Radiannet is a two-band radiation simulation model. Retrievals of the physical properties of volcanic clouds are processed by adjusting the optical and physical parameters in the radiative transfer models to best fit the observed radiances. In the current program, AVHRR Band 4 and Band 5 brightness temperatures are simulated. The assumptions for using this program are:

  1. Spherical Aerosol Particles
  2. Homogeneous Parallel Cloud Layer Parallel to a Homogenous Underlying Surface
  3. Single Type of Aerosol in the Cloud: ice, water, ash(andesite, basalt), or H2SO4
  4. Atmosphere above and below the volcanic cloud are clear windows, with high transmission.

Click on the image to the left to look at a larger version of the IDL widget interface.

Radiannet is composed of many different FORTRAN and IDL subroutines. An IDL widget interface is used to make entering the input parameters easy. The IDL code spawns FORTRAN subroutines, which does the radiative transfer calculations. The results of the calculations are transfered back to IDL and output plots are produced.

Background Information

For information on the basic theory behind the Radiannet Program see "Retrieval of sizes and total masses of particles in volcanic clouds using AVHRR bands 4 and 5" by Shiming Wen and William I. Rose in Journal of Geophysical Research, VOL. 99, NO. D3, Pages 5421-5431, March 20, 1994. This research was presented at the AGU 1993 Fall meeting, and is available online.

For information on the detection of volcanic clouds using AVHRR see Two Channel AVHRR Discrimination of Volcanic Clouds.