基于IAP AGCM4的欧亚大陆春季雪水当量可预报性评估

欧亚大陆积雪是重要的气候预测因子,评估其在气候模式中的预测潜力可为季节气候预测和模式发展提供重要参考。本文利用IAP AGCM4的多年集合后报结果,分析了欧亚大陆春季雪水当量的可预报性。结果表明该模式对提前1月后报的欧亚大陆春季雪水当量的空间分布,主要模态及变化趋势具有较好的可预报能力。此外模式对欧亚中高纬积雪的年际异常也具有较高的预报技巧,特别是高纬度区域。可预报性来源分析则表明,大气初始异常对欧亚中高纬积雪可预报性的影响与海温异常相比显得更为重要。

Potential predictability of Eurasian spring snow water equivalent in IAP AGCM4 hindcasts

The potential predictability and skill of Eurasian spring snow water equivalent(SWE)are explored by using a suite of ensemble hindcast experiments with the fourth-generation IAP AGCM(IAP AGCM4)and observations for the period 1982–2012.IAP AGCM4 is generally capable of reproducing the spatial distribution of Eurasian spring SWE;nevertheless,the model overestimates the SWE over Eurasia,possibly because of positive precipitation biases in wintertime.IAP AGCM4 can successfully capture the long-term trend and leading pattern of Eurasian spring SWE.Additionally,the spring SWE anomalies are generally predictable in many regions over Eurasia,especially at high latitudes;moreover,IAP AGCM4 exhibits a remarkable prediction skill for spring SWE anomalies over Eurasia in many years during 1982 to 2012.In order to reveal the relative impacts of SST anomalies and atmospheric initial conditions on the seasonal predictability of Eurasian spring SWE,two additional sets of experiments are carried out.Overall,atmospheric initial anomalies have a dominant role,though the impact of SSTs is not negligible.This study highlights the importance of atmospheric initialization in seasonal climate forecasts of spring SWE anomalies,especially at high latitudes.