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How are Droughts, Floods and Climate Change Connected? - KALW San Francisco

Featured News - Mon, 12/15/2014 - 12:00
Lamont's Adam Sobel speaks about California's drought, its causes, and how we can manage the increasing risk of future natural disasters.

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.


Mysterious Mineral

Geopoetry - Fri, 12/05/2014 - 08:30
Bridgmanite was identified in a shock-melt vein within the Tenham meteorite. Photograph by Chi Ma, Caltech

Bridgmanite was identified in a shock-melt vein within the Tenham meteorite. The mineral was named in honor of Percy Bridgman, who pioneered the diamond anvil cell for high-pressure research. Photograph by Chi Ma, Caltech


So common, yet far out of sight,

Mineralogists longed for a bite.

Formed deep inside,

Or when rocks collide,

At long last, a name: bridgmanite!



Further reading:

Discovery of bridgmanite, the most abundant mineral in Earth, in a shocked meteorite, Tschauner et al. (2014) Science

Earth’s Most Abundant Mineral Finally Gets a Name, National Geographic

Space Rock Sheds Light on Mysterious Mineral on Earth, LiveScience

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.


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:


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; and for more on the science, check out what the EPA has to say ( 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:



Geopoetry - Fri, 10/31/2014 - 10:00
These lithic artifacts were discovered at almost 4,500 meters elevation in the Peruvian Andes, at the highest-altitude Pleistocene archaeological site yet identified in the world. Figure by E. Cooper, in Rademaker et al. (2014) Science.

These lithic artifacts were discovered at almost 4,500 meters elevation in the Peruvian Andes, at the highest-altitude Pleistocene archaeological site yet identified in the world. Figure by E. Cooper, in Rademaker et al. (2014) Science.


We are high mountain people, hunters and artists,

Our view from this base camp is brilliant and clear.

Cold, thin air sweeps the rocky plateau;

You need a strong heart to live here.


Vicuña, guanaco, taruka our prey,

With razor-sharp points, upon them we close,

Then blaze up a fire, take rest, and prepare:

These creatures we skin to the toes.


Out of the ice age and up from the valley,

Testing the limits of body and spirit.

Descendants: a challenge before you stands tall;

Will you adapt, surmount it, or fear it?


Our tale has been weathered; you’re straining to see us

In smudges of smoke, in scattered remains,

Discarded tools, a wide, ancient landscape,

And one piece yet living: our blood in your veins.



Further reading:

Oldest High-Altitude Human Settlement Discovered in Andes, LiveScience

Paleoindian settlement of the high-altitude Peruvian Andes, Rademaker et al. (2014) Science

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 Institute of Marine and Coastal Sciences at Rutgers University.




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


Geopoetry - Fri, 10/17/2014 - 11:00
 De Pontieu et al., Science 2014

Dopplergrams from the NASA’s space telescope IRIS (Interface Region Imaging Spectrograph) revealing detailed evidence of “twist” between the sun’s surface and outer atmosphere. These phenomena may play a role in driving the temperature difference between the sun’s surface (~6000 K) and the sun’s outer atmosphere (millions of degrees). The reason for this enormous temperature gradient is not fully understood (a puzzle known as the “coronal heating problem”). Image: De Pontieu et al., Science 2014


By Galileo’s careful hand, sunspot details are exquisite,

Through eye of forehead, eye of mind beholds what body can not visit.

If only he could see the sights now rendered from Earth’s outer space,

Ultraviolet sunscapes – Oh, to see his raptured face!

High above Earth’s atmosphere, IRIS probes the edges of our star,

A telescope in orbit, through its lenses, we see far.

Six thousand Kelvin screams the surface, roiling plasma, like hellish seas,

Hotter still, the sun’s corona: millions of degrees!

Mysterious, this source of heat that drives the solar wind our way …

High-speed jets, coronal loops and nanoflares may be at play.

What a thrill to gaze through space with spectrographic eyes,

Fueled by human wonder and a zeal to probe the skies.



Further reading:

Eyeing the Sun, Science Magazine

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 Institute of Marine and Coastal Sciences at Rutgers University.

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

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.

Chemical silence

Geopoetry - Fri, 10/10/2014 - 09:26

 Elkhorn coral colony near Akumal, Mexico. John Bruno (Science).

Photo: Elkhorn coral colony near Akumal, Mexico. John Bruno (Science).


