Abstract
AbstractThe changes in the frequency, duration, and intensity of summer heatwaves over central Asia during the period 1917–2016 were studied. On average, the frequency, duration, and intensity of heatwaves showed significant positive trends during the period 1917–2016, with enhanced rates during the last 50 years. During 1967–2016, the heatwave indices increased significantly in most of central Asia, especially in the western part. The number of heatwaves has increased by 1.3 times since the 1960s. Remarkable changes in the frequency and duration of heatwaves occurred during the 1990s in association with the inter‐decadal shift in the Silk Road pattern of atmospheric circulation around 1997. The results based on the ERA‐Interim reanalysis data set were well‐matched with the station observations during the period 1979–2016, whereas those based on the NCEP‐NCAR data set were less well matched. Heatwaves in central Asia were closely related to a zonal wave circulation pattern at 500 hPa with a centre of positive geopotential height anomalies over central Asia. This anomalous circulation pattern was rapidly enhanced during the 1990s, suggesting that large‐scale patterns of atmospheric circulation had a role in modulating the occurrence of heatwaves in central Asia.
Highlights
Heatwaves can have widespread effects on human health and mortality (Luber and McGeehin, 2008; McMichael and Lindgren, 2011), the regional economy (Easterling et al, 2000; Zander et al, 2015), and biophysical systems (Welbergen et al, 2008; Karoly, 2009)
Reanalysis data sets have been widely used in regional climate studies (Song and Zhang, 2007; Bao and Zhang, 2012), but their suitability and accuracy for describing the effects of climate change on heatwaves in central Asia need to be evaluated by comparison with station observations
The roughly opposite distribution of the 500-hPa geopotential height anomalies (Figure 7b) and the anomalous anticyclonic circulation (Figure 7f) in the later period suggests that there should have been a systematic change in the large-scale patterns of atmospheric circulation during the 1990s, which favoured the increase in the frequency of heatwaves in central Asia, consistent with the inter-decadal variation in the Silk Road pattern in the same period (Wang et al, 2017)
Summary
Heatwaves can have widespread effects on human health and mortality (Luber and McGeehin, 2008; McMichael and Lindgren, 2011), the regional economy (Easterling et al, 2000; Zander et al, 2015), and biophysical systems (Welbergen et al, 2008; Karoly, 2009). The scarcity or lack of long-term, homogeneous daily observations may lead to large uncertainties in studies of these events in central Asia (Klein Tank et al, 2006; Mamtimin et al, 2011; Hu et al, 2014) It has been well-known that non-climate factors such as changes in station location, environment, instrumentation, etc. Reanalysis data sets have been widely used in regional climate studies (Song and Zhang, 2007; Bao and Zhang, 2012), but their suitability and accuracy for describing the effects of climate change on heatwaves in central Asia need to be evaluated by comparison with station observations. This study analysed several heatwave indices in central Asia for the periods 1917–2016 and 1967–2016 based on quality-controlled and homogenized station observations. Running mean Tmax anomaly (Tmax minus the threshold of the day) during an event; and the heatwave amplitude (HWA), the largest Tmax anomaly (Tmax minus the threshold of the day) during all the heatwave events
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
