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Cooperative Institute for Meteorological Satellite Studies / University of Wisconsin-Madison
CIMSS Tropical Cyclone Team
Saharan Air Layer (SAL) - Product Description

GOES Upper-Level Water Vapor Imagery:
Background: This imagery is created using the 6.2 µm channel on the GOES-East satellite. This infrared upper-level water vapor band is sensitive to both temperature and water vapor in the atmosphere and has a weighting function that peaks at ~340 hPa. Weighting functions describe the layer of the atmosphere from which the radiation measured by a particular satellite channel was emitted. The weighting function for the 6.2 µm channel is fairly broad and typically detects temperature and water vapor in a layer from ~200-600 hPa.
Uses: This imagery is useful for tracking upper-level water vapor features such as tropical cyclone outflow layers and cold lows and can also be used for estimating mid- to upper-level atmospheric motion vectors (AMVs).
• Due to the elevated weighting function of the 6.2 µm channel, low- to mid-level atmospheric features (e.g., the Saharan Air Layer) may not be readily detectable using this imagery.

For more SAL information, please visit the SAL Background Information page.