GOES Advanced Baseline Imager (ABI) Color Product Development Don Hillger NOAA/NESDIS/StAR CoRP Third Annual Science Symposium August 2006

GOES ABI advances Improved resolutions: –Spatial (0.5 km visible, 2 km IR) –Temporal (5 min full-disk, 30 s rapid scan) –Spectral (16 vs. 5 bands) –Radiometric (lower noise) Also improved navigation/registration Leading to new and improved image products

GOES-R ABI vs. Current GOES GOES-R ABI BandCentral Wavelength (μm)Current GOES Band* 1 (blue) (red) * Current GOES contains 5 of the 6 listed bands, GOES-8/11 with band-5 and GOES-12/13/etc. with band-6.

GOES-R ABI Bands and Bandwidths GOES-R ABI Band Central Wavelength (μm) Wavelength Range (μm) Spatial Resolution nadir 1 (blue) (red)

Comparison of GOES-R ABI with MODIS bands GOES-R ABIMODIS Band NumberWavelength (μm)Band NumberWavelength (μm) 1 (blue)0.473 (blue) (red)0.641 (red) No Equivalent No Equivalent

Product example: New Daytime Fog/Stratus Product Start with current products used for fog/stratus detection –Shortwave Albedo “Fog” product Apply MSG “natural” 3-color product idea Apply/re-apply to new ABI bands and adjust bands as needed to improve discrimination of features in the product.

First fog/stratus case

Summary of 3-color image combinations for fog/stratus detection/discrimination * The counts in these bands/images are non-linearly gamma-adjusted (to a power of 1/1.7) before combining (Gaertner 2005). ** Albedo is the solar-zenith-angle corrected reflectance. 3-color Product Name Red Component Green Component Blue Component Image Example MSG “natural” 3- color product 1.6 μm0.86 μm0.6 μmSecond from last slide MSG “day snow-fog” product 0.8 μm*1.6 μm*3.9 μm (solar/reflected part only)* Not shown Modified 3- color fog/stratus product 0.6 μm albedo** 1.6 μm albedo** 3.9 μm (“shortwave”) albedo** Last slide

Second fog/stratus case

Product example: New Blowing Dust Product Start with current products used for detecting blowing dust –Longwave difference product (IR vs. visible bands are generally better for dust, also then works day and night) –Rosenfeld* 3-color dust product Apply Principal Component Image (PCI) transformation (as a pseudo-enhancement) to same bands as Rosenfeld, plus. Apply/re-apply to new ABI bands, and adjust bands as needed to improve the discrimination of features in the product. * Daniel Rosenfeld, Hebrew University, Jerusalem

First blowing dust case

Summary of 3-color image combinations for blowing dust detection/discrimination 3-color Product Name Red Component Green Component Blue Component Image Example Rosenfeld 3- color “dust” product 12.0 – 10.8 μm*10.8 – 8.7 μm*10.8 μm* First color slide 3-color blowing dust product PCI-2 (of 3 PCIs) PCI-3 (of 3 PCIs) PCI-1 (of 3 PCIs) Middle color slide Modified 3- color blowing dust product PCI-2 (of 4 PCIs) PCI-4 (of 4 PCIs) PCI-3 (of 4 PCIs) Last color slide * Special stretching/enhancements are applied to each difference or band image before combining.

Second blowing dust case

Summary Important factors in band selection: –Start with bands available with GOES-R ABI –Use spectral regions important for the feature of interest –Prefer window/lower atmospheric bands –Leverage existing products as foundation for improvement –Use Principal Component Image (PCI) analysis, if needed to extract explained variances Important factors in color selection: –Bright colors for feature of interest, neutral background color –Strongly contrasting colors for discriminating different image (cloud and surface) features