scholarly journals WRF‐based dynamical downscaling of ERA5 reanalysis data for High Mountain Asia: Towards a new version of the High Asia Refined analysis

2020 ◽  
Vol 41 (1) ◽  
pp. 743-762 ◽  
Author(s):  
Xun Wang ◽  
Vanessa Tolksdorf ◽  
Marco Otto ◽  
Dieter Scherer
Keyword(s):  
Dynamical Downscaling ◽  
Reanalysis Data ◽  
High Mountain ◽  
High Asia

High Asia Refined Analysis Version 2 (HAR v2): a New Atmospheric Data Set for the Third Pole Region

2020 ◽  
Author(s):  
Xun Wang ◽  
Vanessa Tolksdorf ◽  
Marco Otto ◽  
Dieter Scherer
Keyword(s):  
Natural Hazards ◽  
Dynamical Downscaling ◽  
Data Access ◽  
Reanalysis Data ◽  
The Tibetan Plateau ◽  
Climate Data ◽  
Data Set ◽  
The Third ◽  
High Asia ◽  
Atmospheric Data

<p>Climatic-triggered natural hazards such as landslides and glacier lake outburst floods pose a threat to human lives in the third pole region. Availability of accurate climate data with high spatial and temporal resolution is crucial for better understanding climatic triggering mechanisms of these localized natural hazards. Within the framework of the project “Climatic and Tectonic Natural Hazard in Central Asia” (CaTeNA), High Asia Refined analysis version 2 (HAR v2) is under production, and is freely available upon request. HAR v2 is a regional atmospheric data set generated by dynamical downscaling of global ERA5 reanalysis data using the Weather Research and Forecasting (WRF) model. Compared to its predecessor (HAR), HAR v2 has an extended 10 km domain covering the Tibetan Plateau and the surrounding mountains, as well as a longer temporal coverage. It will be extended back to 1979, and will be continuously updated in the future. This presentation will contain the following aspects: (1) summarizing the WRF configuration; (2) validating HAR v2 against observational data; (3) comparing HAR v2 with other gridded data sets, such as the newly developed ERA5-Land reanalysis data; (4) providing information about data format, variable list, data access, etc.  </p>

scholarly journals Hydrologic modeling by means of a hybrid downscaling approach: an application to the Sai Gon–Dong Nai Rivers Basin

2021 ◽  
Author(s):  
T. Trinh ◽  
V. T. Nguyen ◽  
N. Do ◽  
K. Carr ◽  
D. H. Tran ◽  
...  
Keyword(s):  
Machine Learning ◽  
Dynamical Downscaling ◽  
Watershed Modeling ◽  
Reanalysis Data ◽  
Hydrologic Model ◽  
Substantial Contribution ◽  
Observation Data ◽  
Data Set ◽  
Hydrological Data ◽  
Calibration And Validation

Abstract The spatial and temporal availability and reliability of hydrological data are substantial contribution to the accuracy of watershed modeling; unfortunately, such data requirements are challenging and perhaps impossible in many regions of the world. In this study, hydrological conditions are simulated using the hydrologic model-WEHY, whose data input are obtained from a hybrid downscaling technique to provide reliable and high temporal and spatial resolution hydrological data. The hybrid downscaling technique is coupled a hydroclimate and a machine learning models; wherein the global atmospheric reanalysis data, including ERA-Interim, ERA-20C, and CFSR are used for initial and boundary conditions of dynamical downscaling utilizing the Weather Research and Forecasting model (WRF). The machine learning model (ANN) then follows to further downscale the WRF outputs to a finer resolution over the studied watershed. An application of the combination of mentioned techniques is applied to the third-largest river basin in Vietnam, the Sai Gon–Dong Nai Rivers Basin. The validation of hybrid model is in the ‘satisfactory’ range. After the estimation of geomorphology and land cover within the watershed, WEHY's calibration and validation are performed based on observed rainfall data. The simulation results matched well with flow observation data with respect to magnitude for both the rising and recession time segments. In comparison among the three selected reanalysis data sets, the best calibration and validation results were obtained from the CFSR data set. These results are closer to the observation data than those using only the dynamic downscaling technique in combination with the WEHY model.

