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SMEX03 Aircraft Polarimetric Scanning Radiometer (PSR) Data

Summary

The Polarimetric Scanning Radiometer (PSR) is an airborne microwave imaging radiometer developed and operated by the National Oceanic and Atmospheric Administration (NOAA) Environmental Technology Laboratory. This data set includes brightness temperature data for the C-band and X-band. Measurements were taken 25 June through 17 July 2003 in regional areas of Alabama, Georgia, and Oklahoma, USA and the Little Washita Watershed of Oklahoma, USA during the Soil Moisture Experiment 2003 (SMEX03). The PSR/CX band radiometer is similar to the low-frequency channels of the Advanced Microwave Scanning Radiometers (AMSR-E) on the NASA Aqua satellite. The radiometer operates at vertical (V) and horizontal (H) polarizations. Data are provided in ASCII text files and available from via FTP.

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.

Citing These Data

The following example shows how to cite the use of this data set in a publication. For more information, see our Use and Copyright Web page.

Jackson, T., R. Bindlish, A. J. Gasiewski, M. Klein, and B. Stankov. 2007. SMEX03 Aircraft Polarimetric Scanning Radiometer (PSR) Data. [indicate subset used]. Boulder, Colorado USA: NASA DAAC at the National Snow and Ice Data Center.

Overview Table

Category
Description
Data format ASCII text files
Spatial coverage and resolution Alabama
Southernmost Latitude: 34.66º N
Northernmost Latitude: 35.19º N
Westernmost Longitude: 87.09º W
Easternmost Longitude: 85.77º W

Georgia
Southernmost Latitude: 30.96º N
Northernmost Latitude: 31.89º N
Westernmost Longitude: 83.97º W
Easternmost Longitude: 83.36º W

Oklahoma
Southernmost Latitude: 34.42º N
Northernmost Latitude: 36.87º N
Westernmost Longitude: 98.34º W
Easternmost Longitude: 97.42º W
Temporal coverage and resolution 25 June through 17 July 2003
File naming convention Processed data: SSMDD.txt
Raw data: PPPPMDD##.txt
File size File sizes range 107 KB to 4.6 MB
Parameter(s) Brightness temperatures
Procedures for obtaining data Data are available via FTP.

Table of Contents

1. Contacts and Acknowledgments
2. Detailed Data Description
3. Data Access and Tools
4. Data Acquisition and Processing
5. References and Related Publications
6. Document Information

1. Contacts and Acknowledgments

Investigator(s)

Thomas J. Jackson and Rajat Bindlish
US Department of Agriculture (USDA) - Agricultural Research Service (ARS)
Hydrology and Remote Sensing Lab
Beltsville, MD 20705
USA

Albin J. Gasiewski and Marian Klein
University of Colorado at Boulder - National Oceanic & Atmospheric Administration (NOAA)
Center for Environmental Technology (CET)
Boulder, CO 80305
USA

Boba Stankov
National Oceanic & Atmospheric Administration (NOAA)
Environment Technology Laboratory (ETL)
Boulder, CO 80305
USA

Technical Contact

NSIDC User Services
National Snow and Ice Data Center
CIRES, 449 UCB
University of Colorado
Boulder, CO 80309-0449  USA
phone: +1 303.492.6199
fax: +1 303.492.2468
form: Contact NSIDC User Services
e-mail: nsidc@nsidc.org

2. Detailed Data Description

Format

Data are provided as ASCII text files. Table 1 describes the format of the processed data files. Table 2 describes the format of the raw data files.

