The NASA Terra and Aqua spacecraft provide new remote sensing capabilities for the observation of planet Earth. Both of these platforms have a direct broadcast X-band downlink that allows MODIS (Terra and Aqua) and AIRS/AMSU/HSB and AMSR-E (Aqua) data to be received in real time by sites having the proper reception hardware.

    The International MODIS/AIRS Processing Package (IMAPP) allows ground stations capable of receiving EOS direct broadcast to create the following products:

• MODIS Level 1 calibrated and geolocated radiances (Terra or Aqua)
• MODIS Level 2 geophysical products (Terra or Aqua)
• AIRS/AMSU/HSB Level 1 calibrated and geolocated radiances (Aqua only)

IMAPP is derived from the operational EOS processing software developed at NASA GSFC and JPL, and has been modified to be compatible with direct broadcast data. The main differences between IMAPP and the operational software are

• IMAPP has been ported to a range of UNIX platforms,
• the only tool kit required by IMAPP is NCSA HDF4,
• the IMAPP processing environment is greatly simplified,
• downlinked spacecraft ephemeris and attitude data may be used for real-time geolocation,
• overpasses of arbitrary size may be processed.

Requirements

    IMAPP software and test data are available from our FTP site (also see the links below for each IMAPP release). Please read the top level README file for installation instructions. IMAPP is licensed under the terms of the GNU General Public License. IMAPP MODIS Level 1 and Level 2 software supports the following UNIX platforms:

• SGI MIPS, IRIX 6.5
• Sun Ultra, Solaris 7, 8
• IBM RS/6000, AIX 4.3
• HP PA-RISC, HP-UX B.10.20
• Intel Pentium, Red Hat Linux 7.2 (with gcc/g77 2.96)
• Intel Pentium, Sun Solaris 8 (with gcc/g77 2.96)

IMAPP AIRS/AMSU/HSB software supports the following UNIX platforms:

• Red Hat Intel Linux: 7.3, 8.0, Enterprise
• Sun Solaris (SPARC): 7, 8, 9

The input expected by IMAPP is EOS Level 0 data, defined as reconstructed time-ordered CCSDS packets with all communication artifacts (including duplicate packets) removed. This includes PN and Reed Solomon decoding as well as reassembly of the raw telemetry packets. Processing of the data stream to this stage is the responsibility of the user. Data in this format is known as a Production Data Set (PDS). Many X-band ground station vendors supply processing hardware and/or software that creates IMAPP compatible Level 0 files in PDS format. Pat Coronado's group at GSFC has also developed a Java application named RT-STPS which handles CCSDS packet reassembly. For more information, see the GSFC direct readout website.

    MODIS Level 2 science products require MODIS Level 1B HDF radiance and geolocation files in either IMAPP or GSFC/DAAC format (both formats are supported). These HDF data are extracted into flat binary files and used as input to the science product software. Some products also require external dynamic ancillary data files as input. For example, the cloud mask product requires the Near Real-Time SSM/I EASE-Grid Daily Global Ice Concentration and Snow Extent (NISE) dataset for optimal performance over snow covered regions. All required dynamic ancillary data sets are updated daily and are available from our ancillary data FTP site.

Release History

• Source code which uses the IMAPP Level AMSR-E 1B binary files as input to generate:
  
• Snow Water Equivalent (SWE) in HDF-EOS format
  
• Values are stored as byte values scaled by 2 (multiply value by 2 to get SWE in mm)
• Values are stored on a 25 km Equal-Area Scalable Earth Grid (EASE-Grid)
  
• The sofware uses the AMSR-E B05 science algorithm to produce the retrievals.   For more information, please see the AMSRE_SWE_README.txt file.

• Updates include:
• New automated run scripts with the use of a dynamic ancillary data set (NCEP gdas files)
  
• New regression coefficients
• New number of channels is 1450 (only wavenumbers below 2400 cm-1 are used)
• Surface Pressure and Surface Reflectivity will not be retrieved anymore
• Additional predictors: surface pressure and solar zenith angles;
        i.e. these parameters need to be provided. Current Software uses NCEP
        gdas1 surface pressure and AIRS L1B solar zenith information
• Retrieved variables below surface pressure are set to -9999
  

• Source code which uses the IMAPP Level 1B binary files as input to generate:
  
• Soil Moisture in HDF-EOS point format (2 byte integers scaled by 1000)
• The output product is identical to the official NSIDC DAAC product in format.  Small differences in retrieved values are due to the use of L1B as input as opposed to Level 2A.  Please see the AMSRE_SM_README.txt file for more information.
  

