Circumpolar and regional analysis of the relationship between sea-ice variability, summer land-surface temperatures, Arctic tundra greenness and large-scale climate drivers
Uma
Bhatt, U. Alaska Fairbanks (UAF), Geophysical Institute & College of Natural Sciences and Mathematics (CNSM), bhatt@gi.alaska.edu
Donald
A. (Skip)
Walker, UAF, Institute of Arctic Biology & CNSM, ffdaw@uaf.edu
(Presenting)
Martha
K.
Raynolds, UAF, Institute of Arctic Biology & CNSM, fnmkr@uaf.edu
Josefino
Comiso, NASA Goddard Space Flight Center, josefino.c.comiso@nasa.gov
Recent dramatic reductions in summer sea ice may also impact the ecosystem at high latitudes. It is hypothesized that an earlier ice melt can force atmospheric and land-surface temperatures changes, leading to increased summer warmth and enhanced greenness of vegetation. Our study examines the time-series relationships between sea-ice concentrations, summer land-surface temperatures, vegetation greenness, and large-scale climate drivers within a 50-km buffer of the Arctic coastline for the total Arctic domain and regionally using the Arctic Ocean divisions of the Russian Arctic Atlas. The analysis employs 25-km resolution SSMI passive microwave 18 Jun-22 Jul sea ice concentration and AVHRR Surface Temperature data from 1982 to 2007. The 1982-2006 NASA GIMMS data at a 25-km resolution are used to represent summer NDVI.
Sea ice decreased (-5.8 % / decade) and the summer warmth index (SWI) increased (+1.2 ˚C month / decade) over the 1982-2007 period over the entire Circum-Arctic domain. In conjunction, maximum and integrated NDVI displayed modest increases of 0.0006 and 0.06 units per decade, respectively. Sea-ice concentration and SWI are correlated at -0.80 (95% or greater t-test significance), which is consistent with the notion that cooler land-surface temperatures are found with above average ice conditions. Integrated NDVI is correlated positively with SWI and negatively with sea ice concentration, indicating that enhanced greenness of tundra vegetation occurs with a warmer growing season and reduced sea ice. Relationships with large-scale climate indices are varied but show consistent relationships between the NAM, the PDO and the NAO. These general relationships also hold true within each Arctic region, but there are differences in the strength of the trends and variability across the Arctic.
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