Table 1: Column Descriptions for Processed Data Files
Column
Description
Column 1 UTM - Northing
Column 2 UTM - Easting
Column 3 C-band (7.32 GHz) V
Column 4 C-band (7.32 GHz) H
Column 5 X-band (10.7 GHz) H

Table 2: Column Descriptions for Raw Data Files
Column
Description
Column 1 UTM - Northing
Column 2 UTM - Easting
Column 3 Latitude
Column 4 Longitude
Column 5 C-band (7.32 GHz) V
Column 6 C-band (7.32 GHz) H
Column 7 X-band (10.7 GHz) H

 

File and Directory Structure

Data are organized in directories based on study area (AL = Alabama, GA = Georgia, LW = Little Washita, ON = Oklahoma North, OS = Oklahoma South). Within each study area directory are a processed and a raw directory. The processed directories contain gridded brightness temperatures. The raw directories contain the raw brightness temperature observations.

File Naming Convention

The processed files are named according to the following convention.

SSMDD.txt

where

SS = study area (AL=Alabama, GA=Georgia,LW = Little Washita, ON = Oklahoma North, OS = Oklahoma South)
M = month
DD = day

The raw files are named according to the following convention.

PPPPMDD##.txt

where

PPPP = processing level (L23i)
M = month
DD = day
## = 2 digit number

File Size

File sizes range from 107 KB to 4.6 MB.

Spatial Coverage

Table 3 lists the spatial coverage of each study area. All locations are UTM zone 14 in NAD83/WGS84 datum.

Table 3: Spatial Coverage
 
Easting
Northing
Latitude
Longitude
Alabama Regional Area
Upper Left 492000 3894600 35.194353404 -87.087877924
Upper Right 612000 3894600 35.188137035 -85.769834626
Lower Right 492000 3837000 34.674943785 -87.087325703
Lower Left 612000 3837000 34.668845602 -85.777562595
Georgia Regional Area
Upper Left 219000 3532200 31.890956391 -83.970846870
Upper Right 219000 3429000 30.961064855 -83.941646829
Lower Right 274200 3429000 30.972927502 -83.364252777
Lower Left 274200 3532200 31.903257457 -83.387736190
Oklahoma Little Washita Watershed
Upper Left 219000 3532200 31.890956391 -83.970846870
Upper Right 219000 3429000 30.961064855 -83.941646829
Lower Right 274200 3429000 30.972927502 -83.364252777
Lower Left 274200 3532200 31.903257457 -83.387736190
Oklahoma North Regional Area
Upper Left 585800 4081000 36.871048244 -98.037331796
Upper Right 641000 4081000 36.864419443 -97.418165280
Lower Right 641000 3997000 36.107428397 -97.433484464
Lower Left 585800 3997000 36.113877589 -98.046657639
Oklahoma South Regional Area
Upper Left 560400 3920100 35.422485463 -98.334661234
Upper Right 618000 3920100 35.417323871 -97.700276141
Lower Right 618000 3812100 34.443677450 -97.715544713
Lower Left 560400 3812100 34.448656578 -98.342479279

 

Temporal Coverage

Measurements were collected from 25 June through 17 July 2003 in the study areas. Table 4 lists the collection dates for each area.

Table 4: PSR Collection Dates
Location
Dates
Alabama 25, 27, 29, 30 June
2 July
Georgia 25, 29, 30 June
Little Washita 3, 5, 7, 10, 17 July
Oklahoma North 3, 5, 7, 10, 11, 12, 13, 14, 15, 17 July
Oklahoma South 2, 3, 5, 7, 10, 12, 13, 14, 15, 17 July

Data collection was timed to coincide with a 3 hour window centered on the Aqua equatorial overpass time of 13:30 LST.

Parameter or Variable

Parameter Description

Parameters in this data set are brightness temperatures for the C-band (7.32 GHz) V and H and for the X-band (10.7 GHz) H. Observations at the X-band (10.7 GHz) V are not available due to calibration problems.