• Updates include:
• IDL code to convert the binary file into HDF format
• New regression coefficients based on the AIRS forward model (SARTA) from April 2005
• Small changes to ensure that output files are written correctly on Sun platforms
  

• Source code which uses the AIRS L1B hdf file as input, and creates a binary output file at a single AIRS field of view containing:
  • Surface Pressure [hPa]
  • Surface Skin Temperature [K]
  • Atmospheric Temperature [K] at 101 pressure levels
  • Total Precipitable Water Vapor [cm]
  • Atmospheric Moisture [g/kg] at 101 pressure levels
  • Total Ozone [Dobson units]
  • Atmospheric Ozone [ppm/v] at 101 pressure levels
  • Surface Emissivity at 15 wavenumbers
  • Surface Reflectivity at 15 wavenumbers
  and a separate binary matching file containing latitude and longitude information

• The retrieval algorithm is a statistical eigenvector regression method, using a large global (clear-sky) training set of representative profiles and surface prameters, and their associated calculated (using forward model SARTA) radiances. A set of 1688 selected "good" channels are used for the calculations. Regression coefficients for 6 classes of brightness temperatures (at 1000 cm-1), and 11 classes of scanning angles (between 0 and 49 deg) are calculated. The only dynamic user input required by the algorithm is the AIRS L1B radiance product. The major differences in the UW-Madison package are:
  • (a) the horizontal resolution is ~14 km (i.e. AIRS FOV size, with 90x135 pixels in one granule), whereas the horizontal resolution of the operational product is ~ 50 km (AMSU footprint),
  • (b) the vertical resolution is 101 pressure levels; for the operational product it is 28 pressure levels,
  • (c) the algorithm is a regression method only,
  • (d) the algorithm is applied to every AIRS FOV in the granule, regardless of cloud conditions (the products are not valid over clouds).

August 30, 2005 (MODIS Level 2 Product Collect 5 Updates) Updates to MODIS Level 2 Cloud Mask, Cloud Top Properties, Atmospheric Profiles and Ancillary software packages (v1.8)

• Represents significant improvements to the MODIS  Level 2 product algorithms consistent with MODIS collection 5 DAAC product updates.
  
• Cloud Mask:
  
• Improvement of cloud retrieval in sun-glint, nighttime and high latitude regimes.
  
• Code now requires the GDAS and SST ancillary files as required inputs.
• Cloud Top Properties: 
  
• New 101 level forward model is now used.
  
• New fast model coefficient files have been generated.
  
• The numerical data month must now be used as an input argument.
  
• SST files are now used as input to improve the estimation of the surface temperature over water.
• Atmospheric Profiles:
  
• Updates to the training data used to create the regression coefficients, including new profiles and better characterization of the surface.
• Ancillary:
  
• extract_ncep_gdas1.csh now extracts 54 fields out of the GDAS grib file instead of 30.  These extra fields are used by the cloud top properties software.
• NISE files sizes are now 218 MB instead of the former 222 MB.

July 06, 2005 (AMSR-E Level 2 Rain Rate/Rain Type ) First AMSR-E Level 2 Release:

• The release consists of software that converts direct broadcast binary Level 1B output files into HDF-EOS formatted Rain Rate (mm/hr) and Rain Type (Convective Rain percentage) product files.
• The software has been converted from the original DAAC software to run on direct broadcast input files. The output files are very similar to the files distributed by the NSIDC DAAC. Please see the AMSR-E Rain Rate product web page for information on the algorithm and algorithm developers.
• This release is supported on Red Hat Linux 8.0, 9.0 and Enterprise only.

April 25, 2005 (AMSR-E Level 1B (also known as Level 2A)) First AMSR-E Level 1Release:

• Allows any ground station capable of receiving direct broadcast from Aqua to produce calibrated and geolocated AMSR-E Level 1B (also know as Level 2A) products.
• This software was developed by Remote Sensing Systems (RSS). The output consists of two binary files. One contains brightness temperatures, the other geolocation, time, velocity information, etc.
• This is a binary-only release for Red Hat Linux 7.3,8.0,9 and Enterprise and Sun Solaris (SPARC)7, 8, 9 platforms. No source code is included

December 20, 2004 ( MODIS Level 2 v1.7) Aqua/Terra Near-Infrared Total Precipitable Water Vapor Product Release:

October 5, 2004 ( MODIS Level 2 v1.6) Aqua/Terra Aerosol Product Release:

