# Computer Modeling Laboratory 1

Written report due: 2 February

## Planck function and main radiation laws. Passive microwave remote sensing of sea-ice.

REQUIRED MATERIALS:
Lecture 2, S 4.5.1

NSIDC tutorial All about sea ice

Instruction
To calculate and plot the Planck function in the wavelength domain use Bλ (T)

To calculate and plot the Planck function in the wavenumber domain use Bν (T)

Thermal emission provides a basis for many important remote sensing applications. This task is designed to give you a better understanding of the nature of thermal emission and how to use the Planck function.
1. Calculated values of the Planck function integrated over the terrestrial (IR) region for a blackbody with T=250K in the wavelength domain and in the wavenumber domain. Do these two values agree?
2. For the same blackbody, calculated a broadband flux using the Stefan-Boltzmann law. Compare to your results from Planck function calculations. Would you expect to have a good agreement between your calculations?
3. The region from about 8 μm to 12 μm is called an atmospheric window. What fraction of total blackbody radiation is emitted in the atmospheric window? Compare it to the fraction of total blackbody radiation emitted in the microwave region.
Consider a blackbody with T=250K?
4. The emissivity of sand in the IR window is about 0.9. Calculate the radiance measured by a detector at 9.5 μm, assuming that sand has T=250 K. Then calculate the brightness temperature of sand. Would you expect this temperature to be higher or lower than physical temperature (T=250K)? Briefly explain why.