stratigraphy and collect a sample for dating. The river that flows through the area used to me 300 meters (1000 ft) wide, now it is only a few meters. The silting in banks have been occupied by squatters using the new land for shrimp farming. The Islam family moved here in 2002.

Fisherman on the Pusur River using the incoming tide to sweep fish into their nets

Fisherman on the Pusur River using the incoming tide to sweep fish into their nets

When we arrive, it is hard to recognize the site. The government is excavating the river, widening it so boats can use it again. There are large piles of mud everywhere. Finally we find the right place and are relieved to find that they went around our instruments. In the afternoon, I met the engineer doing the work and he reassured us that our instruments will be untouched. Only time will tell if the measurements will be affected.

I was the least successful of the groups. We collected the data from the 6 compaction meters and surveyed between the GPS and wells to look at changes in the surface elevation. However, the cap of the well collecting water level data was rusted shut. When we really tugged on it, the pipe started to bend. We will have to return with WD-40.

We arrived to find that 2 weeks earlier excavations had started to widen the river. It has shrunk from 300 to 3 meters wide.  Gratefully, they left our instruments intact.

We arrived to find that 2 weeks earlier excavations had started to widen the river. It has shrunk from 300 to 3 meters wide. Gratefully, they left our instruments intact.

Even worse the GPS was dead. Some problem with the solar panel system, but with the tool kit back in the states, I couldn’t diagnose it. I will take the receiver back to Dhaka to download the data, but Humayun will have to come to repair the power system. At least the students had a more successful time talking to farmers and measuring arsenic. It was their first time talking to rural Bangladeshis and spending time in the countryside. They thoroughly enjoyed it.

Collecting a water sample for testing arsenic levels at the well of the Islam family, host of the compaction meter.  It came out clean.

Collecting a water sample for testing arsenic levels at the well of the Islam family, host of the compaction meter. It came out clean.

Liz augurs through the sediments on the riverbank  to get a sample for OSL dating, attracting a crowd

Liz augers through the sediments on the riverbank to get a sample for OSL dating, attracting a crowd

Sailing Around Political Unrest in Bangladesh

Geohazards in Bangladesh - Sun, 03/15/2015 - 07:24
Opposition leader Khaled Zia (left) and Prime Minister Sheikh Hasina (right)have been alternating as Prime Minister since 1996.

Opposition leader Khaled Zia (left) and Prime Minister Sheikh Hasina (right) have been alternating as prime minister since 1996.

I am once again teaching a Sustainable Development course on hazard in Bangladesh. The highlight of the course is that the 10 students, the teaching assistant and I are all traveling to Bangladesh over Spring Break. However, our plans have been disrupted by the continuing political unrest in Bangladesh. The opposition BNP party is calling for new fair elections by calling for a continuous blockade of travel and periodic hartals – general transportation strikes. They have been trying to enforce it by tossing Molotov cocktails at vehicles that defy it. Over 120 people have been killed so far. The ruling Awami League refuses to give into violence and neither the UN, EU or US

Visiting the Shahid Minar, the memorial to students killed in 1952 protesting against Urdu as the sole language of Pakistan. Now February 21 is a major celebration of the Bangla language.

Visiting the Shahid Minar, the memorial to students killed in 1952 protesting against Urdu as the sole language of Pakistan. Now Feb. 21 is a major celebration of the Bangla language.

have been able to make a dent in the situation. The two parties and their women leaders hate each other. Neither side will back down on the unrest that started with the Jan 5 anniversary of the election. While more and more people are defying the blockade, after 2 months people have to make a living, the risk is too high to take a bus load of undergraduate students around the country.

Our solution, Plan B, is to stay off the roads and travel the country by boat. Dhaka, the capital is quiet, so we are visiting there at the beginning and end of the trip. The boat we were planning to use to visit the Sundarbans Mangrove Forest came up to Dhaka to meet us after we had a difficult trip. The 14 of us (Chris Small of Lamont and Liz Chamberlain of Tulane University are also joining us) made it to JFK skirting traffic

One of the sculptures we saw at the Art Institute in Bangladesh near the National Museum and Shahbag Square.

One of the sculptures we saw at the Art Institute in Bangladesh near the National Museum and Shahbag Square.

only to find a 4-hour delay on our flight. The airline nicely rebooted us for the next connection to Dhaka and escorted us through the airport to catch it. However 4 bags missed the connection. By the time we got to our hotel it was midnight and we still hadn’t had dinner. It was two AM by the time we go to bed. My TA, Matt, had to go back to the airport in the morning with Sukhen, but only 3 of the bags arrived. The missing one was Matt’s, but having lived in Dhaka, he had clothes in storage there.

The rest of us went to Dhaka University to meet our Bangladeshi counterparts, 8 students and 2 professors that are traveling with us. After a quick tour of a few spots around Dhaka, we headed to meet the Kokilmoni. I have sailed on her twice before. With Plan B, we will have to skip some areas, like the Brahmaputra River, that we cannot get to by boat in our limited time. However, we will get more time at other spots of interest and see what will be new parts of the country for me from a different vantage point. We started on a the Shitalakhya River east of Dhaka and sailed south in larger rivers finally passing the confluence of the Padma (combined Ganges and Brahmaputra) with the Meghna River before tying up at Chandpur for the night.

The students catch up on texts and e-mails at Dhaka University after 2 days without a connection

The students catch up on texts and e-mails at Dhaka University after two days without a connection.

A boat is a much more pleasant way to travel than a bus with more places to hang out and rest from jet lag. The food is good and plentiful. The cabins are tiny and hot, while the showers are cold. The main thing the students missed is any opportunity to buy Bangladeshi clothes. Along the way we made two quick stops, one above and one below the confluence, for Liz to take samples for OSL analysis, a dating technique that uses electrons trapping in quartz to determine the last time the sediments were exposed to sunlight. The samples, collected by hammering a tube into the outcrop, must not be exposed to sunlight. Otherwise, these first days are quiet as it will take us until tomorrow afternoon to reach our first extended field stop. Boats are a comfortable, but slow way to travel.

 

Sitting on deck between Liz Chamberlain and Miriam Kaplan and we sail across Bangladesh.

Sitting on deck between Liz Chamberlain and Miriam Kaplan as we sail across Bangladesh.

Liz Chamberlain of Tulane University takes samples for OSL analysis from the bank of the Meghna River.

Liz Chamberlain of Tulane University takes samples for OSL analysis from the bank of the Meghna River.

Students board the launch that will ferry us to the Kokilmoni.

