IAPP

CIMSS is pleased to announce the availability of the International ATOVS Processing Package (IAPP), version 2.01. The software operates in the Unix environment on IBM, SGI, and Sun workstations. Documentation is included with the software, describing how to install the IAPP, the design structure, and how each module operates.

The IAPPv2.01 is designed to work with the AAPP (ATOVS and AVHRR Preprocessing Package) HIRS-3 level 1-D output file. That package was developed under the auspices of EUMETSAT; distribution is currently handled by the UK Meteorological Office. For information on the AAPP, and how to obtain it, see http://www.metoffice.com/research/interproj/nwpsaf/atovs/aapp/.

Below is a short description of the IAPP contents, licensing issues, and how to obtain the package.

IAPP Contents

The IAPP currently uses radiances from HIRS-3, AMSU-A, and AMSU-B on NOAA-15, -16, and -17, preprocessed into the AAPP 1-D format, for retrieval. Ancillary data inputs for retrieval are high resolution topography (supplied), surface observations (see below) and numerical model data (see below). The IAPP performs temperature and moisture retrieval calculation on a 3x3 HIRS field of view (fov) matrix, or field-of-regard (FOR). HIRS and AMSU-A radiances are used for clear/cloudy fov determination. Depending on clouds, a HIRS + AMSU-A + AMSU-B retrieval, an AMSU-A + AMSU-B (i.e., no-HIRS) retrieval, or no retrieval is made for each FOR. The output file is in NetCDF format. Detailed information is provided in the documentation.

Surface data in the WMO Metar format is used, if available, to improve surface condition definition. If surface observations are not available, numerical model data is used (see next item) to define surface conditions, or, with neither available, window channel radiances are used to best approximate surface conditions. We strongly recommend using Metar surface information and/or NWP output to better describe surface conditions in retrieval processing.

Numerical model output can be used as a first guess field for the atmosphere and surface. Any model can readily be adapted to fit into the IAPP retrieval scheme. Clearly written documentation makes this task relatively straightforward. Alternatively, a regression scheme, based on synthetic radiance calculations, can be used to provide a first guess. Again, detailed information is provided in the documentation.

Licensing

The IAPP source code and supporting fixed datasets have been bundled as Open Source in accordance with the terms of the GNU General Public License http://www.gnu.org/licenses/licenses.html#GPL. The package is freely available under the terms of that License.

Obtaining the IAPP

To download the IAPP, you can go here: ftp://ftp.ssec.wisc.edu/pub/iapp/.

Subdirectory "release_2.01" contains the complete IAPPv2.01 package, as well as related software packages for decoding NWP and surface data (decoders.tar.gz) and for reading and writing netCDF files (netcdf-3.4.tar.gz).

Subdirectory "patch_2.0" is provided for users who already have a working installation of IAPPv2.0, and wish to update to version 2.01 without doing a complete re-install.

Technical Contact:

Harold M. Woolf
Cooperative Institute for Meteorological Satellite Studies
Space Science and Engineering Center
University of Wisconsin - Madison
Phone 608-262-0986
Fax 608-262-5974
Email: email contact form