scholarly journals Recent glacier and lake changes in High Mountain Asia and their relation to precipitation changes

2019 ◽  
Vol 13 (11) ◽  
pp. 2977-3005 ◽  
Author(s):  
Désirée Treichler ◽  
Andreas Kääb ◽  
Nadine Salzmann ◽  
Chong-Yu Xu
Keyword(s):  
Shuttle Radar Topography Mission ◽  
Reanalysis Data ◽  
Tien Shan ◽  
Water Volume ◽  
High Mountain ◽  
The Tibetan Plateau ◽  
Glacier Surface ◽  
Spatially Resolved ◽  
Lake Volume ◽  
Precipitation Increase

Abstract. We present an updated, spatially resolved estimate of 2003–2008 glacier surface elevation changes for the entire region of High Mountain Asia (HMA) from ICESat laser altimetry data. The results reveal a diverse pattern that is caused by spatially greatly varying glacier sensitivity, in particular to precipitation availability and changes. We introduce a spatially resolved zonation where ICESat samples are grouped into units of similar glacier behaviour, glacier type and topographic settings. In several regions, our new zonation reveals local differences and anomalies that have not been described previously. Glaciers in the Eastern Pamirs, Kunlun Shan and central TP were thickening by 0.1–0.7 m a−1, and the thickening anomaly has a crisp boundary in the Eastern Pamirs that continues just north of the central Karakoram. Glaciers in the south and east of the TP were thinning, with increasing rates towards southeast. We attribute the glacier thickening signal to a stepwise increase in precipitation around ∼1997–2000 on the Tibetan Plateau (TP). The precipitation change is reflected by growth of endorheic lakes in particular in the northern and eastern TP. We estimate lake volume changes through a combination of repeat lake extents from Landsat data and shoreline elevations from ICESat and the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) for over 1300 lakes. The rise in water volume contained in the lakes corresponds to 4–25 mm a−1, when distributed over entire catchments, for the areas where we see glacier thickening. The precipitation increase is also visible in sparse in situ measurements and MERRA-2 climate reanalysis data but less visible in ERA-Interim reanalysis data. Taking into account evaporation loss, the difference between average annual precipitation during the 1990s and 2000s suggested by these datasets is 34–100 mm a−1, depending on region, which can fully explain both lake growth and glacier thickening (Kunlun Shan) or glacier geometry changes such as thinning tongues while upper glacier areas were thickening or stable (eastern TP). The precipitation increase reflected in these glacier changes possibly extended to the northern slopes of the Tarim Basin, where glaciers were nearly in balance in 2003–2008. Along the entire Himalaya, glaciers on the first orographic ridge, which are exposed to abundant precipitation, were thinning less than glaciers in the dryer climate of the inner ranges. Thinning rates in the Tien Shan vary spatially but are rather stronger than in other parts of HMA.

scholarly journals A 12-year high-resolution climatology of atmospheric water transport over the Tibetan Plateau

2015 ◽  
Vol 6 (1) ◽  
pp. 109-124 ◽  
Author(s):  
J. Curio ◽  
F. Maussion ◽  
D. Scherer
Keyword(s):  
High Resolution ◽  
Tibetan Plateau ◽  
Water Transport ◽  
Summer Monsoon ◽  
East Asian ◽  
High Mountain ◽  
The Tibetan Plateau ◽  
Atmospheric Water ◽  
Data Set ◽  
High Asia

