摘要:青藏高原冬春积雪和地表热源的气候效应是青藏高原气候动力学的两个重要内容。大量资料分析和数值试验研究均表明这两个因子对亚洲季风有一定的预测意义,本文对此做了比较系统的回顾和总结,并进一步比较了青藏高原积雪和地表热源影响东亚和南亚夏季降水的异同。结果表明,东亚夏季降水在年际和年代际尺度上均存在"三极型"和"南北反相"型的空间分布特征,高原春季地表热源在年代际和年际尺度上主要影响东亚夏季降水"三极型"模态;在年代际尺度上它是中国东部出现"南涝北旱"格局的重要原因,而高原冬季积雪的作用相反。另一方面,高原冬季积雪在年际和年代际尺度上对印度夏季风降水的预测效果均要优于高原地表热源。无论是空间分布还是时间演变特征,高原冬季积雪与春季地表热源整体上均无统计意义上的显著联系。不断完善高原地面观测网和改进模式在高原地区的模拟性能,将是进一步深入理解高原积雪和地表热源影响亚洲季风物理过程和机制的关键所在。
关键词:青藏高原/
积雪深度/
地表热源/
亚洲夏季风
Abstract:The climate effect of the Tibetan Plateau (TP) snow depth and surface heat source are two major topics of the TP climate dynamics. Numerous results from data analysis and numerical modeling have confirmed that both the TP snow depth and surface heat source can be utilized as the precursors of the Asian summer monsoon anomaly. This paper provides an overall review on relevant studies, and the differences and similarities between impacts of these two factors on the East Asian and South Asian summer precipitation are further discussed. It is shown that East Asian summer precipitation has two typical spatial patterns on both the interannual and interdecadel timescales, i.e., the triple pattern and the North and South reversed-phase pattern. On the interannual and interdecadel timescales, the triple rainfall pattern is mainly affected by the TP surface heat source, and decadal changes in the South flood-North drought rainfall pattern over eastern China is also largely affected by the surface heat source. However, the impact of the TP snow depth seems to be opposite to that of the surface heat source. Particularly, the TP winter snow depth has a better predictive meaning for the Indian summer monsoon rainfall than the TP surface heat source on both timescales. Statistically, there is no robust relationship between the TP winter snow depth and spring surface heat source on both their spatial distributions and time series. A better ground observation network and improved model performance over the TP are imperative to obtain more insights of the potential physical progresses and mechanisms for the impacts of the TP snow depth and surface heat source on the Asian summer monsoon.
Key words:Tibetan Plateau/
Snow depth/
Surface heat source/
Asian summer monsoon
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