scholarly journals An integration of gauge, satellite and reanalysis precipitation datasets for the largest river basin of the Tibetan Plateau

2020 ◽  
Author(s):  
Yuanwei Wang ◽  
Lei Wang ◽  
Xiuping Li ◽  
Jing Zhou ◽  
Zhidan Hu
Keyword(s):  
Tibetan Plateau ◽  
River Basin ◽  
Spatial Scales ◽  
Water Security ◽  
The Tibetan Plateau ◽  
Brahmaputra River ◽  
Hydrological Simulation ◽  
Precipitation Product ◽  
Basin Scale ◽  
Long Term Trends

Abstract. As the largest river basin of the Tibetan Plateau, the Upper Brahmaputra River Basin (also called “Yarlung Zangbo” in Chinese) has profound impacts on the water security of local and downstream inhabitants. Precipitation in the basin is mainly controlled by the Indian Summer Monsoon and Westerly, and is the key to understand the water resources available in the basin; however, due to sparse observational data constrained by a harsh environment and complex topography, there remains a lack of reliable information on basin-wide precipitation (there are only nine national meteorological stations with continuous observations). To improve the accuracy of basin-wide precipitation data, we integrate various gauge, satellite and reanalysis precipitation datasets, including GLDAS, ITP-Forcing, MERRA2, TRMM and CMA datasets, to develop a new precipitation product for the 1981–2016 period over the Upper Brahmaputra River Basin, at 3-hour and 5-km resolution. The new product has been rigorously validated at different temporal scales (e.g. extreme events, daily to monthly variability, and long-term trends) and spatial scales (point- and basin-scale) with gauge precipitation observations, showing much improved accuracies compared to previous products. An improved hydrological simulation has been achieved (low relative bias: −5.94 %; highest NSE: 0.643) with the new precipitation inputs, showing reliability and potential for multi-disciplinary studies. This new precipitation product is openly accessible at https://doi.org/10.5281/zenodo.3711155 (Wang et al., 2020) and, additionally at the National Tibetan Plateau Data Center (https://data.tpdc.ac.cn, login required).

scholarly journals An integration of gauge, satellite, and reanalysis precipitation datasets for the largest river basin of the Tibetan Plateau

2020 ◽  
Vol 12 (3) ◽  
pp. 1789-1803 ◽  
Author(s):  
Yuanwei Wang ◽  
Lei Wang ◽  
Xiuping Li ◽  
Jing Zhou ◽  
Zhidan Hu
Keyword(s):  
Tibetan Plateau ◽  
River Basin ◽  
Spatial Scales ◽  
Water Security ◽  
The Tibetan Plateau ◽  
Brahmaputra River ◽  
Hydrological Simulation ◽  
Precipitation Product ◽  
Basin Scale ◽  
Long Term Trends

Abstract. As the largest river basin of the Tibetan Plateau, the upper Brahmaputra River basin (also called “Yarlung Zangbo” in Chinese) has profound impacts on the water security of local and downstream inhabitants. Precipitation in the basin is mainly controlled by the Indian summer monsoon and westerly and is the key to understanding the water resources available in the basin; however, due to sparse observational data constrained by a harsh environment and complex topography, there remains a lack of reliable information on basin-wide precipitation (there are only nine national meteorological stations with continuous observations). To improve the accuracy of basin-wide precipitation data, we integrate various gauge, satellite, and reanalysis precipitation datasets, including GLDAS, ITP-Forcing, MERRA2, TRMM, and CMA datasets, to develop a new precipitation product for the 1981–2016 period over the upper Brahmaputra River basin, at 3 h and 5 km resolution. The new product has been rigorously validated at different temporal scales (e.g., extreme events, daily to monthly variability, and long-term trends) and spatial scales (point and basin scale) with gauge precipitation observations, showing much improved accuracies compared to previous products. An improved hydrological simulation has been achieved (low relative bias: −5.94 %; highest Nash–Sutcliffe coefficient of efficiency (NSE): 0.643) with the new precipitation inputs, showing reliability and potential for multidisciplinary studies. This new precipitation product is openly accessible at https://doi.org/10.5281/zenodo.3711155 (Wang et al., 2020) and additionally at the National Tibetan Plateau Data Center (https://data.tpdc.ac.cn, last access: 10 July 2020, login required).

