Indian irrigation effects on precipitation over the Tibetan Plateau

2020 ◽  
Author(s):  
Yaqiong Lu ◽  
Shan Lin
Keyword(s):  
Heat Flux ◽  
Water Vapor ◽  
Tibetan Plateau ◽  
Climate Model ◽  
Regional Climate ◽  
Sensible Heat Flux ◽  
Summer Precipitation ◽  
Back Trajectory ◽  
The Tibetan Plateau ◽  
Irrigation Effects

<p>Indian agriculture equipped the most intensive irrigation worldwide and still maintains an increasing trend of irrigation due to the decreasing of Indian summer monsoon rainfall. Irrigation could largely increase soil moisture and evapotranspiration while cooling air temperature. Several researches showed that Indian irrigation did not significantly contribute to local precipitation, so will the Indian irrigation affect the adjacent regions, such as the Tibetan Plateau is unclear. Here, we set up 10-years simulations for two nested domains (30-10km) over the South-East Asia to quantify the irrigation effects with a coupled dynamic crop model and regional climate model (WRF4.0-CLM4Crop). Besides the numeric simulations, we adopted a water vapor back trajectory tracking method to track where the evaporation from the irrigated land fall as precipitation. Our preliminary results showed that Indian irrigation did not significantly affects temperature, sensible heat flux, and latent heat flux over the Tibetan Plateau, but the water vapor from Indian irrigation contributed to 10% of the summer precipitation on the Tibetan Plateau.</p>

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.

Projected changes in precipitation recycling over the Tibetan Plateau based on a global and regional climate model

2021 ◽  
Author(s):  
Hongwen Zhang ◽  
Yanhong Gao
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate Model ◽  
Climate Model ◽  
Seasonal Pattern ◽  
Regional Climate ◽  
Back Trajectory ◽  
The Tibetan Plateau ◽  
Climate System Model ◽  
Precipitation Recycling ◽  
Mean Square Errors

AbstractPrecipitation recycling, as represented by the precipitation contributed by locally evaporated water vapor, is a key indicator of regional changes in the water cycle. The Quasi Isentropic Back-Trajectory method, combined with a global climate model [Community Climate System Model (CCSM)] and regional climate model [Weather Research and Forecasting (WRF) model simulation forced by CCSM (WRF-CCSM)], was used to analyze historical (1982–2005) and future (2090–2099) precipitation recycling over the Tibetan Plateau (TP). The study focuses on the differences in the projection of precipitation recycling ratio (PRR) changes and relevant mechanisms between the fine-resolution (30 km) WRF-CCSM and coarse-resolution (~110 km) CCSM simulations. Compared with CCSM, the biases and root-mean-square errors of the historical evapotranspiration and precipitation over the TP were greatly reduced in the WRF-CCSM simulation, particularly in precipitation. Using WRF-CCSM outputs, higher PRRs in all elevation bands, as well as the opposite seasonal pattern and linear trend of PRR for the river basins in the northern TP, were revealed. Unlike the CCSM projections, WRF-CCSM projects increasing trends of PRR changes with elevation under the RCP4.5 and RCP8.5 scenarios, with the largest increase at an elevation of about 5000 m. WRF-CCSM projects a diverse spatial and seasonal pattern of PRR changes, in contrast to the uniform decrease projected by CCSM. The larger fractional increases of future evapotranspiration contribution (precipitation contributed by local evapotranspiration) per unit warming than precipitation changes in WRF-CCSM suggests an enhanced contribution of locally evaporated moisture to total precipitation in the future under the RCP4.5 and RCP8.5 scenarios.

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 Method Development for Estimating Sensible Heat Flux over the Tibetan Plateau from CMA Data

2009 ◽  
Vol 48 (12) ◽  
pp. 2474-2486 ◽  
Author(s):  
Kun Yang ◽  
Jun Qin ◽  
Xiaofeng Guo ◽  
Degang Zhou ◽  
Yaoming Ma
Keyword(s):  
Heat Flux ◽  
Tibetan Plateau ◽  
Method Development ◽  
Sensible Heat Flux ◽  
Atmospheric Stability ◽  
Surface Energy Budget ◽  
New Method ◽  
The Tibetan Plateau ◽  
Sensible Heat ◽  
Hourly Data

Abstract To clarify the thermal forcing of the Tibetan Plateau, long-term coarse-temporal-resolution data from the China Meteorological Administration have been widely used to estimate surface sensible heat flux by bulk methods in many previous studies; however, these estimates have seldom been evaluated against observations. This study at first evaluates three widely used bulk schemes against Tibet instrumental flux data. The evaluation shows that large uncertainties exist in the heat flux estimated by these schemes; in particular, upward heat fluxes in winter may be significantly underestimated, because diurnal variations of atmospheric stability were not taken into account. To improve the estimate, a new method is developed to disaggregate coarse-resolution meteorological data to hourly according to statistical relationships derived from high-resolution experimental data, and then sensible heat flux is estimated from the hourly data by a well-validated flux scheme. Evaluations against heat flux observations in summer and against net radiation observations in winter indicate that the new method performs much better than previous schemes, and therefore it provides a robust basis for quantifying the Tibetan surface energy budget.

