Category Archives: Our news

WRF Langtang paper available online

The paper by Emily and Walter on the modelling of high-altitude precipitation processes in the Langtang catchment using WRF is now available online (open access):

  • Abstract
    High-altitude meteorological processes in the Himalaya are influenced by complex interactions between the topography and the monsoon and westerly circulation systems. In this study, we use the Weather Research and Forecasting model configured with high spatial resolution to understand seasonal patterns of near-surface meteorological fields and precipitation processes in the Langtang catchment in the central Himalaya. Using a unique high-altitude observational network, we evaluate a simulation from 17 June 2012 to 16 June 2013 and conclude that, at 1 km horizontal grid spacing, the model captures the main features of observed meteorological variability in the catchment. The finer representation of the complex terrain and explicit simulation of convection at this grid spacing give strong improvements in near-surface air temperature and small improvements in precipitation, in particular in themagnitudes of daytime convective precipitation and at higher elevations. The seasonal differences are noteworthy, including a reversal in the vertical and along-valley distributions of precipitation between the monsoon and winter seasons, with peak values simulated at lower altitudes (~3000m above sea level (asl)) and in the upper regions (above 5000m asl) in each season, respectively. We conclude that there is great potential for improving the local accuracy of climate change impact studies in the Himalaya by using high-resolution atmospheric models to generate the forcing for such studies.

Lirung Glacier ice cliff energy balance modelling

The first paper on energy balance modelling of Lirung is now available online (open access):

  • Abstract
    Ice cliffs have been identified as a reason for higher ablation rates on debris-covered glaciers than are implied by the insulation effects of the debris. This study aims to improve our understanding of cliff backwasting, and the role of radiative fluxes in particular. An energy-balance model is forced with new data gathered in May and October 2013 on Lirung Glacier, Nepalese Himalaya. Observations show substantial variability in melt between cliffs, between locations on any cliff and between seasons. Using a high-resolution digital elevation model we calculate longwave fluxes incident to the cliff from surrounding terrain and include the effect of local shading on shortwave radiation. This is an advance over previous studies, that made simplified assumptions on cliff geometry and radiative fluxes. Measured melt rates varied between 3.25 and 8.6 cm d–1 in May and 0.18 and 1.34 cm d–1 in October. Model results reproduce the strong variability in space and time, suggesting considerable differences in radiative fluxes over one cliff. In October the model fails to reproduce stake readings, probably due to the lack of a refreezing component. Disregarding local topography can lead to overestimation of melt at the point scale by up to ~9%.

 

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Two new papers published

Two new papers with contributions from our research team have been published in Journal of Glaciology and International Journal of Water Resources Development:

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