Spatiotemporal characteristics of water budget dynamic in the Yarlung Tsangpo River basin of Tibetan Plateau based on multi-source datasets

2020 ◽  
Author(s):  
Yao Jiang ◽  
Zongxue Xu
Keyword(s):  
Tibetan Plateau ◽  
River Basin ◽  
Water Budget ◽  
Water Resource Management ◽  
The Tibetan Plateau ◽  
Water Budgets ◽  
Climate Conditions ◽  
Basin Scale ◽  
Yarlung Tsangpo ◽  
Yarlung Tsangpo River

<p>Understanding the dynamics of basin-scale water budgets over the Tibetan Plateau (TP) is significant for hydrology and water resource management in the southern and eastern Asia. However, a detailed water balance analysis is limited by the lack of adequate hydro-climatic observations in this region. In this study, we investigate the spatiotemporal variation of water budget components (e.g. precipitation P, evapotranspiration ET and runoff Q etc.) in the Yarlung Tsangpo River basin (YTB) of southeast TP during the period of 1975-2015 through using multi-source datasets (e.g. insitu observation, remote sensing data products, reanalysis outputs and model simulations etc.). The change trend of water budget components and vegetation parameters was analyzed in the YTB on interannual scale. The results indicated that the detailed water budgets are different from upstream to downstream YTB due to different temperature, vegetation cover and evapotranspiration, which are mainly affected by different climate conditions. In the whole basin, precipitation that are mainly during June to October was the major contributor to the runoff. The P and Q were found to show a slight but insignificant decrease in most regions of YTB since the late 1990s, which showed positive relationships with the weakening Indian summer monsoon. While the ET showed an insignificant increase across most of the YTB, especially in the middle basin. The runoff coefficient (Q/P) exhibited an indistinctively decreasing trend which may be, to some extent, due to the overlap effects of ET increase and snow and glacier changes. The obtained results offer insights into understanding the evolution mechanism of hydrological processes in such a data-sparse region under changing environment.</p>

scholarly journals Performance of the RegCM4.6 for High-Resolution Climate and Extreme Simulations over Tibetan Plateau

Atmosphere ◽  
2020 ◽  
Vol 11 (10) ◽  
pp. 1104
Author(s):  
Huanghe Gu ◽  
Xiaoyan Wang
Keyword(s):  
High Resolution ◽  
Tibetan Plateau ◽  
River Basin ◽  
Regional Climate ◽  
The Tibetan Plateau ◽  
Brahmaputra River ◽  
Temperature And Precipitation ◽  
Resolution Model ◽  
Resolution Simulation ◽  
Precipitation Trends

This paper presents an evaluation of the Regional Climate Model version 4.6.1 (RegCM4) at a high-resolution simulation at 10 km applied over the Tibetan Plateau. This simulation covers the period from 1980 to 2010 and is nested in a RegCM4 simulation at 30-km resolution, which is driven by the main European Centre for Medium-Range Weather and Forecasting reanalysis (ERA-Interim reanalysis) dataset. A new daily observational dataset is employed as reference data to evaluate the temperature and precipitation simulations for the inner model domain and the five largest river basins that originated in the Tibetan Plateau (TP) (i.e., the source region of Yangtze River, Yellow River, Mekong River, Salween River, and Brahmaputra River). In comparison with the low-resolution model run (R30), the cold biases for the area-averaged temperature were reduced from −2.5 to −0.1° C and the wet biases in summer mean precipitation were reduced from 58% to 25% in the high-resolution model run (R10). The substantial warming trends and slight wetting trends were basically reproduced by both RegCM4 simulations. Annual mean precipitation trends from both simulations show a better agreement with the observations than the ERA-Interim, which underestimates the annual mean precipitation trends in most regions, whereas both the RegCM4 and ERA-Interim consistently underestimate the annual mean temperature trends when compared with the observations. In addition, the overall improvement in the modeling trends for annual mean temperature and precipitation in R10 is limited when compared with R30. The extreme precipitation was also captured reasonably in both RegCM4 simulations, and the better performance is detected in the R10 simulation. The findings above show that RegCM4 with a high-resolution of 10 km is capable of reproducing the major regional climate features over the TP, but a great deal of uncertainties still exist, especially in the subregion of the Brahmaputra River basin. Thus, the 10-km resolution simulation in RegCM4 may still not be fine enough to resolve the topoclimates over the complex Himalayan terrain in the Brahmaputra River basin.

