资源环境科技发展态势分析平台

The present study investigates the dominant pattern of precipitation variability over the mid-high-latitude Asia during summer for the period 1981–2018 and associated precursory signals in the atmosphere. An in-phase co-variability is identified in July precipitation between the Kazakhstan-Xinjiang region and North China, which is the leading mode of precipitation variability. Geopotential height anomalies over the Mediterranean Sea and Kara Sea regions show persistence from June to July and contribute to July geopotential height and associated precipitation anomalies over the Kazakhstan-Xinjiang region through the dispersion of Rossby wave energy. The geopotential height anomalies over the Kara Sea also affect downstream geopotential height anomalies from the eastern coast of China to the Okhotsk Sea and related precipitation over North China through a Rossby wave from the Kara Sea to the Okhotsk Sea via the Lake Baikal. In addition, the Tibetan Plateau geopotential height anomaly during June may modulate downstream geopotential height anomalies around the Okhotsk Sea during the ensuing July through a slowly-varying northeastward shift and extension of atmospheric anomalies on intraseasonal timescale. The joint effect of geopotential height anomalies over the three regions during June leads to the co-variability of precipitation between the Kazakhstan-Xinjiang region and North China in July. Based on the above physical connection, we defined a June Kara-Mediterranean-Tibetan Plateau geopotential height index. This atmospheric precursory index shows a high skill in predicting the co-variability of July precipitation.