Calculating the MCI Drought Index Using Short-Term Records of High-Density Meteorological Stations: A Feasibility Study

Precise drought monitoring is necessary for refined assessment of drought disasters. Usually, the meteorological drought composite index (MCI) is calculated based on long time series data over 30 years so as to fit stable probability distribution of precipitation. In order to fully utilize short-term high-density station data that are usually less than 20 years for drought monitoring, a parameter method is introduced in this study. The parameter method is to calculate the parameters of the probability distribution function of precipitation using data from neighboring long-term stations, and then interpolate them to that of short-term stations, so that MCI of short-term stations can be calculated. In this study, 31 national stations in 9 provinces/regions were selected for cross-checking and analysis of the errors of MCI calculated from the parameter method, as well as the interpolation method and the replacement method. The results show that except in the areas of Northwest China where meteorological stations are comparatively sparse, the MCI calculated by the parameter method is significantly better than that from the other two methods. Compared with the interpolation method, the accuracy of MCI calculated by the parameter method is improved in the central and eastern China, with improved accuracy by over 20% in most parts of North China, Northeast China, Yangtze River basin, Southwest China, and South China. The magnitude of error caused by the parameter method is close to or smaller than that caused by climate change, representing a good stability of the method. During the serious drought in the Yangtze River basin in 2022, comparison of the MCI results from 86 long-term stations and 2688 short-term high-density stations in Jiangxi Province shows that the parameter method used for calculating MCI of short-term stations can create high-resolution map for drought monitoring and provide refined services for drought disaster reduction.