Elevation-dependent sensible heat flux trend over the Tibetan Plateau and its possible causes

2018 ◽  
Vol 52 (7-8) ◽  
pp. 3997-4009 ◽  
Author(s):  
Lihua Zhu ◽  
Gang Huang ◽  
Guangzhou Fan ◽  
Xia Qü ◽  
Zhibiao Wang ◽  
...  
Keyword(s):  
Heat Flux ◽  
Tibetan Plateau ◽  
Sensible Heat Flux ◽  
The Tibetan Plateau ◽  
Sensible Heat

Decomposition of Future Moisture Flux Changes over the Tibetan Plateau Projected by Global and Regional Climate Models

2019 ◽  
Vol 32 (20) ◽  
pp. 7037-7053
Author(s):  
Hongwen Zhang ◽  
Yanhong Gao ◽  
Jianwei Xu ◽  
Yu Xu ◽  
Yingsha Jiang
Keyword(s):  
Tibetan Plateau ◽  
Climate Model ◽  
Dynamical Downscaling ◽  
Regional Climate ◽  
Moisture Flux ◽  
Historical Period ◽  
The Tibetan Plateau ◽  
Dynamic Component ◽  
Coarse Resolution ◽  
The Future

Abstract To meet the requirement of high-resolution datasets for many applications, a dynamical downscaling approach using a regional climate model (the WRF Model) driven by a global climate model (CCSM4) has been adopted. This study focuses on projections of future moisture flux changes over the Tibetan Plateau (TP). First, the downscaling results for the historical period (1980–2005) are evaluated for precipitation P, evaporation E, and precipitation minus evaporation P − E against Global Land Data Assimilation System (GLDAS) data. The mechanism of P − E changes is analyzed by decomposition into dynamic, thermodynamic, and transient eddy components. Whether the historical period changes and mechanisms continue into the future (2010–2100) is investigated using the WRF and CCSM model projections under the RCP4.5 and RCP8.5 scenarios. Compared with coarse-resolution forcing, downscaling was found to better reproduce the historical spatial patterns and seasonal mean of annual average P, E, and P − E over the TP. WRF projects a diverse spatial variation of P − E changes, with an increase in the northern TP and a decrease in the southern TP, compared with the uniform increase in CCSM. The dynamic component dominates P − E changes for the historical period in both the CCSM and WRF projections. In the future, however, the thermodynamic component in CCSM dominates P − E changes under RCP4.5 and RCP8.5 from the near-term (2010–39) to the long-term (2070–99) future. Unlike the CCSM projections, the WRF projections reproduce the mechanism seen in the historical period—that is, the dynamic component dominates P − E changes. Furthermore, future P − E changes in the dynamical downscaling are less sensitive to warming than its coarse-resolution forcing.

scholarly journals Evaluation of Noah-MP Land-Model Uncertainties over Sparsely Vegetated Sites on the Tibet Plateau

Atmosphere ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 458
Author(s):  
Guo Zhang ◽  
Fei Chen ◽  
Yueli Chen ◽  
Jianduo Li ◽  
Xindong Peng
Keyword(s):  
Heat Flux ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
Tibetan Plateau ◽  
Sensible Heat Flux ◽  
Limiting Factors ◽  
Tibet Plateau ◽  
The Tibetan Plateau ◽  
Annual Total ◽  
The Impact

The water budget and energy exchange over the Tibetan Plateau (TP) region play an important role on the Asian monsoon. However, it is not well presented in the current land surface models (LSMs). In this study, uncertainties in the Noah with multiparameterization (Noah-MP) LSM are assessed through physics ensemble simulations in three sparsely vegetated sites located in the central TP. The impact of soil organic matter on energy flux and water cycles, along with the influence of uncertainties in precipitation are explored using observations at those sites during the third Tibetan Plateau Experiment from 1August2014 to31July2015. The greatest uncertainties are in the subprocesses of the canopy resistance, soil moisture limiting factors for evaporation, runoff (RNF) and ground water, and surface-layer parameterization. These uncertain subprocesses do not change across the different precipitation datasets. More precipitation can increase the annual total net radiation (Rn), latent heat flux (LH) and RNF, but decrease sensible heat flux (SH). Soil organic matter enlarges the annual total LH by ~26% but lessens the annual total Rn, SH, and RNF by ~7%, 7%, and 39%, respectively. Its effect on the LH and RNF at the Nagqu site, which has a sand soil texture type, is greater than that at the other two sites with sandy loam. This study highlights the importance of precipitation uncertainties and the effect of soil organic matter on the Noah-MP land-model simulations. It provides a guidance to improve the Noah-MP LSM further and hence the land-atmosphere interactions simulated by weather and climate models over the TP region.

