Abstract
Decreasing spring snow cover may amplify Arctic warming through the snow albedo feedback. To examine the impact of snowmelt on increasing temperature we used a 5,000 m elevation gradient in Yukon, Canada, extending from valley-bottom conifer forests, through middle elevation tundra, to high elevation icefields, to compare validated downscaled reanalysis air temperature patterns across elevational bands characterized by different patterns of spring snowmelt. From 2000 to 2014 we observed surface warming of 0.01 °C/a·1,000 m in May (0.14 °C/a at 1,000 m to 0.19 °C/a at 5,000 m), and uniform cooling of 0.09 °C/a in June at all elevations. May temperature trends across elevationally dependent land cover types were highly correlated with each other despite large variations in albedo and snow cover trends. Furthermore, a clear dependency of infrared skin temperature on snow cover mediated albedo decline was observed in tundra, but this was insufficient to influence average diurnal air temperature. We observed negative June temperature trends which we attribute to increasing daytime cloud cover because albedo and snow cover trends were unchanging. We conclude that 8-day and monthly averaged Spring air temperature trends are responding to a synoptic external forcing that is much stronger than the snow albedo feedback in sub-Arctic mountains.
Highlights
Meteorological observations of air temperature and snow cover observations originated from three locations within the study area
While snow albedo and air temperature trends are highly correlated, the snow albedo feedback appears to have a minimal influence on air temperature trends, both at the monthly and 8-day time scales
MODerate resolution Imaging Spectroradiometer (MODIS) Solar noon LST (snLST) indicates the SAF is occurring, but appears to be insufficient to modify average diurnal air temperature. These results suggest that SAF does not scale from discrete, localised events, to coarse temporal and spatial resolutions
Summary
Meteorological observations of air temperature and snow cover observations originated from three locations within the study area. There are two Environment Canada meteorological stations within the study area (Burwash Landing and Haines Junction) we could not confirm whether the Burwash Landing station was used in the production of NARR data. We use only data provided from the Haines Junction Station. Snow cover observations are recorded at the Haines Junction Environment Canada stations. Air temperature measurements were made at the Haines Junction Environment Canada station (in the conifer land cover), the Divide station (on the snow covered icefield) east of Mount Logan, and at Pika Camp (alpine tundra). Validation of the NARR downscaled temperature product for the three land cover types uses data from the Haines Junction, Divide and Pika Camp stations. The Pika Camp station is located at 61.21°N; 138.28°W (1,635 m)
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