When we left Stratton Air Field almost two weeks ago, I recall smiling when a mechanical issue temporarily pulled us from the aircraft and the woman shepherding us back into the waiting area remarked, “Don’t worry, we keep doing it until we get it right!” Today we are faced with just that type of day. Testing a new system is all about running through the same set of operations “until you get it right.” For our team, this means flying the same patterns over the same locations looking for repeat targets to test and retest our instruments.
The aircrew arrives each morning ready to fly the patterns and routes we have selected. They are willing to redirect if the weather changes, or if our priorities shift, but we have stayed fairly consistent in our requests. Of course, being in Greenland, we talk about varying our plan and picking some of our science team’s favorite targets. It seems almost unfair to be here and not venture off to the fast changing Jakobshavn or Petermann glaciers. But we are a disciplined group with a specific mission…we need to do it “until we get it right.” The navigator programs the plans into his system and we are ready to fly.
We are lucky. No matter how many times we fly over the Sondrestrom Fjord, it always looks stunning: the water a deep blue, the ice pieces feathered along the edge where the floating tongue ends. Once we move over the deeper ice in the center of the glacier, we still marvel at the twisting, refrozen meltwater streams that wind across the ice face.
Over the rocky edges of the landmass it is still fascinating to see the twisting rolls of collapsing ice that pile and swirl along the brim of the flat-topped frozen lakes. The mountains themselves look like painted rocks with their smooth and shiny surfaces.
It is hard to believe one could ever tire of these flights. Each area we fly over is more stunning than the next. Today our flight is cut short. Engine trouble brings us back to the base, but we’re hoping that tomorrow we’ll be back up in the air trying one more time, “until we get it right.”
For more on this project: http://www.ldeo.columbia.edu
Holidays vary around the world with their dates and traditions, so it should have come as no surprise that we would find a holiday in our scheduled Greenland visit. Today, April 26, is “Store Bededag,” which translates as “Great Prayer Day,” brought by the Danish to Greenland when they ventured to this island from their homeland. Kangerlussuaq, and other populated areas of Greenland, are a mix of Danish and Greenlandic in people, language, food and tradition. The holiday does not stop our survey flights today, but a snow storm with low-visibility has brought us to the ground. In the end it is a good day to focus on data.
Prior to today we have completed several flights, each with a tightly designed purpose, and there is plenty of data to be gone through. With our newly designed system, each instrument must be tested individually for operational capability and range, and then assessed for the enhancement that comes from aligning the results with the data from the other instrumentation. Calibration runs are also required for some of the instruments. In the end, each flight ends with a stack of data disks which need to be reviewed in detail.
Each flight has a list of priorities designed around specific target locations and weather availability. Yesterday our target instruments were the visible and infrared cameras, the laser system and the deep ice radar system. For the two cameras we would fly down Sondrestrom Fjord building a set of matching images.
The Bobcat, our visible image camera, showed a wide swath of surface imagery, noting where fast moving ice had crumpled into bands of ridges, as well as where it had thinned, cracked, and showed evidence of refrozen melt water streams.
The Infrared Camera operates at a higher frame capture than the Bobcat, and collects temperature differences from the places where the ice has thinned or opened. The colder the surface, the blacker the infrared image; warmer surfaces show as white. The tongue of the fjord is an excellent testing area for this.
The Deep Ice Radar was being fine-tuned on this flight. Following the first Greenland test flight, the system was adjusted and the team was anxious to see the results. We headed up Russell Glacier to get to enough ice depth to receive the radar returns, but with the weather worsening and the winds kicking up, we didn’t go any further than needed.
The LIDAR (Laser Imaging Detection And Ranging) testing was our last test of the day. Designed to give us surface elevation, with repeat use it can show change in ice surface elevation over time. In order to show small change in ice elevation, a very tight accuracy is needed, on the order of 10 cms. The LIDAR calibration was designed as a gridded pattern of 4 by 4 lines flown at 170 knots of air speed. Calibration flights can be bumpy and twisty, as the plane will roll with the turns needed to create the pattern. The 20-knot headwinds cause some additional turbulence, but the full eight passes are completed before a return to the airfield.