Students board the launch that will ferry us to the Kokilmoni.

The M/V Kokilmoni, our home for the next 8 days. This tourist boat for the Sundarbans Mangrove Forest came all the way to Dhaka to pick us up.

The M/V Kokilmoni, our home for the next 8 days. This tourist boat for the Sundarbans Mangrove Forest came all the way to Dhaka to pick us up.

Abyssal Rhythm

Geopoetry - Fri, 03/13/2015 - 11:00
 ADAPTED BY P. HUEY/SCIENCE

When sea level drops, pressure at mid-ocean ridges decreases, which may influence the production of ocean crust. A new study suggests that the pattern of hills on the sea floor reflects the timing of sea-level change during ice age cycles. Illustration: adapted by P. Huey/Science

 

Since the dawn of mankind, I imagine we’ve gazed

In wonder and awe at the sky’s starry crown;

More recently, we have been deeply amazed

By the long-obscured, staggering view looking down

To the depths of the sea, through crust, and below

Where rock moves like taffy, dark forge of the Earth,

Great molten sculptures and stark chasms grow;

A womb steeped in intrigue, the mantle gives birth

To breath-taking mountains, and wide rolling hills,

We humans gaze down from our ships, our sea cruises

We probe this vast landscape with sound waves and drills;

From ridges of awesome proportions, crust oozes

With a rhythm, it seems, that’s tied to the sun!

Our planet’s history, scrawled on ripped pages

Of rock and of sediments, piled by the ton

Rippled and riddled with tales of ice ages;

From ridges revealed, a pattern discovered

Orbital rhythms in a seafloor slice,

The pulse of the planet, a sculpture uncovered,

Does the deep earth exhale in concert with ice?

 

_________________________________________________________

Further reading:

How climate influences sea floor topography, Conrad 2015 Science

Glacial cycles drive variations in the production of ocean crust, Crowley et al. 2015 Science

Mid-ocean ridge eruptions as a climate valve, Tolstoy 2015 Geophysical Research Letters

This is one in a series of poems written by Katherine Allen, a researcher in geochemistry and paleoclimate at the Lamont-Doherty Earth Observatory and the Department of Marine and Coastal Sciences at Rutgers University.

 

The Most Astonishing Thing

Geopoetry - Fri, 02/27/2015 - 09:00
A super-massive black hole, roughly 12 billion times as massive as our sun, has been discovered at the center of a bright quasar. The light reaching us now from that distant location has been traveling for billions of years, and thus offers a glimpse into the earliest stages of the universe.

A super-massive black hole, roughly 12 billion times as massive as our sun, has been discovered at the center of a bright quasar. The light reaching us now from that distant location has been traveling for billions of years, and thus offers a glimpse into the earliest stages of the universe. Image: NASA/JPL-Caltech

 

The most astonishing thing about the universe, in my eyes,

Is not merely its gargantuan, unfathomable size,

But the way its vastness ferries gorgeous, primordial light,

So that as we look up into the night,

The farther afield our gaze penetrates, the higher we climb,

The farther we can see back in time.

Like ancient missives carefully tucked into a bottle,

Flashes of history race towards us full-throttle,

At the speed of light traversing a fabric expanding,

These waves touch our shores, and fuel our understanding

Of quasars and black holes, the light and the dark,

The Very Beginning, the bright cosmic spark

From which all this sprang – upon us, the story rains:

Of how we arose with star stuff in our veins.

 

_________________________________________________________

Further reading:

Gigantic Black Hole Discovered from the Dawn of Time, National Geographic

An ultraluminous quasar with a twelve-billion-solar-mass black hole at redshift 6.30, Wu et al. (2015) Nature

This is one in a series of poems written by Katherine Allen, a researcher in geochemistry and paleoclimate at the Lamont-Doherty Earth Observatory and the Department of Marine and Coastal Sciences at Rutgers University.

Exploring Antarctica by Sea, Air and Land

Peering Through Polar Ice - Mon, 12/08/2014 - 12:26
Antarctica map NASA

(Click on map for larger image)

Early winter in the Northern Hemisphere marks the start of austral summer in the Southern Hemisphere, and the beginning of the Antarctic field season. Each year, several thousand scientists head to the icy continent to take advantage of the relatively mild, though still very harsh, weather and the 24-hour daylight; the next time the sun will fall below the horizon at Antarctica’s McMurdo Station is February 20, 2015.

Lamont-Doherty Earth Observatory scientists are among the many researchers currently doing fieldwork in Antarctica. They’re leading and participating in expeditions near, above and on the continent, doing critical studies that will advance understanding of Antarctica’s land and sea processes.

Lamont biogeochemist Sonya Dyhrman is aboard an icebreaking ship, the R/V Nathaniel B. Palmer, for one month. In that time she’ll slowly travel south from Punta Arenas, Chile to research sites located off the Western Antarctic Peninsula. Dhyrman, graduate student Harriet Alexander and the other cruise scientists are investigating polar food web dynamics, with a focus on the feeding and swimming behavior of krill, a small shrimp-like crustacean. During the research cruise, Dyhrman and Alexander will collect samples of water and phytoplankton from a number of different sites. Their goal is to understand the physiological ecology of phytoplankton, which form the base of the marine food web in the Southern Ocean, and are a major source of food for krill.

 Lamont-Doherty scientists Robin Bell, Chris Bertinato, Nick Frearson, Winnie Chu and Tej Dhakal with IcePod.

Lamont-Doherty scientists Robin Bell, Chris Bertinato, Nick Frearson, Winnie Chu and Tej Dhakal with IcePod.

More than two thousand miles south, six scientists from Lamont’s Polar Geophysics Group are at McMurdo Station, a U.S. Antarctic research center located on Ross Island. They’re deploying an ice imaging system, known as IcePod, which consists of ice-penetrating radar, infrared and visible cameras, a laser altimeter and other data-collection instruments. IcePod attaches to a New York Air National Guard LC-130 aircraft and measures, in detail, the ice surface and the ice bed; important data that enables the scientists to track changes in ice sheets and glaciers.

The scientists are testing the instrumentation and training the New York Air National Guard in the deployment and operation of the instrument; this is the first time IcePod is being used in Antarctica. After the testing and training, IcePod will be operated in up to 15 other flights for routine data collection.

Also at McMurdo Station are Lamont geologists Sidney Hemming and Trevor Williams. The two scientists and their colleagues Kathy Licht and Peter Braddock will soon fly to a field site in the remote Thomas Hills, near the Weddell Sea in the Atlantic sector of Antarctica. There they’ll spend four weeks making observations and collecting rock samples from the exposed tills on the edge of the massive Foundation Ice Stream, as well as from the Stephenson Bastion and Whichaway Nunataks.

