Parameterisation of summertime surface winds near mountain glaciers

Glaciers in mountain valleys create unique local climates consisting of glacier winds, valley winds and slope winds. These local winds together with the synoptic winds mediate the turbulent heat fluxes between the glacier surface and the atmosphere, and contribute up to one-third of the total glacier melt. The knowledge of on-glacier wind speed distribution is required to estimate these fluxes, which can be either obtained through weather stations or climate reanalysis products. Weather station data is sparse on glaciers due to logistic reasons. Large scale climate models on the other hand, fail to capture these local winds entirely due to their coarse resolution. Hence we develop a parameterisation for summertime hourly wind speed at any glacier around the world using freely available large scale climate and topographic data. We calibrate and validate this parameterisation using station data from 25 near-glacier weather stations around the world. Our method reduces the prediction errors of wind speed and turbulent heat fluxes by a factor of 1.6 and 3 respectively, as compared to the state-of-the-art climate data product. This will help improve the glacier- to basin- scale melt and runoff estimates by regional and global models.