2 m temperatures along melting mid-latitude glaciers, and implications for the sensitivity of the mass balance to variations in temperature

In calculations of the variation in the 2 m temperature along glaciers, the lapse rate is generally assumed to be constant. This implies that the ratio of changes in the 2 m temperature above a glacier to changes in the temperature outside the thermal regime of that glacier (“climate sensitivity”) is equal to 1. However, data collected during the ablation season on several mid-latitude glaciers show that this sensitivity is smaller than 1. The lowest measured value (0.3) was obtained on the tongue of the Pasterze, a glacier in Austria. The measured temperature distribution along the Pasterze cannot be described by a constant lapse rate either. However, there is almost a linear relationship between potential temperature and the distance along die glacier. This paper introduces a simple, analytical, thermodynamic glacier-wind model which can be applied to melting glaciers and which explains the observed “climate sensitivities” and temperature distributions much better than calculations based on a constant lapse rate.This way of modelling the 2 m temperatures has implications for the sensitivity of the surface mass balance to atmospheric warming outside the thermal regime of the glacier. The magnitude of this sensitivity is computed with a surface energy-balance model applied to the Pasterze. When a constant lapse rate is used instead of the proposed glacier-wind model to compute changes in the 2 m temperature along the glacier, the negative change in mass balance due to 1°C warming is overestimated by 22%.

2 m temperatures along melting mid-latitude glaciers, and implications for the sensitivity of the mass balance to variations in temperature

In calculations of the variation in the 2 m temperature along glaciers, the lapse rate is generally assumed to be constant. This implies that the ratio of changes in the 2 m temperature above a glacier to changes in the temperature outside the thermal regime of that glacier (“climate sensitivity”) is equal to 1. However, data collected during the ablation season on several mid-latitude glaciers show that this sensitivity is smaller than 1. The lowest measured value (0.3) was obtained on the tongue of the Pasterze, a glacier in Austria. The measured temperature distribution along the Pasterze cannot be described by a constant lapse rate either. However, there is almost a linear relationship between potential temperature and the distance along die glacier. This paper introduces a simple, analytical, thermodynamic glacier-wind model which can be applied to melting glaciers and which explains the observed “climate sensitivities” and temperature distributions much better than calculations based on a constant lapse rate.This way of modelling the 2 m temperatures has implications for the sensitivity of the surface mass balance to atmospheric warming outside the thermal regime of the glacier. The magnitude of this sensitivity is computed with a surface energy-balance model applied to the Pasterze. When a constant lapse rate is used instead of the proposed glacier-wind model to compute changes in the 2 m temperature along the glacier, the negative change in mass balance due to 1°C warming is overestimated by 22%.

Wind Regimes And Heat Exchange On Glacier De Saint-Sorlin

During the summers of 1969 and 1970, we recorded in the ablation zone of the Glacier de St-Sorlin (Massif des Grandes Rousses, France) temperature, air moisture, and wind profiles, as well as the radiation balance and the daily ablation. Numerous profiles characterize a katabatic flow following the line of greatest slope, and there appears to be a correlation between the speed of the “glacier wind” and the corresponding temperature gradients. Computed according to Prandtl’s theory of turbulent transfers, the flux of sensible and latent heat added to the radiation flux leads to theoretical values for the daily melting in good agreement with the measured values. The relative importance of the radiation balance on the melting of the snow is 57%; that of the sensible heat flux is 43%; the latent heat flux is very weak and negative.

Wind Regimes And Heat Exchange On Glacier De Saint-Sorlin

During the summers of 1969 and 1970, we recorded in the ablation zone of the Glacier de St-Sorlin (Massif des Grandes Rousses, France) temperature, air moisture, and wind profiles, as well as the radiation balance and the daily ablation. Numerous profiles characterize a katabatic flow following the line of greatest slope, and there appears to be a correlation between the speed of the “glacier wind” and the corresponding temperature gradients. Computed according to Prandtl’s theory of turbulent transfers, the flux of sensible and latent heat added to the radiation flux leads to theoretical values for the daily melting in good agreement with the measured values. The relative importance of the radiation balance on the melting of the snow is 57%; that of the sensible heat flux is 43%; the latent heat flux is very weak and negative.