Evaluation of the dependence of the sensible heat flux trend on elevation over the Tibetan Plateau in CMIP5 models

2020 ◽  
Author(s):  
Lihua Zhu ◽  
Gang Huang ◽  
Guangzhou Fan ◽  
Xia Qü ◽  
Zhibiao Wang ◽  
...  
Keyword(s):  
Heat Flux ◽  
Tibetan Plateau ◽  
Sensible Heat Flux ◽  
Cmip5 Models ◽  
The Tibetan Plateau ◽  
Sensible Heat

scholarly journals Surface-sensible and latent heat fluxes over the Tibetan Plateau from ground measurements, reanalysis, and satellite data

2014 ◽  
Vol 14 (11) ◽  
pp. 5659-5677 ◽  
Author(s):  
Q. Shi ◽  
S. Liang
Keyword(s):  
Heat Flux ◽  
Tibetan Plateau ◽  
Latent Heat ◽  
Latent Heat Flux ◽  
Vegetation Index ◽  
Sensible Heat Flux ◽  
Heat Fluxes ◽  
Future Research ◽  
The Tibetan Plateau ◽  
Mean Square Errors

Abstract. Estimations from meteorological stations over the Tibetan Plateau (TP) indicate that since the 1980s the surface-sensible heat flux has been decreasing continuously, and modeling studies suggest that such changes are likely linked to the weakening of the East Asian Monsoon through exciting Rossby wave trains. However, the spatial and temporal variations in the surface-sensible and latent heat fluxes over the entire TP remain unknown. This study aims to characterize the spatial and seasonal variability of the surface-sensible and latent heat fluxes at 0.5° over the TP from 1984 to 2007 by synthesizing multiple data sources including ground measurements, reanalysis products, and remote-sensing products. The root mean square errors (RMSEs) from cross validation are 14.3 Wm−2 and 10.3 Wm−2 for the monthly fused sensible and latent heat fluxes, respectively. The fused sensible and latent heat-flux anomalies are consistent with those estimated from meteorological stations, and the uncertainties of the fused data are also discussed. The associations among the fused sensible and latent heat fluxes and the related surface anomalies such as mean temperature, temperature range, snow cover, and normalized difference vegetation index (NDVI) in addition to atmospheric anomalies such as cloud cover and water vapor show seasonal dependence, suggest that the land–biosphere–atmosphere interactions over the TP could display nonuniform feedbacks to the climate changes. It would be interesting to disentangle the drivers and responses of the surface-sensible and latent heat-flux anomalies over the TP in future research from evidences of modeling results.

scholarly journals Future Climate in the Tibetan Plateau from a Statistical Regional Climate Model

2013 ◽  
Vol 26 (24) ◽  
pp. 10125-10138 ◽  
Author(s):  
Xiuhua Zhu ◽  
Weiqiang Wang ◽  
Klaus Fraedrich
Keyword(s):  
Tibetan Plateau ◽  
Regional Climate Model ◽  
Climate Model ◽  
Regional Climate ◽  
Early Summer ◽  
Maximum Temperature ◽  
Boreal Summer ◽  
The Tibetan Plateau ◽  
Temperature Trends ◽  
Precipitation Increase

Abstract The authors use a statistical regional climate model [Statistical Regional Model (STAR)] to project the Tibetan Plateau (TP) climate for the period 2015–50. Reanalysis datasets covering 1958–2001 are used as a substitute of observations and resampled by STAR to optimally fit prescribed linear temperature trends derived from the Max Planck Institute Earth System Model (MPI-ESM) simulations for phase 5 of the Coupled Model Intercomparison Project (CMIP5) under the representative concentration pathway 2.6 (RCP2.6) and RCP4.5 scenarios. To assess the related uncertainty, temperature trends from carefully selected best/worst ensemble members are considered. In addition, an extra projection is forced by observed temperature trends in 1958–2001. The following results are obtained: (i) Spatial average temperature will increase by 0.6°–0.9°C; the increase exceeds 1°C in all months except in boreal summer, thus indicating a reduced annual cycle; and daily minimum temperature rises faster than daily maximum temperature, resulting in a narrowing of the diurnal range of near-surface temperature. (ii) Precipitation increase mainly occurs in early summer and autumn possibly because of an earlier onset and later withdrawal of the Asian summer monsoon. (iii) Both frost and ice days decrease by 1–2 days in spring, early summer, and autumn, and the decrease of frost days on the annual course is inversely related to the precipitation increase. (iv) Degree-days increase all over the TP with peak amplitude in the Qaidam Basin and the southern TP periphery, which will result in distinct melting of the local seasonal frozen ground, and the annual temperature range will decrease with stronger amplitude in south TP.

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