Identification of Synchronicity in Deterministic Chaotic Attractors for the Downscaling Process in the Bogotá River Basin

2021 ◽  
Author(s):  
Santiago Duarte ◽  
Gerald Corzo ◽  
Germán Santos
Keyword(s):  
Time Series ◽  
Time Delay ◽  
River Basin ◽  
Spatial Scales ◽  
Climatic Variables ◽  
Chaotic Attractors ◽  
Multiple Attractors ◽  
Nearest Neighbours ◽  
Basin Scale ◽  
Non Linear

<p>Bogotá’s River Basin, it’s an important basin in Cundinamarca, Colombia’s central region. Due to the complexity of the dynamical climatic system in tropical regions, can be difficult to predict and use the information of GCMs at the basin scale. This region is especially influenced by ENSO and non-linear climatic oscillation phenomena. Furthermore, considering that climatic processes are essentially non-linear and possibly chaotic, it may reduce the effectiveness of downscaling techniques in this region. </p><p>In this study, we try to apply chaotic downscaling to see if we could identify synchronicity that will allow us to better predict. It was possible to identify clearly the best time aggregation that can capture at the best the maximum relations between the variables at different spatial scales. Aside this research proposes a new combination of multiple attractors. Few analyses have been made to evaluate the existence of synchronicity between two or more attractors. And less analysis has considered the chaotic behaviour in attractors derived from climatic time series at different spatial scales. </p><p>Thus, we evaluate general synchronization between multiple attractors of various climate time series. The Mutual False Nearest Neighbours parameter (MFNN) is used to test the “Synchronicity Level” (existence of any type of synchronization) between two different attractors. Two climatic variables were selected for the analysis: Precipitation and Temperature. Likewise, two information sources are used: At the basin scale, local climatic-gauge stations with daily data and at global scale, the output of the MPI-ESM-MR model with a spatial resolution of 1.875°x1.875° for both climatic variables (1850-2005). In the downscaling process, two RCP (Representative Concentration Pathways)  scenarios are used, RCP 4.5 and RCP 8.5.</p><p>For the attractor’s reconstruction, the time-delay is obtained through the  Autocorrelation and the Mutual Information functions. The False Nearest Neighbors method (FNN) allowed finding the embedding dimension to unfold the attractor. This information was used to identify deterministic chaos at different times (e.g. 1, 2, 3 and 5 days) and spatial scales using the Lyapunov exponents. These results were used to test the synchronicity between the various chaotic attractor’s sets using the MFNN method and time-delay relations. An optimization function was used to find the attractor’s distance relation that increases the synchronicity between the attractors.  These results provided the potential of synchronicity in chaotic attractors to improve rainfall and temperature downscaling results at aggregated daily-time steps. Knowledge of loss information related to multiple reconstructed attractors can provide a better construction of downscaling models. This is new information for the downscaling process. Furthermore, synchronicity can improve the selection of neighbours for nearest-neighbours methods looking at the behaviour of synchronized attractors. This analysis can also allow the classification of unique patterns and relationships between climatic variables at different temporal and spatial scales.</p>

scholarly journals Evaluating the streamflow simulation capability of PERSIANN-CDR daily rainfall products in two river basins on the Tibetan Plateau

