Eleven Year Soil Climate Trends: McMurdo Sound Region of Antarctica.

Soil moisture and temperature are important in Antarctic soil ecosystem processes and accessing impacts of climate change. In the McMurdo Sound Region of Antarctica, a soil climate monitoring network was established to determine the effects of climate change on the seasonally thawed layer (active-layer) and upper permafrost. Four of the stations were established in 1999 and have 11 years of data, which are the focus of this presentation. Two of the four longer-term sites are located on the coast (i.e., Scott Base and Marble Point) and two are in the McMurdo Dry Valleys (i.e., Victoria and Wright Valleys). The stations monitor air temperature, relative humidity, wind speed and direction, solar radiation, and soil moisture and temperature at various depths in which hourly average measurements are recorded. Soils are generally sandy with significant amounts of rock fragments. Mean liquid soil moisture contents of the active-layer varied from year to year and the variability decreased with depth, but were stable over the 11-year period. Maximum active layer depths also showed year to year variability, but had a slight increasing trend over the 11-year monitoring period at all four sites. Conversely, the mean annual air temperature (MAAT) and mean annual soil temperature (MAST) trended to be stable over the 11-year monitoring period showing less than a 2°C inter-annual variation. The mean winter (Jun, Jul, Aug) air temperature (MWAT) and mean winter soil temperatures (MWST) varied together and did not differ by more than 2°C, but inter-annual variation ranged up to 8°C. The mean summer (Dec, Jan, Feb) air temperature (MSAT) and mean summer soil temperature (MSST) varied together and were more stable with an inter-annual variation ranging up to 4°C. Soil climate trends at the four sites tend to be fairly stable over the 11-year monitoring period. All data and metadata for the soil climate stations are available through the USDA-NRCS National Soil Survey Center's web page http://soils.usda.gov/survey/scan.