Seasonality and spatial variability of dynamic precipitation controls on the Tibetan Plateau

Abstract

Abstract. The Tibetan Plateau (TP) is the origin of many large Asian rivers, which provide moisture for large regions in South and East Asia. Therefore, the water cycle on the TP and adjacent high mountain ranges and especially the precipitation distribution plays an important role for the water availability for billions of people in the regions downstream of the TP. Based on the High Asia Refined analysis (HAR) we analyse the influence of dynamic factors on precipitation, enhancing or suppressing precipitation development. We selected six precipitation controls, the horizontal and vertical wind speed at 300 hPa and in about two kilometres above ground, the atmospheric water transport, and the planetary boundary layer height. Focus of the study are the seasonality and the spatial variability of these precipitation controls and their dominant patterns. The results show that precipitation controls have different effects on precipitation in different regions and seasons. This depends mainly on the type of precipitation, convective or frontal/cyclonic precipitation. Additionally, the study reveals that the mid-latitude westerlies have a high impact on precipitation distribution on the TP and its surrounding year-round.

Atmospheric Water Transport to the Endorheic Tibetan Plateau and Its Effect on the Hydrological Status in the Region

“…In winter (December–February), the AW source only appears in the water bodies to the west of the ETP, such as the eastern Mediterranean, the Red Sea, and the Persian Gulf, as well as partial land areas adjacent to the southwestern ETP, with most of AW contributions less than 2 mm (Figures m–o). The local recycling almost disappears in this season due to frozen ground and high wind speed over the ETP that inhibit the formation of convection systems (Curio & Scherer, ; Guo & Wang, ). AW input to the ETP in winter is only 3–7% of the annual totals (Figure ).…”

“…Generally, AW transport to the ETP is dominated by the seasonal interaction between the westerlies and the Indian monsoon (Joswiak et al, ; Yao et al, , ), and the change of hydrological states over the TP is highly consistent with the interannual variability of large‐scale circulation systems (Curio & Scherer, ; Jiang & Ting, ; Li & Garzione, ; Mölg et al, ). For example, Gao et al () revealed that the humid southeastern TP was getting drier while the vast arid and semiarid northwest was getting wetter in 1979–2011; this was attributed to the poleward shift of the westerly jet and the intensification of Indian monsoon.…”

The Formation of a Dry‐Belt in the North Side of Central Himalaya Mountains

“…Nevertheless, the precipitation in WRF control case and GPM differs in the amount but generally consistent in the spatial pattern with respect to the dry‐belt detected region. Besides, other studies also support the finding that WRF is capable of depicting the spatial pattern of precipitation over the TP (Maussion et al, ; Curio & Scherer, ; Ma et al, ; Collier & Immerzeel, ; Bookhagen & Burbank, , Bookhagen & Burbank, ).…”

“…There has been many studies in the water vapor transport (WVT) and precipitation over the TP. For example, Curio and Scherer () indicated that the WVT from outside the region can contribute to about 40% precipitation over the TP. Bookhagen and Burbank (, ) showed that the high terrain is a barrier that rarely permits the water vapor to enter the TP and only the valleys over HMs are the primary vapor channels.…”

“…Precipitation in mountains directly affects hydrological processes and water resources downstream (Curio & Scherer, ). The central Himalayas possess the world highest and steepest mountains (e.g., Mt.…”