Abstract. The Tibetan Plateau (TP) plays a key role in the water cycle of high Asia and its downstream regions. The respective influence of the Indian and East Asian summer monsoon on TP precipitation and regional water resources, together with the detection of moisture transport pathways and source regions are the subject of recent research. In this study, we present a 12-year high-resolution climatology of the atmospheric water transport (AWT) over and towards the TP using a new data set, the High Asia Refined analysis (HAR), which better represents the complex topography of the TP and surrounding high mountain ranges than coarse-resolution data sets. We focus on spatiotemporal patterns, vertical distribution and transport through the TP boundaries. The results show that the mid-latitude westerlies have a higher share in summertime AWT over the TP than assumed so far. Water vapour (WV) transport constitutes the main part, whereby transport of water as cloud particles (CP) also plays a role in winter in the Karakoram and western Himalayan regions. High mountain valleys in the Himalayas facilitate AWT from the south, whereas the high mountain regions inhibit AWT to a large extent and limit the influence of the Indian summer monsoon. No transport from the East Asian monsoon to the TP could be detected. Our results show that 36.8 ± 6.3% of the atmospheric moisture needed for precipitation comes from outside the TP, while the remaining 63.2% is provided by local moisture recycling.

scholarly journals High Mountain Asia glacier elevation trends 2003–2008, lake volume changes 1990–2015, and their relation to precipitation changes

2018 ◽  
Author(s):  
Désirée Treichler ◽  
Andreas Kääb ◽  
Nadine Salzmann ◽  
Chong-Yu Xu
Keyword(s):  
Reanalysis Data ◽  
Tien Shan ◽  
Water Volume ◽  
High Mountain ◽  
The Tibetan Plateau ◽  
Volume Changes ◽  
Spatially Resolved ◽  
Lake Volume ◽  
Precipitation Increase ◽  
The Difference

Abstract. We present an updated, spatially resolved estimate of 2003–2008 glacier volume changes for entire High Mountain Asia (HMA) from ICESat laser altimetry data. The results reveal a diverse pattern that is driven by spatially greatly varying glacier sensitivity, in particular to precipitation availability and changes. We introduce a spatially resolved zonation where ICESat samples are grouped into units of similar glacier behaviour, glacier type, and topographic settings. In several regions, our new zonation reveals local differences and anomalies that have not been described previously. A step-increase in precipitation around 1997–2000 on the Tibetan Plateau (TP) caused thickening of glaciers in the Eastern Pamirs, Kunlun Shan and central TP by 0.1–0.7 m a−1. The thickening anomaly has a crisp boundary in the Eastern Pamir that continues just north of the central Karakoram. Glaciers in the south and east of the TP were thinning, with increasing rates towards southeast. The precipitation increase is reflected by growth of endorheic lakes in particular in the northern and eastern TP. We estimate lake volume changes through a combination of repeat lake extents from Landsat data and shoreline elevations from ICESat and the SRTM DEM for over 1300 lakes. The rise in water volume contained in the lakes corresponds to 4–25 m a−1, when distributed over entire catchments, for the areas where we see glacier thickening. The precipitation increase is also visible in sparse in-situ measurements and MERRA-2 climate reanalysis data, but less well in ERA Interim reanalysis data. Considering evaporation loss, the difference between average annual precipitation during the 1990s and 2000s suggested by these datasets is 34–100 m a−1, depending on region, which can fully explain both lake growth, and glacier thickening (Kunlun Shan) or glacier geometry changes (eastern TP). The precipitation increase reflected in these glacier changes possibly extended to the northern slopes of the Tarim Basin, where glaciers were nearly in balance in 2003–2008. Along the entire Himalaya, glaciers on the first orographic ridge, which are exposed to abundant precipitation, are thinning less than glaciers in the dryer climate of the inner ranges. Thinning rates in the Tien Shan vary spatially but are rather stronger than in other parts of HMA.

scholarly journals Moisture sources and synoptic conditions of summer precipitation in the glacial zone of the East Sayan Range

