Modification of CI Comprehensive Meteorological Drought Index and Its Application in Ningxia
Based on daily mean temperature and precipitation data in recent 50 years at 20 meteorological stations in Ningxia,the CI index were corrected by using cumulative frequency method.The corrected CI index was more reasonable than the uncorrected one in reflecting the drought development and better in monitoring the drought events,so it was more suitable for drought monitoring in Ningxia.The applied analysis of corrected CI index indicates that the drought days increased and the intensity enhanced in Mahuangshan,Haiyuan,Guyuan and Xijiin spring,summer and fall.The drought days in all areas increased with a large increment in most areas and the intensity enhanced in fall.The increased trend of drought in Guyuan and its north was more obvious than that in southern humid regions in Ningxia,while the drought center transfered to the west,and Tongxin and Xingren had been the drought center since the 21st century.The change of drought days with most different drought levels were similar to the trend of the drought days and intensity variation.The increase of heavy and extreme drought days in most regions in spring had the largest contribution to drought days,while in summer,the change of the extreme drought days in Yanchi,Mahuangshan,Guyuan and Jingyuan had the largest contribution to drough days variation,and in fall,the middle drought days was the largest.From the 21 st century,the frequency of drought events reached the largest or the second largest in many areas in spring and summer,but in middle arid area it was larger than that in southern mountain region,and the extreme drought days were also the largest.Moreover,in fall,the frequency of drought events decreased,and the drought days with all levels were less than that in the 1980s and the 1990s.
NETL
NSTL
万方数据
维普
