Cooperative Institute for Research in Environmental Sciences

Synoptic climatology and recent climate trends at Lake El'gygytgyn

Matt Nolan, Elizabeth Cassano, and John Cassano

2013, Climate of the Past Discussions, 9, 1271-1286. doi: 10.5194/cp-9-1271-2013

We developed a synoptic climatology for Lake El'gygytgyn, Chukotka Russia, and explored modern climate trends affecting air temperatures there to aid in paleoclimate reconstructions of a 3.6 million year old sediment core taken from the lake. Our self-organized mapping (SOM) approach identified 35 synoptic weather patterns, based on sea level pressure, that span the range of synoptic patterns that influence the study domain over the 1961-2009 NCEP/NCAR reanalysis period. We found strong seasonality in modern weather patterns, with summer weather primarily characterized by weak low pressure system over the Arctic Ocean or Siberia and winter weather primarily characterized by strong high pressure over the Arctic Ocean and strong low pressure in the Pacific Ocean. In general the primary source of variation in air temperatures came from the dominant patterns in each season, which we identify in the text, and nearly all of the dominant weather patterns here have shown increasing temperatures. We found that nearly all of the warming in mean annual temperature over the past 50 years (about 3°C) occurred during sub-freezing conditions on either side of summer (that is, spring and autumn). Here we found that the most summer-like weather patterns (low pressures to the North) in the shoulder seasons were responsible for much of the change. Finally we compared the warmest 15 years of the record (1995-2009) to the coolest (1961-1975) and found that changes in thermodynamics of weather were about 3 to 300 times more important than changes in frequency of weather patterns in controlling temperature variations during spring and autumn, respectively. That is, in the modern record, general warming (local or imported) is more important by orders of magnitude than changes in storm tracks in controlling air temperature at Lake El'gygytgyn. We conclude with a discussion of how these results may be relevant to the paleoclimate reconstruction efforts and how this relevancy could be tested further.