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 Product Description

GOES-West Split Window:

Background: This imagery is created by differencing the 12.0 and 10.7µm infrared channels on the GOES-West imager. The algorithm is sensitive to the presence of dry and/or dusty air in the lower atmosphere (~600-850 hPa or ~4,500-1,500 m) and is denoted by the yellow to red shading.

Uses: This imagery is useful for monitoring the position and movement of dry air masses such as the Saharan Air Layer (SAL). Animations of the imagery are useful for tracking these features and can also help identify the source of the dry and/or dusty air that is indicated in the imagery.

Notes:

  • Dry air and suspended aerosols (e.g. mineral dust) both contribute to a positive "SAL" signal in this imagery, but the relative contribution of each cannot be determined from this imagery alone.
  • Polar air originating from the mid-latitudes produces a positive signal in this imagery that is similar to that of the SAL. This is because both air masses contain substantial dry air in the lower to middle troposphere. The JAVA movie is a useful tool for determining which type of air mass is being indicated in the imagery.
  • Areas of very cold water (e.g. west of South America) can affect the split window algorithm and produce a false positive "SAL" signal. These regions can be easily identified using the JAVA movie because they tend not to move or change form for several consecutive days.