It is said that a picture says a thousand words…well in this case let’s just say 434 words, as are contained in this post. Anyway, I’d like to point out six features in this morning’s Nighttime Microphysics RGB. The image below (MODIS Nighttime Microphysics RGB) showed several features of varying degrees of operational relevance.
A myriad of cloud features can be observed, including fog in the valleys of central Appalachia, deep convective clouds along the Florida coast, patches of thin and thick cirrus over north-central Alabama, and low stratus clouds in Missouri…to name just a few. Sure, this isn’t an exhaustive list of the potential cloud features to observe, but showcases the ability to contrast effectively between different cloud types. Of perhaps significant interest is the ability to see the contrasting airmasses displayed across the Southeast region. Notice the pinkish colors north and west of the yellow curved line that stretches from central Louisiana to southern Virginia. This represents a lower relative contribution of blue color, or lesser longwave radiation at the 10.8 µm wavelength, which is indicative of cooler temperatures. To the south and east of this line, much more blue is apparent, which is thus indicative of warmer temperatures. Surface observations valid at about the same time have been overlaid with the RGB image to provide temperature data context. Air and dew point temperatures are around 10 degrees F cooler behind the line/front, but notice that the northerly wind shift is still on the south/east side of the line at such locations as Montgomery, AL and Columbus, GA. At those locations, dew point temperatures were still 70 and 71 F, respectively, with air temperatures at 72 F. So, the gradient in temperatures still lingered behind the surface front and is well depicted in the RGB imagery. This type of information can be valuable to forecasters, as temperature, moisture, and wind characteristics are often complex in the vicinity of surface fronts. Thus, while wind shifts may be observed initially, as in this case, the imagery shows the location of the temperature gradient much better.
The importance of this type of imagery is that it offers a much more effective assessment of meteorological phenomena than existing GOES imagery. The only problem currently is the limitation of available imagery to forecasters, since these are from polar-orbiting platforms (Terra, Aqua, Suomi NPP), and thus provide just a few snapshots per night over a given location. Nevertheless, the imagery form the VIIRS and MODIS instruments offer added value to existing GOES imagery and serve as valuable teaching and preparatory aids for future GOES-R and JPSS missions.