Monthly means of full disk GOES-17 brightness temperatures¹ for Bands 8, 10, and 13 have been computed from 2019 to 2021, totaling 36 months. This is an expansion of similar work that had been done for Band 13 for a single year. Band 8, centered on 6.2 µn, is sensitive to upper-level water vapor. While Band 10, centered on 7.3 µn, is sensitive to low-level water vapor. Band 13 is the clean longwave infrared window channel and observes at 10.3 µn.

Brightness temperature can be thought of as the amount energy (radiance) being reflected or emitted from Earth and measured by satellite sensors. These fields of averaged brightness temperature are useful for assisting forecasters in knowing what can be expected from satellite retrievals on monthly timescales, especially in remote Pacific regions where forecasters are heavily reliant on satellite data.

While a large amount of smoothing is expected for a monthly average, the resulting full disk fields are not homogenous. Certain patterns appear. The ITCZ is noticeable. Also, an area of warmer brightness temperature is visible west of Hawaii during winter months in the animations for Bands 8 and 10. This is likely associated with a synoptic high pressure for that region.

Reference to a Climatic Atlas created by Sadler et al. (1987) from the School of Ocean and Earth Science and Technology confirms potential for a synoptic high pressure region that is usual for that time of year. However, because the Sadler fields are derived surface measurements (temperature, pressure, wind, and stress), comparing them to GOES-17 ABI brightness temperatures is not exactly an “apples to apples” situation.

¹ Brightness temperatures are computed from radiances.

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The Community Software Processing Package (CSPP) includes Flood Detection algorithms that can be applied to VIIRS data at Direct Broadcast sites (such as at CIMSS). The daytime NOAA-20 orbit over California on 22 January 2023 overflew mostly clear skies, resulting in the True Color and False Color imagery shown above, and the diagnosed regions of floods, mainly in the Sacramento and San Joaquin River basins. Note that flooding in these two river basins can also be a result of agricultural diversions to support rice farming. So a good question is: Was the water put there intentionally — or did it flood? The modest flood signal in the Salinas River basin (south and east of Salinas) is more likely actual flooding.

These images were created using geotiff images from CSPP that were inserted into Google Earth and are courtesy Kathy Strabala, SSEC/CIMSS. VIIRS flood imagery (including imagery displayed in concert with ABI and AHI data) are also available here.

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GOES-16 (GOES-East) Near-Infrared “Snow/Ice” (1.61 µm) images (above) displayed industrial plumes (from sources such as power plants) that produced brief periods of light snow as they drifted over a few sites in northern Wisconsin on 22 January 2023. Particles emitted from industrial stacks acted as cloud condensation nuclei, “seeding” the surrounding supercooled water cloud droplets which then created a higher concentration of smaller cloud droplets — and these smaller cloud droplets were more efficient reflectors of incoming solar radiation, making the plumes appear slightly brighter than the surrounding clouds.

GOES-16 Day Snow-Fog RGB images (below) provided a bit more cloud-top contrast, helping to slightly enhance the appearance of the industrial plumes.

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Overlapping 1-minute Mesoscale Domain Sectors provided GOES-16 (GOES-East) imagery at 30-second intervals over the Mid-Atlantic states on 20 January 2023 — and Mid-level Water Vapor (6.9 µm) images (above) revealed widespread mountain waves east of the Appalachians (produced by strong westerly flow interacting with the terrain). There were numerous pilot reports of light to moderate turbulence associated with these mountain waves.

The 1200 UTC Water Vapor image with plots of rawinsonde sites (below) indicated that Sterling, Virginia KLWX (which replaced the Washington-Dulles site KIAD) was located within the region of drier air where mountain waves were prevalent at that time.

Plots of GOES-16 Water Vapor spectral band (08, 09 and 10) weighting functions calculated using 1200 UTC rawinsonde data from Washington-Dulles, Virginia (KIAD) are shown below — due to the presence of dry air throughout the middle and upper troposphere over that location (Skew-T plot), the water vapor weighting functions were shifted to lower altitudes; the peak of the 6.9 µm (Band 09) weighting function was at the 617.5 hPa pressure level, with significant upwelling radiation contributions originating from as low as the 700 hPa level.

30-second GOES-16 “Red” Visible (0.64 µm) images are shown below.

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