GPM Ground Validation Advanced Microwave Precipitation Radiometer (AMPR) MC3E

Table of Contents

General Information

The Principal Investigator on the AMPR instrument is Dr. Brent Roberts of the NASA Marshall Space Flight Center. These data are archived at the GHRC as part of the AMPR data set which includes more than fifteen field experiments.

Instrument Mission and Objectives

The Advanced Microwave Precipitation Radiometer (AMPR) remotely senses passive microwave signatures of geophysical parameters from an airborne platform. The instrument is a low noise system which can provide multi-frequency microwave imagery with high spatial and temporal resolution. AMPR data are collected at a combination of four microwave frequencies (10.7, 19.35, 37.1, and 85.5 GHz) with two orientations each (Vpol-to-Hpol and Hpol-to-Vpol) which are complimentary to current aircraft and satellite instrumentation. These frequencies are best suited to the study of rain systems, but are also useful to studies of other atmospheric, oceanic, and land surface processes.

Principles of Operation

The AMPR is a cross-track scanning total power microwave radiometer with four channels centered at 10.7, 19.35, 37.1 and 85.5 GHz. It has a dual-lens antenna to accommodate two separate feed horns. The horn that feeds the three higher frequency channels is a copy of the Special Sensor Microwave/Imager (SSM/I) space borne multi-frequency feed horn currently flying aboard the Defense Meteorological Satellite Program (DMSP) satellites. A separate AMPR feed horn, which was built by the Georgia Technology Research Institute (GTRI), accommodates the 10.7 GHz frequency.

AMPR Performance Characteristics

The following table lists several of the AMPR performance characteristics.

Instrument Geometry

The AMPR radiometer has flown on the NASA ER-2 and DC-8 aircraft. The instrument has a 90 degree total scan centered at nadir. The data footprints are designed to be contiguous (for altitude of 20 km and aircraft speed of 200 m/s) at 85.5 GHz and coincident at all four channels leading to over-sampling at the lower frequencies. The polarization varies from vertical/horizontal at 45 degrees to the left of nadir, an equal mixture of vertical and horizontal polarization at nadir, and horizontal/vertical at 45 degrees to the right of nadir.

The NASA MC3E (Midlatitude Continental Convective Clouds Experiment) mission investigated the atmospheric structure, properties and processes in the U.S. Great Plains region. For more on MC3E visit http://www.nasa.gov/topics/earth/features/rain-campaign.html.

The MC3E mission was sponsored by the NASA Headquarters Global Precipitation Measurement (GPM) Program. The field experiment phase was completed during April through June 2011 with ER-2 operations based out of Offutt AFB, Nebraska.

MC3E AMPR Data

AMPR Data Format

The datasets consist of AMPR calibrated and navigated brightness temperatures at 10.7, 19.35, 37.1, and 85.5 GHz in ASCII files, with browse imagery (GIF).

File Naming Conventions

The AMPR file naming convention is as follows:

Data: exp_ampr_yyyymmdd_ghrc_ver1.txt.gz
Browse: exp_ampr_yyyymmdd_hhmmss-hhmmss.gif

where:

exp is the experiment name (full name or abbreviation)
yyyymmdd is the data date
hhmmss is the start and stop times

Data are available in ASCII (numeric) format and each file represents one flight. The data files are compressed using gzip. The browse files are in gif format, and are a composite of images for each frequency for the entire flight and for selected flight legs.

Record Structure

The AMPR data record structure is as shown in the following table. The aircraft latitude, longitude, and altitude are GPS when available.

Sample Read Software

A Fortran read program ampr_reader_MC3E.f is given below, or may be downloaded along with this documentation from this site: ftp://ghrc.nsstc.nasa.gov/pub/doc/gpmgv/mc3e/gpmamprmc3e/. Copy this program, or pertinent sections of it, into your own source code with modifications as necessary.

====================== Beginning of FORTRAN-77 code ======================

      program ampr_reader_MC3E
c
c Sample read program for AMPR data from MC3E.
c

      integer*4 NR
      parameter (NR=6400)

      integer*2 elev(50,NR)
      integer*4 ntime(11,NR), ner2_time(4,NR), icon(NR)
      real*4 tbs(8,50,NR)
      real*8 er2_nav(18,NR), dplat(50,NR), dplon(50,NR), flnd(3,50,NR)

      integer*4 i, n, nscans
      logical done

      print*,' Started'

      open (42, file='mc3e_ampr_2011127_tbs_v01.txt')

      i = 1
      done = .false.
      do while (.not. done)

            read (42, 4201, end=999) n, (ntime(j,i),j=1,3),
    >            (ner2_time(j,i),j=1,4), icon(i),
    >            ((tbs(k,j,i),j=1,50),k=1,8),
    >            (dplat(j,i),j=1,50), (dplon(j,i),j=1,50),
    >            (er2_nav(j,i),j=1,18),
    >            ((flnd(k,j,i),j=1,50),k=1,3),
    >            (elev(j,i),j=1,50)
            i = i + 1
      enddo

999 close (42)
      nscans = i - 1

4201 format ( i5, 1x,i4,2(1x,i2), 1x,i3,3(1x,i2), 1x,i3,1x,
    >      400(1x,f6.2), 118(1x,f11.5), 150(1x,f7.5), 50(1x,i5) )


      print*,' Done'
      stop
      end

========================= End of FORTRAN-77 code ========================

Access to AMPR Browse Images

Browse imagery for MC3E AMPR can be viewed or downloaded at this web location: ftp://gpm.nsstc.nasa.gov/gpm_validation/mc3e/ampr/browse/. A sample image is shown below.