March 30, 2004: Nanjing Remote Sensing Symposium June 6-12, 2004 (Conference Flyer, SeaSpace Announcement)

March 3, 2004 ( MODIS Level 2 v1.5) Aqua/Terra Sea Surface Temperature Product Release:

January 16, 2004 (MODIS Level 1 patch) Update for Terra MODIS calibration following spacecraft safe hold:

• Following the restoration of Terra MODIS direct broadcast on 2004/01/15, we discovered a problem with the IMAPP MODIS Level-1 calibration code.
• The primary symptom is that most of the earth view image data in the Level-1B product files will be set to "Invalid", even though the raw earth view counts are valid.
• To fix the problem, minor patches are required to three of the IMAPP MODIS v1.4/v1.5 calibration source code files.
• We strongly recommend that all IMAPP MODIS Level-1 users install this patch as soon as possible. Please note that Aqua MODIS data is unaffected by this problem, and the patch has no effect on the processing of Aqua MODIS.

November 19, 2003 (MODIS True Color) New Tutorial on Producing MODIS True Color Images:

• The tutorial describes in detail a method for creating high quality true color MODIS images using freely available software.
• Required input data includes MODIS Level 1B 1000, 500, and 250 meter radiances, and 1000 meter geolocation.
• Either IMAPP or DAAC format MODIS Level 1B data may be used.
• Tutorial includes documentation, source code, and sample data.
• Examples of MODIS true color images created using this method are available at the SSEC MODIS Gallery.
• Created by Liam Gumley, Jacques Descloitres, and Jeffrey Schmaltz.

November 6, 2003 (MODIS Level 1 v1.5) Update for Terra and Aqua MODIS:

• Included in this release is an updated version of the geolocation code; an updated set of calibration lookup tables (LUTs); and an updated MODIS Level 1 master script.
• An important feature of the new geolocation algorithm is that it resolves some recent problems (Oct/Nov 2003) which have been observed with Terra MODIS geolocation. Symptoms reported by IMAPP users in the United Kingdom, Germany, Australia, and Alaska include (a) geolocation algorithm exits prematurely, (b) geolocation data produced for Terra MODIS is incorrect. In all cases, the new version of the geolocation algorithm has fixed the problem.
• This release contains a new set of calibration lookup tables (LUTs) for the MODIS reflected solar bands and thermal emissive bands. The new versions of the LUTs are Terra: V 4.1.2.6 (April 15, 2003); Aqua: V 4.1.3.5 (April 29, 2003). For a history of lookup table changes, please see the MCST website under the "LUTs Version" links for Terra and Aqua.
• Note that the calibration LUTs are not identical to the current versions used at the GSFC DAAC, as they do not include the new time-dependent coefficients for the MODIS ocean bands. A new version of the IMAPP calibration algorithm is under development which includes the most recent MODIS LUTs. The time-dependent coefficients have a small effect on the calibration of the MODIS ocean bands only.

November 5, 2003 (AIRS/AMSU/HSB Level 1 v1.0) First AIRS/AMSU/HSB Release:

• Allows any ground station capable of receiving direct broadcast from Aqua to produce calibrated and geolocated AIRS, AMSU, and HSB Level 1B products. This package is functionally identical to the operational AIRS/AMSU/HSB Level 1B package running at the GSFC DAAC.
• This is a binary-only release for Red Hat Intel Linux and Sun Solaris (SPARC) platforms. No source code is included.
• The package has been tested on the following platforms: Red Hat Intel Linux: 7.3, 8.0, 9; Sun Solaris (SPARC): 7, 8, 9.

September 18, 2003 (MODIS Level 2 v1.4) Aqua/Terra Atmospheric Profiles and Water Vapor Product Release:

February 19, 2003 (MODIS Level 2 v1.3) Aqua/Terra Cloud Mask and Cloud Top Properties Release:

October 1, 2002 (MODIS Level 2 v1.2) Atmospheric Profiles and Water Vapor Product Release:

• Second MODIS science product release. The key parameters of this product (MODIS product MOD07) are retrievals of vertical profiles of atmospheric temperature and moisture, total column ozone, total column water vapor, stability parameters (lifted index, K index, total totals), as well as low level moisture (water vapor between surface and 700 hPa) and high level moisture (water vapor between 400 and 100 hPa).This software is equivalent to the current DAAC version 3.1.0 delivered to GSFC on 4 March 2002.

