Wednesday, July 23, 2014

Frozen Solid - Permafrost Beneath the Tundra

It's hard to imagine that soils can be frozen for hundreds of years. But try to dig a hole into the Arctic tundra and you'll quickly find that the job is almost impossible due to permafrost; soil frozen solid.

Permafrost is technically defined as soil that is frozen for two or more consecutive years. It can be found throughout much of the North Slope, occurring at several inches to many feet below the soil surface. In Barrow, the depth to permafrost averages 18 inches (plus or minus), but does vary depending on landscape position (e.g., slope and aspect), water saturation, vegetation cover, and thickness of any moss or organic layer.
Today while working on the Barrow Environmental Observatory (BEO), it was all I could do to get a shovel into the ground to a depth of 6 to 8 inches. Having dug a hole, it was easy to see that the upper soil was largely composed of recent organic matter, with gray to black mineral soil deeper in the soil profile, and then frozen soil. A quick measurement with a temperature probe confirmed that soil temperatures were close to zero and considerably colder than that at depth. Sensors placed deep into the permafrost at our field site show that temperatures can be as low as -9 C and stay that temperature year round.




The layer of soil above permafrost is referred to as the active layer. This layer will continue to thaw and deepen throughout the season. By the end of September the active layer will be thicker than it is today and mark the true depth to permafrost.

One of the questions that the NGEE Arctic project is trying to understand is just how much rising temperatures will continue to thaw permafrost (or deepen the active layer) in the coming decades. This information needs to be incorporated into models if we are to predict changes to Arctic ecosystems in the future. Assuming that warmer temperatures will accelerate thaw depth, this may have significant consequences for the release of CO2 and CH4 from tundra landscapes. This can occur directly through an acceleration of microbial processes responsible for CO2 and CH4 production or indirectly through changes in landscape topography and water distribution. Our team is studying this latter dynamic by looking at CO2 and CH4 fluxes from low- and high-center polygons. High-center polygons form as a result of long-term changes in ice content due to rising temperature and they can have very different soil and vegetation characteristics than more common low-center polygons.

I'll show how we measure the flux of greenhouse gases from polygons on the tundra later this week...

Tuesday, July 22, 2014

Summer Science in Barrow...

Any plant ecologist knows that field research requires patience and an ability to cope with changing weather conditions.  Like this morning when we woke to snow and temperatures slightly below freezing.  Such is summer science in Barrow, Alaska.  It looked all the more frigid while driving out of town along the Arctic Ocean.  Although the waters have generally been clear of ice, a shift in winds caused sea ice to move towards shore.  Just visual evidence that this is a harsh, remote, and beautiful region of the world.  Now, off to the field…


Monday, July 21, 2014

Scientists Come and Go from Barrow...

Summer, if there is one in Barrow, is marked by the coming and going of researchers. A constant flux of scientists who spend weeks at a time studying the landscapes, plants, and animals in and around this Inupiat community 330 miles north of the Arctic Circle.

Today I join that long procession of scientists as I depart Knoxville for the North Slope of Alaska. It will be a long trip taking 16 hours and covering 4600 miles as I make my way to Chicago, Anchorage, Fairbanks, Prudhoe Bay, and eventually Barrow. Hopefully my travels will be uneventful, although NGEE Arctic scientists have experienced delays in recent weeks largely due to fog along the coast of the Arctic Ocean. This made landing difficult and a few of our colleagues spent several days in Anchorage earlier in the month waiting for conditions to improve. They finally made it to Barrow and many are there now conducting various measurements in support of the project.
Conditions this year for field measurements have not been ideal. It has been unusually cold and wet. Air temperatures have been restricted to the 30's with just a handful of days warming into the 40's. It snowed as recently as last week. It has also been rainy, with this being the wettest summer by far in our four years working in Barrow. None of this seems to slow down our researchers, however, as they have been actively working in the field since May measuring snowmelt and water table depths; geophysics; fluxes of energy, CO2, and CH4; components of soil evaporation and transpiration; spectral reflectance of vegetation; and leaf gas exchange. It has been a busy year!

I'll provide daily updates for the next 10 days as our project scientists undertake various research activities at our field sites on the Barrow Environmental Observatory (BEO). To the extent possible I'll do my best to relate those to the objectives of the NGEE Arctic project and to our goal of improving climate models.
You can expect to hear more from me once I get to Barrow and join my colleagues...




