- 1Ca' Foscari University of Venice Department of Environmental Sciences, Informatics and Statistics, Ca’ Foscari University of Venice, Venezia-Mestre 30172, Italy
- 2Laboratory for Models and Measurements for Air Quality, and Climate Observations SSPT-CLIMAR-AOC ENEA, 00123 Rome, Italy
- 3Istituto Nazionale di Geofisica e Vulcanologia, Rome 00143, Italy
- 4Laboratory for Models and Measurements for Air Quality, and Climate Observations SSPT-CLIMAR-AOC ENEA, 00044 Frascati, Italy
The land surface albedo is one of the key parameters of the global radiation budget, since it regulates the shortwave radiation absorbed by the Earth’s surface. The polar regions, in particular, a decrease in snow and ice cover results in a decrease of surface albedo and in the intensification of solar heating further reducing the snow and ice areas (ice-albedo feedback). In remote areas, where in-situ instruments are absent, satellites are crucial to measure surface albedo changes.
In this work, a comparison of satellite and in-situ measurements of broadband shortwave surface albedo is conducted. The area of interest selected is around the Thule High Arctic Atmospheric Observatory (THAAO) on the North-western coast of Greenland (76.5°N, 68.8°W), where the measurements of down-welling and up-welling shortwave irradiance have been started in 2009 and 2016, respectively (https://www.thuleatmos-it.it/).
Albedo determinations based on MODIS observations from both Terra and Aqua (MODIS MCD43A3 dataset), consisting of daily values with a spatial resolution of 500 m, have been compared with the ground-based measurements.
The analysis has been conducted for all-sky and clear-sky conditions with a focus on some events to better understand the behavior of MODIS data with respect to ground-based measurements, taking advantage of the additional information (meteorological parameters, cloudiness, precipitation) available at THAAO.
The results for the period 2016-2024 show an underestimation of the albedo measurements from satellite compared to the ground-based measurements at the THAAO over a large part of the period considered. The best agreement is found in the summer when there is no snow around the Observatory, and the mean measured albedo value is 0.1633 for cloud-free conditions and 0.1903 for all-sky conditions. The mean bias during this season is around -0.0074 for cloud-free conditions and 0.0067 for all sky conditions. In spring, when the in-situ albedo values are highly variable, between 0.350 and 1, the mean bias is around -0.0645 for cloud-free conditions and -0.0159 for all sky conditions.
The fast changes in surface albedo occurring after short snow precipitation or removal events are seldom captured by satellite observations.
How to cite: Tosco, M., Meloni, D., Calì Quaglia, F., Muscari, G., Di Iorio, T., Pace, G., Ciardini, V., and di Sarra, A. G.: Measurements of land surface albedo at the Thule High Arctic Atmospheric Observatory (THAAO) in Pituffik, Greenland and comparison with MODIS data., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17123, https://doi.org/10.5194/egusphere-egu25-17123, 2025.