September 13, 2002 (MODIS Level 1 v1.4) First version to support both Terra and Aqua MODIS:

• The Terra MODIS calibration and geolocation algorithm and lookup tables are unchanged from the MODIS Level 1 v1.3 release.
• The Aqua MODIS calibration algorithm and lookup tables are versions 3.0.1 and 3.1.0.2, respectively. This version includes post-launch calibration data acquired following the Aqua MODIS nadir door opening. It will handle all Aqua MODIS data acquired to date.
• The Aqua MODIS geolocation algorithm requires that ephemeris and attitude files be used, since spacecraft position is not encoded in the Aqua MODIS Level 0 PDS files. For realtime processing, the GBAD data (APID 957) transmitted as part of the X-band downlink may be used in conjunction with the GSFC GBAD processor to produce IMAPP-compatible ephemeris and attitude input files. Our experience has shown that realtime geolocation using GBAD derived ephemeris and attitude data is accurate to within 500 meters. For non-realtime processing, the definitive Aqua ephemeris and attitude files (see Links below) may be used, providing the same geolocation accuracy as the operational processing at GSFC. Note that the definitive ephemeris and attitude files are usually not available for at least 24 hours.
• The IMAPP MODIS Level 1 processing script (util/imapp.csh) has been updated to handle both Terra and Aqua data. This script combines the functionality of the level1a.csh, geolocate.csh, and calibrate.csh scripts and allows all input files to be specified on the command line. The user is responsible for identifying the satellite (Terra or Aqua).

May 1, 2002 (MODIS Level 2 v1.1) First science product release for Terra MODIS:

• This release includes the MODIS Cloud Mask (MOD35) and Cloud Top Properties (MOD06CT) algorithms. The release consists of an ancillary data extractor, a set of flat file radiance/geolocation extractors, the cloud mask software and the cloud top properties software. The extractors serve as data preprocessors for the science software packages. Production scripts exist as part of both the cloud mask and cloud top properties packages which will execute the extractors and product software in sequence. Please see the README files. The cloud mask software is updated to production version 3.1.1, whereas the cloud top properties and cloud phase software is updated to version 3.1.0.

December 3, 2001 (MODIS Level 1 v1.3) Third update for Terra MODIS:

• The calibration algorithm and lookup tables are updated to versions 3.0.0 and 3.0.0.7, respectively. This version includes calibration data for the A-side electronics on MODIS following the outage which occurred from June 15 to July 3, 2001. The calibration algorithm in IMAPP v1.3 is date sensitive, and may be used for all Terra MODIS data back to February 2000.
• The geolocation algorithm now has improved interpolation/extrapolation of ephemeris and attitude information. This prevents bad lat/lon values toward the beginning and ending sections of a pass (originally released as a patch for IMAPP v1.2 on August 31, 2001).

April 13, 2001 (MODIS Level 1 v1.2) Second update for Terra MODIS:

• Calibration algorithm and lookup tables are updated to versions 2.5.5 and 2.5.5.1 respectively, which includes calibration data for the B-side electronics on MODIS (the switch to B-side electronics occurred on 1 November 2000). The calibration in IMAPP v1.2 is date sensitive, and may be used for all Terra MODIS data back to February 2000. This version also includes a bug fix for aggregation of the 250 m and 500 m spectral bands to higher spatial resolution.
• Geolocation is significantly improved when using only the Level-0 platform ephemeris and attitude information (i.e. in near-realtime). Terrain correction is now available as an option (requires that DEM data files be installed: see the installation instructions). Definitive Terra ephemeris and attitude data are now available via FTP for input to IMAPP (see Links).
• Level-1A algorithm is more resistant to Level-0 input file anomalies. Processing now terminates gracefully if a packet with an improper length is encountered in the Level-0 input file.

November 1, 2000 (MODIS Level 1 v1.1) First update for Terra MODIS:

• Calibration algorithm and lookup tables are updated to version 2.4.3. This includes many post-launch improvements and bug fixes from the MODIS Calibration Team at GSFC
• Added support for definitive ephemeris and attitude data
• Solarisx86 is now supported on Intel Pentium platforms

May 12, 2000 (MODIS Level 1 v1.0) Initial release including the following functionality for Terra MODIS:

• Reformatting from time-ordered CCSDS Level-0 packets to Level-1A
• Geolocation for every 1000 m pixel
• Calibration for every pixel in bands 1-2, 1-7, and 1-36 at 250, 500 and 1000 m resolution respectively

File Formats

    The format of the IMAPP MODIS Level 1B files is very similar (but not identical) to the format of the GSFC DAAC Level-1B output files. In particular, IMAPP output files are written using HDF only (not HDF-EOS), and IMAPP output files store metadata in separate global attributes. The difference can best be seen by comparing an alphabetized listing of the HDF SDS and Vdata objects in an IMAPP Level 1B 1000 meter file and the corresponding DAAC file. Similarly, the format of the geolocation files produced by IMAPP is very similar (but not identical) to the GSFC DAAC format, as seen in the alphabetized listing of the HDF SDS objects in an IMAPP geolocation file and the corresponding DAAC file.

