Large-scale pattern of the wintertime diurnal temperature range variations over North America during 1979–2018

Abstract

The atmospheric circulation and remote forcing of SST anomalies play an imporant role in the formation of large-scale cloud cover and precipitation anomalies as well as the patterns of diurnal temperature range (DTR) variability. In this study, the dominant patterns of the wintertime DTR variations over North America (NA) and the underlying mechnisms are investigated based on observational and reanalysis datasets during 1979–2018. The first leading mode is characterized by a widespread same-sign loading in the majority of NA. The corresponding principal component (PC) shows an obvious interannual time-scale variations. The second mode displays a north-south dipole-like pattern in the NA and the corresponding PC exhibits a decline trend during 1979–2018. Both patterns of DTR variations are closely associated with the changes in local cloud cover and precipitation. Furthermore, clear effects are identified of El Niño-Southern Oscillation (ENSO) and Tropical/Northern Hemisphere (TNH) teleconnection on the formation of the two dominant patterns of wintertime DTR variabilty over NA through changing the atmospheric circulation and associated transportation of temperature and moisture. Our findings provide a new insight into understanding the DTR changes during recent decades.