Mitigation of Sea Ice Contamination in QuikSCAT Wind Retrieval

Scatterometers provide frequent estimates of near-surface wind vectors over the Earth's oceans. However, in the polar oceans, the presence of sea ice in or near the measurement footprint can adversely affect scatterometer measurements, resulting in inaccurate wind estimates. Currently, such ice contamination is mitigated by discarding measurements within 50 km of the detected sea ice. This approach is imperfect and causes loss of coverage. We present a new algorithm that detects ice-contaminated measurements based on a metric called the ice contribution ratio (ICR), which measures the spatial ice contribution for each measurement. Determined by simulation, we threshold the ICR depending on local wind, ice backscatter, and cross-track location. Using ICR processing, wind is retrieved almost 40 km closer to sea ice than has been previously possible, while ensuring wind accuracy. Using ICR processing, retrieved wind distributions more closely resemble uncontaminated distributions than winds retrieved using previous methods. The algorithm is applied to QuikSCAT in this paper, but could be applied to other scatterometers such as the Oceansat-2 scatterometer.