92nd American Meteorological Society Annual Meeting (January 22-26, 2012)

Tuesday, 24 January 2012
Sea Surface Emissivity Retrieval in Gulf of Mexico Using GOES Sounder Measurements
Hall E (New Orleans Convention Center )
Yong Zhang, NSMC/China Meteorological Adiministration, Beijing, China; and Z. Li, J. Li, and T. J. Schmit

On April 20, 2010, an explosion damaged the semi-submersible offshore drilling rig, the Deepwater Horizon in the Gulf of Mexico. This significant spill posed a serious threat to wildlife, affecting many species along the coastal areas of Louisiana, Mississippi, Alabama, and Florida. Infrared oil spill detection utilizes either sea surface temperature (SST) or sea surface emissivity (SSE) contrast of native and oil-covered water surfaces. It is known that the oil-covered water surface could be warmer or cooler than native water surface depending on the solar heating and the thickness of the oil, which makes it difficult to use to detect the oil spill. On the other hand, the oil-covered water surface always has slightly smaller SSE than seawater in the thermal window region, which makes it a perfect candidate for oil spill detection. This research uses measurements from channels 6 (12.66 μm), 7 (12.02 μm) and 8 (11.03 μm) of the Geostationary Operational Environmental Satellite (GOES-13) Sounder. The algorithm is based on the assumption of time continuity; the SST is temporally variable while the SSE is temporally invariable within a short period of time, i.e. several hours. The presence of an oil spill is detected by temporal analysis of the retrieved SSE; it is expected the retrieved SSE will be smaller than usual with the presence of oil spill. The detection of oil spill is complicated by cloud contamination, which may affect the retrieved SSE on a similar order of magnitude. Simulation analysis was carried out to study the impacts by thin cirrus clouds and low water cloud. The results showed that both clouds pose positive SSE bias to 11.03 μm, and negative bias to 12.66 μm. These opposite behaviors in the two channels are used to screen out cloud contamination, greatly improve the quality of the retrieved SSE, and thereafter improve detecting and monitoring the oil spill. The advantages of the geostationary satellite data in environmental protection and disaster management are their high temporal resolutions. GOES Sounder can obtain the infrared remote sensing data of Gulf of Mexico area on hourly basis. So the spread of the oil spill can be monitored timely and accurately. Similar spectral bands will be on the next generation GOES Imager, the Advanced Baseline Imager (ABI), although with improved spatial and temporal resolutions.

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