A 12-year high-resolution climatology of atmospheric water transport over the Tibetan Plateau

J Curio,D Scherer,F Maussion

doi:10.5194/esd-6-109-2015

J Curio, D Scherer + Show 1 more

Open Access

https://doi.org/10.5194/esd-6-109-2015

Copy DOI

Abstract

Abstract. The Tibetan Plateau (TP) plays a key role in the water cycle of high Asia and its downstream regions. The respective influence of the Indian and East Asian summer monsoon on TP precipitation and regional water resources, together with the detection of moisture transport pathways and source regions are the subject of recent research. In this study, we present a 12-year high-resolution climatology of the atmospheric water transport (AWT) over and towards the TP using a new data set, the High Asia Refined analysis (HAR), which better represents the complex topography of the TP and surrounding high mountain ranges than coarse-resolution data sets. We focus on spatiotemporal patterns, vertical distribution and transport through the TP boundaries. The results show that the mid-latitude westerlies have a higher share in summertime AWT over the TP than assumed so far. Water vapour (WV) transport constitutes the main part, whereby transport of water as cloud particles (CP) also plays a role in winter in the Karakoram and western Himalayan regions. High mountain valleys in the Himalayas facilitate AWT from the south, whereas the high mountain regions inhibit AWT to a large extent and limit the influence of the Indian summer monsoon. No transport from the East Asian monsoon to the TP could be detected. Our results show that 36.8 ± 6.3% of the atmospheric moisture needed for precipitation comes from outside the TP, while the remaining 63.2% is provided by local moisture recycling.

Highlights

The Tibetan Plateau (TP) is often referred to as the “world water tower” (Xu et al, 2008), as it is the source of many large Asian rivers such as the Indus, Ganges, Brahmaputra, Yellow River, Yangtze and Mekong
We provide an estimation of the budget of atmospheric water transport (AWT) and its share of the precipitation falling on the TP
The water vapour (WV) transport through the Brahmaputra Channel towards the Tibetan Plateau is higher for ERA-Interim than for HAR30

Summary

Introduction

The Tibetan Plateau (TP) is often referred to as the “world water tower” (Xu et al, 2008), as it is the source of many large Asian rivers such as the Indus, Ganges, Brahmaputra, Yellow River, Yangtze and Mekong. The TP is one of the most active centres in the word water cycle and constitutes an essential source of moisture for the downstream regions in East Asia (Immerzeel et al, 2010). The transport of moisture to the TP is crucial for a sustainable water supply in the downstream regions like the Yellow and Yangtze river valleys (Zhang et al, 2013). Moisture transport in and to the TP is influenced by mesoscale features (Sugimoto et al, 2008), but it is driven by large-scale atmospheric circulation, most notably the monsoon systems (Webster et al, 1998) and the mid-latitude westerlies (Schiemann et al, 2009). The surrounding high mountain ranges, Himalaya, Karakoram, Pamir, Tien Shan and Kunlun Shan, act as a barrier for the atmospheric moisture transport

Objectives

Results

Discussion

Conclusion