Proxy Visible Satellite Imagery

Visible satellite imagery is widely used by operational forecast centers (e.g., National Hurricane Center (NHC), Central Pacific Hurricane Center (CPHC), Joint Typhoon Warning Center (JTWC)) for tropical cyclone (TC) track forecasting, intensity estimates, and the tracking of low-level cloud motion. The absence of visible imagery at night is significantly limiting the amount of information available to forecasters. The unique Visible Infrared Imaging Radiometer Suite (VIIRS) Day-Night Band (DNB) imagery provided by Suomi National Polar-orbiting Partnership (SNPP) and planned for Joint Polar Satellite System – 1 (JPSS1) satellite has proven to have multiple applications for the TC forecasting, including center fixing for weak and sheared systems, and other applications such as determining the presence of the eye and detecting exposed low-level centers of circulation. However, the DNB imagery lacks Geostationary Operational Environmental Satellite (GOES) temporal resolution and thus has limited utility for monitoring short-term changes via the animation of cloud structure changes and motions. The new proxy-visible imagery, developed at CIRA, uses VIIRS DNB radiances to create an improved product that dynamically combines 3.9 µm with long-wave infrared (IR) channels, depending on the background. This proxy visible imagery is robust for a large range of the background surfaces and SSTs, and accounts for ice phase clouds. The proxy-visible imagery was shown to be superior to the existing products (e.g. 3.9 µm channel enhanced to highlight low-level clouds or difference between 3.9 µm and 10.35 µm channels ) for visualization of low-level clouds at night at a wide range of conditions. The VIIRS IR bands used in the algorithm have closely matching GOES-16 and Himawari-8 channels. These similar channels allow for direct application of the proxy-visible algorithm to GOES-16 and other geostationary data, which allows the production of nearly continuously available DNB-like data from geostationary imagery.

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