COSMO-SkyMed

Long name COSMO-SkyMed
Short name COS
Sensor type Synthetic-aperture radar (SAR)
Platform Constellation of Small Satellites for the Mediterranean Basin Observation (COSMO-SkyMed)
Frequency 9.65 GHz
Band (wavelength) X (3.1 cm)
Polarization HH, HV, VH, VV
Key file name (use to open data set) *.h5
Supported file extensions *.h5
Data distributor e-GEOS (Agenzia Spaziale Italiana (ASI) and Telespazio)
Sections

Data product name and description
Distribution disk files
Returned data for supported format
References

Data product name and description

COSMO-SkyMed has three acquisition modes:
  • Spotlight
    • Spotlight-1 [S1] (military use only)
    • Spotlight-2 [S2]
  • Stripmap
    • PingPong [PP]
    • Himage [HI]
  • ScanSAR
    • WideRegion [WR]
    • HugeRegion [HR]
Note: The information provided herein is based on the reference documentation cited under References.
Mode Swath width (km) Resolution (range x azimuth, m)* Polarization Description/notes

Spotlight: Spotlight-2 [S2]

10 1.0 x 1.0 Single (HH or VV) The antenna maneuvers (both in the azimuth and on the elevation plane) during the overall acquisition time to illuminate the required scene for a time longer than that of the standard strip-side view, increasing the length of the synthetic antenna and, therefore, the azimuth resolution (at the expense of the azimuth coverage).
Stripmap: PingPong [PP] 30 15.0 x 15.0 Dual (HH+VV or HH+HV or VV+VH) Stripmap: Imaging mode acquired by pointing the antenna in a fixed direction along the flight path of the platform. The antenna footprint covers a strip on the illuminated surfaces as the platform moves and the system operates.

[PP] submode acquires a strip by alternating a burst of Tx/Rx polarization pairs (cross-polarization) with the antenna. The data is acquired in strip mode, alternating between two possible signal polarizations; for example, VV, HH, HV, and VH.

Stripmap: Himage [HI] 40 3.0 x 3.0 Single (HH or HV or VH or VV) Stripmap: Imaging mode acquired by pointing the antenna in a fixed direction along the flight path of the platform. The antenna footprint covers a strip on the illuminated surfaces as the platform moves and the system operates.

[HI] has Tx/Rx radar configurations that are time invariant, and receives the full Doppler bandwidth allowed by the azimuth aperture of the antenna beam width from each ground scatterer.

ScanSAR: WideRegion [WR] 100 16.0 x 16.0 Single (HH or HV or VH or VV) ScanSAR: Acquires a larger swath in range than Stripmap, but with lower spatial resolution, obtained by periodically stepping the antenna beam to neighboring subswaths. Because only a part of the synthetic-antenna length is available in azimuth, the azimuth resolution is reduced.

[WR] groups the acquisition in three adjacent subswaths, achieving ground coverage of approximately 200 kilometers in the range direction.

ScanSAR: HugeRegion [HR] 200 30.0 x 30.0 Single (HH or HV or VH or VV) ScanSAR: Acquires a larger swath in range than Stripmap, but with lower spatial resolution, obtained by periodically stepping the antenna beam to neighboring subswaths. Because only a part of the synthetic-antenna length is available in azimuth, the azimuth resolution is reduced.

[HR] groups the acquisition in up to six adjacent subswaths, achieving ground coverage of approximately 200 kilometers in the range direction.

* Resolution is always single-look complex (SLC) unless noted otherwise.

Processing level Acquisition mode Description/notes

0
(RAW)

N/A Not supported.

1A
Single-look complex (SSC)

[S2]
[PP], [HI]
[WR], [HR]

Complex images in slant-range azimuth projection.

1B
Detected ground multilook (DGM)

[S2]
[PP], [HI]
[WR], [HR]

Detected images projected (interpolated) on ground and multilooked. Multilook is not applied to Spotlight images.

