The dependence of albedo on different factors for refreezing melt ponds in the Arctic

Abstract. Sea ice plays an important role in the heat transfer into the Arctic Ocean whereas the presence of melt ponds on sea ice complicates the scenario. However, the refreezing pond is less focused and documented in comparison with the well-established seasonal variation. To better evaluate the effect of melt pond on the freezeup of sea ice, we conducted a series of observations with 81 melt ponds in the central Arctic during freezeup, 2012–2020. The melt ponds are categorized into five types based on the surface state to effectively investigate the various characteristics. The total albedo of each type is 0.14 (water pond), 0.20 (water-ice pond), 0.25 (ice pond), 0.39 (ice-snow pond), 0.74 (snow pond), respectively, showing the increase on albedo in August and September (0.0036 d−1) due to the changes of the surface state. The albedo dependence on the surface state, ice lid, pond depth and underlying ice is examined using both in-situ measurements and modified radiative transfer model, with result indicating the dominance of surface state followed by ice lid thickness. The total albedo of ice ponds decreases with increasing pond depth, and the raising of ice lid thickness reduces the albedo while rises that of ice-snow ponds. In addition, further analysis reveals the capacity of different ratios of spectral albedo on the distinction between snow-covered pond and unponded ice, potentially improving the melt pond retrieval algorithms.