辽宁春末霜冻年代际变化特征及其与海温的关系

中国东北地处高纬度地区,春季霜冻频繁发生,对农业生产有严重威胁,分析东北春末霜冻的气候特征及影响因子可以为其中长期预测提供可靠科学依据。该研究以辽宁省为例,利用近60年气象台站观测资料和气象再分析资料,采用诊断分析方法,根据辽宁作物生育期,定义4月20日-5月31日辽宁地区春末霜冻指数（LSFI）,研究其年代际尺度变化特征及对应的大尺度环流和前期海温关键区。结果如下：LSFI存在周期为14.25 a的年代际变化。辽宁地区春末霜冻事件的增强在年代际尺度上对应大气环流特征为中高纬度有明显波列,东北亚上空为深厚气旋性异常,东北冷涡偏强,与西伯利亚附近的反气旋性异常结合,伴随副高偏南,有利于冷空气持续影响辽宁。此外,LSFI的年代际变化与海温显著相关,相关联的海温关键区在1997年前后出现变化,1997年以前与春季（3、4月）北大西洋“三极子”海温模态显著相关,而1997年之后则与前冬北太平洋年代际振荡联系密切,转变原因可能为海温模态的年代际转变。以上结果可以提高霜冻灾害的预测能力,为辽宁地区春末霜冻长期风险预报提供有效预测因子。

The interdecadal variation of last spring frost and the relationship with SST in Northeast China, Liaoning

The spring frost events in Northeast China pose a serious threat to agricultural production. To clarify the characteristic of late spring frost events in Northeast China and provide reliable predictor is very important. Based on the meteorological observation data and meteorological reanalysis data in recent 60 years, the late spring frost index in Liaoning province (LSFI) was defined. The relationship with the temporal characteristics of LSFI and the related large-scale circulation and the sea surface temperature (SST) anomaly factor was investigated. The results show that the LSFI is characterized by interdecadal variation with 14.25-a periods. The interdecadal enhancement is corresponding to a "Silk Road" pattern at middle latitudes, with anomalous cyclones over Northeast Asia, which is beneficial to the cold air transport. Meanwhile, there is a strong cyclonic anomaly over the Okhotsk Sea, which makes the cold air invaded at high latitudes affecting Liaoning province. And the southerly subtropical high is disadvantage to warm and humid air to north. In addition, SST also have important effects on frost events. And there is a shift between the interdecadal variation of late spring frost event and SST around 1997. Before 1997, it was significant correlated with the North Atlantic "+-+" triple mode of SST in the early spring (March and April). The wave energy originated from the North Atlantic converged in Northeast Asia, which strengthens the cyclone anomaly. After 1997, it was positively correlated with the Pacific Decadal Oscillation (PDO) in the previous winter. The wave energy mainly originated from the Pacific Ocean and spread eastward to Northeast Asia via the North Atlantic. Therefore, the results provide reliable prediction factors for the long-term risk prediction of the late spring frost in Liaoning.