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Use of either asphalt or concrete emissivity values for Toronto thermal map

I am currently working on a thermal map of Toronto- with Landsat 8 imagery- and I am wondering as to whether there is a way of determining the surface emissivity without using known values for known land covers. For example, after classification I know that certain areas are either asphalt or concrete, but I don't know which emissivity values to use! And I have looked for statistics on Toronto rooftops, but to no avail. Furthermore, in industrial areas, the rooftops may also be composed of other materials.

So is there any way of determining the emissivity values on the surface, or any article which can justify the use of one material`s emissivity value over another?

Saad Jamaluddin

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Hi,

There is no way to determine the emissivity of materials from a Landsat-8 classification.
Typical values for asphalt are around 0.95, rough concrete is around 0.94, but aged or dirty materials are somewhat higher.
Typical values for vegetation are 0.97 - 0.98, for bare soil 0.96 to 0.97, water around 0.985 (all values for the 11 - 12 µm spectrum).

Hope this helps,
Sarah

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