2016 ◽  
Author(s):  
Xiaomang Liu ◽  
Tiantian Yang ◽  
Koulin Hsu ◽  
Changming Liu ◽  
Soroosh Sorooshian
Keyword(s):  
Tibetan Plateau ◽  
River Basin ◽  
Yangtze River ◽  
Yellow River ◽  
Yangtze River Basin ◽  
Information Source ◽  
Hydrologic Model ◽  
The Tibetan Plateau ◽  
Climate Data ◽  
Streamflow Simulation

Abstract. On the Tibetan Plateau, the limited ground-based rainfall information owing to a harsh environment has brought great challenges to hydrological studies. Satellite-based rainfall products, which allow a better coverage than both radar network and rain gauges on the Tibetan Plateau, can be suitable observation alternatives for investigating the hydrological processes and climate change. In this study, a newly developed daily satellite-based precipitation product, termed Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks–Climate Data Record (PERSIANN-CDR), is used as input of a hydrologic model to simulate streamflow in the upper Yellow and Yangtze River Basin on the Tibetan Plateau. The results show that the simulated streamflow using PERSIANN-CDR precipitation is closer to observation than that using limited gauge-based precipitation interpolation in the upper Yangtze River Basin. The simulated streamflow using gauge-based precipitation are higher than the streamflow observation during the wet season. In the upper Yellow River Basin, PERSIANN-CDR precipitation and gauge-based precipitation have similar good performance in simulating streamflow. The evaluation of streamflow simulation capability in this study partly indicates that PERSIANN-CDR rainfall product has good potentials to be a reliable dataset and an alternative information source besides the sparse gauge network for conducting long term hydrological and climate studies on the Tibetan Plateau.

scholarly journals Comparison of satellite-based evapotranspiration estimates over the Tibetan Plateau

2016 ◽  
Vol 20 (8) ◽  
pp. 3167-3182 ◽  
Author(s):  
Jian Peng ◽  
Alexander Loew ◽  
Xuelong Chen ◽  
Yaoming Ma ◽  
Zhongbo Su
Keyword(s):  
Tibetan Plateau ◽  
Vegetation Index ◽  
Water Cycle ◽  
Global Climate ◽  
Spatial Scales ◽  
Accurate Estimation ◽  
The Tibetan Plateau ◽  
North West ◽  
Comparison Results ◽  
Normalised Difference Vegetation Index

Abstract. The Tibetan Plateau (TP) plays a major role in regional and global climate. The understanding of latent heat (LE) flux can help to better describe the complex mechanisms and interactions between land and atmosphere. Despite its importance, accurate estimation of evapotranspiration (ET) over the TP remains challenging. Satellite observations allow for ET estimation at high temporal and spatial scales. The purpose of this paper is to provide a detailed cross-comparison of existing ET products over the TP. Six available ET products based on different approaches are included for comparison. Results show that all products capture the seasonal variability well with minimum ET in the winter and maximum ET in the summer. Regarding the spatial pattern, the High resOlution Land Atmosphere surface Parameters from Space (HOLAPS) ET demonstrator dataset is very similar to the LandFlux-EVAL dataset (a benchmark ET product from the Global Energy and Water Cycle Experiment), with decreasing ET from the south-east to north-west over the TP. Further comparison against the LandFlux-EVAL over different sub-regions that are decided by different intervals of normalised difference vegetation index (NDVI), precipitation, and elevation reveals that HOLAPS agrees best with LandFlux-EVAL having the highest correlation coefficient (R) and the lowest root mean square difference (RMSD). These results indicate the potential for the application of the HOLAPS demonstrator dataset in understanding the land–atmosphere–biosphere interactions over the TP. In order to provide more accurate ET over the TP, model calibration, high accuracy forcing dataset, appropriate in situ measurements as well as other hydrological data such as runoff measurements are still needed.

scholarly journals Spatio-Temporal Variations of Water Vapor Budget over the Tibetan Plateau in Summer and Its Relationship with the Indo-Pacific Warm Pool

Atmosphere ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 828
Author(s):  
Deli Meng ◽  
Qing Dong ◽  
Fanping Kong ◽  
Zi Yin ◽  
Yanyan Li ◽  
...  
Keyword(s):  
Water Vapor ◽  
Indian Ocean ◽  
Tibetan Plateau ◽  
River Basin ◽  
Large Scale ◽  
Warm Pool ◽  
The Tibetan Plateau ◽  
Southern Boundary ◽  
Pacific Warm Pool ◽  
Water Vapor Budget