Lamont-Doherty's Trevor Williams and Sidney Hemming (left), with colleagues Kathy Licht and Peter Braddock.

Lamont-Doherty’s Trevor Williams and Sidney Hemming (left), with colleagues Kathy Licht and Peter Braddock.

The group is examining how ice sheets in the Weddell Sea embayment will respond to changing climate, specifically how Antarctic ice retreats and which parts of the ice sheet are most prone to retreat. Understanding the behavior of the Antarctic ice sheets and ice streams provides critical information about climate change and future sea level rise.

Thanks to the Internet and the scientists’ dedication to outreach, it’s possible to join their Antarctic expeditions without donning extreme cold weather gear. Follow the Dyhrman’s cruise activities on Twitter via @DyhrmanLab and #TeamDyhrman, and learn more about their research on the cruise website.

The IcePod team is blogging about their fieldwork on State of the Planet, and updates from the Lamont geologists in the Thomas Hills can be found on Twitter via @Trevor_On_Ice and #AntarcticaG297.

 

A Texas-Sized Block of Ice…

Peering Through Polar Ice - Thu, 12/04/2014 - 22:20
Icepod flying over the Antarctic ice towards Mt. Erebus (photo W. Chu)

Icepod and the LC-130 flying over the Antarctic ice towards Mt. Erebus. Photo: W. Chu

The first dedicated Antarctic Icepod mission was flown out across the center of the Ross Ice Shelf. Ice shelves are thick floating extensions of the ice sheet that form as the ice flows off the continent and into the surrounding ocean. These are critical ice features in Antarctica, bounding a full 44 percent of her coastline, where they serve as a buttress to slow the ice movement off the continent into the ocean.

Icepod flying over the front of the Ross Ice Shelf. Along the shelf edge sections of thinner sea ice appear grey on the water surface. (Photo W. Chu)

Icepod flying over the front of the Ross Ice Shelf. Along the shelf edge sections of thinner sea ice appear grey on the water surface. Photo: W. Chu

The Ross Ice Shelf is the largest of the Antarctic ice shelves, measuring just under the size of the state of Texas. It is several hundred meters thick, although most of this is below the water surface. Along the ~ 600 kilometer front edge of the shelf, the ice towers up to 50 meters in height; a sheer vertical wall of white and the iridescent blue of compressed ice. 

The goal of the six-and-a-half-hour mission was to test how the Icepod could image the varying processes at the base of the ice shelf and how well the gravimeter would work flying 90m/sec.

Sea ice covers much of the polar oceans both in the Arctic and Antarctic during the winter months.  Unlike the ice sheet which forms over land, sea ice freezes directly on the surface of the ocean when the temperature is cold enough. It influences our Earth's climate, and holds a critical place in the food web in these regions.

Sea ice covers much of the polar oceans both in the Arctic and Antarctic during the winter months. Unlike the ice sheet, which forms over land, sea ice freezes directly on the surface of the ocean when the temperature is cold enough. Sea ice influences our Earth’s climate, and holds a critical place in the food web in these regions. Photo: W. Chu

The gravimeter is a new addition to the Icepod suite of instruments. Housed separately inside the plane, the gravimeter requires a very stable platform. The instrument will be critical for determining the water depth beneath the Ross Ice Shelf, the least explored piece of ocean floor on our planet. The plan was to cross the front of the ice shelf towards Roosevelt Island, then fly inland until the plane crossed the J9 site where the first hole through the ice shelf was drilled in the early 1970s as part of the Ross Ice Shelf Project (RISP). Icepod would then fly back toward McMurdo along a line where there are plans for another science project to drill next year.

Roosevelt Island in the Ross Ice Shelf, Antarctica (Image from NSIDC)

High resolution satellite image of Roosevelt Island in the Ross Ice Shelf, Antarctica. Floating ice appears flat and smooth like the ice in this image from NSIDC.

The collected radar data showed remarkable variability over the ice. Crossing over Roosevelt Island, the change from floating shelf ice to marginal crevasses (deep cuts or openings in the ice) to ice sitting directly on the bedrock was imaged. The variation in the reflection from the bottom of the ice probably represented the different processes occurring at the ice sheet base. In some places there was evidence of ice being added to the bottom of the shelf.

When the RISP team, which included Lamont’s Stan Jacobs, drilled through J9 in the 1970s, they found refrozen ice with a structure that resembled waffles. That team also captured pictures of fish beneath the ice shelf, demonstrating that the area below was not the wasteland that it was originally believed to be. Icepod overflew the best fishing hole on the Ross Ice Shelf while the team looked at the pictures of the bright-eyed fish in the Science paper, and smiled. It is almost 50 years later, and while we have a much better understanding of Antarctica, there remains so much that is unexplored.

Icepod and the LC-130 returned to Willie Field and began immediately to plan for the next flight.

The LC-130 sitting on the ice runway (Credit N. Frearson)

The LC-130 sitting on the ice runway. Photo: N. Frearson

For more on the IcePod project: http://www.ldeo.columbia.edu/res/pi/icepod/

 

AGU 2014: Key Events from The Earth Institute

American Geophysical Union Fall Meeting - Wed, 12/03/2014 - 12:03

Scientists at Columbia University’s Earth Institute will present important talks at the Dec. 15-19 meeting of the American Geophysical Union, the world’s largest gathering of earth and space scientists. Here is a journalists’ guide in rough chronological order. Unless otherwise noted, presenters are at our Lamont-Doherty Earth Observatory. Formal abstracts of all presentations are on the AGU meeting program.  Reporters may contact scientists directly, or call press officers: Kevin Krajick, kkrajick@ei.columbia.edu 917-361-7766 or Kim Martineau, kmartine@ldeo.columbia.edu 646-717-0134. 