    The IMAPP MODIS Level 2 science product files are not in HDF format. They consist of 8-bit unsigned integer (cloud mask) or 32-bit floating point (cloud top properties) files plus header files. Quality assurance files are also produced. Comparison between the HDF SDS listings of the operational versions and the direct broadcast product flat file header files assist in revealing the differences. The radiance/reflectance/geolocation and cloud top properties flat files can be displayed using the freely distributed FreeLook application or with the commercial ENVI application. Please see the Cloud_Mask_Visualization.txt file for suggestions on viewing the cloud mask product file.

    The IMAPP AIRS/AMSU/HSB Level 1B files are in HDF-EOS format, identical to the operational format produced at NASA/GSFC.

Credits

    The IMAPP team at SSEC includes Tom Rink (Level 1 software development); Kathy Strabala and Russ Dengel (Level 2 software development); Liam Gumley (program management); and Allen Huang (principal investigator). Eurico D'Sa at the University of South Florida was instrumental in porting IMAPP to Linux, and Alexander Shumilin of ScanEx ported IMAPP to Windows. Development of IMAPP is supported by NASA under grant NAG5-13402.

    The operational versions of the MODIS Level-1 software were developed at NASA GSFC by the MODIS Science Data Support Team (SDST) and Characterization Support Team (MCST) under the direction of Vince Salomonson (MODIS Science Team Leader). The operational versions of the MODIS Level-2 cloudmask, cloud top properties and cloud phase software and atmospheric profiles were developed at the University of Wisconsin-Madison by Kathy Strabala, Richard Frey, Liam Gumley, Bryan Baum, Jun Li and Suzanne Wetzel-Seemann under the direction of Paul Menzel and Steve Ackerman (MODIS Science Team Members).

The AIRS/AMSU/HSB package was developed at NASA Jet Propulsion Laboratory by Quyen Nguyen, Richard Forrister and Evan Manning under NASA RTOP 622-40-45-03 in support of the AIRS Project at NASA Jet Propulsion Laboratory under NASA NPO-21132.

Related Links (updated 2004/05/06)

IMAPP References:
    Conference Paper SPIE Remote Sensing of the Atmosphere, October 2002
    Conference Paper AMS 12th Conference on Satellite Meteorology and Oceanography, February 2003.

IMAPP ancillary data:
    leapsec.dat | utcpole.dat | Level-2 product ancillary data

GSFC definitive attitude and ephemeris:
    Terra | Aqua

MODIS browse images:
    Univ. of Wisconsin |  Louisiana State Univ.  | Univ. of South Florida | Univ. of Dundee (UK)
    DLR (Germany) | ACRES (Australia) | WASTAC (Australia) | ScanEx (Russia) | USGS (USA)

MODIS Level 1B data:
    Univ. of Wisconsin: Terra FTP, HTTP, DODS; Aqua FTP, HTTP, DODS (what is DODS?)
    NASA/GSFC: Terra and Aqua Direct Broadcast | Terra Global | Aqua Global

AIRS Level 1B data:
    Univ. of Wisconsin: FTP, HTTP, DODS (what is DODS?)

MODIS calibration:
    Algorithm Theoretical Basis | Calibration Support Team | Level-1B Product Information

MODIS visualization/analysis software:
    IDL | Msphinx | HDFLook-MODIS | Freelook | HDF Explorer | Geomatica FreeView
    MS2GT (bowtie removal) | McIDAS | McIDAS Lite | SeaDAS | MODIS Swath Reprojection Tool

MODIS information:
    Home | Land | Atmosphere | Oceans | Specifications | Design & Engineering | ATBDs

Spectral Response Data:
    Terra | Aqua

Terra and Aqua spacecraft:
    Terra home | Aqua home | Terra orbit tracks | Aqua orbit tracks | NORAD TLEs | NASA TLEs
    Overpass Predictor

EOS direct broadcast information:
    Home | DAAC | Univ. Dundee FAQ

Deep Space Network:
    Home | Turn-off schedule

AIRS:
    Home | ATBDs

Liam Gumley (last update September 22, 2005)