Southern Great Plains 1997 (SGP97) Hydrology Experiment Plan
Section 6 - Satellite Data Acquisition


Goto Section in Document:
Table of Contents and Executive Summary            
1. Overview
2. Soil Moisture and Temperature
3. Vegetation and Land Cover
4. Soil Physical and Hydraulic Properties
5. Planetary Boundary Layer Studies
6. Satellite Data Acquisition
7. DOE ARM CART Program
8. Oklahoma Mesonet Program
9. Operations
10. Data Management and Availability
11. Science Investigations
12. Sampling Protocols
13. Local Information
14. References
15. List of Participants

6. SATELLITE DATA ACQUISITIONS

6.1. Landsat Thematic Mapper (TM)

TM scenes have been acquired for four dates from previous years to assist in the site selection and vegetation studies. We will attempt to acquire two dates of coverage during the experiment period in 1997.

6.2. Priroda

Priroda is a module on the Russian MIR spacecraft. It is in a circular orbit at an altitude of 360 km over the Earth surface and inclination of 51.7o. Priroda includes a variety of unique remote sensing instruments, especially passive microwave. Major features are described in Table 16 Data are being requested for all possible coverages, however, there are potential conflicts that may limit coverage. Pending other problems with the spacecraft, there should be some coverage in late June. In addition, data turnaround is uncertain at this time since there have been no data sets provided to date.

Table 16. Priroda Sensors.
Sensor Wavelength Beamwidth (Degrees) Spatial Resolution (km) Swath (km)
Passive Microwave (IKAR)

IKAR-N (Nadir)

0.3, 0.8, 1.35, 2.25, 6 cm

9

60

60

IKAR-D (Scanning)

0.3, 0.8, 1.35, 4 cm

1, 1.5, 2, 6

5, 8, 15, 50

400

IKAR-P (Pushbroom)

2.25 and 6 cm)

6,12

75

750

Radar (Travers)

SAR

9.2 and 23 cm

1x4, 2.5 x 4

0.15

100

Visible and Infrared

ISTOK

3.6 -16 m>

64 channel

1 x 6

6

MOS-OBZOR

0.415 -1.03 m>

17

0.6

80

MSU-SK

0.5 -12.>

5

120 m

350

MSU-E

0.5 - 0.9 m>

3

35 m

27

6.3 Advanced Very High Resolution Radiometer (AVHRR)

This is a TIROS-N series satellite designed to operate in a near-polar, sun-synchronous orbit. There may be two satellites in this series that are in orbit during the experiments. The NOAA-14 satellite in the ascending node (northbound Equator crossing) has a daytime pass of approximately 1340 hours local solar time. The NOAA-12 satellite in the descending node (southbound Equator crossing) has a daytime pass of approximately 0730 hours. Sensor characteristics are described below.

Sensor Band Characteristics:

Band 1 0.58 - 0.68 (micrometers)

          2 0.725 - 1.10

          3 3.55 - 3.93

          4 10.3 - 11.3

          5 11.5 - 12.5

 
Sensor Spatial Resolution: 1.1 Km (all bands) at Nadir pass
Temporal Resolution: 14.1 orbits/day
Swath: 2048 pixels wide
Scan Angle Range: -55.4 to +55.4 degrees

6.4. Radar Satellites

Data from three different synthetic aperture radar (SAR) satellites will be acquired, pending negotiations. These are Radarsat, JERS, and ERS.

Radarsat is operated by the Canadian Space Agency. It is a C band SAR with HH polarization. It is in a sun­synchronous orbit at an altitude of 798 kilometers above the Earth, at an inclination of 98.6 degrees to the equatorial plane. The sun­synchronous orbit also means that the satellite overpasses are always at the same local mean time. As opposed to the other radar satellites, Radarsat can provide a variety of beam selections. It has the ability to shape and steer its beam from an incidence angle of less than 20 degrees to more than 50 degrees, in swaths of 35 to 500 kilometers, using resolutions ranging from 10 to 100 meters. The following scenes will be acquired (various dates, configurations and coverage areas), however, these data are subject to distribution limitations due to Radarsat regulations.

Proposed schedule:

Date Area Mode # Scenes Orbit

6-11 South Scan-A 1 D

6-18 South Scan-A 1 D

6-21 Full EXTL1 3 D

6-25 Full Scan-B 1 D

6-28 Full Scan-A 2 D

6-29 South EX-4 2 D

7-2 South Scan-B 1 D

7-5 South Scan-A 1 A

7-5 Full Scan-A 2 D

7-12 South Scan-A 1 D

7-19 South Scan-B 1 D

JERS-1 (the Japanese Environmental Satellite) is an L-band HH SAR operating at an incidence angle of 30o. With a coverage frequency of 44 days it is difficult to get coverage when needed. At least one set of coverage will be acquired that will include June 20 and 22. Distribution may be restricted.

