Refined Characteristics of Moisture Cycling over the Inland River Basin Using the WRF Model and the Finer Box Model: A Case Study of the Heihe River Basin (original) (raw)
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In this study, the moisture source/sink and long-distance moisture transport associated with the summer precipitation in the mid-lower reaches of the Yangtze River Valley (YRV) over China have been investigated based on both data analysis and numerical simulations using the regional climate model RegCM3. The study focused on both a case of the 1998 summer flood events and the interannual variation of summer precipitation during 1961-2005 in the YRV. The results show that 1) the low latitudinal band from the Bay of Bengal, Indochina Peninsula, South China Sea to the Philippine Island is the major moisture source region for the summer precipitation in the YRV; 2) an eastward moisture transport from the Bay of Bengal and a westward moisture transport from the Philippines Sea meet at the South China Sea, where a main water vapor channel forms and advances north-northwestward and turns northeastward in the vicinity of the eastern Tibetan Plateau and South China to the YRV; 3) the long-distance moisture transport from the eastern Indian Ocean-South China Sea to the YRV contributes to more than half of the summer precipitation in the YRV. Furthermore, it is shown that RegCM3 driven by the NCEP/NCAR reanalysis is able to reproduce the overall climatological water vapor transport in East Asia and the features of the water vapor flux for flooding and drought years in the YRV as well as simulate the YRV flood events in the summer of 1998 reasonably well. 1
Climate Dynamics, 2018
Current climate models commonly overestimate precipitation over the Tibetan Plateau (TP), which limits our understanding of past and future water balance in the region. Identifying sources of such models' wet bias is therefore crucial. The Himalayas is considered a major pathway of water vapor transport (WVT) towards the TP. Their steep terrain, together with associated small-scale processes, cannot be resolved by coarse-resolution models, which may result in excessive WVT towards the TP. This paper, therefore, investigated the resolution dependency of simulated WVT through the central Himalayas and its further impact on precipitation bias over the TP. According to a summer monsoon season of simulations conducted using the weather research forecasting (WRF) model with resolutions of 30, 10, and 2 km, the study found that finer resolutions (especially 2 km) diminish the positive precipitation bias over the TP. The higher-resolution simulations produce more precipitation over the southern Himalayan slopes and weaker WVT towards the TP, explaining the reduced wet bias. The decreased WVT is reflected mostly in the weakened wind speed, which is due to the fact that the high resolution can improve resolving orographic drag over a complex terrain and other processes associated with heterogeneous surface forcing. A significant difference was particularly found when the model resolution is changed from 30 to 10 km, suggesting that a resolution of approximately 10 km represents a good compromise between a more spatially detailed simulation of WVT and computational cost for a domain covering the whole TP.
Precipitation recycling ratio and water vapor sources on the Tibetan Plateau
Precipitation recycling ratio (i.e., evaporation-precipitation feedback strength) and water vapor sources are two key aspects of regional water cycle, and their quantification is essential for understanding water cycle processes and their changes. The results of existing studies on the precipitation recycling ratio and water vapor sources for the Tibetan Plateau were highly controversial. This article clarifies different frameworks for understanding the water cycle. It points out that (1) the ratio of evaporation to precipitation depends mainly on climate regimes, while the precipitation recycling ratio is closely related to both the climate regimes and the scale of the region of interest, and (2) the water vapor sources depend on the traced period (precipitating or non-precipitating period) and the degree of tracing. Within the same theoretical framework, there is no fundamental conflict among the results of different studies on the water cycle in the Tibetan Plateau.
Atmospheric moisture budget and floods in the Yangtze River basin, China
Theoretical and Applied Climatology, 2009
In this paper, we explored the trends of the atmospheric moisture budget, precipitation, and streamflow in summer during 1961 to 2005 and possible correlations between them by using the linear regression method in the Yangtze River basin, China. The results indicate that: (1) increasing tendencies can be detected in the atmospheric moisture budget, precipitation and streamflow in the Yangtze River basin; however, the significant increasing trends occur only in the atmospheric moisture budget and precipitation in the middle and lower Yangtze River basin;
2015
To obtain long term accurate high resolution precipitation for the Heihe River Basin (HRB), Weather Research and Forecasting (WRF) model simulations were performed using two different initial boundary conditions, with nine microphysical processes for different analysis parameterization schemes. High spatial-temporal precipitation was simulated from 2000 to 2013 and a suitable set of initial, boundary, and micro parameters for the HRB was evaluated from the Heihe Watershed Allied Telemetry Experimental Research project and Chinese Meteorological Administration data at hourly, daily, monthly, and annual time scales using various statistical indicators. It was found that annual precipitation has gradually increased over the HRB since 2000. Precipitation mostly occurs in summer and is higher in monsoon-influenced areas. High elevations experience winter snowfall. Precipitation is higher in the eastern upstream area than in the western upstream, area; however, the converse occurs in winter. Precipitation gradually increases with elevation from 1000 m to 4000 m, and the maximum precipitation occurs at the height of 3500-4000 m, then the precipitation slowly decreases with elevation from 4000 m to the top over the Qilian Mountains. Precipitation is scare and has a high temporal variation in the OPEN ACCESS Remote Sens. 2015, 7 9231 downstream area. Results are systematically validated using the in situ observations in this region and it was found that precipitation simulated by the WRF model using suitable physical configuration agrees well with the observation over the HRB at hourly, daily, monthly and yearly scales, as well as at spatial pattern. We also conclude that the dynamic downscaling using the WRF model is capable of producing high-resolution and reliable precipitation over complex mountainous areas and extremely arid environments. The downscaled data can meet the requirement of river basin scale hydrological modeling and water balance analysis.
