NASA Interdisciplinary Science (IDS): Mapping Alaska permafrost processes and their impact on regional carbon fluxes
We are producing the first-ever remote sensing based maps of soil profile characteristics in Alaska permafrost landscapes using time series airborne low frequency (P- and L-band) synthetic aperture radar (SAR). Our guiding hypothesis is that low frequency SAR backscatter measurements are sensitive to soil profile structure, moisture and thermal dynamics that are responsive to permafrost conditions and can be used to improve regional estimation of surface hydrology and carbon cycle processes. The SAR observations are obtained using AirMOSS and UAVSAR instrument platforms, while permafrost properties are retrieved using techniques developed from the NASA AirMOSS Earth Ventures 1 (EV-1) mission. Primary permafrost soil properties examined include soil active layer moisture and freeze-thaw depth profiles overlying permafrost. The airborne SAR retrievals are guided by detailed ground network measurements of soil and permafrost conditions, and forward model simulations of radar backscatter properties and parameter retrieval uncertainty analyses extending across Alaska permafrost landscapes. The SAR retrievals are being used to inform a succession of land surface hydrology and terrestrial carbon (CO2) flux model simulations to investigate the impact of permafrost and soil hydrologic conditions on the net ecosystem carbon budget. The project results provide robust regional assessments and predictions of ecosystem vulnerability to recent climate trends, including potential ecosystem shifts from a predominant sink to a source of atmospheric CO2.
Du, J., J.S. Kimball, and M. Moghaddam, 2015. Theoretical modeling and analysis of L- and P-band Radar backscatter sensitivity to soil active layer dielectric variations. Remote Sensing 7, 9450-9472.
Park, H., Y. Kim, and J.S. Kimball, 2016. Widespread permafrost vulnerability and soil active layer increases over the high northern latitudes inferred from satellite remote sensing and process model assessments. Remote Sensing of Environment 175, 349-358.
Yi, Y., J.S. Kimball, R. Chen, M. Moghaddam, R.H. Reichle, U. Mishra, D. Zona, and W.C. Oechel, 2018. Characterizing permafrost soil active layer dynamics and sensitivity to landscape spatial heterogeneity in Alaska, The Cryosphere 12, 145-161.
Yi, Y., J.S. Kimball, M.A. Rawlins, M. Moghaddam, and E.S. Euskirchen, 2015. The role of snow cover and soil freeze/thaw cycles affecting boreal-arctic soil carbon dynamics. Biogeosciences 12, 5811-5829.
Yi, Y., J.S. Kimball, and R.H. Reichle, 2014. Spring hydrology determines summer net carbon uptake in northern ecosystems. Environmental Research Letters 9, 064003.
Zona, D., B. Gioli, R. Commane, et al., 2016. Cold season emissions dominate the Arctic tundra methane budget. PNAS, 113, 1, 40-45.
John Kimball (UMT PI), Jinyang Du, Youngwook Kim, Yonghong Yi
Other Project Personnel
Mahta Moghaddam (USC, Project PI), Walt Oechel and Dona Zona (SDSU), Randy Koster and Rolf Reichle (NASA GSFC), Scott Goetz (WHRC), Charles Miller (JPL, Caltech), Vladimir Romanovsky (UAF)