The Influence of Surface Sediment Presence on Observed Passive Microwave Brightness Temperatures of First-Year Sea Ice during the Summer Melt Period

Abstract

Knowledge on the influence of sea ice sediment on passive microwave brightness temperatures (TB) is currently limited, leading to potential inaccuracies in derived sea ice concentrations where this ice exists. We propose that sediment may influence TB in two ways: (i) by altering the surface dielectrics, or (ii) by generating differential melt rates across the ice surface, increasing surface roughness. This study will examine the second proposed hypothesis through a multi-platform analysis, combining in-situ passive microwave and unmanned aerial vehicle (UAV) data. UAV image analysis shows a negative relationship between surface elevation and sediment concentration. Comparing this with observed TB shows that horizontally polarized emissions are the most sensitive to rougher ice surfaces with 19 and 37 GHz TB decreasing rapidly with increased incidence angle. At a 55° incidence angle, 89 GHz offers the greatest potential for discriminating sea ice surfaces influenced by sediment presence, as TB are greater in both polarizations in comparison with non-sediment-laden ice. Results from this research provide evidence for a relationship between sea ice surface sediment and passive microwave signature, meriting future research in this field.