AAPP User Guide

ATOVS and AVHRR Pre-processing Package (AAPP)

Document: NWPSAF-MO-UD-036
Version: 8.8
Date: August 2022

Author: Nigel Atkinson (Met Office)

This documentation was developed within the context of the EUMETSAT Satellite Application Facility on Numerical Weather Prediction (NWP SAF), under the Cooperation Agreement dated 29 June 2011 between EUMETSAT and the Met Office, UK, by one or more partners within the NWP SAF. The partners in the NWP SAF are the Met Office, ECMWF, DWD and Météo France.

Copyright 2016, EUMETSAT, All Rights Reserved.

Introduction

The ATOVS and AVHRR Pre-processing Package (AAPP) originated in the late 1990s, in response to the need for a processing package for the direct readout data from NOAA-15 and its successors. Since then, many extensions have been added, e.g. a major enhancement to accommodate Metop in 2006 (AAPP v6) and extension to Suomi-NPP in 2012 (AAPP v7). The package is maintained by the EUMETSAT Satellite Application Facility for Numerical Weather Prediction (NWP SAF). The current major release is v8.

This guide provides information on the capabilities of AAPP, with practical hints on its use that are relevant to both new and experienced users. It also addresses some of the questions that have been posed by users of the over the years. It is intended to be used in conjunction with the other documents which are available on the AAPP web page, including:

• • Installation Guide
  • Scientific Description
  • Software Description
  • AAPP overview
  • Data Formats
  • OPS-LRS User Manual
  • AAPP Top Level Design documents

Summary of AAPP capabilities

AAPP consists of a large number of tools for different aspects of polar-orbiter satellite data processing. These tools are mainly concerned with level 0 and level 1 processing, i.e. to generate basic quantities such as brightness temperatures, on the original satellite swath. It has a capability to generate cloud mask and sea surface temperature, but does not perform atmospheric temperature/humidity retrievals and is not intended as a visualisation tool: resources for those purposes are available elsewhere (see Links to external resources).

AAPP tools are available for the following functions:

• Raw data to level 1 processing for HRPT from NOAA POES satellites.
• Level 0 to level 1 processing for AHRPT from Metop.
• Ingest of level 1B files for NOAA POES or Metop satellites and onward processing to level 1c (original instrument grid) or level 1d (one instrument mapped to another).
• Ingest of Scientific Data Record (SDR) files from Suomi NPP, JPSS and FY-3 satellites. The input files are in hdf5 format.
• Spatial and/or spectral filtering, and re-mapping.
• Cloud mask generation (MAIA), for AVHRR and VIIRS.
• BUFR encoding and decoding.
• Conversion of AAPP outputs to hdf5 format (from v7.8)

• On NOAA POES: AMSU-A, AMSU-B, MHS, HIRS, AVHRR, MSU
• On Metop: AMSU-A, MHS, HIRS, IASI, AVHRR
• On Suomi-NPP and JPSS: ATMS, CrIS, VIIRS
• On FY-3: MWTS, MWHS, IRAS, HIRAS, MWRI

What’s new in AAPP v8?

The main changes in AAPP version 8, compared with the earlier v7, are as follows:

• Replacement of the old versions of MAIA cloud mask. Previously MAIA2.1 was used for AVHRR on HIRS grid and MAIA3 for AVHRR native grid. Now MAIA4 will be used for both AVHRR and VIIRS. One advantage of that is that GFS forecast fields can be used (readily available on the internet). For details, see MAIA cloud masks.
• Addition of interfaces to ecCodes, ECMWF’s new BUFR/GRIB software library. At this stage the interfaces to the old BUFRDC and GRIB_API packages are being retained, with the new software available as an option. For details, see BUFR conversion tools.
• Support for JPSS-1 (NOAA-20).

Some obsolete features of AAPP (e.g. support for Spot messages) have been removed.

