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Quantifying the Spatial Characteristics of the Moisture Transport Affecting Precipitation Seasonality and Recycling Variability in Central Asia

Abstract

Moisture contribution and transport pathways for Central Asia (CA) are quantitatively examined using the Lagrangian water cycle model based on reanalysis and observational data to explain the precipitation seasonality and the moisture transport variation during 1979–2015. Westerly-related (northwesterly and westerly) transport explains 42% of CA precipitation and dominates in southwest CA, where precipitation is greatest in the cold season. Southeast CA, including part of Northwest China, experiences its maximum precipitation in the warm season and is solely dominated by southerly transport, which explains about 48% of CA precipitation. The remaining 10% of CA precipitation is explained by northerly transport, which steadily impacts north CA and causes a maximum in precipitation in the warm season. Most CA areas are exposed to seasonally varying moisture transport, except for southeast and north CA, which are impacted by southerly and northerly transport year-round. In general, the midlatitude westerlies-driven transport and the Indian monsoon-driven southerly-related transport explain most of the spatial differences in precipitation seasonality over CA. Moreover, the contribution ratio of local evaporation in CA to precipitation exhibits significant interdecadal variability and a meridionally oriented tripole of moisture transport anomalies. Since the early 2000s, CA has experienced a decade of anomalously low local moisture contribution, which seems jointly determined by the weakened moisture contribution from midlatitudes (the Atlantic, Europe, and CA itself) and the enhanced contribution from high latitudes (West Siberia and the Arctic) and tropical areas (South Asia and the Indian Ocean).

摘 要

本文基于再分资料和观测资料,利用拉格朗日框架下的水循环模型定量化分析了1979–2015中亚地区降水的水汽贡献和输送路径及其季节性变化。研究表明,中亚西南部地区的降水在冷季达到其最大值,该区域的水汽来源主要受西风(包括西北风和西风)水汽输送控制 ,且整体而言西风水汽输送贡献了42%的中亚降水。中亚东南部地区(含中国西北)则相反,最大降水通常出现在暖季,且常年相对稳定地受控于南风水汽输送。南风水汽输送则解释了中亚整体降水的48%。除以上两支主要的输送带外,北风水汽输送供给了剩余约10%的中亚降水,且其常年稳定地影响中亚北部地区,并导致该区域的最大降水季出现在暖季。整体而言,除了东南部地区和北部地区分别全年稳定地受控于南风水汽输送和北风水汽输送外,中亚其他区域的水汽来源路径存在明显的季节变化。这种降水季节变化的空间差异主要是由中纬度西风驱动的水汽输送与印度季风驱动的南风水汽输送共同作用所决定的。作为另一重要的水汽来源,中亚区域的局地蒸发引起的降水占比例存在显著的年代际变率,并同时对应了经向三极型水汽输送异常型。自2000s早期开始,来自中亚内部局地蒸发的水汽贡献处于长达十余年的异常低值期。这一时期出现了持续减弱的来自中纬度地区(包括大西洋、欧洲和中亚自身)的水汽贡献,同时伴随着增强的来自高纬度地区(包括西西伯利亚和北极)和热带地区(包括南亚和印度洋)的水汽贡献。

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Acknowledgements

This research was jointly supported by the Strategic Priority Research Program of Chinese Academy of Sciences under Grant No. XDA20020201 and the National Natural Science Foundation of China (NSFC) under Grant Nos. 41975099, U2006210, and 41475072.

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Correspondence to Lijuan Hua.

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Article Highlights

• The moisture contribution and transport pathway for Central Asia in relation to the seasonal variability of the precipitation is quantitatively examined.

• The areas affected by westerly transport and monsoon transport to Central Asia, as well as their seasonal variations of precipitation, are presented.

• The interdecadal variability of the moisture contribution from local evaporation in Central Asia combined with the external moisture transport is revealed.

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Zhong, L., Hua, L., Gong, Z. et al. Quantifying the Spatial Characteristics of the Moisture Transport Affecting Precipitation Seasonality and Recycling Variability in Central Asia. Adv. Atmos. Sci. 39, 967–984 (2022). https://doi.org/10.1007/s00376-021-1383-5

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  • DOI: https://doi.org/10.1007/s00376-021-1383-5

Key words

  • Central Asia
  • precipitation seasonality
  • recycling ratio
  • moisture transport
  • dynamical recycling model
  • interdecadal variability

关键词

  • 中亚
  • 降水季节变化
  • 再循环比
  • 水汽输送
  • 动力再循环模型
  • 年代际变率