For more on Icepod: http://www.ldeo.columbia.edu/icepod
Half of the people lining the walls of the Kangerlussuaq International Science Support (KISS) building are waiting to go north to the top of the ice sheet at Summit Camp, and the other half are waiting to go east to the top of the ice sheet at Raven Camp. The science and support teams have been ready and waiting for several days now, hoping for a break in the weather up on the ice sheet.
Ice sheets are large enough that they can create their own weather. Large mountains of ice several miles thick, they stretch into higher elevations and gather the clouds around them. The sunny but cold weather (-21 to -9 degrees C) is a tease to the group ready each morning and waiting for clearance, day after day.
For the Icepod team the waiting is just as difficult. A series of flight options have been drafted, but with the target of getting equipment and teams out to the camps, our flights are shifted for the moment to “piggybacks” with other flight missions. Piggybacks are actually an excellent opportunity for the project to show how the pod might work once the full system is tested and ready for science use. The project design is for the pod to be fully integrated into the guard’s NSF Operation Deep Freeze mission of supporting science in the polar-regions. In the future, as the LC130’s deliver cargo and personnel to the polar science camps, the pod can be switched on by the loadmaster to gather data as the aircraft transits.
Word comes mid-morning that the first flight of carpenters and materials will head to Raven Camp. There is not room for us but we are set for the second flight. The runway at Raven Camp is a groomed strip on the ice sheet, so the pod will make its first ice landing.
The first morning flight and ice landing go well for the pod, but one aircraft engine is causing some concern. The aircraft is looked over and the engine is cleared for us to take off late in the day with the second cargo delivery. We will fly out at high altitude before we stop at camp to install a temporary GPS for an Icepod GPS calibration. A forklift is used to load two large pallets of cargo onto the metal tracks that run the length of the aircraft and that assist the quick release of the supplies. The delivery at Raven Camp will be a “combat offload” with the cargo unstrapped and the plane moving forward on the ice so that the load slides out the back.The pod team is loaded and ready to head out.
Cargo Combat Offload
“Combat Offload at Camp Raven April 23, 2013 with the Icepod project. (credit Matt Patmore)”
With the cargo delivered, several of us exit the aircraft to install a GPS base station on the ice sheet so that the pod can complete its GPS calibration. A cloverleaf design will be flown with 20 to 30 degree turns closing the loops and straight lines between, while the GPS tracks the changes in direction and the movement in the air. In the pod design an array of GPS’s were mounted, one on the aircraft hatch and several on the pod itself, in order to determine the best location for “seeing” the satellites and yet be close to the instruments. The GPS is critical to all the data, used to tie back to a specific point on Earth. One station is set up back at Kangerlussuaq, and the second set up at Raven Camp will provide us a closure point so that we can tie together and adjust all the points in between.
The station is set to operate. The team returns to the aircraft from the ice sheet and the calibration is flown. A follow-up flight to Raven Camp over the next few days will retrieve the GPS station. Once completed, the team heads for home over the ice sheet for a 9 p.m. touchdown. Although the aircraft loses an engine in the return transit, the day is determined a success with the completed piggyback flights, ice ramp landings and the GPS instrument calibration.
For More on Icepod: http://www.ldeo.columbia.edu/icepod
Ravens dominate the Kangerlussuaq landscape. Perhaps it is their deep ebony color and solid frame, or perhaps it is the white stillness of winter with little else but humans moving about, but whatever the cause the ravens are a recognized presence. The towering black hill rising above the glacially carved fjord is aptly named Raven Hill and boasts a steady circling of the mythical black winged creatures calling out in their raspy voices. With ravens being much a part of the region, it seems only fitting that our first flight would be to Raven Camp in search of deep enough ice to test the Deep Ice Radar system or “D-Ice” as it is referred to.