Regarding operating systems and compilers:

• The obsolete g77 compiler is no longer supported. Any g77 users should migrate to gfortran.
• HP-UX and Solaris are no longer supported (there are no known users)
• The NWPSAF no longer has access to an AIX test system, though we will endeavour to assist AIX users.
• Mac OS is now supported.

Building AAPP and preparing to run

Detailed instructions for installing AAPP are provided in the AAPP Installation Guide. AAPP is usually distributed in the form of source code which must be compiled by the user, though this approach may change in the future as some users have indicated a desire to be able to download binaries. Note that one or more external libraries may be needed to achieve the functionality that you need, for example BUFRDC, ecCodes or hdf5 libraries. The GRIB-API library has been superseded by ecCodes.

You can find an example build script install_aapp8.sh in the downloads directory, which you can download to your workstation and customise to suit your requirements. It includes configuration and build steps for the external libraries, for AAPP and for OPS-LRS. Type ./install_aapp8.sh to see usage instructions.

An example configuration for AAPP could be:

./configure --prefix=/software/nwpsaf/aapp_run_8.1/ --fortran-compiler=gfortran --station=exeter --site-id=UKM \
  --external-libs="-L$DIR_BUFRDC/lib -lbufr -L${DIR_HDF5}/lib -lhdf5 -lhdf5_hl -lhdf5_fortran -lhdf5hl_fortran -L$DIR_ECCODES/lib -leccodes -leccodes_f90" \
  --external-includes="-I$DIR_HDF5/include -I$DIR_ECCODES/include"

where DIR_BUFRDC, DIR_HDF5 and DIR_ECCODES are the installation directories of the external libraries. The configure step would be followed by make and (optionally) make install. The AAPP Installation Guide gives more examples.

The IASI level 1 processor, OPS-LRS, is distributed as a separate sub-package – see the OPS-LRS User Manual. Before building OPS-LRS you should first build AAPP and the external libraries fftw-3.0.1 and xerces 7.0. The external libraries are available via the OPS-LRS auxiliary data link on the AAPP Downloads page. Note that xerces 7.0 is quite an old library, but later versions are not compatible with OPS-LRS. OPS-LRS is built using the usual configure > make > make install process. An example configuration for OPS-LRS could be:

./configure --prefix=/software/nwpsaf/OPS-LRS-V7.0/ --aapp-prefix=/software/nwpsaf/aapp_run_8.1/ --xrcs-prefix=/software/nwpsaf \
--fftw-prefix=/software/nwpsaf/ --arch=Linux-gfortran --site-id=UKM --nthreads=4 --optimize=normal

You should specify an appropriate number of threads at the configure step, e.g. --nthreads=4 or 8 depending on your computer resources. If you want to change it after building OPS, simply edit the OPS_SD.cfg file in the OPS-LRS-run/OPS/conf directory. Note that OPS-LRS runs 6 threads at start-up (WOM, MSGS, MP, JDBS, TES, SD_FRW) and then N threads for processing the IASI data. Usually N is 1 or a multiple of 4 (as IASI has 4 fields of view).

Depending on which components of AAPP you wish to run, you may also need to download some data files from the NWP SAF web site, e.g. data files for MAIA, and auxiliary files for the IASI instrument (the “BRD”, “GRD”, “ODB” files used by OPS-LRS). These are available from the AAPP Downloads page, together with a script that simplifies the downloading of the IASI files.

It is also recommended to run some of the test cases available on the AAPP Downloads page.

According to a 2015 survey, the following computer platforms were in use to run AAPP: (i) Linux, (ii) IBM AIX, (iii) Mac OS, (iv) windows running a unix emulator like Cygwin. In the past, HPUX and Solaris were also supported but there are now no known users for these platforms. Commonly used Fortran compilers include (most popular first): (i) gfortran, (ii) g95, (iii) g77 (no longer supported), (iv) ifort, (v) xlf, (vi) pgf. In 2020, it was established that the majority of users are running Linux: CentOS7 operating system is popular; there are a few Ubuntu users.

