Exploring Abrupt Alternations Between Wet and Dry Conditions on the Basis of Historical Observations and Convection-Permitting Climate Model Simulations

Exploring the dynamic evolution of the abrupt alternation between wet and dry spells in adjacent months plays a crucial role in water resources planning and agricultural development in a changing climate. The dry-wet abrupt alternation (DWAA) has been studied based on hydrometeorological observations over the past several years. However, little effort has been made to explore DWAA from a climate projection standpoint. Furthermore, few studies have investigated potential interrelationships between DWAA and heavy rainfall. In this study, the interrelationships between DWAA events and heavy rainfall with various intensities as well as potential evapotranspiration are revealed explicitly through the convection-permitting climate simulations for 10 climate divisions over Texas in the United States. Our findings disclose that the increasing heavy rainfall and potential evapotranspiration lead to more frequent occurrence of DWAA events over a larger spatial extent. Heavy rainfall with daily precipitation greater than 20 mm contributes most to the occurrence of DWAA. In addition, a severe phenomenon of dry-wet-dry alternation is projected to appear due to the increasing number of heavy rainfall and drought events as well as the deteriorated soil water holding capacity under global warming.