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Landsat 8 nighttime thermal infrared image of Yellowstone from 28 January 2022

Detailed Description

Landsat 8 nighttime thermal infrared image of Yellowstone from 28 January 2022.  Inset images are zoomed in on the area outlined by the white square.  Inset image (A) has the raw data values, which range from 9070 to 21284.  Inset image (B) shows the same image converted to spectral radiance, where values range from 3.13 to 7.21 W/m2/micron/sr.  Inset image (C) is a calculated temperature image, with values ranging from about -30 °C to 11 °C (-22 °F to 52 °F).  These 3 images look the same in terms of their pixel brightness tones and textures, but quantitatively, they contain different information.  The dark pixels at the bottom of the inset images are from Pelican Creek Valley, a broad, open valley with a very cold (snow-covered) surface.  The moderately bright (warm) pixels in the upper right are part of the Astringent Creek thermal area.  The brightest (warmest) pixels in the image are in the Sulphur Hills thermal area in the lower left.  11 °C (52 °F), may seem cold considering that Sulphur Hills is one of the hottest thermal areas in Yellowstone, with numerous boiling (93 °C, or 200 °F) fumaroles scattered around the area, but a single pixel is about the size of a soccer field, and the retrieved pixel temperature represents a mixture of all the cold and hot materials inside the pixel.  Compared to its immediate surroundings, which are around -23 °C (-9 °F), Sulphur Hills is up to 34 °C (61 °F) degrees warmer.


Public Domain.