Drought characteristics and causes during summer maize growth period on Huang-Huai-Hai Plain based on daily scale SPEI

Huang-Huai-Hai Plain is an important area for summer maize production in China. The study of drought characteristics during summer maize growing period is of guiding significance for preventing drought and flooding and ensuring grain production. Based on daily meteorological data from 1960 to 2020 on Huang-Huai -Hai Plain, daily drought indicators were used to quantitatively identify drought conditions during summer maize growing period, analyze spatial and temporal evolution characteristics of drought, and explore the tele-connection between climate change and drought characteristics. Results showed that the most frequent and long-lasting drought occurred during the summer maize sowing-jointing stage on Huang-Huai-Hai Plain in the ]1960 s, and the entire plain was basically in a drought-prone area in the last 61a. Drought occurred less frequently, was short-lived throughout the reproductive stage during jointing-flowering, and was concentrated in the light drought zone. Drought frequency in the flowering-maturation stage was highest during the entire growth period, and drought frequency displayed a ' high-low-high ' three-stage distribution from south to north, mainly in drought-prone and extremely drought-prone areas. The drought barycenter during the sowing-jointing stage showed an east-west distribution pattern, and moved eastward from 1970 to 2000, displaying a south-north distribution pattern during jointing-flowering and flowering-maturation stages. Drought conditions at the sowing-jointing and flowering-maturation stages of summer maize displayed positive correlation with the occurrence of El Nin tilde o-Southern Oscillation (ENSO) warm events, and the flowering-maturation stage displayed a negative correlation with the occurrence of ENSO cold events. Oceanic Nino Index (ONI) was the most suitable climatic factor for analyzing causes of drought during summer maize growing period on Huang-Huai-Hai Plain.