Help for MASTERHOT

PURPOSE:

   MASTERHOT is a program that accepts as input MASTER TIR radiance at sensor 
image data and outputs upwelling radiance at surface for the thermal infrared
channels (Channels 41-50).  Also required as input are a valid MODTRAN input
file, to define the atmospheric model, and a MASTER TIR spectral response
file.  It is identical to MASTERTIR, except that output is fullword (32 bit
integer), to accomodate hotter temperatures.

OPERATION:

   MASTERHOT takes as input the 10 Channels of MASTER TIR radiance at sensor
data in units of Watts per square meter per steradian per micrometer, and a
file containing the the MASTER TIR spectral response functions. This second
file must be a VICAR labelled file consisting of ten lines (one for each TIR
channel) and 800 samples (one for the spectral response at each wavelength
from 7.00 to 14.99 micrometers, in 0.01 micrometer increments). The spectral 
response functions must be normalized, i.e., the sum of all values on each 
line must be 1.0.
   The atmospheric model used is defined by a user supplied MODTRAN input
file.  MASTERHOT uses these parameters to run MODTRAN twice; once with a
nadir looking geometry, and once for the case of viewing at maximum deflection
from nadir.  From these two runs, the atmospheric transmittance, path
radiance, and downwelling sky radiance at surface are calculated for the ten
MASTER TIR bandpasses.  The downwelling sky radiance values are placed in
the VICAR label of the output dataset.
   Values of transmittance and path radiance are calculated for each pixel
location in the scene by interpolation, where it is assumed that each
quantity varies linearly with path length.
   The upwelling radiance at surface is then computed by the following 
formula:

        Rad(at sensor) = RAD(upwelling)*transmittance + Rad(path)

It should be noted that the output quantity (upwelling radiance) of MASTERHOT
differs from the output quantity of TIMSCAL2 (surface emitted radiance). It
it includes both the surface emitted component plus the surface reflected
component.
   The output dataset consists of 10 channels of 32 bit signed integer 
pixels, in units of milliWatts per square meter per steradian per
micrometer.  Note that these units are 1000 times smaller than the input
units.  The downwelling sky irradiance values that are placed in the VICAR
label are in units of milliWatts per square meter per micrometer.  To 
convert to radiance in units consistent with the output images, one must
divide by pi.


WRITTEN BY:  Ron Alley         August 12, 1998

COGNIZANT PROGRAMMER:  Ron Alley

REVISION: 1.3 Oct 21, 1999