Before running any of the commands listed in the following sections, you need to set up your environment variables using the ATOVS_ENV8 file which is located in the top directory:

AAPP_PREFIX=name_of_top_directory

. $AAPP_PREFIX/ATOVS_CONF

This will automatically add the necessary AAPP directories to your $PATH, so that you can run them from any directory that you choose.

You may also need to set LD_LIBRARY_PATH, if you have installed external libraries locally (e.g. hdf5 or ecCodes).

Important note: please avoid the use of accents such as é in directory names, for both the AAPP installation and the test cases. The Fortran code cannot cope with accents and is likely to fail.

Orbital elements and the satpos file

Orbital elements are required for the navigation process. They are bulletins that provide the satellite position and velocity at a given time, and hence allow the software to predict future positions. Usually, 2-line elements (often abbreviated to TLE) are used. Some users prefer TBUS bulletins, but these are not available for all satellites and are not described in this section. You don’t need to know the TLE format in order to use them, but for reference it is described on the Celestrak web site. There are various sources on the internet for these bulletins, including:

https://service.eumetsat.int/tle/ Metop-A/B/C, NOAA-15/18/19/20, Suomi-NPP. The Metop bulletins are generated by EUMETSAT directly, the NOAA bulletins are generated from 4-line elements.

https://is.sci.gsfc.nasa.gov/ancillary/ephemeris/tle/drl.tle Aqua, Terra, Suomi-NPP, NOAA-20. Generated by NASA.

https://www.space-track.org/ Requires registration. Generated by NORAD for many satellites using satellite tracking techniques.

http://celestrak.com/NORAD/elements/ File “weather.txt” contains the satellites of interest. Same data as space-track.

http://www.shinetek.com.cn/eos_data/ Also includes the “1line” elements that are needed for FY-3 level 1 processing.

https://satellite.nsmc.org.cn/portalsite/default.aspx FY-3 only.

Alternatively, you can extract TLE data for NOAA and Metop satellites from the Metop Multi-Mission Administration Message (MMAM). This can be obtained from the direct broadcast HKTM file, or they can be viewed from the EUMETSAT web site here. Instructions for extracting TLE bulletins from the HKTM level 0 files are given in the AAPP v7.4 Release Note.

For the web-based bulletins, we recommend using the EUMETSAT and NASA TLEs (the first 2 sources in the list), as the bulletins take account of satellite manoeuvres. With bulletins from space-track and celestrak, note that sometimes (rarely) the bulletins are not updated for several days, and this can cause problems for satellite tracking. There are also occasional issues with inconsistency in the orbit numbers.

For historical bulletins it is best to use the space-track web interface. To process HRPT data for a given day you must have a TLE bulletin that is valid before the start of that day.

There is an AAPP tool available to download current bulletins – called get_tle. It uses the environment variables PAR_NAVIGATION_TLE_URL_DOWNLOAD and optionally PAR_NAVIGATION_TLE_USER, PAR_NAVIGATION_TLE_PASSWD that are defined in your ATOVS_ENV8 file. In the AAPP structure, files are normally placed in monthly subdirectories of $DIR_NAVIGATION/tle_db (where $DIR_NAVIGATION defaults to $AAPP_PREFIX/AAPP/orbelems). You can either use the get_tle tool or you can retrieve the files yourself. The files must have names of the form tle_yyyymmdd_hhmm.txt, where yyyymmdd_hhmm is the date/time of your download.