The day starts out a bit hazy and the weather is forecast to deteriorate during the day. Most flights have been cancelled, but the Icepod team has been cleared for flight if we can manage a departure by noon and return to base by 2 p.m. Sensor and equipment adjustments keep the team busy until mid morning, and weather maps are continually being consulted for updates. Several times the planning team reconfigures the flight lines looking for the optimal plan to maximize the testing of the equipment with available time and weather considerations. Our NYANG partners are as anxious for the flight to go as the Icepod team, but if there are any weather concerns, caution must override enthusiasm. With the camp being at a higher elevation than Kangerlussuaq, the weather can vary considerably from the base.
Raven Camp lies at close to 2000 meters (~6800 ft.) elevation, where the glacial ice is approximately 1800 meters thick. “Noise” in the radar system drops after 1200-1500 meters of ice thickness, so although the weather is poor, we are hoping to get to this ice thickness to run a first real test of the D-Ice. Unlike our optical systems, the radar is not affected by poor visibility, so this is the right decision for the flight today. The plane is loaded with cold weather emergency gear, standard protocol when flying in the polar regions, and we take off down Sondrestrom fjord, making the noon flight departure time.
This series of flights is designed for instrument testing, so the science team is troubleshooting as they fly. Every instrument is tested in the short two-hour flight, and procedures are reviewed. The sound in the aircraft is deafening and earplugs are mandatory, which makes communicating challenging, but communicating is an essential part of the testing.
The plane reached the edge of the deep ice and the aircraft lowers to a survey elevation of 900 meters (3000 ft.) above the surface flying along the ice contour. The radar system is up and recording. In too short a time, the plane has reached Raven Camp, but the poor weather conditions limit our ability to see the camp below. The aircraft turns and we head back to base. In our post-flight debrief, reviewing data takes a top priority for tomorrow. With a limited number of flight hours available, every flight is precious, so we need to be sure that assessment and adjustment is made to the instruments as we go.
For more on this program see: http://www.ldeo.columbia.edu/icepod
Icepod joined the first large wave of science teams headed to Greenland via the NYANG LC130 transport system. Four LC130 aircraft were packed to bursting with pallets of equipment, supplies and science teams anxious to get to their designated research locations. Planes one and three were designated for cargo load, plane two would carry the bulk of the science personnel, including half the Icepod team, and plane four would carry Icepod with its skeletal engineering support team. 5:00 a.m. pick-ups for the science members set up the planes for staggered departures every 30 minutes starting at 8:00 a.m. With a flight time of seven hours from Schenectady NY to Kangerlussuaq Greenland, an early departure facilitates moving through customs and getting settled with the science support staff that awaits the group in Greenland.
All the aircraft were packed from end to end with either cargo or personnel. While we waited for the pallets of cargo to be loaded onto the planes the science teams’ discussion focused on how Greenland’s ice will be dissected and examined in the upcoming season. One group will look at ice surface processes using ground penetrating radar and shallow ice cores starting at the Dye 2 location, another will drop into the high elevation Summit camp to start an overland traverse examining the ice (although we learned that nighttime temperatures are running at -50 degrees C, a bit too low currently for set up). A third group will examine the firn layer (that section in the ice that is just starting to compress) over Jakonbshavn glacier, and the Icepod team will be doing their first set of instrument test flights in polar conditions looking at the ice from the bed up to the ice surface.
The science personnel were finally loaded into Plane two, which had been divided across the middle of the main cabin, to accommodate cargo aft and science teams foreward packed knee to knee in two sets of facing rows. With this heavy load the aircraft would need to stop to refuel in Goose Bay, in Labrador, Newfoundland, Canada. Goose Bay Air Base, affectionately known by many as “The Goose”, was once home to Strategic Air Command’s 95th Strategic Wing. The ice cream served to the visitors of the airfield has become part of the travel lore of the teams en route to Greenland, so by the time the wheels touched down, everyone’s thoughts had moved from polar ice to ice cream. Two baskets full of assorted Good Humor truck style ice cream were quickly dispensed and we were back up in the air and underway for the last half of the journey.
When the west coast of Greenland came into view the sun was just peaking through the clouds lying low along the tops of the coastal mountains. The shadowy ridgeline just visible through the mist was a welcome sight after seven hours of flight. Tomorrow will be a day of setting up base stations and reviewing some of the transit data, then the Icepod project will launch into its first set of Greenland test flights.
