Study Revealed Increased Compound Droughts and Heatwaves in a Double Pack in Central Asia

Compound droughts and heatwaves (CDHWs) are likely to cause more severe natural disasters than a single extreme event, and they have been exacerbated by rapid global warming. Quantitatively assessing the occurrence and scope of such extreme compound events is crucial.

In light of global warming, extreme weather events in arid regions of Central Asia are receiving increasing attention, largely due to the region’s role as the economic hub of the Silk Road. Moreover, with an oasis economy as the mainstay, a fragile desert ecosystem is more susceptible to extreme events. An in-depth understanding of the characteristics of climate change in Central Asia’s arid regions would provide a scientific basis for disaster prevention and mitigation, as well as for an active response to climate change.

Based on the Empirical Orthogonal Function (EOF), researchers from Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, The spatial and temporal changes of composite events in Central Asia from 1981 to 2018 and the intensity of composite events and single heat wave events were evaluated.

The results show that the number of CDHWs in the study region have increased over time and expanded in terms of area, especially in eastern and southwestern Central Asia. The tsum (total frequency of CDHWs) was 0.5 times higher than the total heatwave frequency and it increased at a rate of 0.17/yr. The maximum duration of tmax (maximum duration of CDHWs in days) was 17 days. Furthermore, the occurrence rate of tmax was 96.67%, and the AH (CDHWs’ accumulated heat) had a rate of 97.78%, which, upon examination of the spatial trend pattern, accounted for the largest increase in terms of area. We also found that the TAH (CDHWs’ average temperature anomalies, SPEI < ?0.5) shows obvious seasonality, with the increases in winter and spring being significantly greater than the increases in summer and autumn. The intensity of the CDHWs was stronger than that of a single extreme event, the temperature anomaly was higher than the average of 0.4–0.8 °C, and there was a north–south spatial pattern across the study region. In eastern and northwestern Central Asia, the AH and heatwaves (SPEI < ?0.5) increased by 15–30 times per year on average. During the transition from the base period to the reference period, CDHWs increased by 25%, and the number of dry days prior to the CDHWs decreased by 7.35 days.

The related results were published in Remote Sensing, entitled " Increased compound droughts and heatwaves in a double pack in Central Asia ".

Article link: https://www.mdpi.com/2072-4292/14/13/2959/htm 

Fig. 1 Schematic diagram of the principle of compound events

Fig. 2 Intensity comparison of compound event and single heat wave event