Question

Remote Sensing:

Thermal Infrared and BT

Question: A satellite measures a spectral radiance of 8 Watts/m2/um/ster at a wavelength of 10 microns. Assuming a surface emissivity of 0.95, what would be the estimated temperature?

Question: You are looking at satellite data for a cloud. It reflects about 40% of the light that hits it, and has a brightness temperature of 270 K. The surface surrounding the cloud appears to have a brightness temperature of 295 K. What would be a good estimate for the temperature of the cloud? Explain your reasoning.

Answer 1

The brightness temperature is given by

T he = b ak zhez en (Italian where hi Planck's constant 34 6.626 X 10 J.S, k: Boltzman constant 23 JIK, = 1.38X10 in vacuum e: speed of light = 3x 108 m/s. 7: cavelength = 10 um =(10x10-6 m =105m, Iai spectral radiance =8 watt m 2 sa-l

Here $\epsilon$ is the emissivity.
In this case, $\epsilon =0.95$ .

Therefore

- To he encore zhe 2 € Inns _34 6.626 X 10 To * 3x108 = 10-581-38x10-23 X -34x9x1016 2 X 6.626 X 10 en + en 0.95 x 8 x 10 -585 K 그 76.33 K.