31 Mar 2022
31 Mar 2022

Mid-Holocene climate of the Tibetan Plateau and hydroclimate in three major river basins based on high-resolution regional climate simulations

Yiling Huo, William Richard Peltier, and Deepak Chandan Yiling Huo et al.
  • Department of Physics, University of Toronto, Toronto, M5S 1A7, Canada

Abstract. The Tibetan Plateau (TP) exerts strong influence on both regional and global climate through thermal and mechanical forcings. The TP also contains the headwaters of large Asian rivers that sustain billions of people and numerous ecosystems. Understanding the characteristics and changes to the hydrological regimes on the TP during the mid-Holocene (MH) will help understand the expected future changes. Here, an analysis of the hydroclimates over the headwater regions of three major rivers originating in the TP, namely the Yellow, Yangtze and Brahmaputra rivers is presented, using an ensemble of climate simulations, which have been dynamically downscaled to 10-km resolution with the Weather Research and Forecasting Model (WRF) coupled to the hydrological model WRF-Hydro. Basin-integrated changes in the seasonal cycle of hydroclimatic variables are considered. In the global model, we have also incorporated Green Sahara (GS) boundary conditions in order to compare with standard MH simulations (which do not include GS) and to capture interactions between the GS and the river hydrographs over the TP. Model-data comparisons show that the dynamically downscaled simulations significantly improve the regional climate simulations over the TP in both the modern day and the MH, highlighting the crucial role of downscaling in both present-day and past climates, although both global and regional models have a cold bias in modern-day simulations and underestimate the wet anomalies inferred from proxy data in the east and southeast part of the TP. TP precipitation is also greatly influenced by the inclusion of a GS, with a particularly large increase predicted over the southern TP, as well as a delay in the monsoon withdrawal. The model performance was first evaluated over the upper basins of the three rivers before the hydrological responses to the MH forcing in streamflow as well as temperature, rainfall and snowmelt for the three basins were quantified via the WRF simulations.

Yiling Huo 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 egusphere-2022-40', Anonymous Referee #1, 29 Apr 2022
    • AC1: 'Reply on RC1', Yiling Huo, 24 Jul 2022
  • RC2: 'Comment on egusphere-2022-40', Anonymous Referee #2, 10 Jun 2022
    • AC2: 'Reply on RC2', Yiling Huo, 24 Jul 2022

Yiling Huo et al.

Yiling Huo et al.


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Short summary
Understanding the hydrological changes on the Tibetan Plateau (TP) during the mid-Holocene (MH; a period with warmer summers than today) will help understand the expected future changes. This study analyses the hydroclimates over the headwater regions of three major rivers originating on the TP, using dynamically downscaled climate simulations. Model-data comparisons show that the dynamically downscaling significantly improves both the present-day and MH regional climate simulations on the TP.