Abstract
The development of methods for quantifying meltwater from glaciated areas is very important for better management of water resources and because of the strong impact of current and expected climate change on the Alpine cryosphere. Radiative fluxes are the main melt-drivers, but they can generally not be derived from in situ measures because glaciers are usually located in remote areas where the number of meteorological stations is very low. For this reason, focusing, as a case study, on one of the few glaciers with a supraglacial automatic weather station (Forni Glacier), we investigated methods based on both satellite records and off-glacier surface observations to estimate incoming short- and long-wave radiation at the glacier surface (SWin and LWin). Specifically, for SWin, we considered CM SAF SARAH satellite gridded surface solar irradiance fields and data modeled by cloud transmissivity parametrized from both CM SAF COMET satellite cloud fractional cover fields and daily temperature range observed at the closest off-glacier station. We then used the latter two data sources to derive LWin too. Finally, we used the estimated SWin and LWin records to assess the errors obtained when introducing estimated rather than measured incoming radiation data to quantify glacier melting by means of an energy balance model. Our results suggest that estimated SWin and LWin records derived from satellite measures are in better agreement with in situ observations than estimated SWin and LWin records parametrized from observations performed at the closest off-glacier station. Moreover, we find that the former estimated records permit a significantly better quantification of glacier melting than the latter estimated ones.
Highlights
The global warming period temperature increase has been strong in the Alpine region, which has recorded a significantly higher temperature trend than Earth’s average one
We evaluated the performance of the different models by means of (i) mean bias error (MBE), (ii) mean absolute error (MAE), (iii) root-mean-square error (RMSE), (iv) bias-removed root-mean-square error (BRRMSE), and (v) common variance (R2)
Statistical indicators (Table 2) show better performance for incoming radiation values obtained from cloudiness satellite data than for corresponding values obtained from daily temperature range measured at the closest off-glacier station
Summary
The global warming period temperature increase has been strong in the Alpine region, which has recorded a significantly higher temperature trend than Earth’s average one (see, e.g., [1]). The strong temperature trend, together with high vulnerability to climate change, has strongly enhanced the impact of global warming in high-elevation areas of this region that in the last decades have experienced relevant environmental changes. These changes are strong in glacierized areas because glaciers have lost a relevant fraction of their volume with a wide range of impacts, including significant changes in the amount and in the seasonality of meltwater discharge [2]. Expected temperature increase for the decades will further strengthen the current changes with dramatic impacts on the Alpine cryosphere [3] In this context, investigating Alpine glacier melting processes is becoming increasingly important. Whenever the glacier surface is at the melting point (i.e., 0 ◦C), melting occurrence and rate are regulated by radiative, sensible, and latent heat fluxes; of these, sensible and latent heat fluxes are strongly dependent on turbulence allowing heat and water vapor transport in the atmospheric layer over the glacier surface
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
