Construction and application of the combined drought index based on the development process of drought in the atmosphere-soil-vegetation system

An appropriate drought index and high-resolution data are the basis of accurate and precise drought monitoring. In this study, we constructed a Combined Drought Index (hereafter CDI) based on the response relationships between meteorological drought (SPEI), soil drought (SMP) and vegetation drought (LAIP) using integrated multisource data of China National Meteorological Observatory, Soil Moisture of CMA Land Data Assimilation System with 0.0625°×0.0625° resolution and MODIS LAI with 500 m×500 m resolution. The monitor results of CDI were assessment at station scale and regional scale with 10 km×10 km resolution in Northeast China. The results show that CDI overcomes the shortcomings of single meteorological drought index, which cannot accurately reflect agricultural drought. The misjudgment that attributes the vegetation growth variation caused by other disasters to drought based on single vegetation growth index is corrected. The CDI can reflect the effects of irrigation on drought and monitor the occurrence and development of drought and its impact on crops and other vegetation growth. The above results indicate that CDI classification monitoring results have a clear biophysical significance, a fine spatial resolution and a strong practical guidance. It has application potentials in the monitoring, assessment and prediction of drought occurrence and development and drought impact on agriculture and other green vegetations.