PALSAR-2:Phased Array type L-band Synthetic Aperture Radar

Scheme of 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

The most detailed observation mode with 1 by 3 meters resolution (observation width of 25 km)

◆Strip Map mode

A high-resolution mode with the choice of 3, 6 or 10 meters resolution (observation width of 50 or 70km)

◆ScanSAR mode

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

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)

*1:The values are defined as those in single look processing and at the incidence angle 37 deg.

PALSAR-2 Specifications
Observation Mode Stripmap * Full (Quad.) Polarimetry *
[3m] [6m] [10m] [6m] [10m]
Obs. Mode ID(code) UBS/UBD HBS/HSD FBS/FBD HBQ FBQ
Width(East-West)
(Length of Range Direction)
55km
(max)
55km
(max)
70km
(max)
40-50km 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 9.1m 5.1m 8.7m
Azimuth Resolution*1 3.0m 4.3m 5.3m 4.3m 5.3m
Pixel Spacing
Levels 1.5/3.1
2.5m 3.125m 6.25m
(2look)
3.125m 6.25m
(2look)
Pixel Spacing
Level 2.1
2.5m/5.0m
/10.0m
3.125m/6.25m
/12.5m
6.25m
/12.5m
3.125m/6.25m
/12.5m
6.25m
/12.5m
Polarization Single(HH, HV, VH, or VV)
Dual(HH+HV or VH+VV)
Full (Quad.) Polarimetry
(HH+HV+VH+VV)

*Stripmap and Full (Quad.) Polarimetry modes define category names by resolution: Ultra-Fine(3m), High-sensitive(6m), Fine(10m)

■PALSAR-2 Product Data Size(Volume) by Processing Levels

PALSAR-2 Product Data Size(GBytes)
Observation Mode Spot
light
Stripmap * Full (Quad.) Polarimetry * ScanSAR
3m 6m 10m 6m 10m 350km 490km
Method 1 Method 2 Method 1 Method 2
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.

Geo-referenced

Map projection based on satellite along track direction

Geo-referenced

Geo-coded

Map projection based on north-oriented map direction

Geo-coded

■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 Yes Yes Yes Yes
Range compressed Yes Yes Yes Yes
Single look azimuth compressed Yes Yes
Multi-look azimuth compressed Yes Yes
Phase data Yes
Amplituide data Yes Yes Yes
Map projection
(Georeferenced or Geo-coded)
Yes Yes
*Geo-coded ONLY
Yes
Orthorectification Yes
Image quality corrections
(noise reduction)
Yes
Image quality corrections
(dynamic range compression)
Yes
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.

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Contact information : order@alos-pasco.com

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Copy right of images used in this website is as follows.

ALOS-2(PALSAR-2),ALOS(PRISM and AVNIR-2): JAXA

ALOS(PALSAR): METI and JAXA