Surface data in the WMO Metar format is used, if available, to improve surface condition definition. Numerical model output can be used as a first guess field for the atmosphere and surface. Any model can easily be adapted to fit in the IAPP retrieval scheme. Clearly written documentation makes this task relatively easy. Alternatively, a regression of raob radiance comparisons can be used to provide a first guess.
Detailed information is provided in the documentation.
Licensing As stated at the International TOVS Working Group meeting in Boulder, CO in February 1999, the IAPP source code will be provided to ITWG members. This software will have licensing restrictions similar to ITPP, in that you can use it at your site, but cannot re-distribute any portion of the software. If you cannot contribute to IAPP development, do nothing with the invoice, and consider the software to be freeware. We will respond with an ftp address and instructions to download the software. The .tar file is about 200 mb in size.