The ERS (European Remote Sensing Satellite) is a global environmental monitoring satellite that has a fixed incidence angle of 23o. It is a C-band synthetic aperture radar (SAR) operating at VV polarization. Availability is uncertain.

6.5. Special Sensor Microwave Imager (SSM/I)

The (SSM/I) has been a part of the Defense Meteorological Satellite Program (DMSP) since July, 1987. It is a multifrequency imaging radiometer that utilizes conical scanning at an incidence angle of 50o. It operates in a circular sun­synchronous near polar orbit at an altitude of 833 km and an inclination of 98.8o. Basic parameters for the sensors are listed in Table 17. At the present time the primary satellite available is F13 which has an ascending equator crossing time of 17:43 local.

The total swath is 1400 km. We will attempt to acquire data from all passes and satellites during the study period. These data will be resampled to a standard grid.


Table 17. SSM/I Sensors


Frequency (GHz)


Polarizations

Resolution (km)

(along and cross track)

19.35

V and H

69 x 43

22.235

V

60 x 40

37.0

V and H

37 x 28

85.5

V and H

15 x 13

6.6. GOES

Two second-generation Geostationary Operational Environmental Satellites, GOES-8 and GOES-9, are in operation as of this writing. While both of these satellites view the SGP97 Region, GOES-8, positioned over the equator at 75 degrees west longitude, has the less severe angle of view (approximately 45 degrees to the ARM-CART Central Facility Site), making it the preferred data source.

Wavelengths, horizontal resolution, temporal frequency

The GOES imager is a five-band instrument measuring terrestrial radiation in one visible wavelength region (0.52-0.72 micrometers) and in four thermal infrared (TIR) bands between 3.7 and 12.5 micrometers. The spatial resolutions at nadir are approximately one and four km for the visible and thermal infrared imager data, respectively (with the exception of TIR channel 3 at 6.7 micrometers, which has approximately an eight-km nadir resolution) and the nominal time interval of imaging is fifteen minutes. An atmospheric sounding instrument on the GOES satellites measures emitted atmospheric and surface thermal radiation in an additional 19 channels in the 3 to 14 micrometer wavelength region at a nominal time interval of one hour. The horizontal resolution of these sounder data is approximately ten km at nadir.

Spatial Coverage

While GOES-8 provides data which covers the entire continental United States, an approximate maximum longitude for the quantitative use of GOES-8 data is 105 degrees west (due to view angle considerations).

Data Access

GOES visible and infrared imager data is digitized at 10 bits while the GOES sounder data is digitized at 13 bits. Data for the SGP97 will be available through several sources.

1) The National Oceanic and Atmospheric Administration (NOAA) archives these data and distribution is handled by the National Climate Data Center (NCDC). For ordering information, see the NCDC home page at http://www.ncdc.noaa.gov/.

2) The Department of Energy (DOE) maintains a limited archive of GOES data for the ARM effort. Information on data access is available through the ARM home page at http://www.arm.gov/.

3) George Diak at the Space Science and Engineering Center (SSEC), University of Wisconsin-Madison will be maintaining a small archive of GOES-8 visible and infrared imager data (daytime hours, at approximately a one-hour interval) for the region of the SGP97 experiment, 18 June to 18 July, 1997. They will be available by anonymous ftp at no charge after approximately 1 August, 1997. For details, email George Diak (after 20 July, 1997 please) at george.diak@ssec.wisc.edu.

4) The NCDC maintains a browse library of GOES imagery, which can be used to evaluate data quality, applicability, etc. These GOES images are viewable at http://www.ncdc.noaa.gov/psguide/satellite/goesbrowse/. Real-time GOES (GIF) imagery is viewable on the SSEC home page at http://www.ssec.wisc.edu/.

NOAA and the NCDC maintain a complete catalog of information on the GOES satellites, including instrument specifications, data access and more. General information can be found on the NCDC home page at http://www.ncdc.noaa.gov/. The GOES Satellite technical manual and other related literature is available on line at the NCDC at http://140.90.207.25:8080/EBB/pubs/TR82/toc.html. Additional information on the GOES satellites, as well as real-time cloud, water vapor and surface temperature products (GIF, MPEG, FLI images) derived from the sounder data, is available on the Cooperative Institute for Meteorological Satellite Studies (CIMSS) home page at http://cimss.ssec.wisc.edu/.


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