57A057
Antarctic ice-edge detection using Ku-band scatterometer data
Penelope Wagner, Cathleen Geiger, Tracy DeLiberty, David G. Long, Stephen F. Ackley, Hongjie Xie
Corresponding author: Penelope Wagner – penelope@udel.edu
Sea-ice edge detection is an integral component of both climate models and forecast projections, as well as ice charting analysis for navigational purposes. Scatterometers were originally designed to measure the radar cross section (σ°) and dielectric properties of the ocean surface to measure near-surface winds. However, they have been found also to have a high sensitivity for monitoring ice edge and ice extent compared with the National Aeronautics and Space Administration Team (NT) 30% ice edge derived from passive data and Radarsat-1 (SAR) products. Previous studies using passive microwave signatures and the NT algorithm produce ice-edge estimates with errors up to 15% as compared with in situ measurements and SAR products are ineffective in accurately detecting the ice edge based on overlapping signatures between thin sea ice and open water. The Brigham Young University (BYU) Microwave Earth Remote Sensing (MERS) Laboratory developed a QuikSCAT (QSCAT) dataset containing the total archive from 19 July 1999 to 31 December 2008 at 2.225 and 4.450 km resolutions. Their dataset implements the BYU Scatterometer Image Reconstruction (SIR) algorithm for the purpose of resolution enhancement. The algorithm outputs a binary sea-ice mask for ice/ocean detection. Statistical analysis has been used to define a threshold to validate the QSCAT/Seawinds scatterometer enhanced-resolution data for the Arctic ice edge based on comparisons with SAR data and passive microwave, but not for the Antarctic ice edge. Though the QSCAT dataset with the SIR algorithm improves the ability of the scatterometer instrument to distinguish ice/ocean signatures by averaging various satellite passes for 1 day, it has yet to be validated with more reliable and/or in situ measurements. The National Ice Center (NIC) has generated ice-edge charts from 1972 to the present using a combination of various passive and active microwave and visible satellite products. The accuracy of the NIC charts is validated with previous studies that have paired samples of charts with ship-based observations and/or visible satellite products. This study directly and statistically compares ice extent between QSCAT ice-edge and NIC daily ice-edge charts using the full QSCAT archive at both product resolutions for the entire Southern Ocean. The long-term goal is to provide validation for scatterometer instruments for systematic application in operational and logistical ice-charting capabilities. The development of such a product for operational centers optimizes applications for near-real-time forecasting and archiving of long-term records for climate modeling. A manuscript is in preparation for the Annals volume of this IGS Symposium based on this work.
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