Monitoring Sea Ice Evolution with Ultrawideband Microwave Radiometry in the MoSAIC Campaign

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The evolution of the Arctic is a key question for the future of our planet. One key aspect is to understand how processes in the atmosphere, ocean, and sea ice interact and affect Arctic ocean sea ice behavior and distribution. As part of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign, this project is deploying an ultra-wideband microwave radiometer to improve the ability to remotely determine sea ice thickness information. The long term measurements of sea ice available from MOSAiC's one year deployment of the RV Polarstern into an Arctic ice floe, combined with the extensive ice, ocean, and atmosphere in-situ measurements to be acquired, provide an optimal environment for sea ice monitoring studies, which in turn enable better models of sea ice evolution. Those models are criticall important to advancing Arctic system science and predicting the future of the Arctic. Student training will also provide societal impact by preparing the next generation of researchers in polar science and observation.The difficult conditions of the Arctic along with its spatially heterogeneous forcing motivate remote Earth observations from satellites or airborne platforms. Remote sensing systems have proven to be effective in monitoring sea ice extent and fractional cover, as well as sea ice thickness and type to a lesser extent. Current L-band (1.4-GHz) microwave radiometers and laser altimeters have limited sensitivity to ice thickness in the range from 0.5 to 2 meters, which is increasingly common as compared to thicker multi-year ice. An ability to sense sea ice temperature and salinity properties, and particularly their variations within the ice itself, could also provide important new benefits for understanding ice formation and dissolution.The project is deploying a four channel ultra-wideband microwave radiometer observing from 0.5 to 2 GHz as part of the MOSAiC central observatory in order to acquire a unique dataset of ice thermal emissions and their variations with thickness and other ice properties. By measuring thermal emissions from sea ice at multiple frequencies, and frequencies lower than 1.4 GHz, more information on ice properties, and to greater depth, will be possible. The measurements acquired will further play an important role in bridging between the point in situ measurements to be acquired by other MOSAiC program investigators and the approximately 9 m x 26 m instrument footprint that will provide ice properties averaged over the "intermediate" scales associated with ice floes. The three year project includes instrument preparation and planning in year one, campaign participation in year 2 (including staffing by project personnel during MOSAiC legs I and II), and extensive data analysis in year 3.By advancing understanding of the spatial scaling between sea ice properties at point (in situ) and floe scales, the project will provide an important link to enable "sub-grid-scale" phenomena parameterization in sea ice forecast models. The time histories of thickness, salinity, and temperature acquired will also represent important datasets for characterizing the sea ice energy budget over relevant spatial scales. The advancement achieved in the use of passive microwave remote sensing will also provide new insights into the electromagnetic properties of sea ice for use in future development of new instrumentation and satellite observation methods.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.