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

摘要

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