Cloud plume from an industrial source in Ontario, Canada
Thanks go out to Jason Alumbaugh from NWS Marquette, who sent the following in an email:
Taking a look at the initial daytime formation of the plume on 20 October 2018, a very subtle signature could be seen at times in GOES-16 (GOES-East) “Red” Visible (0.64 µm) images, but the plume was more obvious in the Near-Infrared “Snow/Ice” (1.61 µm), Near-Infrared “Cloud Particle Size” (2.24 µm) and Shortwave Infrared (3.9 µm) imagery (above). Emissions from an industrial source (likely a power plant, or perhaps the Domtar paper mill?) acted as cloud condensation nuclei, causing a higher concentration of smaller supercooled cloud droplets downwind of the plume source — and this plume of smaller particles was more reflective and thus appeared brighter in the 1.61/2.24 µm images and warmer (darker gray) in the 3.9 µm images.
“Previous shift here at NWS Marquette passed along interesting feature on satellite last night. Origin of the feature is approx. 49.23 N and 91.00 W (just west of CWDV – Upsala in Ontario) but eventually the plume spread as far south as south central Upper Michigan and northeast Wisconsin (IMT to MNM). Our meteorologists said it looked like a fire and called Environment Canada overnight but they had not heard of anything reported.”
Color-enhanced 3.9 µm Shortwave Infrared imagery (below) showed the transition from a warmer (darker red) plume during the day — due to enhanced reflection of incoming solar radiation — to a colder (darker blue) plume at night.The higher spatial resolution of MODIS and VIIRS imagery from the polar-orbiting Terra/Aqua and NOAA-20/Suomi NPP satellites offered alternative views of the plume. A comparison of Suomi NPP VIIRS Visible (0.64 µm), Day/Night Band (0.7 µm), Near-Infrared “Snow/Ice” (1.61 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images (below) showed the early stage of the plume during the day on 20 October — as was seen with GOES-16, the plume signature was most obvious in the 1.61 µm Snow/Ice and 3.74 µm Shortwave Infrared imagery. A nighttime comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm), Shortwave Infrared (3.74 µm), Infrared Window (11.45 µm) and Fog/stratus Brightness Temperature Difference (11.45-3.74 µm) images (below) revealed signatures of the plume at 0716 UTC or 2:16 am CDT on 21 October, after it had traveled nearly 350 miles from the Ontario source to the Green Bay, Wisconsin area. Cloud-top 11.45 µm infrared brightness temperatures of the plume and the surrounding supercooled clouds were generally in the -13º to -16ºC range. A sequence of nighttime Fog/stratus BTD images from Terra/Aqua MODIS and NOAA-20/Suomi NPP VIIRS (below) showed the plume moving southeastward across the Upper Peninsula of Michigan into northeastern Wisconsin. BTD values associated with the plume were in the 3-5ºC range (darker shades of red). [Note: the NOAA-20 VIIRS images are incorrectly labeled as Suomi NPP]