Evidence for elevation-dependent warming in the St. Elias Mountains, Yukon, Canada

• The climate of high, mid-latitude mountains appears to be warming faster than the global average, but evidence for such elevation-dependent warming (EDW) at higher latitudes is presently scarce. Here, we use a comprehensive network of remote meteorological stations, proximal radiosonde measurements, downscaled temperature reanalysis, ice cores, and climate indices to investigate the manifestation and possible drivers of EDW in the St. Elias Mountains, subarctic Yukon, Canada.  Linear trend analysis of comprehensively validated annual downscaled North American Regional Reanalysis (NARR) gridded surface air temperatures for the years 1979 to 2016 indicates a warming rate of 0.028°C a-1 between 5500 and 6000 m a.s.l., which is 2.6 to 5.8 times larger than the global average.  The warming rate between 5500 and 6000 m a.s.l. was ~ 1.5 times greater than the rate at the 2000 to 2500 m a.s.l. bin (0.019°C a-1), which is similar to the majority of warming rates estimated worldwide over similar elevation gradients.  Warming since 1979 measured by radiosondes indicates a maximum rate at 400 hPa (~7010 m a.s.l.).  EDW in the St. Elias region therefore appears to be driven by recent warming of the free troposphere.  MODIS satellite data show no evidence for an enhanced snow albedo feedback above 2500 m a.s.l., and declining trends in sulfate aerosols deposited in high elevation ice cores suggests a modest increase in radiative forcing at these elevations.  In contrast, increasing trends in water vapour mixing ratio at the 500 hPa level measured by radiosonde suggests that a long-wave radiation vapour feedback is contributing to EDW.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Klimatforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Climate Research (hsv//eng)

Nyckelord

climate change

mountains

Canada

subarctic

atmosphere

Earth Science with specialization in Physical Geography

Geovetenskap med inriktning mot naturgeografi

Publikations- och innehållstyp

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