Global pattern of short-term concurrent hot and dry extremes and its relationship to large-scale climate indices

The short-term concurrent hot and dry extreme (SCHDE) event has recently stimulated intensive scientific interests due to its rapid onset, severe intensity, and devastating impacts on agriculture and natural ecosystems. The SCHDE is mainly caused by an increase in actual evapotranspiration (ET) accompanied with a decrease in soil moisture (SM) due to anomalously high surface temperature (T (air)). Based on the daily datasets of precipitation (P), T (air), ET, and SM from four global modelling products as well as large-scale climate indices, we analyse globally the spatio-temporal evolution of SCHDE events at both grid and basin scales. Results indicate that SCHDE events occur mostly in Northern Hemisphere regions with relatively low P. During 1980-2010, due to significant global warming (0.30 degrees C center dot decade(-1)) the global mean occurrence frequency of SCHDE has an significantly increasing trend (0.34%center dot decade(-1)) along with a weakly decreasing trend of SM (-0.08%center dot decade(-1)) and a significantly increasing trend of ET (8.34 mm center dot decade(-1)). Overall, North America and Asia have a higher frequency of SCHDE occurrence than other continents. The variability of T (air) is mainly responsible for the variability of SCHDE occurrence over the equator regions, while the variability of ET (SM) plays an important role in SCHDE occurrence variability in the cropland-dominant (mid- and high-latitude) regions. Globally, the relative contribution of T (air) to SCHDE variability is the largest, followed by ET and SM. Lastly, we found that the cold phases of the Pacific Decadal Oscillation during the La Nina events (i.e., negative Multivariate ENSO Index) are conducive to the intensification of SCHDE events in southern South America and Australia.