For more information on the IcePod project: http:www.ldeo.columbia.edu/icepod
By Ana Camila Gonzalez
“You can do math on excel?” I ask. I immediately imagine a face-palm response, but Dario, one of my advisors, is nice enough to hide it. I’ve collected tree core samples, I’ve prepared them and cross-dated them. Now what?
Oh, right. The Science.
I guess I never really understood there could be so much involved in answering a question. When I imagine the scientific method I’ve learned since the sixth grade, I somehow imagine a question that can be answered with a yes or no. If I let go of this apple, will it fall to the ground? Hypothesis: yes, it will. Experiment: yes, it does. Conclusion: yes, it will. To the credit of my high school science teachers, it’s not that they didn’t make it perfectly clear that the why and the how are just as important as the yes or the no. I just couldn’t imagine that you’d have to explain why the apple falls with four different figures: haven’t you seen an apple fall too?
Dario is helping me understand how to analyze the data from the black oak samples I have already been working with for some time now. I know these samples. Or at least I think I know these samples. I’m learning there’s more to know about them than I initially thought.
We’re analyzing the climate response, which proves to be exactly what it sounds like. We have recorded measurements of climate (precipitation records, temperature records) and a proxy for tree growth (our ring width measurements!) and by comparing those we can see how a tree population responds to a range of climactic conditions. Alright. I can do this. I’ve made graphs before.
“So we’re going to find correlations,” says Dario.
“Click on an empty cell.” I start to make a scatter plot; I think what we’re going to do is look at the slope of a line of best fit.
“So we’re going to see if the correlation is positive or negative?” I ask.
“Yes, but we also have to see if the correlations are significant.” Isn’t any correlation higher than a zero significant? They’re showing a relationship.
Dario continues, “Any correlation above a 0.2 or so is significant for the hundred years of ring width and climate that you have for this analysis.” I learn how to use the =correl function to compare the populations to temperature and I have to say I’m disappointed. I thought 0.2 sounded so low, but some of my data is showing a much lower correlation, and the data that is significant only ranges from about really close to 0.2 to 0.38 or so. I wanted to see a 0.5 correlation like I did between tree samples within a species as I was cross-dating. Comparing precipitation to ring width gives me slightly higher correlations, a few in the 0.3 range, but I’m still feeling underwhelmed.
“No, but it’s still significant! It matters!” Dario tells me to make a scatter plot comparing precipitation to ring-width measurements over time at both sites. At first it looks like a ball of yarn, but as I mask the plot out I can see why those 0.3 correlations are significant. I follow each curve, visually skateboarding up and down the peaks and valleys and noticing that I’m going up and down a lot of very similar hills as I do so. What’s most rewarding is looking for years I know are drought years (1966 and 1954 were big droughts) and seeing relatively low measures of precipitation and ring width during those years. I knew while I was cross-dating that those years were important when I saw how small the rings were, but now I can prove it. Like the apple falling, I can’t just say that because I see the rings are small those were dry years. I have to compare it to precipitation records, temperature records, and, dare I say it, the Palmer Drought Severity Index (I have to admit I don’t entirely understand the mechanics behind the index, but I understand that dryness is a composite of precipitation and temperature forcings).
Dario, over multiple days, teaches me a few more nuances of Excel and helps me understand the ARSTAN program and how we use it to make our ring-width measurements more effective as proxies for tree growth. He mentions this would all be easier if I knew how to use R. I make a mental note: learning R is the next step. If I thought that was scary, now I have to put this information on a poster. That real people will see. At a real conference.
Neil shows me a few poster examples, and the message is clear. Show your data instead of describing it in words. That also means I’ll have to explain my data by actually… talking… about it. Gulp. The North East Natural History Conference is next weekend, but I feel like I’m ready. I understand the why and how after analyzing my data. At least I understand it enough to give an answer better than yes or no.
Ana Camila Gonzalez is a first-year environmental science and creative writing student at Columbia University at the Tree Ring Laboratory of Lamont-Doherty Earth Observatory. She will be blogging on the process of tree-ring analysis, from field work to scientific presentations.