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

ADDITIONAL MATERIALS:
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)

 

TASK 1
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.

 

TASK 2

The National Snow and Ice Data Center (NSIDC) is one of the NASA EOS data centers (see Supplement Materials: NASA EOS Data Centers). NSIDC manages and distributes satellite data products and some scientific data related to polar regions and cryosphere, including the snow, ice, glaciers, frozen ground, and climate interactions. NSIDC also manages data products from NOAA and DoD satellites.

In this task you will learn how the properties of sea-ice retrieved from passive remote sensing. One of the longest records of sea-ice observations from space has been provided by the SSM/I (Special Sensor Microwave Imager) since about 1987. SSM/I was flown aboard several Defense Meteorological Satellite Program (DMSP) satellites. The SSM/I is a seven-channel, four-frequency (19.35, 22.235, 37.0, and 85.5 GHz), linearly-polarized, passive microwave radiometric system.

Here is the link to brief definitions of sea-ice data products retrieved from satellites.

The theoretical basis is described in the NASA Team Sea Ice Algorithm. Read the description of the algorithm first, and then apply it to SSM/I observations of brightness temperatures to retrieve the concentration of first-year sea-ice, multiyear sea-ice and total sea-ice in the regions A and B marked on SSM/I images. Do your results look reasonable? Briefly explain why.

SSM/I images of brightness temperature for Jan.29, 2002
Channel 19V
Channel 19H
Channel 37V