Monday, July 14, 2014

Another Fun Day with the Students...

Today was Day 2 for the Nuna 2014 Summer Camp being held at Ilisagvik Community College in Barrow, Alaska. Alessio reminds me that working with middle school students is not a simple undertaking. One must remain mindful of group dynamics, and find a balance with play and work. Alessio is making it a priority to share his enthusiasm for science. So far that approach seems to be working as the students are having a great time. The students are busy and spending a lot of time outdoors.

As a result, Day 2 was epic. Alessio and the students started off by preparing a permafrost sample. Each student prepared a mixture of soil and water and put it in the freezer. With this they were simulating ice rich vs. ice poor permafrost. After “making permafrost”, the students headed out to the NGEE Arctic field sites on the Barrow Environmental Observatory (BEO). This time Alessio tried to focus their activities on plants and animals. They discussed the importance of water, and how surface hydrology is conditioned by the ice wedge polygons discussed the day before. Kids love being outside. It was easy to see how the distribution of plants was controlled by water with sedges and forbs in water inundated areas with grasses and short woody shrubs on the drier upland areas. Not many animals were present, but Alessio and the students talked about how birds and other animals might nest on areas that were “high and dry” as opposed to areas that flooded easily.

In the afternoon the students did something very special. David Masak, a smiley man in his fifties who work for Ilisagvik, asked his dad if they could see his meat-cellar, four meters below ground, dug in permafrost. This was quite an experience, for Alessio and for the students. The cellar was dug in 1969 with an icepick, it took 3 months to dig, and since then, has provided shelter for the wild game. The students truly enjoyed the experience. First they could touch permafrost and observe it very closely. Second, they obtained a glimpse of Inupiat culture, and finally third the roof of the cellar was full of beautiful hoarfrosts which fascinated many of the students.

Alessio writes that it was a long but good day. Everyone had fun. Tomorrow is another day.
 


 

Wednesday, July 9, 2014

Nuna 2014 - Summer "Science" Camp in Barrow

Alessio Gusmeroli from the University of Alaska Fairbanks has a lot of energy and personality, and this week is using all that to host a week long summer camp for middle school students from the North Slope of Alaska.
 
Alessio writes that today was Day 1 and they began with a successful venture out to the Barrow Environmental Observatory (BEO). It was windy and cold for early July, but the students proved fearless. They visited the NGEE Arctic field sites and learned how to identify low- and high-centered polygons. Alessio and the students, all from one of several villages on the North Slope, measured thaw depth using a metal tile probe and the temperature of the permafrost using an infrared thermometer. Students recorded the depth of thaw, then dug down using a shovel through the active layer to the underlying frozen soil, and used the hand-held thermometer to measure temperature. The students quickly learned that although it's summer, the soils had only thawed to a depth of just 6 to 7 inches. At those depths the soil temperature was still only a few degrees below zero.

Alessio and the students gathered up their data and went back to the classroom to compile field observations. They did this as a group while watching Tunnelman videos. Those of you not familiar with this crusader of permafrost, should know that it is Dr. Kenji Yoshikawa from the Institute of Northern Engineering (INE) and the International Arctic Research Center (IARC) at the University of Alaska Fairbanks. Alessio writes that after working in the field and having watched the videos, the students have now renamed the tile probe device used to measure thaw depth as Tunnelman’s "sword". We may see more of this as the week goes along. 

In the afternoon Alessio and the students headed to the beach. They observed how sediments deposited within even short distances of one another can be different. They sampled mud, silt, sands and gravels, and brought everything back to the laboratory for analysis under the microscope. In addition the students took the opportunity to fly a kite, and with the help of Margi Dashevsky, a graduate student at the University of Colorado Boulder, the students learned how to take video. Margi then used her technical editing skills to put together the final project of the day: a video-summary! Check it out - http://youtu.be/BpdnKm5TKJU

Nice job guys!



Wednesday, June 11, 2014

This Trip Comes to a Successful Ending…

Cathy left earlier in the week, but Go and I continue to conduct snow surveys across our four research sites on the Barrow Environmental Observatory (BEO). Go learned the protocol for these surveys from Cathy and, as a result, is quite efficient at gathering snow depth measurements from 300 or more low- and high-center polygon locations. He is equally efficient in collecting snow samples from which we will calculate water equivalents. Both of these measurements and their changes over time will be useful to our modelers, who will use this information to incorporate snow accumulation and resulting water discharge into their high resolution landscape models where we are concerned with microtopography and the contribution of different types of polygons to hydrology. While Go was busy collecting this information I had the opportunity to grab several replicated snow and surface water samples for Baohua Gu (ORNL), one of our team’s geochemists. This was not too difficult. However, we had hoped to get pore water samples as well, but the depth of the active layer is not sufficient to insert sample collection tubes into the soil. I will do this again in mid-summer when the soil has thawed and it is easier to collect pore water for analysis.