For space-track.org retrieval, you can specify which satellites you are interested in via the environment variable PAR_NAVIGATION_TLE_CATALOGUE – a list of NORAD catalogue numbers. It defaults to a list that includes NOAA, Metop, NPP, FY3 and Terra/Aqua satellites (see the get_tle script)

When AAPP ingests a TLE file it updates the various “index” files, one for each satellite of interest, e.g. tle_noaa19.index. The TLE index file is updated whenever you run the top level script AAPP_RUN_NOAA or AAPP_RUN_METOP (see section 5). The software only looks for TLE files that are newer than the index file, so to force older files to be ingested you have to use the unix touch command to change the time stamp of the bulletins. If you want to ingest TLE files by hand you can do it like this (after setting up your AAPP environment):

tleing -s noaa19

The next step (also performed automatically by AAPP_RUN_NOAA or AAPP_RUN_METOP) is to generate a “satpos” file for a particular time period. This is done by program satpostle. You can run it by hand, if needed, like this:

satpostle -o -s noaa19 -n 1.2

The above example generates a satpos file for today, containing 1.2 days, with position/velocity information every 2 minutes. There are various options if you want to use, for example, a different time period. The result is stored in directory $DIR_NAVIGATION/satpos. If you suspect a problem with a satpos file (e.g. you get an error when reading the file), simply delete it and re-generate it.

You should make sure that the lists of satellites (PAR_NAVIGATION_DEFAULT_LISTESAT) and bulletins (PAR_NAVIGATION_DEFAULT_LISTEBUL) in your ATOVS_ENV7 file are appropriate.

Processing direct broadcast data

NOAA satellites

AAPP assumes that the input HRPT file has been unpacked into 16 bit words (only the least significant 10 bits are used), with 11090 words per “minor frame”, and 6 minor frames per second. For details, see section 4.1 of the NOAA KLM User Guide. AAPP doesn’t care whether the data are in big-endian (most significant byte first) or little-endian (least significant byte first) format, it can handle both.

However, not all reception systems deliver this unpacked format. Some deliver a packed format, which is in effect a continuous bit stream of 10-bit words, packed into 16-bit words. The complication here is that 11090 10-bit words equates to 13862.5 bytes, so fill bits are often inserted. Different stations have different ways of doing this. If you know the format of your reception station then there is an AAPP tool unpack_noaa_hrpt that can unpack it. But you may need to modify the source file unpack_noaa_hrpt.F, in particular the parameters bytes_in and words_out (normally set to 27740 and 22180 respectively, to suit Met Office raw files). If you don’t know the format of your raw files then please contact the NWP SAF Helpdesk and we can help either by providing an analysis tool or by examining a sample of your data.

The main processing is done by script AAPP_RUN_NOAA. You need to make sure that the environment variable $WRK points to a valid working directory. Then run the command like this:

AAPP_RUN_NOAA -i "$instruments" -g "$grids" hrptfile

e.g. if instruments=”AMSU-A MHS HIRS AVHRR” and grids=”HIRS” then the output will include a HIRS level 1d file (with mapped AMSU, MHS and AVHRR), plus the various level 1b and 1c files. If you don’t need level 1d then just set grids to ” ” (a string containing a blank character). If you need AVHRR 1b but not mapped to HIRS add the “-z” flag.

If you want the MAIA cloud mask on the full-resolution AVHRR grid, you will have to run MAIA separately: see MAIA_cloud_masks.

See also Figure 1 of the AAPP version 7 Top Level Design.

Metop satellites

The input to AAPP is “EPS level 0”. Some reception systems deliver this format. But if you only have CADU data (or other raw data) you will have to convert to level 0 yourself. EUMETSAT have made available the Metopizer tool which can do this conversion. It is available via their User Portal (use the search box at top right to locate metopizer or other software packages). The Metopizer tools that you are most likely to need to use are cadu_to_ccsds and ccsds_to_l0. Note that Metopizer version 3.51 has a new version of ccsds_to_l0 that correctly handles the Metop Multi-Mission Administration Message (MMAM) and generates EPS level 0 files that can be input directly to AAPP: see the AAPP test case metopizer_and_AAPP. With earlier versions of the Metopizer, additional steps were needed (see next paragraph).

