Abstract

Moist enthalpy hereafter referred to as equivalent temperature (TE), expresses the atmospheric heat content by combining into a single variable air temperature (T) and atmospheric moisture. As a result, TE, rather than T alone, is an alternative metric for assessing atmospheric warming, which depicts heat content. Over the mid-latitudes, TE and T generally present similar magnitudes during winter and early spring, in contrast with large differences observed during the growing season in conjunction with increases in summer humidity. TE has generally increased during the recent decades, especially during summer months. Large trend differences between T and TE occur at the surface and lower troposphere, decrease with altitude, and then fade in the upper troposphere. TE is linked to the large scale climate variability and helps better understand the general circulation of the atmosphere and the differences between surface and upper air thermal discrepancies. Moreover, when compared with T alone, TE is larger in areas with higher physical evaporation and transpiration rates and is more correlated to biomass seasonal variability.