Remote Sensing, 2015
To obtain long term accurate high resolution precipitation for the Heihe River Basin (HRB), Weather Research and Forecasting (WRF) model simulations were performed using two different initial boundary conditions, with nine microphysical processes for different analysis parameterization schemes. High spatial-temporal precipitation was simulated from 2000 to 2013 and a suitable set of initial, boundary, and micro parameters for the HRB was evaluated from the Heihe Watershed Allied Telemetry Experimental Research project and Chinese Meteorological Administration data at hourly, daily, monthly, and annual time scales using various statistical indicators. It was found that annual precipitation has gradually increased over the HRB since 2000. Precipitation mostly occurs in summer and is higher in monsoon-influenced areas. High elevations experience winter snowfall. Precipitation is higher in the eastern upstream area than in the western upstream, area; however, the converse occurs in winter. Precipitation gradually increases with elevation from 1000 m to 4000 m, and the maximum precipitation occurs at the height of 3500-4000 m, then the precipitation slowly decreases with elevation from 4000 m to the top over the Qilian Mountains. Precipitation is scare and has a high temporal variation in the OPEN ACCESS Remote Sens. 2015, 7 9231 downstream area. Results are systematically validated using the in situ observations in this region and it was found that precipitation simulated by the WRF model using suitable physical configuration agrees well with the observation over the HRB at hourly, daily, monthly and yearly scales, as well as at spatial pattern. We also conclude that the dynamic downscaling using the WRF model is capable of producing high-resolution and reliable precipitation over complex mountainous areas and extremely arid environments. The downscaled data can meet the requirement of river basin scale hydrological modeling and water balance analysis.
Climate Dynamics, 2021
Rainfall is one of the most influential climatic factors on regional development and environment, and changes in rainfall intensity are of specific concern. In the Huaihe River Valley (HRV), heavy rainfall is a primary trigger of floods. However, the difference in the origin of moisture contributed to heavy rainfall and light rainfall is rarely studied and not entirely understood. This study analyzes the rainfall moisture sources in association with different categories of rainfall intensity over the HRV during 1980-2018 using the Water Accounting Model with ERA-Interim reanalysis and precipitation observations from China Meteorological Administration. The results show that the moisture for the HRV summer rainfall is mainly from terrestrial subregion (40%), the Indian Ocean (27%), the Pacific Ocean (25%), and the local HRV (8%). In addition, moisture sources differ substantially between light and heavy rainfall. Specifically, the local HRV contributes more moisture to light rainfall (12%) compared to heavy rainfall (4%), whereas the Indian Ocean contributes more to heavy rainfall (33%) than to light rainfall (20%). The grids located in the southern source region make higher contribution ratio in heavy rainfall than in light rainfall. These results suggest that moisture from distant oceanic areas, especially the Indian Ocean, plays a crucial role in intense summer rainfall, whereas moisture from the land sources covering local grids plays a dominant role in light rainfall in the HRV.
Journal of Hydrology, 2006
Our study focuses on the simulation of heavy precipitation and floods over the Huaihe River Basin (270,000 km 2 ), one of the seven major river basins in China. The simulation covers two periods in 1998 (June 28-July 3, July 28-August 17) and a third period in 2003 (June 26-July 22). The former two periods, with eight meteorological cases each of duration 72-h, correspond to the Intensive Observation Period of HUBEX/MAGE (Huaihe River Basin Experiment/Monsoon Asian GEWEX Experiment). The period in 2003 with 10 cases is the second most severe flooding event on record. The Canadian atmospheric Mesoscale Compressible Community Model (MC2) is used for precipitation simulation in the hindcast mode for all cases. The Chinese Xinanjiang hydrological model driven by either rain gauge or MC2 precipitation is used to simulate hydrographs at the outlet of the Shiguanhe sub-basin (5930 km 2 ), part of the Huaihe River Basin. The MC2 precipitation is also evaluated using observations from rain gauges. Over the Huaihe River Basin, MC2 generally overestimates the basin-averaged precipitation. Three of the eight 1998 cases have a percentage error less than 50% with the fourth having an error of 54%, while six of the ten 2003 cases have errors less than 50%. The precipitation over five different sub-regions and the Shiguanhe sub-basin of the Huaihe River Basin from MC2 are also compared with values from the Chinese operational weather prediction model; the latter data are only available for the ten a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / j h y d r o l simulation using rain gauge precipitation as revealed by the Nash-Sutcliffe coefficients of 0.91 for both summers of 1998 and 2003. The simulation using MC2 precipitation shows a reasonable agreement of flood timing and peak discharges with Nash-Sutcliffe coefficients of 0.63 and 0.87 for the two 1998 periods, and 0.60 for 2003. The encouraging results demonstrate the potential of using mesoscale model precipitation for flood forecast, which provides a longer lead time compared to traditional methods such as those based on rain gauges, statistical forecast or radar nowcasts.