The EPS level 0 file is supposed to contain a VIADR containing, among other things, information to convert satellite time to UTC time. This is needed for accurate navigation. Sometimes the VIADR is either missing or contains the wrong information. In this case, AAPP has a tool patch-level0-from-mmam.exe to correct it. To run the tool, you can add HKTM to the list of instruments when you call AAPP_RUN_METOP.

If you wish to process IASI, you will need to install the OPS-LRS software (as discussed earlier). Then before running the main AAPP script you will need to set the environment variables DIR_IASICONFIG (to point to the auxiliary files) and PATH_OPS (to point to the OPS-LRS-run/OPS/perl directory containing the ops_process script).

The main processing is done by the script AAPP_RUN_METOP. To process a set of EPS L0 files in the current directory, the command is:

AAPP_RUN_METOP -i "$instruments" -g "$grids"

where instruments can be any of AMSU-A, MHS, HIRS, AVHRR, IASI. You can specify different input and output directories if preferred. The L0 files must have file names of the form *_???_00_M*Z, e.g. AMSA_xxx_00_M02_20020808181206Z_20020808195406Z_N_O_20020808201206Z. Remember that M02 is Metop-A, M01 is Metop-B and M03 is Metop-C. There is no HIRS on Metop-C.

IASI considerations

If IASI is specified in the list of instruments then AVHRR must be included also. First AVHRR is processed to level 1b. Then OPS-LRS is invoked in dump mode using ops_process. The output from OPS-LRS is a IASI l1c file in EPS format, but the AAPP_RUN_METOP script converts this to an AAPP-style “.l1c” format. If you want to access the EPS format file, it is found in the $WRK directory in a hidden directory M01(or M02)/.keep/*/to_pgf.

To run OPS-LRS in granule mode you would have to use lower-level commands – and would need the input L0 files also to be in granule form. The NWPSAF can advise if needed.

After completion of OPS-LRS, if “$grids” includes IASI then atovpp will be run. A key data files is IASI.fdf, which contains the channel selection to be used. Also, if Principal Components are requested in the IASI.fdf then you will need the appropriate eigenvector files; these are specified in file iasi_eigenvectors_spec.dat which by default is in $DIR_PREPROC (i.e. $AAPP_PREFIX/AAPP/data/preproc), but can be elsewhere if you define an environment variable DIR_IASI_PREPROC.

See also Figure 3 of the AAPP version 7 Top Level Design.

Suomi-NPP and JPSS satellites

To process raw S-NPP/JPSS direct readout data you will need to run external programs, as follows:

• • • RT-STPS (from NASA) to convert from raw data to Raw Data Record (RDR, with instruments in separate files).
    • CSPP (from University of Wisconsin) or IPOPP (NASA) to perform the processing to Sensor Data Record (SDR).

FY-3 satellites

Level 0 and Level 1 processors are provided by CMA, see http://satellite.cma.gov.cn/portalsite/default.aspx -> Tools -> Softwares. Currently these tools support MWTS, MWHS, IRAS, HIRAS, MWRI, VIRR and MERSI.

After running the CMA software packages fy3l0db and fy3l1db (or fy3cl0db, fy3cl1db in the case of FY-3C), the AAPP tools iras_sdr, mwhs2_sdr, mwhs_sdr, mwri_sdr, mwts2_sdr, mwts_sdr, hiras_sdr can be used to convert the hdf5 files into AAPP-style binary files.

You can then run tools such as mwhs2_beamwidth, mwhs_beamwidth, mwts2_beamwidth if you wish to do spatial filtering. Also, there are re-mapping tools mwhs2_to_iras, mwhs_to_mwts, mwts2_to_iras, mwts2_to_mwhs2. Key files that you may need to change are mwhs_beamwidth.dat, mwhs2_beamwidth.dat, mwts_beamwidth.dat, mwts2_beamwidth.dat. Note that the MWTS and MWHS “.l1c” files have slots for mapped instruments, so there is no “.l1d” format needed.

