Examining the Spring Discontinuity in Daily Temperature Ranges

Abstract

The atmosphere and biosphere both change rapidly throughout midlatitude spring. Many weather variables are modified during this season, including the diurnal temperature range (DTR). The mean DTR trend displays a discontinuity at the onset of spring characterized by a rapid increase for several weeks, followed by an abrupt leveling off. The trend then remains essentially flat throughout the remainder of the warm season. These DTR changes reflect the interactive role many weather variables play with surface-layer processes. Thus, diagnosing the causes of these variations may provide background information for numerous global change analyses, as daily temperature data become increasingly available worldwide. The results of this study suggest that several factors (snow cover loss, more frequent southerly winds, and increased ceiling heights) are responsible for the initial rapid increase in the DTR. The second half of the discontinuity (subsequent leveling off) is connected with increased atmospheric moisture and coincides with the onset of plant transpiration.