 

 
 
In between our other activities, I had the opportunity to troubleshoot some communication issues with the energy tram and our micrometeorology tower that includes CO2 and CH4 flux measurement capabilities. It has been a few years since I last worked with data transmission systems, but Dave and Bryan spent a couple hours on the telephone with me and we sorted out the troubles. It turns out that while the two systems were designed as standalone units, interference was generated between the two communication links. This introduced sporadic problems, mostly for the eddy covariance tower. By the end of the day, however, both systems were working as designed and data were being collected, stored, and transmitted to the University of Nebraska and LBNL.

 
 
Given that it was my last day in the field I took a break, propped my feet up on my backpack, and gazed off some 1300 miles towards the North Pole. Three years ago when our team first visited this area it seemed like a strange and foreign, albeit exciting environment. Now, our team seems quite comfortable coming and going from the field site, and living for weeks at a time in Barrow. We all agree that the research we are doing – that of conducting field and laboratory studies to improve climate models – is a worthwhile and challenging endeavor. Regardless of your scientific discipline, and we have scientists studying everything from to genomics to geophysics, the North Slope of Alaska is a great place to be conducting research.

 
Finally, and before heading to the airport, Go and I wanted to stop by the Barrow Arctic Research Center (BARC) where we are fortunate to have a modern laboratory space to use in our science. We had asked Karl Newyear, Chief Scientist for UMIAQ, to meet us there so we could check out a freezer that had been purchased and delivered to the BARC in May. Karl was able to locate a secure space for the freezer. It is already being put to good use as it was full of permafrost cores from our sampling trip in April and early May. These cores, many of them extending to 2 meters into the subsurface, were collected by our geophysics colleagues from LBNL and will be shipped to California in the near future for analysis.

 
After saying goodbye to Karl, I had just enough time to take a shower, toss my field clothes into my duffel bag, and head for the airport. Check-in and boarding is fairly painless in Barrow and within 30 minutes of the flight, I was taking off for Anchorage to connecting flights in Chicago and then to Knoxville. It was a successful trip with all signs pointing to a productive field season. I will return later in July when our plant physiology team including Alistair Rogers and Shawn Serbin from Brookhaven National Laboratory (BNL) should be in Barrow conducting photosynthesis measurements on tundra vegetation. I am already looking forward to that…
 
 

Friday, June 6, 2014

High, Dry, and Free of Snow…

Two years ago the NGEE Arctic team established our research sites on the Barrow Environmental Observatory (BEO). We designed our studies around geomorphological features including thaw lakes, drained thaw lake basins, and polygons of which there are three types; low-, flat-, and high-centered polygons. The various types of polygons are of interest to our team because they have what we believe to be marked differences in CO2 and CH4 flux, temperature, and hydrology. Scientists on our team are gathering data and developing models to test this possibility and will then use those models to examine what a change from low- to high-centered polygons due to permafrost thaw might mean to carbon cycle and energy balance processes over the next century.

We have already made great strides in addressing how landscape evolution and the thaw lake cycle will potentially impact CO2 and CH4 fluxes, with an eye towards getting this information into high-resolution climate models. It has been interesting this week to walk the BEO and, when time permits, to consider how snowmelt and associated processes might differ across the polygons that we are studying. What I have observed is that the tops of the high-centered polygons do not have very deep layers of snow and the snow that accumulates on them during the long winter seems to melt first before melting on any of the other features in the landscape.







 
Scientists including Margaret Torn, Bryan Curtis, Melanie Hahn, and others have not yet summarized all of their chamber-based measurements of CO2 and CH4 flux from previous years at this point, so I cannot be overly quantitative about this observation. However, looking at our field sites, especially those in and among high-centered polygons, I can imagine that the growing season is longer, soils are warmer, albeit possibly dryer, and thus environmental conditions may result in different rates and seasonal magnitudes of CO2 and CH4 flux from these features. If so, then we need to incorporate this fine-scale information into our models.