Overpass over the NSA ARM site, Pt. Barrow, Alaska
During this flight, the HIS obtained radiances from approximately 2000 UTC to 2130 UTC. The ER-2 passed over the North Slope of Alaska (NSA) Atmospheric Radiation Measurement site at approximately 2047 UTC. Here is the average upwelling radiance spectrum for the overpass of the NSA ARM site and the corresponding brightness temperature spectrum for all 3 HIS bands. The HIS brightness temperature in the atmospheric window region shows temperatures around 272 K. The corresponding downwelling radiance spectrum at the surface from the same time was measured by the Atmospheric Emitted Radiance Interferometer (AERI) at the NSA ARM site. The fact that the downwelling radiance at the surface is similar to a Planck function indicates that there is low, thick cloud cover at this time. The corresponding AERI brightness temperature spectrum shows a similar temperature to that measured by the HIS. Here are some more AERI radiances throughout the day (980518), showing the effect of various clouds on the downwelling infrared radiance at the surface.
Upwelling HIS radiances from near the SHEBA Ice Camp
Here is the average upwelling radiance spectrum near the SHEBA Ice Camp at approximately 2122 UTC and the corresponding brightness temperature. Notice that the temperatures in the window region are lower than those over Barrow, suggesting either clear sky or a colder cloud deck.
Matlab M-file used to generate figures.
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