 

corals-linsleyWill Rapid Global Warming Resume Soon?
Braddock Linsley blinsley@ldeo.columbia.edu
Global temperatures rose quickly until about 15 years ago, and have since largely plateaued. Now, coral records from the south Pacific Ocean suggest the so-called “hiatus” may soon end. Researchers hypothesize that water in the Pacific has slowed atmospheric warming by storing excess heat generated by CO2 emissions. But when the most recent phase of the 20-some-year Pacific Decadal Oscillation comes to an end, some of this stored heat may end up back in the air. Geochemical analysis of more than 220 years of coral growth rings from the islands of Fiji, Tonga and Rarotonga adds new support to projections that the PDO will switch states within 5-10 years, triggering a new phase of rapid warming.
Monday, Dec. 15, 8 a.m.-12:20 p.m.  Moscone South Posters. A11B-3017
Related: Global Heat Hiding Out in the Oceans

Frontiers of Geophysics Lecture: Jeffrey D. Sachs
Jeffrey Sachs, director of The Earth Institute, is an economist, senior United Nations advisor and best-selling author. In this headliner talk, he will speak on “The Earth Sciences in the Age of Sustainable Development.” Among other initiatives, he will discuss the Deep Decarbonization Pathways Project, a new interdisciplinary effort by scientists from the top 15 carbon-emitting nations to map specific ways each country can reorganize energy systems to limit future warming to 2 degrees C. Journalists wishing to meet with Sachs may contact press officers.
Mon. Dec. 15, 12:30-1:30 p.m., Gateway Ballroom, Moscone South
Sachs’s Earth Institute home page 
Deep Decarbonization Pathways Project

Battling Epidemics With Remote Sensing
Andrew Kruczkiewicz andrewk@iri.columbia.edu, Pietro Ceccato pceccato@iri.columbia.edu (Intl. Research Institute for Climate and Society)
Remote sensing is playing a key role in showing how shifts in weather drive outbreaks of deadly diseases, and how to counteract them. Kruczkiewicz will discuss how remote sensing has linked outbreaks of leishmaniasis in Sudan and South Sudan to dryer than normal conditions during the transmission months of April-July. Imagery suggests that cracks in dried-up soil—the breeding habitat of leishmaniasis-carrying sandflies—proliferate during these months, leading to outbreaks later. Ceccato will discuss programs of The Earth Institute, City University of New York and NASA to develop practical remote-sensing tools aimed at helping African nations predict and prepare for outbreaks of leishmaniasis, as well as malaria, trypanosomiasis and schistosomiasis.
Mon. Dec. 15, 5:15-5:30 p.m., 3020 Moscone West. H14A-05
Fri. Dec. 19, 11:20-11:35 a.m., 3001 Moscone West. GC52A-05
IRI’s work on climate and health
All IRI talks at AGU

Arsenic: A Mass Poisoning In Progress
Alexander van Geen avangeen@ldeo.columbia.edu
It could be the largest mass poisoning in history: the 1990s discovery that newly drilled wells meant to provide clean water across southeast Asia were instead poisoning 130 million people with natural arsenic. OLYMPUS DIGITAL CAMERAInternational efforts have since gone into studying the geology and hydrology of the problem, drilling wells into safer aquifers, and getting people to use them. But as van Geen reveals, many people are still exposed, for reasons that have as much to do with politics and public education as geologic conditions. Van Geen and colleagues are leaders in studying and remediating all aspects of the problem. They are now working in the United States as well, where new health studies are showing that wells laced with arsenic are affecting people in the eastern U.S. and Canada.
Tues. Dec. 16, 9:30-9:45 a.m., 2005 Moscone West. U21A-06 (Invited)
Related: Do Arsenic Concentrations in Groundwater Change Over Time? Therese Chan, Tues. Dec. 16, 1:40-6 p.m., Moscone West Posters. H23E-0921.
Columbia’s arsenic research program
Van Geen’s work in southeast Asia

Low Ground, High Risk Seismic and Flooding Threats in Bangladesh
Christopher Small small@ldeo.columbia.edu, Leonardo Seeber nano@ldeo.columbia.edu
A five-year program has brought into focus the potential for Bangladesh, the world’s most densely populated nation, to suffer catastrophic earthquakes, tsunamis and river-course changes—possibly all at once. Seeber and Small will discuss definitive signs of previous big quakes and at least one great tsunami; hidden features under the Ganges-Brahmaputra delta that may drive these disasters; and rapidly moving urbanization that is making the risks ever greater. The evidence rests on satellite imagery, GPS measurements, seismology and sedimentology. Posters on Thursday will delve into the details of apparent past events that could now be repeated with much greater loss of life and property.
Chris Small: Tues. Dec. 16, 8:15-8:30 a.m. U21A-02 (Invited). Leonardo Seeber: Tues. Dec. 16, 9:15-9:30 a.m. U21A-05 (Invited). 2005 Moscone West. Posters: Paleoseismic Records of Earthquakes Along the Southeastern Coast of Bangladesh., T43B-4712; Evidence for Tsunami Generated by the 1762 Great Arkan Earthquake,T43B-4732. Thurs. Dec. 18, 1:40-6 p.m., Moscone South.
Short film on the project

Warmer Climate Threatens Airplane Takeoffs
Ethan Coffel ec2959@columbia.edu Radley Horton rh142@columbia.edu  (Center for Climate Systems Research)
Climate plays an important, underappreciated role in how much weight aircraft can safely carry at takeoff. Hot weather can reduce lift, forcing airlines to offload cargo and passengers, eating into their bottom line. In what may be the first study to look at the changing economics of flying in a warmer climate, researchers estimate that airlines flying out of four airports—Phoenix, Denver, New York’s LaGuardia and Washington D.C.’s Reagan—will see 50 percent to 200 percent more weight-restricted days in spring and summer by 2050-2070. Worldwide, airports at higher elevations and with short runways and limited room to expand will feel the impacts most. Future airplanes may have to be designed to compensate for reduced lift in the weather of the future.
Tuesday, Dec. 16, 5:30 p.m.-5:45 p.m. Marriott Marquis Salon 13-15 PA24A-07

Lamont-Doherty Earth Observatory/Environmental Sciences Party
More info: Kevin Krajick kkrajick@ei.columbia.edu
Traditionally on Tuesday night at AGU, Lamont-Doherty Earth Observatory and Columbia’s Department of Earth and Environmental Sciences gather staff scientists and the many alumni who have since gone on to other institutions worldwide. It is a great opportunity to make acquaintances, hear informally about the latest ideas and work, and have fun. All journalists covering AGU are welcome.
Tues. Dec. 16, 6:30 p.m.-8:30 p.m. (or beyond), San Francisco Marriott Union Square, 480 Sutter Street, Union Square Ballroom

philly skylineMapping Defenses Against Urban Heat Waves
Alex de Sherbinin adesherbinin@gmail.com (Center for International Earth Science Information Network)
Already vulnerable to heat waves, city dwellers face greater risks as the planet warms. In Philadelphia, where this is already evident, geographers have combined multiple data sets to pinpoint where higher temperatures, less vegetation and a concentration of poor or elderly puts people most at risk. The map is aimed at helping the city plant trees and vegetation where needed (including on rooftops), help social workers respond, and provide other defenses. In 1980-2013, the average number of heat-wave days per year here grew from 4 to 12, largely because streets and buildings trap heat, and there are fewer trees.
Friday, Dec. 19, 8 a.m.-12:20 p.m., Moscone West Posters. GC51B-0417

