CIMSS Satellite Blog

It looks like someone was having fun flying in circles. Check out the contrails southwest of San Diego captured by #GOES16 yesterday afternoon. You can even see its shadow on the low clouds early in the animation. pic.twitter.com/PvUr2jNack

— NWS San Diego (@NWSSanDiego) April 24, 2018

As pointed out by NWS San Diego, an interesting pattern of contrails formed off the coast on 23 April 2018. A comparison of GOES-16 (GOES-East) “Red” Visible (0.64 µm), Near-Infrared “Cirrus” (1.37 µm) and “Clean” Infrared Window (10.3 µm) images (below) showed signatures during the daylight hours — with Visible images revealing contrail shadows cast upon the low-altitude cloud tops at 0142 and 0147 UTC — and an Infrared signature persisting after sunset. These contrails were likely caused by military aircraft performing training exercises, since chaff was seen with radar on the previous day.

GOES-16 “Red” Visible (0.64 µm, left), Near-Infrared “Cirrus” (1.37 µm, center) and “Clean” Infrared Window (10.3 µm, right) images [click to play animation | MP4]

A better post-sunset signature was seen on a NOAA-15 Infrared Window image at 0212 UTC (below). A comparison with the corresponding GOES-16 “Clean” Infrared Window image displayed a significant northwestward GOES-16 displacement due to parallax — and the 1.1 km spatial resolution of AVHRR data resulted in a clearer contrail signature.

NOAA-15 AVHRR Infrared Window (10.8 µm) and GOES-16 ABI “Clean” Infrared Window (10.3 µm) images [click to enlarge]

The contrails could also be followed after sunset using GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) imagery (below).

GOES-16 Low-level (7.3 µm, left), Mid-level (6.9 µm, center) and Upper-level (6.2 µm, right) Water Vapor images [click to play animation | MP4]

The GOES-16 Water Vapor weighting function plots (below) displayed a bi-modal distribution for all 3 spectral bands, with peaks near 300 hPa and 500 hPa. The absence of a contrail signature on the 6.2 µm imagery suggests that these features were located closer to the 500 hPa pressure level.

GOES-16 Water Vapor weighting functions, calculated using rawinsonde data from San Diego CA [click to enlarge]

from CIMSS Satellite Blog http://cimss.ssec.wisc.edu/goes/blog/archives/27856