Glaciers are retreating worldwide, yet, little is known about the influence of these changes on local weather and climate in glacial landscapes. Changes in glacier extent and proglacial lakes alter the thermodynamic forcing in glacier-lake-valley systems that may be of similar or greater importance for future microclimate than direct effects of global warming. To study the impact of these changes, we combine the first set of high-density spatiotemporal observations of a glacier-lake-valley system at Nigardsbreen in western Norway with high-resolution numerical simulations from the Weather Research and Forecasting (WRF) model. The sensitivity of the thermodynamic circulation to glacier extent and proglacial lakes is tested using glacier outlines from 2006 and 2019 as well as varying lake surface temperature. The model represents the evolution of glacier flow and cold air pools well when thermal forcing dominates over large-scale forcing. During a persistent down-glacier flow regime, the glacier-valley circulation is sensitive to lake temperature and glacier extent, with strong impacts on wind speed, convection in the valley, and interaction with mountain waves. However, when the large-scale forcing dominates and the down-glacier flow is weak and shallower, impacts on atmospheric circulation are smaller, especially those related to lake temperature. This high sensitivity to meteorological conditions is related to whether the flow regime promotes thermal coupling between the glacier and the lake. The findings of this study highlight the need for accurate representation of glacier extent and proglacial lakes when evaluating local effects of past and future climate change in glacierized regions.

Wind-driven redistribution of snow is one of the key factors leading to heterogeneous accumulation of snow at small scales. Understanding these processes is, therefore, of great importance to many glaciological and hydrological questions. High-quality information on the wind field is necessary to realistically represent drifting snow. Here, we introduce a novel, intermediate-complexity drifting and blowing snow module for the Weather Research and Forecasting (WRF) model that integrates seamlessly into the standard WRF infrastructure. The module also accounts for snow particle sublimation and considers the thermodynamic feedback on the atmospheric fields. The module was tested in an idealized model environment. The simple and computationally efficient implementation allows this module to be used for small-scale and large-scale simulations in polar and glaciated regions.