Sample Data Record

The following sample shows the first 5 rows from the AL processed file AL625.txt:

492400.00 3837400.00 219.43 162.01 141.87
492400.00 3838200.00 228.56 179.60 170.85
492400.00 3839000.00 244.36 203.46 204.96
492400.00 3839800.00 263.28 230.38 238.26
492400.00 3840600.00 282.41 237.52 260.28


The following sample shows the first 5 rows from the ON raw file L23i70309.txt:

644800.09 3988427.31 36.029610 -97.392853 288.69 280.04 282.86
644817.33 3988714.13 36.032192 -97.392609 0.00 280.38 285.14
644829.49 3989145.96 36.036082 -97.392395 289.11 279.82 284.52
644821.09 3989534.40 36.039584 -97.392417 289.32 280.10 286.49
644796.85 3989932.68 36.043177 -97.392613 289.48 280.16 285.24

3. Data Access and Tools

Data Access

Data are available via FTP.

Volume

Total volume of the data is approximately 530 MB.

Related Data Collections

4. Data Acquisition and Processing

Sensor or Instrument Description

The PSR/CX band instrument was integrated onto the NASA Wallops Flight Facility (WFF) P3B aircraft in the aft portion of the bomb bay and flown over the regional and watershed areas. The PSR scans at a constant incidence angle of 55° with a swath width of 19 km. The flight line has a spacing of 11 km and a length of 80 km. Four regional flight lines at an altitude of ~8000 m were flown over AL, GA, ON, and OS. Two watershed flight lines at an altitude of ~3000 m covered the LW watershed area. The P3 was deployed out of Huntsville, Alabama from 25 June to 2 July 2003 and out of Oklahoma City, Oklahoma from 2 July to 17 July 2003.

Processing Steps

PSR/CX raw data goes through several processing steps. Quality control, time synchronization, calibration, rasterization, and georegistration are considered preprocessing. Following this are removing of Radio Frequency Interference (RFI), adjusting for temporal variations inherent in mapping a large region with an aircraft sensor, and resampling the data to a standard grid that facilitates multitemporal analysis and integration with ancillary data bases for algorithm applications (Jackson et al. 2005).

Grid Resampling

The PSR/CX data consist of beam positions for sequential conical scans. Each beam position footprint is about 3 km in size. Due to sampling rates, the spacing between these footprints is 300 m, which results in over sampling. In addition, each line of data overlaps other lines. In order to produce a data set that can be integrated in further analyses, all the footprint data were used in a kriging-based grid resampling procedure. The output grid selected was 800 m, which matched the nominal field scale in the regions as well as the resolution of other databases. Each channel of data was resampled independently (Jackson et al. 2005).

5. References and Related Publications

Jackson, T. J., R. Bindlish, A. J. Gasiewski, B. Stankov, M. Klein, E. G. Njoku, D. Bosch, T. L. Coleman, C. Laymon, and P. Starks. 2005. Polarimetric Scanning Radiometer C and X-band microwave observations during SMEX03. IEEE Transactions on Geosciences and Remote Sensing 43:2418-2430.

Please see the USDA SMEX03 Web site for in depth information on the science mission and goal of the SMEX project.

6. Document Information

Acronyms and Abbreviations

The following acronyms and abbreviations are used in this document.

AL Alabama
AMSR-E Advanced Microwave Scanning Radiometer - Earth Observing System
ASCII American Standard Code for Information Interchange
FTP File Transfer Protocol
GA Georgia
H Horizontal
LW Little Washita
NAD83 North American Datum of 1983
NASA National Aeronautics and Space Administration
NOAA National Oceanic and Atmospheric Administration
NSIDC National Snow and Ice Data Center
ON Oklahoma North
OS Oklahoma South
PSR Polarimetric Scanning Radiometer
RFI Radio Frequency Interference
SMEX Soil Moisture Experiment
Tb Brightness Temperature
URL Uniform Resource Locator
UTM Universal Transverse Mercator
V Vertical
WFF Wallops Flight Facility
WGS84 World Geodetic System 1984

Document Creation Date

November 2007

Document URL

http:/nsidc.org/data/docs/daac/nsidc0328_smex03_aircraft_psr.gd.html