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

• The climate of high midlatitude mountains appears to be warming faster than the global average, butevidence for such elevation-dependent warming (EDW) at higher latitudes is presently scarce. Here, we use acomprehensive network of remote meteorological stations, proximal radiosonde measurements, downscaledtemperature reanalysis, ice cores, and climate indices to investigate the manifestation and possible drivers ofEDW in the St. Elias Mountains in subarctic Yukon, Canada. Linear trend analysis of comprehensivelyvalidated annual downscaled North American Regional Reanalysis (NARR) gridded surface air temperaturesfor the years 1979–2016 indicates a warming rate of 0.0288Ca21 between 5500 and 6000mabovemeansea level (MSL), which is ;1.6 times larger than the global-average warming rate between 1970 and 2015.The warming rate between 5500 and 6000m MSL was ;1.5 times greater than the rate at the 2000–2500mMSL bin (0.0198Ca21), which is similar to the majority of warming rates estimated worldwide over similarelevation gradients. Accelerated warming since 1979, measured by radiosondes, indicates a maximum rateat 400 hPa (;7010mMSL). EDWin the St. Elias region therefore appears to be driven by recent warmingof the free troposphere. MODIS satellite data show no evidence for an enhanced snow albedo feedbackabove 2500m MSL, and declining trends in sulfate aerosols deposited in high-elevation ice cores suggest amodest increase in radiative forcing at these elevations. In contrast, increasing trends in water vapor mixingratio at the 500-hPa level measured by radiosonde suggest that a longwave radiation vapor feedback iscontributing to EDW.

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Meteorologi och atmosfärforskning (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Meteorology and Atmospheric Sciences (hsv//eng)

Nyckelord

Mountains

climate change

subarctic

Canada

Earth Science with specialization in Physical Geography

Geovetenskap med inriktning mot naturgeografi

Publikations- och innehållstyp

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