 Using Submarines to Chart Arctic Ocean Conditions
Raymond Sambrotto sambrotto@ldeo.columbia.edu
Since the 1990s, U.S. Navy subs cruising under Arctic Ocean ice have produced seminal data not available by other means, including measurements of thinning sea ice. The program, dubbed SCICEX, was recently expanded to sample water temperature, chemistry and biology. Sambrotto presents the latest data from the remote western Arctic, gathered in spring 2014. Among other things, it establishes the levels of nutrients under the ice available for biological productivity the following summer, when melting takes place—critical to understanding how ongoing dramatic changes in ice cover may affect Arctic ecology.
Fri. Dec. 19, 8 a.m.-12:20 p.m., Moscone West Poster Hall. OS51C-0989
SCICEX website

Water Systems of the Future
Upmanu Lall ula2@columbia.edu (Columbia Water Center)
Lall, director of the Columbia Water Center, examines currently overlooked opportunities to redesign water systems to meet rising demand and declining supply. He envisions a new world in which water is treated exquisitely, like a crop of expensive vegetables, for consumption. This would include sophisticated systems to harvest rainwater; new technologies to recycle wastewater; and sensors and smart grids to monitor and manage usage in communities and buildings. He will discuss the technological, financial and social barriers that need to be overcome, and ways to accomplish that. Other talks from the Water Center during the week will cover studies of flooding in rivers from the Hudson to the Danube; newly launched satellite tools to survey global surface moisture; and the operation of China’s Three Gorges Dam.
Fri. Dec. 19, 10:35-10:50 a.m., 2009 Moscone West.
All Columbia Water Center talks

 # # # # #

The Earth Institute, Columbia University, mobilizes the sciences, education and public policy to achieve a sustainable earth. Researchers at our following centers are presenting at AGU:

 Lamont-Doherty Earth Observatory is one of the world’s leading research centers. It seeks fundamental knowledge about the origin, evolution and future of the natural world. More than 300 research scientists study the planet from its deepest interior to the outer reaches of its atmosphere, on every continent and in every ocean.

 The International Research Institute for Climate and Society aims to enhance society’s ability to manage the impact of seasonal climate fluctuations. From environmental monitoring and forecasting to risk management tools in water resources, public health, agriculture and food security, IRI and its partners focus on opportunities to build capacity for bringing climate information into regional planning and decision-making.

Goddard Institute for Space Studies, an affiliate of The Earth Institute, is a NASA-based climate research center that models and monitors earth systems, to predict atmospheric and climate changes. It also plays an important teaching role, conducting science education programs at universities, schools and other organizations.

 The Center for Climate Systems Research was established to enhance interdisciplinary earth and climate research both at Columbia and the Goddard Institute for Space Studies

The Center for International Earth Science Information Network (CIESIN) works at the intersection of social, natural and information sciences. It specializes in spatial data integration, and interdisciplinary research related to human interactions in the environment, providing data that informs decision-makers worldwide.  .

The Columbia Water Center tackles the issue of freshwater scarcity through innovations in technology, public policy and private action. Combining scientific research with policy, it aims to design reliable, sustainable models of water management  on local, regional and global levels.

Why are Past Surface Temperatures and CO2 Concentrations Important?

The Climate Epoch - Wed, 11/26/2014 - 14:36

This blog is an outgrowth of my own research examining the past temperature of Earth’s surface and the relationship of temperature to the Earth’s carbon system. I became interested in the scientific aspects of this work as a geology undergraduate, staring at regular layers of rocks in the countryside of central Italy, back and forth, dark and light. These layers were related to past oscillations of the climate, warmer and cooler, related to long-term changes in the incoming solar radiation entering our planet from the sun. Such changes are small, but positive and negative feedbacks in the Earth system interact to translate the small changes into the radically layered rocks we see in outcrops. This was the start of a journey of discovery that continues to this day and is the foundation of my research at the Lamont-Doherty Earth Observatory.

Oscillating limestone rock layers, Italian Alps

Oscillating limestone rock layers, Italian Alps. Photo: Kelsey Dyez

How does the carbon dioxide (CO2) content of the atmosphere influence climate? This question was first seriously considered in the mid- to late-1800s, amid an accelerating, newfound interest in the natural sciences on the European continent. Specifically, the Victorians were fascinated by looking backward in time, at periodic extreme cold spells, also known as ice ages, when glaciers as tall as skyscrapers covered vast areas of land that today are free from ice.

The discourse about past climates began with this approach, through a discussion about how the driving forces in the Earth system might have caused our globe to periodically enter and exit the ice ages. Many factors, including emissions from volcanoes, the rearrangement of continents, the evolution of plants and vegetation, solar sun-spot cycles, and even asteroid impacts can and do impact the average surface temperature of the planet.

Yet time and again scientists returned to the role that greenhouse gases, and specifically carbon dioxide (CO2), play in the climate system. CO2 molecules in the atmosphere absorb heat (infrared radiation) coming from the Earth’s surface and then re-radiate some of that heat back to the surface to generate a warming effect. How is this related to the glacial ice age cycles of the past?

 CO2 molecules in the atmosphere absorb heat coming from Earth's surface and re-radiate some of that heat back to the surface to generate a warming effect

Simplified greenhouse effect: CO2 molecules in the atmosphere absorb heat coming from Earth’s surface and re-radiate some of that heat back to the surface to generate a warming effect.

One way to think about this problem is to imagine the Earth system as a huge, naturally occurring experiment (though the sample size by most experimental standards is low). Sometimes the Earth has been warmer than today, even ice-free at the poles. When the ice melts, sea level rises, continents spring back after being depressed by the weight of the ice, and plants that need warmer weather expand their habitat pole-ward. The Earth has also been cooler than today, most recently at the last glacial maximum (~20 thousand years ago) when more ice was locked up in the polar ice sheets rather than in the ocean, making for lower sea level, which exposed more of what is today the ocean floor.

Today the framework of thought has turned around, so that instead of looking back through time to understand the climate of the past, we also try to learn lessons from the past to further our understanding of the climate of the future. By burning fossil fuels for heating, electricity, transportation and other purposes, humans add CO2 to the atmosphere. Yet, by comparing ways in which the Earth’s temperature, CO2 concentration, sea level and ice sheets have changed in the past, we are able to learn valuable lessons about the climate system of today and tomorrow. You can share in this adventure here.

