Remote Impact of Preceding Soil Moisture on the May—June Precipitation of Huang‐Huai Wheat Region in China

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Abstract
As a major winter wheat‐producing area, the Huang‐Huai Plain in China relies critically on May–June precipitation during the harvest period for food security. This study identifies preceding March–April soil moisture in the north Black Sea and Caspian Sea (NBC) region as a key precursor for precipitation anomalies in the Huang‐Huai wheat region in May–June, and reveals a significant positive correlation between them. The mechanism responsible for this lag relation involves the persistence of soil moisture, Rossby wave propagation and water vapour transport. Results suggest that the March—April NBC soil moisture anomaly is able to persist until May—June. Through this soil memory, the March–April wetter NBC soil anomaly causes the May–June cold air anomaly locally via the evaporative cooling effect, triggering upper‐level circulation anomalies and Rossby wave train propagating southeastward. The wave train drives anomalous southerly winds, enhancing water vapour transport and leading to the water vapour convergence over the Huang‐Huai region, and finally favours the positive precipitation anomaly over the Huang‐Huai region. The drier NBC soil anomaly corresponds to the opposite circulation and precipitation anomaly. For the detailed Rossby wave dynamics, the numerical experiments confirm that feedback between atmospheric circulation and temperature over the west end of China plays a critical role in guiding the Rossby wave pathway initiated by the NBC soil moisture forcing. This study provides new insights into precipitation prediction during the Huang‐Huai wheat harvest period, emphasising the remote influence of mid‐high‐latitude soil moisture on the climate prediction in the winter wheat‐producing area in China.
Funding Information
  • National Key Research and Development Program of China (2024YFF0808404)
  • National Natural Science Foundation of China (42175048)
  • National Natural Science Foundation of China (42175078)

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