Atmospheric moisture content associated with surface air temperatures over northern Eurasia

Abstract

This study uses both historical station records and Atmospheric Infrared Sounder (AIRS) satellite instrument products to examine the relationship between atmospheric moisture content and surface air temperature over northern Eurasia, with a special emphasis on the summer season. We find that the rate of atmospheric water vapor content change with temperature varies by season and generally decreases with increasing air temperature. The average rate of water vapor pressure increase with air temperature is 7.57%/ °C in winter, 4.78%/ °C in spring, 3.06%/ °C in summer, and 4.39%/ °C in fall based on 80 weather station records over a 55-year period. The average rate of atmospheric total precipitable water increases is about 3.02%/ °C based on AIRS data from the most recent four summers over northern Eurasia. Except for the winter season, these rates are considerably lower than the 7%/ °C rate that the Clausius–Clapeyron relationship and constant relative humidity would suggest. During summer season, we also found decreasing water vapor partial pressure and decreasing total water vapor with increasing air temperature at southern and southwestern study regions where higher mean temperatures are found. The large regional and seasonal variations in water vapor–temperature relationship over Eurasia imply that potential amplified water vapor feedback is most likely to be found in cold regions during the cold season while it may not be as significant as expected during the warm season. Copyright © 2009 Royal Meteorological Society