Processing level 1 data from satellite agencies

NOAA 1b

AAPP is commonly used to process level 1b sounder data from NOAA CLASS archive, or level 1b data disseminated by NOAA in near real time. See Figure 2 of the AAPP version 7 Top Level Design. Since NOAA-15, the NOAA 1b format and AAPP 1b formats for sounder instruments have been identical. You can run atovin and atovpp individually. Input files can be specified by name or you can use the defaults which are aman.l1b, ambn.l1b, hrsn.l1b.

You should be aware that data from NOAA CLASS may include a 512-byte archive header, unless you have disabled it in your user options. This needs to be removed before AAPP processing. To confirm whether or not the archive header exists, run

[[ $(tail -c +31 $file | head -c 42) = $file ]] && echo Y || echo N

If the result of this test is “Y” then remove the header like this:

mv $file ${file}_original; dd bs=512 skip=1 if=${file}_original of=${file}

You can then proceed to run atovin, e.g. for AMSU-A: atovin -f $file AMSU-A.

In the case of AVHRR, and the older NOAA satellites, NOAA level 1b is different from AAPP level 1b. In AAPP v7.6, the tool noaa_class_to_aapp was introduced to convert from NOAA format to AAPP format, and the tool avhrr_aapp_to_class to convert from AAPP format to NOAA format. See the AAPP v7.6 Release Note. In fact, noaa_class_to_aapp calls one of several different executables depending on the instrument that it finds in the 1b header record.

Also, bear in mind that for AVHRR the NOAA 1b files can have 8-bit, 10-bit or 16-bit words for the instrument counts. In the AAPP 1b, these are always 16-bit words. For post-NOAA-15 satellites the differences are described further in the AAPP Data Formats document.

An earlier AAPP tool, hrpt1b_noaa, was used to do a partial conversion of NOAA 1b to AAPP 1b for AVHRR, but this program is superseded by noaa_class_to_aapp. If you find a case that is not correctly handled, please notify the NWPSAF Helpdesk.

See also the NOAA “POD User Guide” and “KLM User’s Guide”, available at https://www1.ncdc.noaa.gov/pub/data/satellite/publications/podguides/

EPS level 1b/1c

The EUMETSAT archive can be used to extract AMSU, HIRS, MHS, IASI and AVHRR files in native EPS format. However whilst AAPP can handle IASI and AVHRR, there are no AAPP tools to handle AMSU, HIRS or MHS in EPS format. The user is recommended to specify BUFR output for these instruments (see BUFR conversion tools).

To convert IASI l1c from EPS format to AAPP format, the tool is convert_iasi1c (part of the “iasi-tools“). For AVHRR, the command is convert_avh1b (in “metop-tools“). The AVHRR tool does not perform a full conversion back to raw counts; it generates scaled radiances instead.

Suomi-NPP, JPSS and FY-3

For these missions the format used by the agency (NOAA or CMA) for SDR files is hdf5, and they can be converted to AAPP-style level 1b files using the previously-mentioned tools atms_sdr, cris_sdr, etc. Data are also commonly distributed in BUFR, see BUFR conversion tools.

Antenna pattern correction for microwave sounders

Microwave sounder brightness temperatures are normally corrected for the fact that antenna sidelobes are sensitive to radiation originating from outside the earth’s disk (i.e. from cold space or the satellite itself). The uncorrected temperatures are known as “antenna temperatures”.

For AMSU and MHS, this is handled in AAPP by the “efficiency factors” provided in data file fdf.dat. For each channel, and each field of view, three numbers are provided: the fraction of the signal that originates from earth, the fraction from the spacecraft and the fraction from space. To simplify the calculation, it is usually assumed that the spacecraft is at the same temperature as the earth.

The efficiency factors are computed from pre-launch measurements of antenna pattern, by the agency responsible for supplying the instrument. However, in some cases there are different versions of the correction available in AAPP, e.g. a version 1 that was available at the time of launch or a version 2 that was issued later. The version number is stored in the level 1c header (e.g. ama1c_h_vnantennacorr).