Browse imagery is available for other AMPR experiments, and can be viewed or downloaded at this web location: ftp://ghrc.nsstc.nasa.gov/pub/browse/ampr/.

Our data sets are provided through the NASA Earth Science Data and Information System (ESDIS) Project and the Global Hydrology Resource Center (GHRC) Distributed Active Archive Center (DAAC). GHRC DAAC is one of NASA's Earth Observing System Data and Information System (EOSDIS) data centers that are part of the ESDIS project. ESDIS data are not copyrighted; however, in the event that you publish our data or results derived by using our data, we request that you include an acknowledgment within the text of the article and a citation on your reference list. Examples for general acknowledgments, data set citation in a reference listing, and crediting online web images and information can be found at: http://ghrc.nsstc.nasa.gov/uso/citation.html

References

Hood, R.E., D. Cecil, F.J. LaFontaine, R. Blakeslee, D. Mach, G. Heymsfield, F. Marks, Jr., E. Zipser and M. Goodman, Tropical cyclone precipitation and electrical field information observed by high altitude aircraft instrumentation. J. Atmos. Sci., 63, 218-233.

Hood, R.E. D.J. Cecil, and F.J. LaFontaine: "Tropical Cyclone Precipitation Types Observed by Microwave Spaceborne and Airborne Instrumentation", The American Meteorological Society 25th Conference on Hurricanes and Tropical Meteorology, San Diego, CA, May 2002.

LaFontaine, F.J. and R.E. Hood: "Tropical Microwave Brightness Temperature Data from AMPR", The American Meteorological Society 24th Conference on Hurricanes and Tropical Meteorology, Fort Lauderdale, FL, May 2000.

Hood, R.E. and F.J. LaFontaine: "Passive Microwave Observations of Hurricanes during CAMEX-3", The American Meteorological Society 24th Conference on Hurricanes and Tropical Meteorology, Fort Lauderdale, FL, May 2000.

Spencer, R.W., Hood, R.E., LaFontaine, F.J., Smith, E.A., Platt, R., Galliano, J., Griffin, V.L., and E. Lobl, 1994: High Resolution Imaging of Rain Systems with the Advanced Microwave Precipitation Radiometer, Journal of Atmospheric and Oceanic Technology, Vol. 11, No. 4, pp.849-857.

Hood, R.E., Spencer, R.W., LaFontaine, F.J., and E.A. Smith, 1994: Simulation of Future Microwave Satellite Instruments Using High Resolution AMPR Aircraft Data, Preprints: Seventh Conference on Satellite Meteorology and Oceanography, Section 3.10, pp.160-163, American Meteorological Society, 6-10 June 1994, Monterrey, CA.

Smith, E.A., Xiang, X., Mugnai, A., Hood, R.E., and R.W. Spencer, 1994: Behavior of an Inversion-based Precipitation Retrieval Algorithm with High Resolution AMPR Measurements Including a Low Frequency 10.7 GHz Channel, Journal of Atmospheric and Oceanic Technology, Vol. 11, No. 4, pp.857-.

Turk, J., Vivekanandan, J., Marzano, F.S., Hood, R.E., Spencer, R.W., and F.J. LaFontaine, 1994: Active and Passive Microwave Remote Sensing of Precipitating Storms During CaPE. Part I: Advanced Microwave Precipitation Radiometer and Polarimetric Radar Measurements and Models, Meteorology and Atmospheric Physics, Special Issue on Retrieval of Hydrological Variables from Space-based Microwave Instruments, Volume 54, pp.3-27.

Marzano, J., Mugnai, A., Smith, E.A., Xiang, X., Turk, J., and J. Vivekanandan, 1994: Active and Passive Microwave Remote Sensing of Precipitating Storms During CaPE. Part II: Intercomparison of Precipitation Retrievals Over Land from AMPR Radiometer and CP-2 Radar, Meteorology and Atmospheric Physics, Special Issue on Retrieval of Hydrological Variables from Space-based Microwave Instruments, Volume 54, pp.29-51.

Evans, K.F., Turk, J., Wong, T., and G.L. Stephens, 1995: A Bayesein Approach to Microwave Precipitation Profile Retrieval, Journal of Applied Meteorology, Volume 34, Number 1, pp.260-279.

Griffin, V. L., A.R. Guillory, M. Susko, and J. E. Arnold, Operations Summary for the Convection and Moisture Experiment (CAMEX), NASA Technical Memorandum, NASA TM-108445, March 1994.

Additional details on the AMPR data sets can be obtained from the GHRC User Services Office or directly with the instrument investigators listed below.

To obtain technical information on the data sets:

Principal Investigator:
Dr. Brent Roberts, NASA
National Space Science and Technology Center
320 Sparkman Drive
Huntsville, Alabama 35805

Mr. Frank LaFontaine, Raytheon, (same address)

Ms. Courtney Buckley, USRA, (same address)

To order these data or for further information, please contact:

Global Hydrology Resource Center
User Services
320 Sparkman Drive
Huntsville, AL 35805
Phone: 256-961-7932
E-mail: support-ghrc@earthdata.nasa.gov
Web: http://ghrc.nsstc.nasa.gov/