Preprints
https://doi.org/10.5194/hess-2022-28
https://doi.org/10.5194/hess-2022-28
 
03 Feb 2022
03 Feb 2022
Status: a revised version of this preprint is currently under review for the journal HESS.

Historical droughts manifest an abrupt shift to a wetter Tibetan Plateau

Yongwei Liu1, Yuanbo Liu1, Wen Wang2, Han Zhou3, and Lide Tian4 Yongwei Liu et al.
  • 1Key Laboratory of Watershed Geography Sciences, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, China
  • 2State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, Hohai University, Nanjing, China
  • 3Wuhan University of Technology, Wuhan, China
  • 4Yunnan University, China

Abstract. The Tibetan Plateau (TP) plays a vital role in Asian and even global atmospheric circulation, through the interactions between land and atmosphere. It experienced significant climate warming and spatially and temporally variant wetting over the past half century. Because of the importance of land surface status to the interactions, determining the wetting/drying of the TP from individual changes in precipitation (Prep) or temperature is difficult. Soil moisture (SM) is the water synthesis of the surface status. The persistent deficit of SM (SM drought) is more sensitive to climate change than normal SM. This study first explored the climate wetting/drying of the TP from variations in historical SM droughts over 1961–2014, with a focus on spatiotemporal patterns, long-term variations, and climate causes of summer (May–September) SM droughts based on multiple observation and reanalysis data. The results showed comparatively frequent and severe droughts in the central and southern regions, particularly in the semi-arid and sub-humid zones. SM drought exhibited an abrupt and significant (p < 0.05) alleviation in the central TP in the mid-1990s. The prominent drought alleviation indicated a hydro-climate shift to a wetter plateau, not merely steady trends in the literature. We demonstrated that the wetting shift was dominated by Prep over potential evapotranspiration (PET). By contrast, the in-phase trends before and after the shift were predominantly driven by the PET. Furthermore, the Prep dominance was largely attributed to a phase transition of the Atlantic multi-decadal oscillation from cold to warm, accompanied by a weakening westerly since the mid-1990s. The PET control on in-phase trends was realized through multiple climate control of temperature, radiation, and vapor pressure deficit. Regionally, the wetting shift was distinct from semi-arid to sub-humid, and from sub-humid to humid climate. Such spatiotemporal changes may affect the TP’s atmospheric circulation and, subsequently, the Asian monsoon and global circulation, in addition to fragile ecosystems in the TP.

Yongwei Liu et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2022-28', Anonymous Referee #1, 28 Feb 2022
    • AC1: 'Reply on RC1', Yongwei Liu, 29 Apr 2022
  • RC2: 'Comment on hess-2022-28', Anonymous Referee #2, 01 Mar 2022
    • AC2: 'Reply on RC2', Yongwei Liu, 29 Apr 2022

Yongwei Liu et al.

Yongwei Liu et al.

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Short summary
This study first investigated the wetting/drying of the Tibetan Plateau (TP) from variations in soil moisture (SM) droughts. We found TP experienced an abrupt and significant wetting shift in the mid-1990s, not merely the steady trends in the literature. This shift is dominated by precipitation and attributed to the North Atlantic Oscillation. The wetting shift indicates a climate regime change. Our innovative work provides critical implications for further knowledge of the TP climate.