A Comparison of the Characteristics of Extreme Drought During the Late 20^th and Early 21^st Centuries Over Eurasia and North America

Abstract

The atmospheric general circulation character during summer droughts over Eastern Europe / Western Russia and North America from 1970 – 2020 is examined here. A criterion to examine atmospheric drought events encompassed the summer season was used to determine which years were driest using precipitation, evaporation, and areal coverage. The relationship between drought and atmospheric character using the Dzerzeevsky climatic classification scheme, atmospheric blocking, teleconnections, and information entropy are used to study the atmospheric dynamics. The National Centers for Environmental Prediction (NCEP) re-analyses data set archived at the National Center for Atmospheric Research (NCAR) in Boulder, CO, USA is used to examine the synoptic character and calculate the dynamic quantities for these dry events. The results demonstrate that extreme droughts over North America are associated with a long warm and dry period of weather and the development of a moderate ridge over the central USA driven by surface processes. Extreme droughts over Eastern Europe and Western Russia are driven by the occurrence of prolonged blocking episodes as well as surface processes.