Predicting Maize Production in Northeastern China: Unraveling the Influence of Summer Compound Heat-Drought Events through Physical Mechanisms

Northeastern China (NEC), known as the granary of China, is significantly affected by compound heat-drought events (CHDEs), which have detrimental impacts on maize production. This study aims to investigate the physical mechanisms underlying the occurrences of CHDEs on maize production in NEC. Our findings indicate that CHDEs are associated with anomalous positive geopotential height at 500 hPa, the presence of anticyclone at 850 hPa and a uniform downward motion in NEC, all of which are adverse to maize production. Using a year-to-year increment method, we reveal that several key factors collectively influence CHDEs and maize production in NEC, including sea ice concentration in the Barents Sea in May, sea surface temperature (SST) in the equatorial East Pacific in February and March, soil water over northwestern Siberia in April, and the North Atlantic Oscillation (NAO) in February. To differentiate the diverse influences of these key factors on CHDEs and maize production, we developed two distinct prediction models (Prediction Model #1 and #2). Both Prediction Model #1 (r=0.90, p<0.01) and #2 (r=0.91, p<0.01) demonstrate high correlation coefficients between predicted and observed values, as validated through leave-one-out cross-validation (Prediction Model #1: r=0.90, p<0.01; Prediction Model #2: r=0.90, p<0.01) and independent hindcasts (Prediction Model #1: r=0.72, p<0.01; Prediction Model #2: r=0.79, p<0.01). This study provides precise predictions of maize production in eastern China, offering significant safeguards for national food security.