CAMEX-4 Mobile X-band Polarimetric Weather Radar
Table of Contents
Introduction
The Convection And Moisture EXperiment (CAMEX) is a series of field research investigations sponsored by the Earth Science Enterprise of the National Aeronautics and Space Administration (NASA). The fourth field campaign in the CAMEX series (CAMEX-4) ran from 16 August to 25 September, 2001 and was based out of Jacksonville Naval Air Station, Florida. CAMEX-4 focused on the study of tropical cyclone (hurricane) development, tracking, intensification, and landfalling impacts using NASA-funded aircraft and surface remote sensing instrumentation.
Mobile X-band Polarimetric Weather Radar on Wheels (X-POW) is an X-band Doppler scanning radar operating at 9.3 GHz. with horizontal and vertical polarization. Used for detection and detailing surface rainfall rate and precipitation classification fields, 3D precipitation microphysical retrievals including water/frozen hydrometeor contents and drop size distribution profiles, X-POW was located in the Florida Keys during the CAMEX-4 field experiment.
Instrument Description
The table below shows the X-POW radar specifications:
| Platform: |
Mobile flatbed truck |
| |
Gasoline generator |
|
| Transmitter: |
Frequency 9.3 GHz (3.2 cm) |
| |
Pulse width 1 s (150 m) Peak power 50 kW |
|
| Polarization diversity: |
Simultaneous transmission of horizontal and vertical polarization |
|
| Antenna: |
Gain 44.3 dB Beam width (3 dB) 0.95 degrees |
| |
Azimuthal scan rate 30 degrees per sec |
| |
Maximum sidelobe -20 dB |
|
| Recorded variables: |
Horizontal and vertical reflectivity, velocity, spectrum width, and differential phase shift |
Data Extraction
This information is for running on UNIX/LINUX machines. Windows documentation is not provided.
Supplied with the documentation is a file named xpow.tar. This tar file contains a data extraction program, instructions and a sample dataset. The program should be used on data from other days to allow the user to manipulate it into a more useable form. Once this file is 'untarred', there will be created a directory named XPOW_READ. In this directory are the following directory and files:
Data/
README.TXT
listfile
xpow_ppi.c
xpow_rhi.c
Makefile
io.c
xpow.h
xpow_ppi2.c
xppack.c
The XPOW_README.TXT is shown below:
This is the README.TXT file for XPOW Version 1.02
*************************************************************************
This file contains information on how to run the C program XPOW, that reads the XPOW data.
*************************************************************************
ftp://ghrc.nsstc.nasa.gov/pub/doc/camex4/c4gxpow/XPOW_README.TXT
This program has been tested on HP and SGI UNIX and LINUX platforms. You do not
need any setup or installation to run it. The main programs are called XPOW_PPI.C (for
reading sector scans), XPOW_PPI2.C (for reading full 360 deg PPI scans), and
XPOW_RHI.C
(for reading RHI scans). These are the programs you need to modify to adjust to
the
specifics of your application.Before run the program it is important to create
five
list files that contain the data you would like to read. The data we read are:
Horizontal polarization reflectivity (listfile with extention .zh), vertical
polarization reflectivity (extention .zv), differential phase shift
(expention phd),
spectral width (extention sw), and radial velocity (extention vel). Be aware the
path of the data (it is hardcoded in the programs).Enjoy!
-----------------------------------------------------------------------
In the second paragraph above, the instructions require the user to
create listfiles. These are already created for use with this example program, and is included with the documentation and software. When
using 'real' instead of the data that comes with XPOW.TAR, you need to do that
yourself. Here is code that will do that.
NOTE: THE CODE BELOW IS NOT SUPPLIED IN THE FILE NAMED XPOW.TAR.:
*****************************************************
# script "xpowlist"
#
# This script reads the data directory and creates the "list" directories
# required by the freq program and puts them in the /Data directory
#
# This script must be run in the /Data directory
#
ls -1 ppi2*.ncp >> list_ppi2_ncp
ls -1 ppi2*.phdp >> list_ppi2_phdp
ls -1 ppi2*.sw >> list_ppi2_sw
ls -1 ppi2*.vdbz >> list_ppi2_vdbz
ls -1 ppi2*.vel >> list_ppi2_vel
ls -1 ppi2*.hdbz >> list_ppi2_hdbz
ls -1 ppi_*.ncp >> list_ppi_ncp
ls -1 ppi_*.phdp >> list_ppi_phdp
ls -1 ppi_*.sw >> list_ppi_sw
ls -1 ppi_*.vdbz >> list_ppi_vdbz
ls -1 ppi_*.vel >> list_ppi_vel
ls -1 ppi_*.hdbz >> list_ppi_hdbz
ls -1 rhi*.ncp >> list_rhi_ncp
ls -1 rhi*.phdp >> list_rhi_phdp
ls -1 rhi*.sw >> list_rhi_sw
ls -1 rhi*.vdbz >> list_rhi_vdbz
ls -1 rhi*.vel >> list_rhi_vel
ls -1 rhi*.hdbz >> list_rhi_hdbz
***************************************************
To prepare the data files for processing, run the above script, and then follow the instructions in paragraph one in the README.TXT file shown above.
If you are running the example file, you'll be able to compare your output to the output file supplied separately with this documentation. (That file is called example_output.dat). Create an output file ('make', then 'freq >output'). Here are the first ten lines of output from the example_output.datfile.
64 0.210000 0.710000
40.796875 40.500000 5.604156 0.500000 5.796875
41.000000 40.593750 5.000000 0.906250 2.703125
41.093750 40.796875 5.197906 0.703125 2.906250
40.406250 40.093750 3.895844 0.406250 5.406250
41.093750 40.593750 2.802094 0.796875 1.203125
40.593750 40.000000 2.802094 0.906250 1.500000
40.093750 39.593750 3.395844 0.703125 2.203125
41.203125 40.593750 7.395844 0.500000 2.406250
40.500000 40.406250 1.197906 0.500000 3.406250
These software and documentation files can be downloaded here:
ftp://ghrc.nsstc.nasa.gov/pub/doc/camex4/c4gxpow/
Data Format
XPOW data are 'tarred' into daily data files of the form:
c4xpow_2001.ddd.tar
where c4xpow represents CAMEX4 and the xpow instrument, yyyy.ddd is the four digit year and day of year. When untarred, these data should be put into the /XPOW_READ/Data directory. Once there, run the xpowlist script shown above to create the listfiles. Note, these listfiles have to be in the /Data directory. At this point, run 'make' and 'freq > [output filename]' and the data is ready for use in radar presentation programs.
Note: It is assumed that the user is familiar with radar presentation programs, and as such, they are not provided here.
Contact Information
The data producer is:
Prof. E.N. Anagnostou
University of Connecticut
manos@engr.uconn.edu
or, as an alternative:
Marios N. Anagnostou
University of Connecticut
ma111@engr.uconn.edu
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/
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