Changes of Extreme Climate Indices on the Mongolian Plateau during 1981-2020 Based on ERA5 Reanalysis

Abstract

Abstract The Mongolian Plateau (MP) is susceptible to extreme climate events due to its unique geographical location and socio-economic conditions. The focus of this study was to analyze the changes in extreme climate indices on the MP based on the ERA5 reanalysis dataset, as well as to investigate the relationship between these indices and atmospheric circulation indices. 1) Results indicated that the inter-annual variation trends of Summer days, Warm days, and Warm nights have significantly increased across the entire MP, with the central region experiencing a higher probability of extreme hot events. The inter-decadal variation of extreme hot indices rose the fastest from period 2 (1991-2000) to period 3 (2001-2010). 2) Results showed a substantial decrease in extreme cold events throughout the study period, with the most rapid decrease observed from period 1 (1981-1990) to period 2 (1991-2000), except for Frost days. 3) There was a decrease in extreme wet indices from 1981-2020. The Simple Precipitation Intensity Index (SDII) and Total precipitation in wet days (PRCPTOT) exhibited a significant descending trend in the northern and northeastern MP. Decadal variations showed a decrease in extreme precipitation, with the most significant decline observed between period 2 (1991-2000) to period 3 (2001-2010). 4) Extreme precipitation indices indicate a negative correlation with the Atlantic Meridional Mode (AMM). The Arctic Oscillation (AO) displayed a negative correlation with extreme cold indices, whereas the Pacific Decadal Oscillation (PDO) demonstrated a negative correlation with extreme hot indices.