Introduction

1. Introduction

Thermal balance observations carried out in natural conditions allow to evaluate the processes of interaction in the “underlying surface - surface layer of the atmosphere” system. Albedo is one of the most important elements of the surface heat balance, especially in the Arctic regions, where mechanisms of positive feedbacks cause “dramatic” changes in the conditions of the snow-ice surfaces (e.g. sea ice, glaciers). As a general rule, albedo values obtained at a point or a limited area of the surface cannot be extrapolated to the entire area of interest. That is why, special space (“ground true”) surveys are carried out. Data on the albedo of snow-glaciers covers are also necessary for correct calculations of the melted layer of snow or ice during the ablation period. Together with the data of direct measurements (e.g. glaciological monitoring), these data make it possible to verify and improve the existing thermodynamic models of glaciers. What is even more important, it allows to evaluate the processes in the marginal zone of glaciers (zone of cracks), where any “ground true” observations are impossible. These zones absorb and reflect the incoming solar radiation with intensity different from the flat areas of a glacier. However, these processes are not taken into account in the classical thermodynamic models of glaciers sufficiently.

The UAV practice demonstrates their high efficiency in the research of hard-to-reach snow-ice surfaces areas, where standard “ground true” surveys are impossible for safety reasons. Such studies make it possible to obtain objective estimates of the spatial distribution of the albedo in the hard-to-reach areas and perform detailed mapping of similar areas mentioned above [1, 2, 3]. Previously, this could be done (and even then, only partially) during the long and laborious walking routes - profile or space surveys [4]. The studies of the albedo of the antarctic land-fast ice and the zone of cracks in the margin zone of the glacier dome in the area of the Russian “Progress” station were carried out within the framework of the 63rd Russian Antarctic Expedition [5]. Such study was done for the first time in domestic practice. The research was based on the use of an original portable measuring device (an analog-to-digital converter paired with a PaspberryPi microprocessor device) mounted on a UAV (DJI Mavic Pro). Finally, within the framework of the international expedition TransArktica-2019 on the RV “Akademik Treshnikov” (Russia), the high level spatial resolution estimates of the albedo and surface temperatures of arctic hummocks were obtained using an UAV, for the first time. Also, there were evaluated vertical turbulent fluxes of sensible heat from the windward and the leeward sides of the hummock ridge [6]. The main goal of this article is to demonstrate the original results related to obtaining albedo estimates for hard-to-reach areas of Svalbard snow-glacial surfaces.

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