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SMEX02 Airborne GPS Bistatic Radar Data, Iowa

Entry ID: NSIDC-0275

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Summary

Abstract: This data set contains measurements of Global Positioning System (GPS) signals reflected from the EarthÂs surface and collected on an airborne platform. The measurements were taken over the Soil Moisture Experiments 2002 (SMEX02) Walnut Creek Watershed area in Iowa, USA. The reflections collected were from flat agricultural land with mostly corn and soybean crops in mid-development. Data were ... collected on 19, 25, 27 June 2002 and 1, 2, 5-8 July 2002. The data are categorized by campaigns and dates, and are processed into levels. Level Â0Â files are text files directly from the receiver. Levels above Â0Â are output in Hierarchical Data Format (HDF) format, ordered in UTC time and gzipped. The HDF files contain metadata in the form of attributes that describe the data seta and variables. The variables also contain attributes to self-describe the individual data pieces. A modified GPS Delay Mapping Receiver (DMR) tracks and measures the direct, line-of-sight, right hand circularly polarized (RHCP) signal of a GPS satellite. It also simultaneously measures the delayed, Earth- reflected, near-specular, left hand circularly polarized (LHCP) GPS signal. The DMR was mounted on the NCAR C-130 along with the Jet Propulsion Laboratory (JPL) Passive and Active L- and S-band (PALS) microwave instrument. GPS signal reflections were collected using the standard hemispherical RHCP antenna mounted on the roof of the aircraft, and a reversed polarization LHCP hemispherical antenna mounted on the belly. The receiver position is computed from either an external navigation source or the receiver's own GPS navigation solution, whichever is more accurate. The GPS surface reflections are georeferenced to a composite Earth consisting of the WGS-84 ellipsoid, the EGM96 geoid, and the GTOPO30 elevation model. The primary objective was to collect land reflections for sensitivity of the reflected GPS power to temporal and spatial soil moisture and foliage attenuation. The measurements are a form of bistatic radar and can be used to estimate the surface scattering coefficient (roughness and/or dielectric properties) and path delays between the direct and reflected GPS signals. Scattering coefficients can be used to estimate changes in surface soil moisture. These data were collected as part of a validation study for the Advanced Microwave Scanning Radiometer - Earth Observing System (AMSR-E). AMSR-E is a mission instrument launched aboard NASA's Aqua Satellite on 04 May 2002. AMSR-E validation studies linked to SMEX are designed to evaluate the accuracy of AMSR-E soil moisture data. Specific validation objectives include assessing and refining soil moisture algorithm performance; verifying soil moisture estimation accuracy; investigating the effects of vegetation, surface temperature, topography, and soil texture on soil moisture accuracy; and determining the regions that are useful for AMSR-E soil moisture measurements.

Related URL

Link: GET DATA

Geographic Coverage

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Spatial coordinates

N: 42.0

S: 41.92

E: -93.4

W: -93.8

Data Set Citation

Dataset Originator/Creator: D. Masters

Dataset Title: SMEX02 Airborne GPS Bistatic Radar, Iowa

Dataset Release Place: Boulder, CO USA

Dataset Publisher: University of Colorado, Colorado Center for Astrodynamics Research

Online Resource: http://ccar.colorado.edu/dmr/campaigns/smex/

Temporal Coverage

Start Date: 2002-06-19

Stop Date: 2002-07-08

Location Keywords

CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA

CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > IOWA

Science Keywords

SPECTRAL/ENGINEERING > RADAR > RADAR IMAGERY

ISO Topic Category

IMAGERY/BASE MAPS/EARTH COVER

Platform

GPS > Global Positioning System Satellites

Instrument

GPS RECEIVERS

Project

EOSDIS > Earth Observing System Data Information System

ISMEX > Iowa Soil Moisture Experiment

ESIP > Earth Science Information Partners Program

SMEX02 > Soil Moisture Experiments in 2002

Use Constraints These data are considered exploratory. The techniques to estimate geophysical parameters from these data are being continuously refined. Usage of these data is granted without restriction, but acknowledgment of the source and PI is appreciated.

Ancillary Keywords

bistatic radar

GPS

Soil Moisture

Surface Roughness

Data Set Progress

IN WORK

Data Center

NSIDC Distributed Active Archive Center

Data Center URL: http://nsidc.org/daac/index.html

Data Center Personnel
Name: NSIDC USER SERVICES Phone: +1 (303) 492-6199 Fax: +1 (303) 492-2468 Email: nsidc at nsidc.org Contact Address: National Snow and Ice Data Center CIRES, 449 UCB University of Colorado City: Boulder Province or State: CO Postal Code: 80309-0449 Country: USA

National Snow and Ice Data Center

Data Center URL: http://nsidc.org
Dataset ID: NSIDC-0275

Data Center Personnel
Name: NSIDC USER SERVICES Phone: +1 (303) 492-6199 Fax: +1 (303) 492-2468 Email: nsidc at nsidc.org Contact Address: National Snow and Ice Data Center CIRES, 449 UCB University of Colorado City: Boulder Province or State: CO Postal Code: 80309-0449 Country: USA

Distribution

Distribution Media: Digital

Distribution Format: UTC time-ordered HDF format (gzipped).

Personnel

DALLAS MASTERS

Role: INVESTIGATOR

Phone: 303.492.4075

Fax: 303.492.2825

Email: mastersd at ucar.edu

Contact Address:

University of Colorado

CB 431/ CCAR

PO Box 3000

City: Boulder

Province or State: CO

Postal Code: 80309-0431

Country: USA

STEPHEN KATZBERG

Role: INVESTIGATOR

Phone: (757) 864-1970

Email: s.j.katzberg at larc.nasa.gov

Contact Address:

M.S. 328

NASA-Langley Research Center

City: Hampton

Province or State: VA

Postal Code: 23681-0001

Country: USA

Creation and Review Dates

DIF Creation Date: 2005-08-03

Last DIF Revision Date: 2010-03-08

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