2020 ◽  
Vol 17 ◽  
pp. 1-8
Author(s):  
Eduard Y. Osipov ◽  
Olga P. Osipova
Keyword(s):  
Atmospheric Circulation ◽  
Northern Hemisphere ◽  
Summer Precipitation ◽  
Reanalysis Data ◽  
High Mountain ◽  
Atmospheric Circulation Patterns ◽  
Circulation Patterns ◽  
Precipitation Record ◽  
Macro Scale ◽  
Synoptic Conditions

Abstract. Precipitation in high-mountain regions is characterized by a strong heterogeneity due to complex interaction between atmospheric circulation and steep topography, however, extremely rare network of high elevation stations hampers the adequate high resolution regional climate modeling. In this study we present new data of precipitation directly measured in high-mountain catchment, on the continental glacier (East Sayan Range, south of East Siberia) during the summer periods of 2015–2017 using automatic weather station. The precipitation record was compared with near located weather stations and ERA Interim and NCEP/NCAR reanalysis data. Precipitation mode similar to the glacier site was found at the stations located west and northwest, while ERA Interim and NCEP/NCAR reanalysis data underestimated the precipitation by 40 % and 70 %, respectively. Atmospheric circulation patterns in days with precipitation were analyzed by using mean sea level pressure, geopotential height at 700 and 500 hPa and classification of macro scale atmospheric processes of the Northern Hemisphere by Dzerdzeevskii. Summer precipitation was mostly associated with meridional southern group of large scale circulation the Northern Hemisphere, while at synoptic scale it basically fell in cyclonic (49 % of precipitation) and low-gradient cyclonic (30 %) baric fields. Six typical atmospheric circulation patterns over the East Sayan were identified for days with precipitation. The sources and atmospheric moisture transfer to the glacier was defined by using the HYSPLIT trajectory model. The most of summer precipitation (70 %) was related with western cyclones, while about 25 % of rainfalls (mainly of moderate to strong intensity) was originated from the south-east (Pacific monsoon influence).

scholarly journals A twelve-year high-resolution climatology of atmospheric water transport on the Tibetan Plateau

2014 ◽  
Vol 5 (2) ◽  
pp. 1159-1196 ◽  
Author(s):  
J. Curio ◽  
F. Maussion ◽  
D. Scherer
Keyword(s):  
High Resolution ◽  
Tibetan Plateau ◽  
Water Transport ◽  
Summer Monsoon ◽  
East Asian ◽  
High Mountain ◽  
The Tibetan Plateau ◽  
Atmospheric Water ◽  
Moisture Recycling ◽  
High Asia

Abstract. The Tibetan Plateau (TP) plays a key role in the water cycle of High Asia and its downstream regions. The respective influence of the Indian and East Asian summer monsoon on TP precipitation and the regional water resources, together with the detection of moisture transport pathways and source regions are subject of recent research. In this study we present a twelve-year high-resolution climatology of the atmospheric water transport (AWT) on and towards the TP, using a new dataset, the High Asia Reanalysis (HAR), which better represents the complex topography of the TP and surrounding high mountain ranges than coarse resolution datasets. We focus on spatio-temporal patterns, vertical distribution and transport through the TP boundaries. The results show that the mid-latitude westerlies have a higher share in summertime AWT on the TP than assumed so far. Water vapour (WV) transport constitute the main part, whereby transports of water as cloud particles (CP) play also a role in winter in the Karakoram and western Himalayan regions. High mountain valleys in the Himalayas facilitate AWT from the south whereas the high mountain regions inhibit the AWT to a large extend and limit the influence of the Indian summer monsoon. No transport from the East Asian monsoon to the TP could be detected. Our results show that 40% of the atmospheric moisture needed for precipitation comes from outside the TP, while the remaining 60% are provided by local moisture recycling. How far precipitation variability can be explained by variable moisture supply has to be studied in future research by analysing the atmospheric dynamic and moisture recycling more in detail.

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