1C
Geocoded ellipsoid corrected (GEC)

[S2]
[PP], [HI]
[WR], [HR]

Obtained by projecting the 1A product onto a regular grid in a selected cartographic reference system.

GEC: Uses an ellipsoid to model the surface of the Earth.

1D
Geocoded terrain corrected (GTC)

[S2]
[PP], [HI]
[WR], [HR]

Obtained by projecting the 1A product onto a regular grid in a selected cartographic reference system.

GTC: Uses a digital elevation model (DEM) to approximate the actual surface of the Earth.

Distribution disk files

COSMO-SkyMed data is delivered in Hierarchical Data Format (HDF5). The format and software has been developed and supported by the National Centre for Supercomputing Applications (NCSA), University of Illinois since 1988 and is available freely. The HDFS format contains both image and auxiliary data. GDB retrieves from the hierarchy all attributes as raster-level metadata from the raster data set (group and its parent or parents).

File name Format Required Contents/details
*.h5 HDF5 Yes Image and auxiliary data, metadata

Returned data for supported format

COSMO-SkyMed images can be opened directly in the raw vendor format or imported into a PCIDSK (.pix) file using the key file name (*.h5). For optimal processing, use the PCIDSK format.

The following table describes the data structure after it is imported into a PCIDSK file. Only the fully supported processing level and acquisition modes are described.

Data product Data returned Details

Level 1-A (SCS)
[HI]

1 x [C16S] Raster channel (uncalibrated)
—or—
1 x [C32R] Raster channel (calibrated)

1 x [ORB] Orbit segment
1 x [BIN] Rational function model
1 x [ARR] Incidence angle array

Data can be calibrated in sigma, gamma, or beta nought.

Level 1-A (SCS)
[PP]*

2 x [C16S] Raster channels (uncalibrated)
—or—
2 x [C32R] Raster channels (calibrated)

1 x [ORB] Orbit segment
1 x [ARR] Incidence angle array

Data can be calibrated in sigma, gamma, or beta nought.

Level 1-A (SCS)
[HR]
[WR]

<swath_no> x [C16S] Raster channels (uncalibrated)
—or—
<swath_no> x [C32R] Raster channels (calibrated)

<swath_no> x [ORB] Orbit segment
<swath_no> x [BIN] Rational function model
<swath_no> x [ARR] Incidence angle array

Data can be calibrated in sigma, gamma, or beta nought.
Note: <swath_no> is the number of subswaths (3,4,5,6).

Level 1-B (DGM)
[S2]*
[HI]
[WR]
[HR]

1 x [16U] Raster channels (uncalibrated)
—or—
1 x [32R] Raster channels (calibrated)

1 x [ORB] Orbit segment
1 x [ARR] Incidence angle array

Data can be calibrated in sigma, gamma, or beta nought.

Level 1-B (DGM)
[PP]

2 x [16U] Raster channels (uncalibrated)
—or—
2 x [32R] Raster channels (calibrated)

1 x [ORB] Orbit segment
1 x [ARR] Incidence angle array

Data can be calibrated in sigma, gamma, or beta nought.

Level 1-C (GEC)/Level-1D (GTC)
[PP]

2 x [16U] Raster channels (uncalibrated)
—or—
2 x [32R] Raster channels (calibrated)

1 x [ORB] Orbit segment

Data can be calibrated in sigma nought.

Level 1-C (GEC)/Level-1D (GTC)
[S2]*
[HI]
[WR]
[HR]

1 x [16U] Raster channels (uncalibrated)
—or—
1 x [32R] Raster channels (calibrated)

1 x [ORB] Orbit segment

Data can be calibrated in sigma nought.

* Support for Spotlight-2 [S2] data not tested by PCI.

References

COSMO-SkyMed SAR Products Handbook. Italian Space Agency (ASI). Rev.2 09/06/09. 105 pages.

COSMO-SkyMed System Description & User Guide. Italian Space Agency (ASI). 46 pages.

For more information, including PDFs of the preceding documents you can download, go to: e-geos.it

You can also learn more about COSMO-SkyMed from the eoPortal directory: eoportal.org

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