NYC emitted 54 million tons of CO2 in 2010

New York City emitted over 54 million tons of CO2 in the year 2010. To imagine this number, every sphere here represents 1 ton of CO2 at the average surface temperature and pressure. Image: Carbon Visuals/Flickr

One last word of caution: At the turn of the last century, people also began to wonder if land-use and manufacturing—human-induced variability—could play a role in climate. Because this issue has become highly politicized, I won’t get into all the back-and-forth arguments here. That forum has other locations online. However, for a modern history of this fascinating topic, check out the American Institute of Physics (which can be found at http://www.aip.org/history/climate/co2.htm); and for more on the science, check out what the EPA has to say (http://www.epa.gov/climatechange/ghgemissions/gases/co2.html). Both purport an objective analysis of both the history and basic science involved.

This Bird Flies South for the Winter

Peering Through Polar Ice - Mon, 11/24/2014 - 22:39
Skier 95 with IcePod visible beneath the rear window lands on the Antarctic ice. (photo R. Bell)

Skier 95 with IcePod visible beneath the rear emergency door lands on the Antarctic ice. Photo: R. Bell

Migrating south in the winter is a behavior that Antarctic scientists share with many species of birds, although the scientists fly just a bit further south. For the IcePod team, it was time to join the migration so they could test their equipment in the most challenging environment the Earth has to offer. After three “equipment shake down” trips to Greenland over the last two years, 20 hours of flight time have been set aside for flights in Antarctica, part of the final hurdle in the commissioning of the pod.

The team arrived early this month at McMurdo Base on a large C-17 to –14°F weather and beautiful clear blue sky as the plane touched down on the Pegasus Blue Ice Runway. The first few days were spent in training for everything from driving trucks in the cold to being environmentally sensitive to the Antarctic microbes to a crash course on interpreting the complex way trash is handled in Antarctica — an impressive 60 percent of everything is recycled. 

Loading the gravity meter on loan from the Kiwi for the Antarctic test flights. (Photo R. Bell)

Loading the gravity meter on loan from the Kiwi for the Antarctic test flights. Photo: R. Bell

The gear arrived soon after the team… first the gravity meter, borrowed from New Zealand, wrapped in a warm, manly pinkish quilt. With many boxes being stacked in the aircraft, the color was selected for its high visibility to assist with quick location and unloading. The IcePod and the equipment rack had paused on their trip down in Pago Pago, arriving a few days after the rest of the gear, but it was all quickly set up and humming in a bright yellow and blue rack tent next to the Willy Airfield on the Ross Ice Shelf. While waiting to fly, a GPS was installed on top of the tent, and equipment was set up to test performance. Both the GPS and the gravity meter measured the movement of the ice shelf as it shifted up and down on the tide ~ 1 meter a day. In addition to the rhythmic up/down movement, the tent, the airfield and the ice shelf are all moving northwards at 30 cm or 1 foot a day.

Scott Brown, Tej Dhakal and Winnie Chu prepare the equipment for take off. (photo R. Bell)

Scott Brown, Tej Dhakal and Winnie Chu prepare the equipment for take off. Photo: R. Bell

Finally, IcePod was cleared to fly and complete her first Antarctic survey mission installed on a Pole Tanker mission flying on Skier 95. The flight was delayed as the C-17 practiced airdrops over the South Pole runway, but as soon as the C-17 was out of the way, icePod took off and headed south.

Icepod flies over the Antarctic ice with Mt. Erebus visible in the background. (Photo R. Bell)

Icepod flies over the Antarctic ice with Mt. Erebus visible in the background. Photo: R. Bell

Low elevation data was collected on the way out to make sure the C-17 was clear. All the instruments worked in the flight across the very flat Ross Ice Shelf, then over the Transantarctic Mountains and across the spectacular East Antarctic Ice Sheet.

IcePod team at South Pole (left to right) Scott Brown, Chris Bertinato, Tej Dhakal, unidentified, Winnie Chu (photo by R. Bell)

IcePod team at South Pole (left to right) Scott Brown, Chris Bertinato, Tej Dhakal, a new Antarctic colleague, Winnie Chu. Photo: R. Bell

The low angle of the sun made the mountains, crevasses and wind scour areas stand out beautifully in the imagery. The deep radar imaged the structure of the Ross Ice Shelf even from 21,000 feet. The infra-red camera showed the variable temperature of the different types of ice in the Beardmore Glacier and the high plateau. The gravity meter that had rolled in on the speed pallet was extremely stable. At the South Pole, Skier 95 offloaded fuel while the IcePod team made a quick trip to the actual pole.

The flight was a success – data collected on an opportune flight and fuel delivered.

For more on the IcePod project: http://www.ldeo.columbia.edu/res/pi/icepod/

 

Demob!

The ENAM Seismic Experiment - Wed, 10/22/2014 - 12:11

After five days in North Carolina we have recovered all of the 80 stations. The stations have been recording for one month along two profiles. Now we are downloading the data at the instrument center at the East Carolina University in Greenville.  The last step is getting the equipment ready for shipping back to PASSCAL in New Mexico.


Beatrice (Bix), Dan and Ana working onsite at the first station recovered. Bix and Ana are checking the parameters of the Reftek with the CLIE, and Dan is saving the GPS waypoint of the recovery site.



Yanjun working on one of the stations recovered on the north line. He is performing a check with the CLIE to see the number of events recorded, the data stored on the disks and stopping the acquisition. He also checks all 3 channels on the L28 sensor. Once the acquisition has been stopped, the sensor can be pulled and the station is taken back to the instrument center.



A few of the Refteks at the instrument center. The upward cap indicates that the data have been downloaded.



Yanjun labeling Reftek flash cards that contain recordings from the past month.



Flash cards labeled with Reftek serial numbers. This is the product of our hard labor!

Being a scientist rocks!

The ENAM Seismic Experiment - Wed, 10/22/2014 - 11:57

We experienced wonderful weather during the past week working in North Carolina. The scenic countryside is filled with tobacco fields, cotton fields, and other crops. One lucky recovery team started the first day on Kitty Hawk Beach demobilizing site 101.


Beach near the easternmost station on the north line of the onshore profiles




One of the many cotton fields in the eastern North Carolina coastal plain

Langseth limericks

The ENAM Seismic Experiment - Fri, 10/17/2014 - 02:19
As we approach the end of the cruise, I think this calls for a round of salty Langseth limericks.  It helps if you imagine a round of hearty “Aye, matey!”  and “Arr!” and such between each verse.

