Overview
---------

airs_decon is a Matlab git repo to translate channel radiances
from AIRS to CrIS, from AIRS to an idealized grating model, and
from CrIS to AIRS.  Translations from AIRS use a deconvolution of
AIRS channel radiances, taking advantage of detailed knowledge of
the AIRS spectral response functions.

airs2cris.m is the main function for AIRS to CrIS translations.
test/demo1.m gives an example of calling it.  The translation has
been tested extensively with both real and simulated AIRS 1c data.
See test/README for more info on the test scripts.  test/airs_test
has CrIS to AIRS translation and AIRS channel shift tests, see the
README there for more info.

The package includes functions to convolve high resolution kcarta
radiances (at a 0.0025 cm-1 grid) to AIRS and CrIS channel radiance,
and simple functions for forward and inverse hamming apodization.

Documentation includes man-page style comments at the top of most
most functions.  doc/decon_atbd.pdf gives an overview and comparison
of the IASI to CrIS, IASI to AIRS, AIRS to CrIS, and CrIS to AIRS
translations.  doc/decon_paper.pdf give a detailed analysis of AIRS
deconvolution and the AIRS to CrIS translation.

Top Level Directories
----------------------

  doc      - documentation
  source   - user source directory
  test     - test source directory
  data     - SRFs and correction weights

User Paths
-----------
  
Application running in the test directory set the following paths

  ../data
  ../source
  /asl/packages/ccast/source

Paths are set in the calling routines, the demo and test routines
here.  The ccast repo provides bandpass, finterp, inst_params, rad2bt 
and bt2rad.  ccast is available at https://github.com/strow/ccast.git

User Functions
---------------

  airs_decon  - deconvolve AIRS radiances
  airs2cris   - translate AIRS to CrIS radiances
  cris2airs   - translate CrIS to AIRS radiances
  mksconv1    - create a general-purpose sparse AIRS SRF matrix
  mksconv2    - create a modified SRF matrix for deconvolutions
  seq_match   - find the matching subsequence of two sequences
  kc2cris     - convolve kcarta to CrIS channel radiances

  mkhamm      - sparse hamming convolution matrix 
  hamm_app    - spectral space forward hamming 
  hamm_inv    - spectral space inverse hamming

The hamming functions are called as an option in airs2cris, and may
be useful for other applications.