An assessment method of annual climatic status in China using extreme climate indices: 2021 as an example

Abstract

A proper assessment of annual climatic status (ACS) is conducive to rationally formulating disaster prevention and mitigation measures. The former definition of ACS lacks either information on extreme climate or an intuitive grade feature service to the public. The ACS defined in the National Standard of the People's Republic of China (GBACS) only considers the accumulated climate effects of each weighted 10-d temperature/precipitation anomaly in a year. Under global warming, the losses caused by extreme climate events often have a significant impact on the grades of ACS, but this impact cannot be reasonably reflected by GBACS. This study proposed the assessment of ACS using extreme climate indices (extreme climate-based ACS (ECACS)) and compared it with GBACS. The results indicated that GBACS and ECACS can be used to evaluate the ACS from different angles. The ECACS is an important supplement to the GBACS, especially considering the years with frequently occurring extreme climate events. The sum of GBACS and ECACS is a reasonable and comprehensive way to evaluate the ACS. The empirical orthogonal function (EOF) analysis indicated a uniform mode (EOF1) and a dipole mode (EOF2) in GBACS and ECACS in China. The interannual variation characteristics of ECACS in northern and southern China (EOF2 pattern) are consistent with real climate features, which is conducive to providing better and more detailed regional information in the ACS forecast service. The results have essential instructive and application value for ACS assessment and government decision making.

Keywords

• Extreme climate indices
• Annual climatic status
• Temperature
• Precipitation