The antenna correction is applied by AAPP routine atovin, called automatically by AAPP_RUN_NOAA or AAPP_RUN_METOP.

The default is to use the first set of antenna corrections for each satellite. However, it is possible for the user to specify that a particular version of the antenna correction be used for a particular satellite, via environment variables, e.g.

export FDFSAT="METO-02 NOAA-18"
export FDFVN="2 1"

will use the second set for Metop-A and the first set for NOAA-18. In fact, this configuration is recommended for DBNet/RARS applications – to maintain consistency with global data generated by EUMETSAT. Be careful with the satellite names, they must be in the above format (7 characters).

If you are processing historic data, please note that that there are some errors in the AMSU-B/MHS sections of the fdf.dat file. For NOAA-15, -16, -17 and -18, channel 19 incorrectly contains the channel 16 corrections and channel 20 incorrectly contains the channel 17 correction. This is a bug dating right back to AAPP v1.0 in 1998. Thanks to Hans et al. (Remote Sens. 2019, 11, 548) for pointing this out. Note also that NOAA-18 MHS contains the NOAA-15 AMSU-B correction, for all channels. These instruments are no longer operating.

AAPP also provides a tool to allow you to apply or undo an antenna correction:

atovin_antcorr [-f "files"] [-z] [instrument1] [instrument2]

where the -z flag is used to undo a correction. The instrument1/2 can be any of AMSU-A, AMSU-B, MHS. The header variable ama1c_h_vnantennacorr or amb1c_h_vnantennacorr is used to determine which version of the correction to undo. If the version number is set to zero then it is assumed that no correction is applied.

In the case of ATMS, the AAPP level 1c format includes both antenna temperatures and brightness temperatures. (The former are taken from the Temperature Data Record, TDR, while the latter are from the Sensor Data Record, SDR). ATMS level 1d only has one set of temperatures, and these are by default brightness temperatures. Different centres may have different conventions: if you need your local data to use antenna temperatures (which was the practice at the Met Office prior to 2019), you will need to modify the Fortran program atms_beamwidth.F: change atms1c_btemps to atms1c_anttemps the first time it appears (not the second time). Then recompile that program.

BUFR conversion tools

The Binary Universal Form for the Representation of meteorological data (BUFR) is a binary data format maintained by the World Meteorological Organization (WMO). It is a table driven code. The latest version of the tables can be found here, in particular note the “BUFR Table B” (descriptors), “BUFR Table D” (sequences), “Code and Flag Tables”, and the “Common Code Tables”.

AAPP has interfaces with the ECMWF BUFRDC software package. AAPP v8 also has interfaces to ecCodes and it is anticipated that in the future there will be a migration from BUFRDC to ecCodes.

Supported instruments and AAPP formats are shown in the following table.

BUFR Section 3 (the data description section) contains either the Table D sequence given in the table, or where there is no sequence number it contains the list of Table B descriptors.

BUFR encode/decode using BUFRDC

To run the AAPP BUFR tools, using the BUFRDC library, you need to do the following:

• • Ensure that AAPP has been built correctly, linked to BUFRDC.
  • Define and export the environment variable BUFR_TABLES – pointing to the directory containing the BUFR tables (with trailing /). Usually it is recommended to use the tables provided with BUFRDC.
  • For encoding, you may also need to define some other environment variables, such as