What if you couldn’t smell smoke?

Or detect flirty signs from a bloke?

Imagine the cost

Of faculties lost,

Of signals that deafness would cloak …

On reefs, it’s chemical cues

That life-forms will commonly use;

With acid on rise,

A fatal surprise:

What senses might reef-critters lose?



Further reading:

Ocean acidification foils chemical signals, Science


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 Institute of Marine and Coastal Sciences at Rutgers University.


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

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)
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:

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

Photo Essay: Sculpting Tropical Peaks

Sculpting Tropical Peaks - Tue, 09/30/2014 - 08:21
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When glaciers retreated from Mount Chirripó at the end of the last ice age some 12,000 years ago, they left behind rocks and debris that formed a natural dam, allowing meltwater to collect and form a lake. This glacial lake at Valle de los Lagos sits at 11,000 feet, just below Chirripó’s summit. 
With a hammer, chisel and bandanna to protect his face from shattering rock, Cunningham chipped away at a boulder left by a receding glacier. Beryllium isotopes in the rock can reveal when the ice withdrew, exposing the rock’s surface to cosmogenic rays from space. (Michael Kaplan)
Two pounds of rock fragments chiseled from the surface of each boulder yields 30 grams of quartz in the lab from which millions of beryllium-10 atoms will be extracted.
Knowing when glaciers last retreated from Chirripó can help scientists pinpoint when the low-sloping “cirque” valleys just below Chirripó’s summit formed, and ultimately, how glacial landscapes erode generally. Cunningham and Kaplan sampled remnants of a large landslide in the above cirque valley to find out when the rocks came crashing down.
They stumbled on some landslides by chance. Others were identified earlier with the help of their Lamont colleague Colin Stark, an expert  in using earthquake data and satellite images to discover landslides in remote places. Picking through dense shrubs, Kaplan climbed a pile of rubble to hammer away more samples for dating in the lab. Glaciers carve out the landscape as they grow and shrink leaving a classic “U” shape on the landscape as seen here in Talari Valley.
Most of the animals on Chirripó are nocturnal, but when the sun comes out after the daily burst of rain, lizards like this one join the geologists on the rocks.
In one low-sloping valley they discovered a winding streambed paved in sharp cobble stones. The stones’ angular edges suggest they experienced minimal erosion after a landslide or eroding glacier dropped them here.  
In another spectacular landscape translating to “Valley of the Lions,” they discovered a stone marker where a man, according to the inscription, had been killed by a mountain lion in 1956. They looked for material to date this ancient valley but most of the rocks that might have established when the ice last withdrew have long eroded away.
As they analyze their rocks in the lab, Kaplan and Cunningham will look for evidence that the ice grew and retreated multiple times. They also hope to understand the processes that created the low-angle summit valleys they visited. Were the valleys eroded beneath the ice or by landslides as the ice withdrew? Future research may take them to Taiwan where similar mountain-top features have been observed.
As they analyze their rocks in the lab, Kaplan and Cunningham will look for evidence that the ice grew and retreated multiple times. They also hope to understand the processes that created the low-angle summit valleys they visited. Were the valleys eroded beneath the ice or by landslides as the ice withdrew? Future research may take them to Taiwan where similar mountain-top features have been observed.

Tropical mountain ranges erode quickly, as heavy year-round rains feed raging rivers and trigger huge, fast-moving landslides. Rapid erosion produces rugged terrain, with steep rivers running through deep valleys. However, in a number of tropical mountain ranges, landscapes with deep, steep valleys transition quickly into landscapes with low-sloping streams and gentle slopes at high elevations. This topographic contrast between high and low elevations poses a problem for geologists. Though heavy rains fall throughout the mountain range, erosion seems to sculpt parts of the mountain differently from others.

Mount Chirripó, Costa Rica’s highest peak, bears exactly this type of terrain, with flat valleys at high elevation capping rugged valleys below. The beveled summit of Mount Chirripó bears striking resemblance to summits as far away as Taiwan, Papua New Guinea and Uganda. Some geologists think that tectonic forces deep below earth’s surface pushed Chirripó into its flat-topped form about 2.5 million years ago. Others think glaciers did the work, sculpting the peak in over hundreds of thousands of years.