There once was the Langseth, a ship

Over wave and trough did she skip.

Many instruments aboard

To always record

Depth, gravity, mag – every blip.

There once was the Langseth, a vessel

Where in their bunks scientists nestled.

‘Til called to their shifts

Their heads they must lift

For with errors and logs they must wrestle.

There once was the Langseth, a boat

On her airguns the crew they would dote.

Oft while in a turn

Guns were brought up astern

To ensure best acoustical note.

There once was the Langseth, seacraft.

Where we launched XBTs down a shaft.

With each probe descent

To the lab data went

So that temperature-depth could be graphed.

There once was the Langseth, a fine tub!

Where the galley crew made us good grub.

But when seas ran high

Up in knots stomachs tied

And to keep the food down, there’s the rub.

There once was the Langseth, fair barge.

To collect seismic data her charge.

Streamer 8-km long

And four gun strings strong

She’s the fleet’s seismic dreadnaught at large!

-Tanya Blacic, aboard the R/V Marcus. G. Langseth

Last Day of the Cruise!

The ENAM Seismic Experiment - Fri, 10/10/2014 - 11:58

October 10th, 2014
1158

Three days ago, at approximately 2130, we recovered our final OBS and started our 36-hour transit back to Narragansett, RI. We began docking procedures at Senesco Marine LLC at around 1300 yesterday and were all tied up by 1400. After the lines were clear, both watches performed some preliminary breakdown of the OBS equipment to help stage it for demobilization this morning. It was impressive how fluidly we took and executed directions after a month of working together. It was clear that the trip had bonded us as a team. After everything was done, the group headed out to enjoy our first night on land, which, as anyone whose been on a ship for an extended period will tell you, is just an incredible feeling. One of the eeriest moments, however, was all of a sudden being surrounded by people besides those you’ve been on the trip with. Also, the “dock rock” is an interesting experience.

This morning, after a wonderful, final breakfast made by our steward, Mike Duffy, we packed up the final gear and the crew began lifting it off the boat, staging it on the pier. All that’s left now is to clean up my stateroom, pack up all my stuff, and head on home. This cruise has been both a great scientific and personal learning experience and I am happy to have worked with these crewmembers, techs, researchers, and students. The lab seems so empty now, as I write this post, and there’s a part of me that is sad that this adventure is ending regardless of how excited I am to get back to life on land.

Anyways, time for me to go. For those who are interested in the data we’ve collected on this cruise, look out for information concerning workshops on data access and processing in the near future.

Signing off,
Dylan Meyer aboard the R/V Endeavor

Figure 1. Evening recovery of the last OBS, there was much rejoicing!
Figure 2. A crewmember, Charlie Bean, tossing a leading line with a monkey fist to the dock.

Figure 3. The WHOI OBS van and SIO OBSs staged on the pier to be loaded onto trucks.

Figure 4. The WHOI OBS van being loaded onto a truck for transit back to Woods Hole.

Figure 5. The, now empty, lab deck of the R/V Endeavor.

Scripps OBS GoPro

The ENAM Seismic Experiment - Sat, 10/04/2014 - 05:16
I had this idea to attach our GoPro cameras to a Scripps OBS that was being deployed on the shelf nearer the coast.  These underwater housings are rated to 100 feet and we deployed them on three different sites at that depth, recording some of the coolest OBS video I have ever seen.  The stills captured from the video are pretty cool too, but one of the unexpectedly groovy features of the video is the audio.  You can hear the acoustic responses, ship noise in the shallow, ocean background biology, and current noise on the seafloor.


Time series of deployment and recovery. Photo Credit: Ernie Aaron.~Ernie
R/V Endeavor

Riding big swells and crossing the Gulf Stream

The ENAM Seismic Experiment - Fri, 10/03/2014 - 15:01

On calm days, you could almost forget that you are in the middle of the ocean.  Its sunny and calm outside, and everything is stable inside.  People get lax and leave cups and other items on table tops unsecured and unattended.  And then some big swells come, and we all remember why chairs are tied to tables, furniture is nailed down to the deck and we use bungie cords and sticky pads to keep computers and other gear in place. Today we are experiencing swells up to 5 m high, in which the ship has rolled up to 25 degrees.  Unsecured items (including people in chairs!) are rolling all over the lab.
Meanwhile, we are also crossing the Gulf Steam, which poses it own challenges to our gear. Fishermen are particularly concentrated here, and today we deviated 10 km off of our profile to avoid fishermen and their gear.  The currents are also pushing our seismic streamer around.  In the ideal case, the streamer extends straight behind the vessel and quietly rides 9 meters below the water surface.  The currents today have pushed it to the side by 70 degrees from the ideal track, and the swells generate noise on the hydrophones.  However, even though conditions may not be ideal, it is essential that we collect data here for our science goals. We think that there are thick accumulations of frozen magmas beneath the Earth’s surface here that formed when the supercontinent of Pangea broke apart to form the Atlantic Ocean.  So we shall push ahead!
Annotated screen capture from our navigation system showing the ship, the streamer, our intended profile and our deviation.
 Donna Shillington from the R/V Langseth

Working hard

The ENAM Seismic Experiment - Tue, 09/30/2014 - 16:07
September 30, 2014

It takes a team of people to get the OBS in the water and back out again. To illustrate the process of deploying a WHOI or SIO OBS, Gary Linkevich has created a time lapse video. The first part of the video captures two WHOI OBS deployments with Peter, Dave, Dylan, Gary, and Kate. The WHOI OBS are the peanut shaped yellow capsules that appear in the background next to the railing. After the WHOI OBS is in the water, we capture an SIO OBS deployment with Mark, Dylan, Gary and Kate. The SIO OBS are the rectangles with a yellow top and white base. Right after we deploy the SIO OBS, we start putting together a new one for deployment. The assembly process involves an instrument test and then attachment of the metal weight, floatation devices, light, and radio together. The deployment of this SIO OBS happened during the midnight crew shift which includes Ernie, Pamela, Afshin and Jenny. Once they pick her up and put her in, they start the assembly process all over again!



Thanks Gary for putting together this time lapse!

See you Later,

Kate Volk aboard the R/V Endeavor

Running the R/V Endeavor

The ENAM Seismic Experiment - Tue, 09/30/2014 - 15:27
September 30, 2014
1527

One of our assistant engineer, Kurt Rethorn, gave us a tour of the engine room. Here's what we learned:

Kurt is an awesome tour guide!