ORIGINATING_CENTRE   e.g. 74=Met Office; defaults to 255=missing
SUB_CENTRE           defaults to 0. Important for DBNet (RARS) stations.
CENTRE_ID            centre code for use in Section 4, where applicable; defaults to 255.
MASTER_TABLE         The version of the BUFR tables to use.
LOCAL_TABLE          Defaults to 0
BUFR_EDITION         Defaults to 4
MESSAGE_SUBTYPE      Local subtype, can be anything you like but if not specified some defaults are provided.
ENHANCED_IASI        Should be set to "Y" if you want to use 340007 sequence.
USE_OB_TIME          Set to Y if you want to put the observation time in Section 1 (recommended). Otherwise it uses clock time.
ATMS_THIN            e.g. set to 3 if you want to only encode 1 spot in 3 in the 1d sequence.
MWTS2_THIN           As above
MWHS2_THIN           As above
IRAS_THIN            As above

aapp_encodebufr_1c -i "${infiles}" "${instruments}"

aapp_decodebufr_1c -i "${bufrfiles}" [${instruments}]

MAIA cloud masks

MAIA4_USE_GFS="yes"

MAIA4_REMOTE_GFS_DIR=url

DIR_FORECAST

Conversion of AAPP binary formats to HDF5

Special considerations for DBNet contributing stations

AAPP_RUN_NOAA -i "AMSU-A MHS HIRS" -g " " hrptfile

eccodes_encodebufr_1c -i "amsual1c*.l1c mhsl1c*.l1c hirsl1c*.l1c" AMSU-A MHS HIRS

gtsheaders_bufr.pl $amsua_in $amsua_out INAX KWBC

AAPP_RUN_METOP -i "AMSU-A MHS HIRS" -g " "

eccodes_encodebufr_1c -i "amsual1c*.l1c mhsl1c*.l1c hirsl1c*.l1c" AMSU-A MHS HIRS

AAPP_RUN_METOP -i "AVHRR IASI" -g " "

iasi_1c_to_pc iasifile.l1c iasifile.lpc

eccodes_encodebufr_1c -i iasifile.lpc PCIASI

sdr=$(ls SATMS_npp_${datestr}_*.h5)

tdr=$(ls TATMS_npp_${datestr}_*.h5)

atms_sdr $sdr $tdr

combine_1c SATMS*.l1c       #generates atms.l1c

eccodes_encodebufr_1c -i atms.l1c ATMS    #generates atms.bufr (or use aapp_encodebufr_1c)

sdr=$(ls SCRIF_npp_${datestr}_*.h5)

cris_sdr $sdr

combine_1c SCRIF*.l1c       #generates cris.l1c

cris_channels cris.l1c cris_selection.l1c    #the channel selection is specified in CRIS_FSR.fdf

eccodes_encodebufr_1c -i cris_selection.l1c CRISFSR    #generates cris_selection.bufr

mwhs2_sdr -o mwhs.l1c $mwhs_file

export USE_VASS_SEQUENCE=Y

eccodes_encodebufr_1c -i mwhs.l1c MWHS2

hiras_sdr -o hiras.l1c $hiras_file

hiras_channels hiras.l1c hiras_channels.l1c

eccodes_encodebufr_1c -i hiras_channels.l1c HIRAS

Visualisation

The AAPP Visualisation Page provides some resources on how to visualise AAPP products.

In particular, aapp1c_quicklook.py is a Python script to visualise brightness temperature fields from sounder instruments. The input is level 1c converted to hdf5 format using convert_to_hdf5. To run the script you will need to have installed on your workstation python (v2.7 or 3.x), with numpy, matplotlib, h5py and cartopy.

Usage instructions for aapp1c_quicklook.py are provided in the AAPP Software Descripton (section 4.3.48). As an illustration, if you have run the NOAA-19 test case, you should find the output hdf5 files in the level1 directory. Then the following commands should generate an AMSU-A plot to the screen, plus a saved png file:

AAPP_PREFIX=[location where you installed AAPP]
. $AAPP_PREFIX/ATOVS_CONF
aapp1c_quicklook.py -i amsual1c_noaa19_20170725_1431_43582.l1c.h5 -c 1 -r "-40 40 30 70" -s 40

There are options to change channel, lat/lon range, symbol size, etc. The BT range is currently auto-scaled. More options may be provided in a future update.

What to do if you encounter a problem

Links to external resources

Change record