KWAJEX radar rain map KWAJEX Home

Operations
Logistics

Participants

Ancillary Data

Aircraft Data
Surface Data
Satellite Data

TRMM Campaigns
Precipitation
DISC Home

Privacy, Disclaimer, Accessibility

 

KU Band Radar Data from the RV Ron Brown

Introduction
Sponsor

The Data
The Ku-band System and Data
Ancillary Data
Problems

The Files

Data Access & Contacts
FTP Site
Points of Contact

KU Band Radar Data

Introduction

Sponsor

The distribution of these data sets is funded by NASA's Earth Science Enterprise. The data are not copyrighted; however, we request that when you publish data or results using these data, please acknowledge as follows:

The authors wish to thank Robert F. Contreras, Dept. of Atmospheric Sciences, University of Washington, Seattle, WA for the production of these data and the Distributed Active Archive Center(Code 610.2) at the Goddard Space Flight Center, Greenbelt, MD, 20771, which archives and distributes them under sponsorship of NASA's Earth Science Enterprise.

The Data

The Ku-band System and Data

The Ku-band (14 GHz) microwave system used on the RV Ronald H. Brown during KWAJ EX was a continuous-wave, dual-polarized, coherent system. The one-way, half-power, full beamwidths were:

  • 6.4 Degrees (vertical V-pol),
  • 6.4 Degrees (vertical H-pol),
  • 6.9 Degrees (horizontal V-pol)
  • 6.8 Degrees (horizontal H-Pol).
The system was downward looking from a height of 16.2 m above the water surface and it stepped through incidence angles ranging from 12.5 Degrees to 76 Degrees.

HH and VV polarization returned powers were recorded at 2 Hz and from this normalized radar cross sections (NRCS) were calculated; mean spectra were recorded every 40 samples (20 seconds). The 20 second mean cross sections were computed, and from these the scattering from rain was removed by eliminating the component of the return with very large Doppler shifts.

Ancillary Data

  • Rain Guage: The Hasse rain guage values for the rain rate were used
  • Neutral Winds: The 10m neutral winds (speed and direction) were calculated using Monin-Obhukov similarity theory. The wind speed and direction, and the fluxes of momentum and heat used to compute the neutral winds were provided by Dr. Jeff Hare and Dr. Chris Fairall (NOAA/ETL Air-Sea Interaction Group). The wind speed, wind direction, heat flux, and momentum flux were provided as 10 minute averages; they were linearly interpolated to 20 second intervals and the neutral winds were computed.

Problems

The transmitted power began to fluctuate August 25. The VV polorization NRCS was completely corrected for this. The HH polarization was corrected for this but there is an increase in the NRCS variance associated with this instrument error. At incidence angles greater than 55 degrees separating the rain signal from the surface signal was difficult; this should be kept in mind when using data at these incident angles.

At incidence angles less than 13.5 degrees the system was seeing the ship and this data should not be used.

The Files

The KU band radar dataset consists of a single 7MB ASCII file named kwaj_proc_ascii.dat, which is tabularly formatted as follows:

ColumnDescriptionUnits
YYYYyear
MMmonth
DDday
HHhour
MMminute
SSseconds
SIGMA0_HNormalized radar cross section, HH polarizationunitless
SIGMA0_VNormalized radar cross section, VV polarizationunitless
INCIDENCEIncidence angle, angle from nadir Degrees
RAIN_RATERain ratemm/hr
WIND_SPEEDNeutral wind speed at 10mm/s
WIND_DIRECTIONClockwise direction between system look direction and the direction from which the wind is blowing.Degrees
NaN was used as the fill value

Data Access

FTP Site

The KU band radar data from KWAJEX may be accessed from this page,

Radar Data Onlinelink to data

or directly via ftp:

ftp disc2.nascom.nasa.gov
logon: anonymous
passwd:
cd data/KWAJ/surface_data/rv_rhbrown/ku_band_radar/

Points of Contact

The Principal Investigator for the KU band radar data is

Robert F. Contreras
Dept. of Atmospheric Sciences
University of Washington, Box 351640
Seattle, WA 98195-1640, USA
robb@apl.washington.edu
206-543-2480 (voice)

For additional information, please contact the GES DISC User Services:

GES DISC User Services
Code 610.2
NASA Goddard Space Flight Center
Greenbelt, MD 20771
301-614-5224
Email: help-disc@listserv.gsfc.nasa.gov

Last update:Fri Dec 5 07:25:15 EST 2003
Page Author: Hydrology Data Support Team -- hydrology-disc@listserv.gsfc.nasa.gov
Web Curator: -- Website Curator: Anthony Drake
NASA official: Steve Kempler, DISC Manager -- kempler@disc.gsfc.nasa.gov 		NASA Logo