Large scale atmospheric forcing and topographic modification of precipitation rates over High Asia – a neural network based approach

Gerlitz, Lars; Conrad, Olaf; Böhner, Jürgen

doi:10.5194/esdd-5-1275-2014

Cited by 12 publications

(13 citation statements)

References 71 publications

(103 reference statements)

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“…The large-scale spatial pattern and the seasonal and interannual variability of precipitation rates over central and High Asia has been widely studied, particularly with regard to its impact on downstream hydrological regimes and hence on the climate-sensitive agriculture-dominated economies of the highly populated downstream areas (Akhtar et al, 2008;Mall et al, 2006;Matthews et al, 1997). The main rivers of South and East Asia such as the Indus, Ganges, Brahmaputra, Huang-He and Yangtze have their upper catchment areas on the Tibetan Plateau or in the adjacent mountain regions and are mainly fed by the enhanced precipitation rates compared with the surrounding lowlands and by snow melting in spring.…”

Section: Introductionmentioning

confidence: 99%

Large-scale atmospheric forcing and topographic modification of precipitation rates over High Asia – a neural-network-based approach

2015

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Abstract. The heterogeneity of precipitation rates in high-mountain regions is not sufficiently captured by stateof-the-art climate reanalysis products due to their limited spatial resolution. Thus there exists a large gap between the available data sets and the demands of climate impact studies. The presented approach aims to generate spatially high resolution precipitation fields for a target area in central Asia, covering the Tibetan Plateau and the adjacent mountain ranges and lowlands. Based on the assumption that observed local-scale precipitation amounts are triggered by varying large-scale atmospheric situations and modified by local-scale topographic characteristics, the statistical downscaling approach estimates local-scale precipitation rates as a function of large-scale atmospheric conditions, derived from the ERA-Interim reanalysis and high-resolution terrain parameters. Since the relationships of the predictor variables with local-scale observations are rather unknown and highly nonlinear, an artificial neural network (ANN) was utilized for the development of adequate transfer functions. Different ANN architectures were evaluated with regard to their predictive performance.The final downscaling model was used for the cellwise estimation of monthly precipitation sums, the number of rainy days and the maximum daily precipitation amount with a spatial resolution of 1 km 2 . The model was found to sufficiently capture the temporal and spatial variations in precipitation rates in the highly structured target area and allows for a detailed analysis of the precipitation distribution. A concluding sensitivity analysis of the ANN model reveals the effect of the atmospheric and topographic predictor variables on the precipitation estimations in the climatically diverse subregions.

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Section: Introductionmentioning

confidence: 99%

Large-scale atmospheric forcing and topographic modification of precipitation rates over High Asia – a neural-network-based approach

2015

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“…Biases in the temperature fields were quantified and corrected taking available time series of observed daily mean temperatures of 78 weather stations into account [27]. The suitability, precision, and limitation of the downscaling approach for the Tibetan Plateau and the Himalaya is discussed in Gerlitz [28] and Gerlitz et al [27,29]. …”

Section: Methodsmentioning

confidence: 99%

Mass elevation and lee effects markedly lift the elevational distribution of ground beetles in the Himalaya-Tibet orogen

et al. 2017

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Mass elevation and lee effects markedly influence snow lines and tree lines in high mountain systems. However, their impact on other phenomena or groups of organisms has not yet been quantified. Here we quantitatively studied their influence in the Himalaya–Tibet orogen on the distribution of ground beetles as model organisms, specifically whether the ground beetle distribution increases from the outer to the inner parts of the orogen, against latitudinal effects. We also tested whether July temperature and solar radiation are predictors of the beetle’s elevational distribution ranges. Finally, we discussed the general importance of these effects for the distributional and evolutionary history of the biota of High Asia. We modelled spatially explicit estimates of variables characterizing temperature and solar radiation and correlated the variables with the respective lower elevational range of 118 species of ground beetles from 76 high-alpine locations. Both July temperature and solar radiation significantly positively correlated with the elevational ranges of high-alpine beetles. Against the latitudinal trend, the median elevation of the respective species distributions increased by 800 m from the Himalayan south face north to the Transhimalaya. Our results indicate that an increase in seasonal temperature due to mass elevation and lee effects substantially impact the regional distribution patterns of alpine ground beetles of the Himalaya–Tibet orogen and are likely to affect also other soil biota there and in mountain ranges worldwide. Since these effects must have changed during orogenesis, their potential impact must be considered when biogeographic scenarios based on geological models are derived. As this has not been the practice, we believe that large biases likely exist in many paleoecological and evolutionary studies dealing with the biota from the Himalaya-Tibet orogen and mountain ranges worldwide.

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“…Unfortunately, the spatial heterogeneity of precipitation in the Karakoram is not adequately characterized and depicted by climate reanalysis products or most regional-scale climate simulations [108]. Furthermore, such annual precipitation patterns do not spatially coincide and thereby explain glacier size or mass distributions due to climate-topographic forcing and highly variably orographic precipitation distributions with time.…”

Section: Climate and Topographymentioning

confidence: 99%

Climate–Glacier Dynamics and Topographic Forcing in the Karakoram Himalaya: Concepts, Issues and Research Directions

Dobreva

Bishop

Bush

2017

Water

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Abstract:Understanding climate-glacier dynamics in High Mountain Asia is of critical importance to address issues including water resources, sea-level rise, mountain geodynamics, natural hazards and ecosystem sustainability. The Karakoram Himalaya is arguably the least understood region, given its extreme topography, climate-system coupling, and advancing and surge-type glaciers that exhibit complex flow patterns. Glacier fluctuations in the Karakoram Himalaya are highly variable in space and time because of numerous controlling factors, including the westerlies, the Indian summer monsoon, various teleconnections, topographic effects, glacier debris-cover characteristics, glacier dynamics, and geological conditions. The influence of the integrative coupling of forcing factors, however, has not been adequately assessed for characterizing the glaciers in the Karakoram Himalaya. Given the scarcity of in-situ data and the difficulty of conducting fieldwork on these glaciers, recent research has focused on utilizing remote sensing, geospatial technologies, and scientific modeling to obtain baseline information about the state of glaciers in the region. This review summarizes our current knowledge of glaciers, climate-glacier interaction, and topographic forcing in the Karakoram Himalaya, and demonstrates the complexities in mountain geodynamics that influence climate-glacier dynamics. Innovative analysis is also presented in support of our review and discussion.

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Large scale atmospheric forcing and topographic modification of precipitation rates over High Asia – a neural network based approach

Cited by 12 publications

References 71 publications

Large-scale atmospheric forcing and topographic modification of precipitation rates over High Asia – a neural-network-based approach

Large-scale atmospheric forcing and topographic modification of precipitation rates over High Asia – a neural-network-based approach

Mass elevation and lee effects markedly lift the elevational distribution of ground beetles in the Himalaya-Tibet orogen

Climate–Glacier Dynamics and Topographic Forcing in the Karakoram Himalaya: Concepts, Issues and Research Directions

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