PALSAR-3
The PALSAR-3 aboard ALOS-4 is an L-band Synthetic Aperture Radar(SAR) sensor,
a microwave sensor that emits L-band radio waves and receives their reflection from the ground to acquire information.
The PALSAR-3 has three modes:
-
Spotlight mode
（SPT）The most detailed observation mode with 1 by 3 meters resolution (observation width of 35 km)
-
Stripmap mode
（SM）A high-resolution mode with the choice of 3, 6 or 10 meters resolution (observation width of 100 or 200km)
-
ScanSAR mode
（WD）A broad area observation mode with observation width of 700km and resolution of 25m
Selecting the most suitable mode for an objective will maximize the effectiveness of monitoring works.
PALSAR-3 Specifications
| Observation modes | Stripmap 3m | Stripmap 6m | Stripmap 10m | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 200km swath |
100km swath |
Full-pol. | 200km swath |
100km swath |
Full-pol. | 200km swath |
100km swath |
Full-pol. | ||
| Resolution [m] (*1) |
Range | 3 | 3 | 3 | 6 | 6 | 6 | 10 | 10 | 10 |
| Azimuth | 3 | 3 | 3 | 6 | 6 | 6 | 10 | 10 | 10 | |
| Swath width [km] (*2) | 200 | 100 | 100 | 200 | 100 | 100 | 200 | 100 | 100 | |
| Polarization number (*3) | Single Dual |
Single Dual |
Full | Single Dual |
Single Dual |
Full | Single Dual |
Single Dual |
Full | |
| Observation modes | Spotlight | ScanSAR | |
|---|---|---|---|
| Resolution [m] (*1) |
Range | 3 | 25 |
| Azimuth | 1 | 25 | |
| Swath width [km] (*2) | 35 | 700 | |
| Polarization number (*3) | Single Dual |
Single Dual |
|
*1: Specified at 37 degrees incidence angle on the ground range plane at the equator.
*2: Specified on the ground range plane at the equator.
*3: Polarization basis is linear (horizontal/vertical).
PALSAR-3 Scene Size by Observation Modes
| Observation modes | Spot light |
Stripmap 3m | Stripmap 6m | Stripmap 10m | ScanSAR | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 200km swath |
100km swath |
Full-pol. | 200km swath |
100km swath |
Full-pol. | 200km swath |
100km swath |
Full-pol. | |||
| Scene width [km] (distance in range direction) |
35 | 50~59 | 50~62 | 50~62 | 50~59 | 50~62 | 50~62 | 39~70 | 43~70 | 43~70 | 703 |
| Scene length [km] (distance in azimuth direction) |
35 | 70 | 70 | 70 | 70 | 70 | 70 | 70 | 70 | 70 | 335 |
Definition of PALSAR-3 product Processing levels
| Level | Definition | Format |
|---|---|---|
| Level 1.1 | Complex image (including amplitude and phase data) projected onto the slant range with range and single-look azimuth compression. | CEOS* |
| Level 1.2 | Signal data converted to a single-beam observation equivalent by applying various correction processes. The users need to visualize the data themselves. | CEOS* |
| Level 1.5 | Amplitude image projected onto the ground range with compression of range and multi-look azimuth (geo-reference or geocode). | CEOS* /GeoTIFF |
| Level 2.1 | Ground range amplitude image with ortho correction to L1.5. | CEOS* /GeoTIFF |
*CEOS format : SAR image file
PALSAR-3 Features by Product Processing Level
| Level 1.2 | Level 1.1 | Level 1.5/2.1 | |
|---|---|---|---|
| Geodetic coordinate system |
ITRF97 | ||
| Ellipsoid | GRS80 | ||
| Scene shift (*1) | -5～4（-25～20） | ||
| Output polarization | can be specified | ||
| Radio frequency interference noise removal |
ON/OFF | ||
| Scene merge | can be specified (*4) | - | |
| User-defined scenes | - | can be specified | |
| Range window function | - | Rectangle | |
| Azimuth window function | - | Rectangle | |
| Range antenna pattern correction |
- | ON/OFF | |
| Azimuth antenna pattern correction (*2) |
- | ON/OFF | |
| Number of multi-looks | - | 1 | |
| Inter-polarization calibration (*3) |
- | ON/OFF | |
| Wide-area observation mode imaging method |
- | Burst/Full-Aperture | Burst |
| Map projections | - | - | UTM/PS/MER |
| Framing | - | - | Geo-reference/Geo-coded |
| Resampling method | - | - | NN/BL/CC/CC66 |
| Pixel spacing | - | - | see below |
| DEM type (*5) | - | - | AW3D30/ Geospatial Information Authority of Japan Digital Map/ SRTM |
*1 Values in parentheses for wide-area observations
*2 This can only be specified for ScanSAR observation L1.1 burst method or ScanSAR observation L1.5/2.1. Otherwise it is always OFF.
*3 Full polarimetry observation only.
*4 PALSAR-3 product processing can create a scene that combines multiple scenes with stripmap 3m/6m/10m modes. Scenes can be
combined in range, but not in azimuth.
*5 DEM type can be specified in L2.1 processing (ortho-rectification)
Pixel spacing [m]
| Observation mode | Spot light |
Stripmap 3m | Stripmap 6m | Stripmap 10m | ScanSAR | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 200km swath |
100km swath |
Full-pol. | 200km swath |
100km swath |
Full-pol. | 200km swath |
100km swath |
Full-pol. | |||
| L1.5 | 0.625 | 2.5 | 2.5 | 2.5 | 3.125 | 3.125 | 3.125 | 6.25 | 6.25 | 6.25 | 25 |
| L2.1 | 0.625 | 2.5 | 2.5 | 2.5 | 3.125 | 3.125 | 3.125 | 6.25 | 6.25 | 6.25 | 25 |
-
Method 1（SPECAN Method）
Range and azimuth compressions are performed per each burst.
Burst data of a sub swath is stored in a same image file sequentially.
In the case of the SPECAN method, an image file per each scan and polarization is generated. -
Method 2（Full-Aperture Method）
In each scan and polarization, the gaps between bursts in a sub swath are filled with zeros and range and azimuth compressions are performed.
An image file per each scan and polarization is generated.