The Engine
The R/V Endeavor is equipped with a two-stroke (providing more power strokes per engine rpm), diesel engine consisting of 16, 350-cubic inch, cylinders with a maximum output of 3050 horsepower. Also, this bad boy is outfitted with a turbo charger which uses the exhaust to increase pressure in the cylinders and improve the power output from the combustion stroke. The engine is kept lubricated by 500 gallons of motor oil, which is changed when the ship is in port based on the number of engine hours. We burn around 1,000 gallons of fuel a day while on station (between the generators and the main engine) and even more when we are in transit between sites. We left port with around 54,000 gallons of fuel stored beneath the berthing decks, but she can hold up to 56,000 gallons of fuel total (the additional space is left to allow for the expansion of fuel due to temperature changes). A fun fact about the R/V Endeavor is that the propeller only spins one direction, meaning that there is no reverse gear. In order to drive the ship in reverse, the pitch of the propeller blades is switched such that the flow of water is reversed. There is also a powerful bow thruster that can be engaged if necessary.

Kurt starting off the tour (Photo credit: Kate Volk)
The engine with the exhaust manifold above and access to each of the piston heads underneath the latched doors (Photo credit: Kate Volk)Fuel gauges. Fuel is consumed from both tanks at a relatively similar rate in order to keep the boat properly balanced (Photo credit: Kate Volk)
The Generators
The R/V Endeavor has four generators. Three below the water line and one above (for emergencies only). The generators produce all our electricity directly (i.e. they do not charge any batteries). In a power failure, an emergency generator will kick on in less than a minute.

These are two of the generators, aligned along the centerline of the ship (Photo credit: Kate Volk)
 Water
We use about 1000 gallons of water a day between showering, cooking, cleaning, and drinking and the ship can only hold approximately 8600 gallons of fresh water. Therefore, we must produce fresh water throughout the cruise and we have two methods of achieving that. We have a reverse osmosis machine, which takes up salt water and pushes it through a long, blue semi-permeable membrane at 800 psi. The high pressure in the membrane causes the salt to drop out of solution producing fresh water. The second way we have of producing water is an evaporator. This brings in salt water under a vacuum at 711 mmHg (13.75 psi). The water is heated up and the condensation is collected, now free of salt. The reverse osmosis machine  and evaporator can produce around 50 and 80 gallons of water per hour, respectively, so that we can theoretically make 3200 gallons of water everyday. However, the evaporative method is dependent upon the engine heat to turn the water into vapor, which means that it runs at a lower efficiency when the engine is cooler. 

Reverse Osmosis machine. You can see the blue membranes that separates the salt and water (Photo credit: Kate Volk)

Water quality (Photo credit: Kate Volk)Sea water temperatures in the Gulf Stream are pretty warm (Photo credit: Kate Volk)

See you later, 

Dylan Meyer and Kate Volk aboard the R/V Endeavor

First Look at OBS Data!

The ENAM Seismic Experiment - Tue, 09/30/2014 - 14:48

September 30th, 2014:
1437

We have our first look at data!! Ernie Aaron merged some of the raw data from the Scripps OBSs with navigation files from the R/V Marcus Langseth such that we can start seeing the seismic waves recorded in the in ENAM project.  In Figure 1, the hydrophone record of OBS 209, which was recovered on Sept. 21st, is shown as a function of space and time. To be clear, this is original seismic data. There are still post-processing methods and inversions to apply to the data back on shore that will help extract the seismic velocity structure down to upper mantle boundary along Line 2 or any of the other seismic lines. Until then, however, here is what we learned thus far.

To remind all, the experimental setup for this study is as follows. We on the R/V Endeavorplaced OBSs on the seafloor at a spacing of approximately 15 km along Line 2. The R/V Langseth then cruised along Line 2 from ESE to WNW with airgun shots spaced every 200 meters. The OBSs were then recovered and the hydrophone and geophone data were downloaded.

Figure 1. Traces recorded from OBS 209 (bottom) with various arrivals identified by color. The dashed line shows the multiple of Slope D. Cartoon (top) shows representative raypaths of seismic waves that produced the arrivals indicated in the trace records (Figure Credit: Kate Volk).
The acoustic signal was then segmented into separate traces using the GPS-coordinated time of each shot. Ten seconds of each trace were then plotted, by shot number (Figure 1). In this data panel we see the direct wave from the R/V Langseth shots to the instrument (Figure 1; Slope B), seismic reflections and refractions from the Earth below (Figure 1; Slopes A, C, and D), and a later multiple of these seismic refractions (Figure 1; dashed magenta line), after they bounced between the seafloor and sea surface.  

The direct wave travels directly from the seismic source to the OBS, helping us identify the location of the OBS on the seismic line. Using the time it took for the direct arrival to reach the OBS at this location and the acoustic velocity of water (1500 m/s), we can estimate the depth to the OBS. In the case of OBS 209, the R/V Langseth traveled over the device around shot 2200 and it was deployed in approximately 3000 meters of water (Figure 1).

The general slope of the seismic refractions in the space-time diagram gives an indication of the speed at which these seismic waves travelled at large depth.  The data in Figure 1 have been plotted such that waves traveling with a seismic velocity of 7000 m/s, such as those turning near the crust-mantle boundary, will appear as flat events. Slower seismic waves will dip towards larger time away from the OBS, while faster waves will slope towards smaller travel times.  

The OBSs show seismic arrivals that are recorded over a very wide range of source-receiver distances. The seismic waves recorded close to the instrument (< 10 km), are the direct wave from the airguns through the water column to the instrument (Figure 1; Time 2). As you move farther from the instrument (longer offset from source to OBS), the seismic waves move through deeper materials with faster acoustic velocities and those waves reach the instrument before the direct waves (Figure 1; Times 1 and 3). At longer offsets, the primary response comes from seismic waves that travel along deep materials with very fast seismic velocities (Figure 1; Time 4). When combining all the traces together, the slope between similar acoustic responses in traces can be used to infer the seismic velocity of the seismic wave, which can be used to infer the properties of the Earth.

For example, between 60 – 80 km and 100 – 120 km, we identify acoustic responses that are relatively flat (Figure 1; Slope D), indicating that the sound wave is moving through material with an acoustic velocity of 7000 m/s. This is important because it confirms that we are imaging down to the crust-mantle boundary, which will allow us to get a well-constrained seismic velocity profile throughout the crust beneath the margin of the US East Coast.

Until next time,
Dylan Meyer aboard the R/V Endeavor

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