scholarly journals Convection-permitting regional climate simulations over Tibetan Plateau: re-initialization versus spectral nudging

2021 ◽  
Author(s):  
Mengnan Ma ◽  
Pinhong Hui ◽  
Dongqing Liu ◽  
Peifeng Zhou ◽  
Jianping Tang
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate ◽  
Spectral Nudging ◽  
Climate Simulations

scholarly journals Convection-Permitting Regional Climate Simulations Over Tibetan Plateau: Re-Initialization Versus Spectral Nudging

2021 ◽  
Author(s):  
Mengnan Ma ◽  
Pinhong Hui ◽  
Dongqing Liu ◽  
Peifeng Zhou ◽  
Jianping Tang
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate ◽  
Wrf Model ◽  
Surface Air Temperature ◽  
Moisture Flux ◽  
Early Morning ◽  
Climate Simulation ◽  
Cold Bias ◽  
The Tibetan Plateau ◽  
Spectral Nudging

Abstract Two regional climate simulation experiments (spectral nudging and re-initialization) at convection-permitting scale are conducted using the WRF model over the Tibetan Plateau (TP). The surface air temperature (T2m) and the precipitation in summer during 2016–2018 are evaluated against the in-situ station observations and the Global Satellite Mapping of Precipitation (GSMaP) dataset. The results show that both experiments can successfully capture the spatial distribution and the daily variation of T2m and precipitation, with reasonable cold bias for temperature, dry bias for precipitation when compared with the station observations. In addition, the diurnal cycle of precipitation is investigated, indicating that both experiments tend to simulate the afternoon precipitation in advance and postpone the night precipitation. The precipitation bias is reduced by using the spectral nudging technique, especially at night and early morning. Possible causes for the differences between the two experiments are also analyzed. The daytime surface net radiation contributes a lot to the cold biases in the re-initialization experiment, and the stronger low-level moisture flux convergence leads to the wet biases. These results can provide valuable guidance for further fine-scale simulation studies over the TP.

scholarly journals Development and evaluation of spectral nudging strategy for the simulation of summer precipitation over the Tibetan Plateau using WRF (v4.0)

2021 ◽  
Vol 14 (5) ◽  
pp. 2827-2841
Author(s):  
Ziyu Huang ◽  
Lei Zhong ◽  
Yaoming Ma ◽  
Yunfei Fu
Keyword(s):  
Climate Change ◽  
Water Vapor ◽  
Tibetan Plateau ◽  
Regional Climate ◽  
Summer Precipitation ◽  
Horizontal Wind ◽  
The Tibetan Plateau ◽  
Model Simulations ◽  
Driving Field ◽  
Spectral Nudging

Abstract. Precipitation is the key component determining the water budget and climate change of the Tibetan Plateau (TP) under a warming climate. This high-latitude region is regarded as “the Third Pole” of the Earth and the “Asian Water Tower” and influences the eco-economy of downstream regions. However, the intensity and diurnal cycle of precipitation are inadequately depicted by current reanalysis products and regional climate models (RCMs). Spectral nudging is an effective dynamical downscaling method used to improve precipitation simulations of RCMs by preventing simulated fields from drifting away from large-scale reference fields, but the most effective manner of applying spectral nudging over the TP is unclear. In this paper, the effects of spectral nudging parameters (e.g., nudging variables, strengths, and levels) on summer precipitation simulations and associated meteorological variables were evaluated over the TP. The results show that using a conventional continuous integration method with a single initialization is likely to result in the over-forecasting of precipitation events and the over-forecasting of horizontal wind speeds over the TP. In particular, model simulations show clear improvements in their representations of downscaled precipitation intensity and its diurnal variations, atmospheric temperature, and water vapor when spectral nudging is applied towards the horizontal wind and geopotential height rather than towards the potential temperature and water vapor mixing ratio. This altering of the spectral nudging method not only reduces the wet bias of water vapor in the lower troposphere of the ERA-Interim reanalysis (when it is used as the driving field) but also alleviates the cold bias of atmospheric temperatures in the upper troposphere, while maintaining the accuracy of horizontal wind features for the regional model field. The conclusions of this study imply how driving field errors affect model simulations, and these results may improve the reliability of RCM results used to study the long-term regional climate change.

scholarly journals Development and evaluation of spectral nudging strategy for the simulation of summer precipitation over the Tibetan Plateau

2020 ◽  
Author(s):  
Ziyu Huang ◽  
Lei Zhong ◽  
Yaoming Ma ◽  
Yunfei Fu
Keyword(s):  
Climate Change ◽  
Water Vapor ◽  
Tibetan Plateau ◽  
Regional Climate ◽  
Summer Precipitation ◽  
Horizontal Wind ◽  
The Tibetan Plateau ◽  
Model Simulations ◽  
Spectral Nudging ◽  
Reference Fields

Abstract. Precipitation is the key component determining the water budget and climate change of the Tibetan Plateau (TP) under a warming climate. This high-latitude region is regarded as the Third Pole of the Earth and the Asian Water Tower and influences the eco-economy of downstream regions. However, the intensity and diurnal cycle of precipitation are inadequately depicted by current reanalysis products and regional climate models (RCMs). Spectral nudging is an effective dynamical downscaling method used to improve precipitation simulations of RCMs by preventing simulated fields from drifting away from large-scale reference fields, but the most effective manner of applying spectral nudging over the TP is unclear. In this paper, the effects of spectral nudging parameters (e.g., nudging variables, strengths and levels) on summer precipitation simulations and associated meteorological variables were evaluated over the TP. The results show that using a conventional continuous integration method with a single initialization is likely to result in the overforecasting of precipitation events and the overforecasting of horizontal wind speeds over the TP. In particular, model simulations show clear improvements in their representations of downscaled precipitation intensity and its diurnal variations, atmospheric temperature and water vapor when spectral nudging is applied towards the horizontal wind and geopotential height rather than towards the potential temperature and water vapor mixing ratio. This altering to the spectral nudging method not only reduces the wet bias of water vapor in the lower troposphere of the ERA-Interim reanalysis (when it is used as the reference fields) but also alleviates the cold bias of atmospheric temperatures in the upper troposphere, while maintaining the accuracy of horizontal wind features for the simulated fields. The conclusions of this study imply how reference fields errors impact model simulations, and these results may improve the reliability of RCM results used to study the long-term regional climate change.

scholarly journals Summer Regional Climate Simulations over Tibetan Plateau: gray-zone versus convection-permitting

2021 ◽  
Author(s):  
Mengnan Ma ◽  
Jianping Tang ◽  
Tinghai Ou ◽  
Shuyu Wang ◽  
Ziyue Guo
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate ◽  
Gray Zone ◽  
Climate Simulations ◽  
Zone Versus

Qinghai-Xizang (Tibetan) Plateau climate simulation using the regional climate model RegCM3

2013 ◽  
Vol 57 (3) ◽  
pp. 173-186 ◽  
Author(s):  
X Wang ◽  
M Yang ◽  
G Wan ◽  
X Chen ◽  
G Pang
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
Climate Simulation
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