Warming and drying of the Arctic: Surface moisture as an integrator of biological, geochemical, geological, physical, and anthropogenicprocesses and interactions.
This project is examining how biological and physical processes interact to control carbon uptake, storage and release in Arctic tundra ecosystems and how the self-organizing nature of these interactions varies across multiple spatial and temporal scales. Approximately 25% of the worlds soil organic carbon reservoir is stored at high northern latitudes in permafrost and seasonally-thawed soils in the Arctic, a region that is currently undergoing unprecedented warming and drying, as well as dramatic changes in human land use. Understanding how changes in annual and inter-annual ecosystem productivity interact and potentially offset the balance and stability of the Arctic soil carbon reservoir is of utmost importance to global climate change science. If there is a net loss of soil carbon to the atmosphere in the form of greenhouse gases (namely CO2 and CH4), greenhouse warming could be enhanced. This non-linear, potentially positive feedback response could very quickly cause Arctic terrestrial ecosystems to function in an unprecedented manner and with globally significant implications. Our research benefits from a foundation and wealth of international and national carbon cycle research undertaken in northern Alaska and other Arctic regions over the past three decades. We have initiated a comprehensive study involving an integrated framework of multi-scale aircraft and satellite remote sensing, micrometeorological and CO2 and CH4 flux measurements and hydro-ecological process model simulations over a 350km North-South transect spanning the dominant Arctic topographic and land cover units of northern Alaska. The study region encompasses many long-term measurement sites that have been in place for 5 to 10 years. We are also conducting an extensive soil moisture manipulation involving a 60 hectare tundra flooding/draining experiment near Barrow Alaska on the Arctic Coastal Plain. The objective of this study is to quantify linkages between soil moisture and carbon uptake, storage and release over multiple spatial (microbial to landscape) and temporal (minutes to decades) scales. Only by increasing the spatial extent of our experimental manipulations and the duration of our observational time series can we better understand and predict the effect of scale on the complex coupling within Arctic ecosystems; namely, how small scale processes participate as components of higher scale phenomenon and how higher scale phenomenon constrain the former lower scale processes. This knowledge will improve our understanding of the current behavior and potential response of arctic tundra to global change, resulting in better predictions of feedbacks to climate and the global carbon cycle.
AIRSAR C-, L-, P-band radar backscatter image over the Barrow Alaska area Ecological Observatory (BEO) showing a complex spatial mosaic of shallow lakes and tundra wetlands. We are conducting a large scale water table manipulation experiment and investigating the use of airborne and microwave remote sensing techniques for mapping and scaling soil moisture and temperature controls on soil CO2 exchange. These techniques will lead to improved satellite based mapping of terrestrial carbon and water cycles for boreal and arctic biomes and a better understanding of the stability of terrestrial soil carbon stocks and potential feedbacks to global warming.
Jones, L.A., J.S. Kimball, K.C. McDonald, S.K. Chan, E.G. Njoku, and W.C. Oechel, 2006. Satellite microwave remote sensing of boreal and Arctic soil temperatures from AMSR-E. IEEE Transactions in Geoscience and Remote Sensing (In press).
Jones, L., J. Kimball, K. McDonald, E. Njoku, and W. Oechel, 2006. MODIS and AMSR-E synergistic modeling of Arctic and boreal terrestrial carbon dynamics. NASA Global Vegetation Workshop 2006: Long-term monitoring of vegetation variables using moderate resolution satellites. August 8-10, 2006, Missoula MT.
Zhang, K., J.S. Kimball, and M. Zhao, 2006. Sensitivity of pan-Arctic terrestrial net primary productivity simulations to daily surface meteorology from NCEP/NCAR and ERA-40 reanalyses. JGR Biogeosciences 112, G01011, 1-14, doi:10.1029/2006JG000249.
Zhang, K., J.S. Kimball, M. Zhao, W.C. Oechel, and S.W. Running, 2006. Analysis of pan-Arctic terrestrial primary productivity from 1982-2005 by combining AVHRR and MODIS products. NASA Global Vegetation Workshop 2006: Long-term global monitoring of vegetation variables using moderate resolution satellites. August 8-10, 2006, Missoula MT.