CIMSS Satellite Blog

GOES-16 “Blue” Visible (0.47 µm, top), “Red” Visible (0.64 µm, center) and Shortwave Infrared (3.9 µm, bottom) images, with hourly surface plots in yellow [click to play animation]

A daytime comparison  of GOES-16 “Blue” Visible (0.47 µm), “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above; also available as an MP4 animation) displayed the smoke plume and “hot spots” (black to yellow to red pixels) associated with the West Mims Fire that was burning in far southeastern Georgia on 25 April 2017. Downwind of the fire in far northeastern Florida, smoke reduced the surface visibility to 2 miles at Jacksonville and 5 miles at Fernandina Beach.

GOES-16 “Snow/Ice” Near-Infrared (1.61 µm, top), “Cloud-Top Phase” Near-Infrared (2.24 µm, center) and Shortwave Infrared (3.9 µm, bottom) images, with hourly surface plots in yellow [click to play animation]

During the subsequent nighttime hours — as the fires were beginning to decrease in both intensity and areal coverage — a comparison  of “Snow/Ice” Near-Infrared (1.61 µm), “Cloud-Top Phase” Near-Infrared (2.24 µm) and Shortwave Infrared (3.9 µm) images (above; also  available as an MP4 animation) showed that a bright glow from the most intense fires was evident in both of the Near-Infrared spectral bands.

Although the spatial resolution of the 1.61 µm Band 5 is 1 km (at satellite sub-point) versus 2 km for the 2.24 µm Band 6, the bright nighttime fire signature was more defined on the 2.24 µm imagery; this is explained by examining a plot of the Spectral Response Function (SRF) for each band (below; courtesy of Mat Gunshor, CIMSS). For a very hot fire target — represented by the red 1200 K line — the 2.24 µm Band 6 SRF is located near the peak of the 1200 K plot, so more of the fire-emitted radiance can be sensed by Band 6 (in spite of its lower spatial resolution).

Spectral Response Function plots for GOES-16 ABI Band 5 (1.61 µm), Band 6 (2.24 µm) and Band 7 (3.9 µm) [click to enlarge]

from CIMSS Satellite Blog http://ift.tt/2q8hIUc