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International ATOVS Processing PackagePart of the CIMSS Web |
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Background on the ITPP and IAPPThe International ATOVS Processing Package (IAPP), and its predecessor the International TOVS Processing Package (ITPP), have been developed to retrieve atmospheric temperature and moisture profiles, total ozone and other parameters in both clear and cloudy atmospheres from ATOVS/TOVS radiance measurements. The IAPP algorithm, which operates on NOAA-15 and later data, retrieves the parameters in 4 steps: 1) cloud detection and removal; 2) bias adjustment; 3) regression retrieval; and 4) nonlinear iterative physical retrieval. A recent publication by Li, Wolf, Menzel, Zhang, Huang and Achtor, Journal of Applied Meteorology (August 2000) provides details on the algorithm. Download SoftwareFor information on the IAPP and how to obtain it free of charge, click here: download software.Real Time Orbital ElementsThese orbital elements are available daily after about 1215 UTC. They originate from the standard TBUS signal, and therefore predict orbital state about 3 days in the future. They have been reformatted so they may be input directly into the ITPP -- for processing data from NOAA-14 and earlier spacecraft -- by running program 'putele'. Each of the following files contains information for the last seven days. The ascii files for NOAA-15 ff. are provided for other applications of satellite navigation. The files orbntbus.n14 through orbntbus.n18 are big-endian binary direct-access. Each one contains all available Brouwer-Lyddane elements from the time TBUS data first became available for that spacecraft. For use in AAPP, original TBUS bulletins, if not available via GTS, can be acquired from the Web in at least two ways. The latest information will be found at http://noaasis.noaa.gov/cemscs/poltbus.txt which is normally updated daily. Data for other days can be obtained from http://noaasis.noaa.gov/NOAASIS/ml/ptbus.html When using the latter site, which presents daily files for an entire year, the user should exercise caution, since the file for a given day may not have been updated and will therefore contain data for other than the current year. NOTICE: This information is provided as a service to the user community. It is not meant to support any operational activity. Although CIMSS expects to be able to provide this information indefinitely, we reserve the right to discontinue such service at any time. Numerical Model Data for Use in the IAPPA limited amount of NWP output from NCEP's GFS model is routinely processed by the GRIB-to-netCDF processor that is supplied with the IAPP, and posted to the SSEC anonymous ftp server in a moving seven-day archive. Each day-of-the-year subdirectory, which is named yyyymmdd (yearmonthday), contains the anl (analysis or 0-hour), plus 6- and 12-hour global forecast files, obtained from the 00, 06, 12, and 18 UTC analysis- forecast cycles. The files are (ideally) posted approximately four hours after cycle time -- e.g., the 00 UTC files are available at 0400 UTC, give or take a minute or so. Occasional delays in receipt of the original files at SSEC will, of course, lead to delay in generating and posting the netCDF files -- this lag should not exceed one hour. The files have been gzip'd for faster downloading. To obtain this data, go to ftp://ftp.ssec.wisc.edu/pub/ssec/halw/grids/. Please see the above NOTICE regarding CIMSS's commitment to providing this information. Surface Data for Use in the IAPPHourly surface data is routinely processed at CIMSS in support of the IAPP. The raw METAR files are posted to the SSEC anonymous ftp server in a moving seven-day archive. Each day-of-the-year subdirectory, which is named yyyymmdd (yearmonthday), contains the files for every UTC hour from 00 to 23. Note that the last element of each file name is hh+30; this serves to denote the midpoint of the hour -- data are actually collected until hh+55. The user can transform these files to netCDF for input to IAPP by using the METAR-to-netCDF processor that is included with the package. To obtain this data, go to ftp//ftp.ssec.wisc.edu/pub/ssec/halw/surface/. Please see the above NOTICE regarding CIMSS's commitment to providing this information. Global Radiosonde DataAnother moving seven-day archive on the SSEC anonymous ftp server that IAPP users may find useful consists of 00 and 12 UTC files of global radiosonde data that have been remapped to the 42-level vertical pressure coordinate employed in the IAPP. This is the format expected by the SRX-to-netCDF processor included with the IAPP. To obtain this data, you can download it from: ftp://ftp.ssec.wisc.edu/pub/ssec/halw/. The file-naming scheme is SRXdddhh, where ddd is day-of-year, and hh is hour (00 or 12). Please see the above NOTICE regarding CIMSS's commitment to providing this information. Radiance Bias Tuning Parameters
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