The water vapor budget (WVB) over the Tibetan Plateau (TP) is closely related to the large-scale atmospheric moisture transportation of the surrounding mainland and oceans, especially for the Indo-Pacific warm pool (IPWP). However, the procession linkage between the WVBs over the TP and its inner basins and IPWP has not been sufficiently elucidated. In this study, the relationship between the summer WVB over the TP and the IPWP was quantitatively investigated using reanalysis datasets and satellite-observed sea surface temperature (SST). The results show that: (1) the mean total summer vapor budget (WVBt) over the TP in the period of 1979–2018 was 72.5 × 106 kg s−1. Additionally, for the 13 basins within the TP, the summer WVB has decreased from southeast to northwest; the Yarlung Zangbo River Basin had the highest WVB (33.7%), followed by the Upper Yangtze River Basin, Ganges River Basin and Qiangtang Plateau. (2) For the past several decades, the WVBt over the TP has experienced an increasing trend (3.81 × 106 kg s−1 decade−1), although the southern boundary budget (WVBs) contributed the most and is most closely related with the WVBt, while the eastern boundary budget (WVBe) experienced a decreasing trend (4.21 × 106 kg s−1 decade−1) which was almost equal to the interdecadal variations of the WVBt. (3) For the IPWP, we defined a new warm pool index of surface latent heat flux (WPI-slhf), and found that an increasing WPI-slhf would cause an anticyclone anomaly in the equatorial western Indian Ocean (near 70° E), resulting in the increased advent of water vapor to the TP. (4) On the interdecadal scale, the correlation coefficients of the variation of the summer WVBt over the TP with the WPI-slhf and Indian Ocean Dipole (IOD) signal were 0.86 and 0.85, respectively (significant at the 0.05% level). Therefore, the warming and the increasing slhf of the IPWP would significantly contribute to the increasing WVB of the TP in recent decades.

scholarly journals Investigating water budget dynamics in 18 river basins across the Tibetan Plateau through multiple datasets

2018 ◽  
Vol 22 (1) ◽  
pp. 351-371 ◽  
Author(s):  
Wenbin Liu ◽  
Fubao Sun ◽  
Yanzhong Li ◽  
Guoqing Zhang ◽  
Yan-Fang Sang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Water Budget ◽  
Water Resource Management ◽  
Yellow River ◽  
Aridity Index ◽  
River Basins ◽  
Surface Model ◽  
The Tibetan Plateau ◽  
Basin Scale

Abstract. The dynamics of basin-scale water budgets over the Tibetan Plateau (TP) are not well understood nowadays due to the lack of in situ hydro-climatic observations. In this study, we investigate the seasonal cycles and trends of water budget components (e.g. precipitation P, evapotranspiration ET and runoff Q) in 18 TP river basins during the period 1982–2011 through the use of multi-source datasets (e.g. in situ observations, satellite retrievals, reanalysis outputs and land surface model simulations). A water balance-based two-step procedure, which considers the changes in basin-scale water storage on the annual scale, is also adopted to calculate actual ET. The results indicated that precipitation (mainly snowfall from mid-autumn to next spring), which are mainly concentrated during June–October (varied among different monsoons-impacted basins), was the major contributor to the runoff in TP basins. The P, ET and Q were found to marginally increase in most TP basins during the past 30 years except for the upper Yellow River basin and some sub-basins of Yalong River, which were mainly affected by the weakening east Asian monsoon. Moreover, the aridity index (PET/P) and runoff coefficient (Q/P) decreased slightly in most basins, which were in agreement with the warming and moistening climate in the Tibetan Plateau. The results obtained demonstrated the usefulness of integrating multi-source datasets to hydrological applications in the data-sparse regions. More generally, such an approach might offer helpful insights into understanding the water and energy budgets and sustainability of water resource management practices of data-sparse regions in a changing environment.

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