Max Cunningham, a graduate student at Columbia University’s Lamont-Doherty Earth Observatory, traveled to Chirripó this past summer to test the idea that mountain glaciers carved the summit we see today. Working with his adviser Colin Stark, a geomorphologist, and Michael Kaplan, a geochemist, both at Lamont-Doherty, Cunningham chiseled away samples of glacial debris to take home for analysis. The researchers hope to eventually pin down when the high-elevation valleys capping Mount Chirripó’s summit eroded into their current form. Read more about their work in the above slideshow.

Photos by Max Cunningham unless otherwise credited.

XBT (a short story)

The ENAM Seismic Experiment - Tue, 09/30/2014 - 00:53
            “Twenty shots until the next XBT.”
            It was nearing time to launch the next expendable bathythermograph probe, or XBT.  The software was readied and two scientists headed out of the lab, radio in hand.  They donned lifejackets that had once been bright orange but were now closer to a dull rust color from long and dirty use on the deck and selected a T-5 probe from the box.
            Out on the deck they were alone, perched partway up the stack of levels in the stern of the ship, the gun deck below them and the paravane deck above.  It seemed that the others working the graveyard shift were all inside, perhaps wrestling with some mechanical puzzle or else simply keeping watch to make sure all was well, sipping strong coffee, playing cards to pass the time.  The scientists snapped the probe into the gun-shaped launcher.  They removed the plastic end cap from the black cylinder that housed the probe and its spool of fine copper wire.
            “We’re in position.”
            There was a pause, then the radio crackled back, “Launch probe.”
            In a moment the probe was sliding down the long tube that extended out and downward from the starboard side.  With a small splash it plunged from the end of the tube into the inky deep.  Now to wait while it made its journey towards the bottom, more than 4000 meters below.  Despite the very late (or very early, depending on your point of view) hour, it was warm.  The air was muggy – not exactly a welcome change from the air-conditioned lab, although the tinge of diesel fumes was less out here in the relative open.  There was little wind and the seas were calm.  Standing on the moving island of light that was the ship the sea quickly disappeared into the surrounding void.  What surface that could be seen appeared to rise disturbingly close up alongside them, like a churning wall of water.  It was only visible at all by the few swirls of foam formed by the ship’s passage and a reflection here and there off the constantly moving face of the black oily-looking water.  They waited for the go ahead to terminate the probe.
            Down in the lab, there was a strange blip on the screen showing the multibeam bathymetry data, but no one noticed as they were too busy entering in location data for the XBT or scrutinizing the movement of the streamer birds that regulated the depth of the hydrophone streamer.  There were, after all, 36 other monitor screens to watch.
            Outside there was a louder than usual splash.  The two scientists peered into the gloom.
            “Dolphin?” one wondered out loud.
            “While we’re shooting?  I hope not,” the other replied, “We’ll end up having to interrupt the line.”
            Was there something just under the water surface?  A pale sinuous shape at the very edge of the ship’s halo of light?  No, it must be a trick of the light and the weird perspective engendered by the lack of any sense of distance.  Perhaps more coffee was in order when they got back inside.
            The radio crackled again, “Terminate probe.”
            The scientists broke the wire that was still spooling out to the probe that was now falling behind them.  “Probe terminated,” they reported.  They were just turning to leave when it emerged.
            At first it looked like a whale back, though pale milky green in color rather than the expected grey.  As it lifted free from the surface it became clear that it was much longer than an orca or even a grey whale, more like an ancient marble column turned soft and rubbery.  It tapered as more of its length was exposed until the tip broke free of the clinging water.  One side of the enormous snake-like shape was covered with round suckers the size of dinner plates in a poisonous green color.  The cyclopean tentacle towered out of the water, waving gently with a sickening sort of grace ten meters or more above the uppermost deck.  Here and there along its length were clots of a coppery tangled substance, almost like seaweed wrapped around it.  “The XBT wire,” one of the scientists realized from the midst of her fascinated horror.
            The tentacle hovered for another movement before swooping down with surprising swiftness.  The two scientists were neatly plucked from the ship in the blink of an eye.  With a clatter, the radio fell to the deck.  They were held above the water for a long moment, crushed together so tightly they couldn’t speak and could barely draw breath.  Then, slowly, the tentacle disappeared beneath the smoothly rolling waves.

            Two hundred and sixty-seven shots until the next XBT.

-by Tanya Blacic aboard the R/V Langseth (with a wink to H. P. Lovecraft)



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