PALSAR-2
The PALSAR-2 aboard ALOS-2 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-2 has three modes:
-
Spotlight mode（SPT）
The most detailed observation mode with 1 by 3 meters resolution (observation width of 25 km)
-
Stripmap mode（SM）
A high-resolution mode with the choice of 3, 6 or 10 meters resolution (observation width of 50 or 70km)
-
ScanSAR mode（WD)
A broad area observation mode with observation width of 350km or 490km, and resolution of 100m or 60m respectively
Selecting the most suitable mode for an objective will maximize the effectiveness of monitoring works.
PALSAR-2 Specifications
| Observation Mode | Spotlight | ScanSAR | ||
|---|---|---|---|---|
| [28MHz] | [14MHz] | [490km] | ||
| Obs. Mode ID (code) | SBS | WWS/WWD | WBS/WBD | VBS/VBD |
| Width (East-West) (Length of Range Direction) |
25km | 350.5km | 350.5km | 489.5km |
| Length(North-South) (Length of Azimuth Direction) |
25km | 355km | 355km | 355km |
| Time Duration of Azimuth Direction |
N/A | 52 sec | 52 sec | 52 sec |
| Range Resolution*1 | 3.0m | 47.5m (5look) |
95.1m (5look) |
44.2m (2look) |
| Azimuth Resolution*1 | 1.0m | 77.7m (3look) |
77.7m (3look) |
56.7m (1.5look) |
| Pixel Spacing Levels 1.5/3.1 |
0.625m | 25m | ||
| Pixel Spacing Level 2.1 |
0.625m/1.25m/2.5m | 25m/50m/100m | ||
| Polarization | Single (HH, HV, VH, or VV) |
Single(HH, HV, VH, or VV) Dual(HH+HV or VH+VV) |
||
| Observation Mode | Stripmap * | ||||
|---|---|---|---|---|---|
| Resorution | [3m] | [6m] | [10m] | ||
| Polarization | Single/Dual | Single/Dual | Full | Single/Dual | Full |
| Obs. Mode ID（code） | UBS/UBD | HBS/HSD | HBQ | FBS/FBD | FBQ |
| Width（East-West） （Length of Range Direction） |
55km (max) |
55km (max) |
40-50km | 70km (max) |
30km |
| Length（North-South） （Length of Azimuth Direction） |
70km | 70km | 70km | 70km | 70km |
| Time Duration of Azimuth Direction |
10 sec | 10 sec | 10 sec | 10 sec | 10 sec |
| Range Resolution*1 | 3.0m | 6.0m | 5.1m | 9.1m | 8.7m |
| Azimuth Resolution*1 | 3.0m | 4.3m | 4.3m | 5.3m | 5.3m |
| Pixel Spacing Levels 1.5/3.1 |
2.5m | 3.125m | 3.125m | 6.25m (2look) |
6.25m (2look) |
| Pixel Spacing Level 2.1 |
2.5m/5.0m /10.0m |
3.125m /6.25m /12.5m |
3.125m /6.25m /12.5m |
6.25m /12.5m |
6.25m /12.5m |
*Stripmap mode defines category names by resolution: Ultra-Fine(3m), High-sensitive(6m), Fine(10m)
*Single（HH, HV, VH, or VV）, Dual（HH+HV or VH+VV）, Full (Quad.) Polarimetry(HH+HV+VH+VV)
PALSAR-2 Product Data Size(Volume) by Processing Levels
| Observation Mode | Spot light |
Stripmap * | Full (Quad.) Polarimetry * |
ScanSAR | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 3m | 6m | 10m | 6m | 10m | 350km | 490km | ||||||
| Method1 | Method2 | Method1 | Method2 | |||||||||
| Level 1.1 （Geo-referenced）*2 |
4.3 | 5.2 | 2.4 | 1 | 5.5 | 2.1 | 3.5 | 6.9 | 27.1 | 54.1 | 6 | 46.8 |
| Levels 1.5 / 2.1 / 3.1 （Geo-referenced） |
3.1 | 1.2 | 0.8 | 0.2 | 0.7 | 0.1 | 0.4 | 0.5 | ||||
| Level 2.1 （Geo-coded）*3 |
6.1 | 2.4 | 1.5 | 0.5 | 5.7 | 0.9 | 0.7 | 1.1 | ||||
Geo-referenced: Map projection based on satellite along track direction
Geo-coded: Map projection based on north-oriented map direction
*The values are defined at the incidence angle 37 deg.
*In the case of dual polarization, the data size is twice as that of a single polarization
(except full polarimetry).
*Stripmap and Full (Quad.) Polarimetry modes define category names by resolution: Ultra-Fine(3m),
High-sensitive(6m), Fine(10m)
*2: Data size of major off-nadir/scan number
*3: Max data size expected
-
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.
Definition of PALSAR-2 product Processing levels
| Level | Definition | Format |
|---|---|---|
| Level 1.1 | This is complex number data on the slant range following compression of the range and azimuth. As one-look data, it includes phase information and will be the basis for later processing. In wide-area mode, image files are created for each scan. | CEOS SAR /GeoTIFF |
| Level 1.5 | This is multi-look data on the slant range from map projection amplitude data, with range and azimuth compressed. | CEOS SAR /GeoTIFF |
| Level 2.1 | Geometrically corrected (orthorectified) data using the digital elevation data from Level 1.1. | CEOS SAR /GeoTIFF |
| Level 3.1 | Image quality-corrected (noise removed, dynamic range compressed) data from Level 1.5. | CEOS SAR /GeoTIFF |
PALSAR-2 Features by Product Processing Level
| Level 1.1 | Level 1.5 | Level 2.1 | Level 3.1 | |
|---|---|---|---|---|
| Scene Extraction | ||||
| Range compressed | ||||
| Single look azimuth compressed |
||||
| Multi-look azimuth compressed |
||||
| Phase data | ||||
| Amplitude data | ||||
| Map projection (Georeferenced or Geo-coded) |
*Geo-coded ONLY | |||
| Orthorectification | ||||
| Image quality corrections (noise reduction) |
||||
| Image quality corrections (dynamic range compression) |
||||
| Remarks | Single Look Complex (SLC) data and Interferometry (InSAR) processing. | Pixel spacing is selectable depending on observation modes. | Pixel spacing is selectable depending on observation modes. |
