Monitoring Surface Water Changes across North American Arctic-Boreal Regions and Associated Impacts on Regional Carbon Fluxes

Jennifer Dawn Watts, University of Montana, jennifer.watts@ntsg.umt.edu (Presenter)
John S Kimball, University of Montana, johnk@ntsg.umt.edu
Jinyang Du, University of Montana, jinyang.du@ntsg.umt.edu

Surface water inundation strongly regulates land-atmosphere energy and carbon exchange in northern environments. However, the dynamic nature of inundation in Arctic-boreal landscapes, and the potential impact of changing surface water extent on wetland methane (CH4) emissions, is not well understood. We examine recent changes and spatiotemporal variability in surface inundation across Alaska and Canada using passive microwave remote sensing retrievals of fractional open water extent (Fw) derived from Advanced Microwave Scanning Radiometer for EOS (AMSR-E) 18.7 and 23.8 GHz brightness temperatures (Tb) and similar calibrated overlapping Tb observations from FY3B-MWRI and AMSR-2 sensors. The 12+ year (2003 to > 2014) 25-km resolution AMSR global Fw record has advantages over optical-IR remote sensing by being insensitive to solar illumination and cloud, smoke and atmosphere aerosol contamination effects, enabling continuous daily observations over northern land areas. A multi-year analysis of the AMSR Fw record over tundra and boreal landscapes indicates strong contrasts in ecosystem wetting and drying patterns, including those observed over the North Slope, the Mackenzie River Basin, and Interior Alaska. We find these Fw patterns to correspond closely with regional thermokarst expansion, fire disturbances, and increasing annual non-frozen season lengths. We also find that accounting for dynamic high-temporal Fw variability in terrestrial carbon models significantly reduces northern high latitude CH4 emission budgets by better representing regional drought conditions and surface wetting following spring thaw and precipitation events. The continued monitoring of surface inundation supported by ongoing AMSR-2 operations, in conjunction with finer (6.25-km) resolution Fw retrievals using 89 GHz AMSR Tb observations and new enhanced (3-9 km) resolution L-band active/passive microwave retrievals from the NASA Soil Moisture Active Passive (SMAP) mission, will greatly improve understanding of long-term trends and variability in open water lakes and wetlands, and regional impacts to terrestrial carbon cycling under changing climate conditions.

Presentation: 2015_Poster_Watts_249_94.pdf (3370k)

Presentation Type:  Poster

Session:  General Contributions   (Tue 4:35 PM)

Associated Project(s): 

• Kimball, John: Analysis and Attribution of Recent Changes in Net Ecosystem CO2 Exchange Using MODIS and AMSR-E ...details

Poster Location ID: 249