ALOS-4
Calibration and Validation
Calibration Result of ALOS-4/PALSAR-3 JAXA Standard Products
JAXA/EORC are regularly conducting the calibration and validation of the PALSAR-3 and its standard products using the data over the calibration sites in the world. This page reports evaluation results of the PALSAR-3 standard products and radiometric calibration factors to convert digital number to backscatter value.
ALOS-2/PALSAR-2 Evaluation results are here
https://www.eorc.jaxa.jp/ALOS/en/alos-2/a2_calval_e.htm
Update Information
Evaluation Results
Notes on the usage of PALSAR-3 standard product
- Explanation of PALSAR-3 images with variable PRF and fixed PRF (Update: Dec. 12,2025)
- Phase errors due to differences in the stored radar wavelength values between ALOS-2 and ALOS-4 datasets
- Announcement of deviation from orbit control window
- ALOS-4 has sometime deviate from nominal orbit control window (500m tube) due to "debris avoidance maneuver", "Influence of solar activity". If you use out of nominal orbit control window period data for interferometry analysis, please note for accuracy result decreased due to long Baseline distance than the normal observation. Please check History of ALOS-4 Orbit keeping range deviation from Nov 2024.
- PALSAR-3 Standard Product Information(Ver Mar. 2025)
Calibration factor
Digital number in the PALSAR-3 JAXA standard product is converted to backscattering coefficient (sigma naught, sigma zero) using the following equations:
(for L1.5, L2.1)
(for L1.1)
σ0: Backscattering coefficient (Sigma naught or Sigma zero) [unit: dB]
DN: Digital number (or raw pixel value)
CF1, A: Calibration factor [unit: dB]
| Calibration factor | Value [dB] |
|---|---|
| CF1 | -83.0 |
| A | 32.0 |
ALOS-4 Calibration/Validation and Science Team
The ALOS-4 CVST (Calibration/Validation and Science Team) will conduct the following research on calibration/validation of standard products and maintenance of validation data (calibration/validation) as one of the themes of the EORC Earth Observation Research Announcement.
- Methods of calibration, validation, and accuracy improvement for standard products
- Assessing accuracy and applicability of standard products from the initial Cal/Val phase to the beginning of the operational phase
- Development and sharing of high-level products and analysis tools for fundamental applications
- Experiment and demonstration using new features of ALOS-4 such as ionospheric correction mode, extended swath width, and frequent time-series data.
- Research and assessment on cross-calibration with other SAR satellites
- Research on new technology for future missions
| Name | Institution | Research Theme |
|---|---|---|
| Angel Matias Palomeque | CONAE | ALOS-4/PALSAR-3 external calibration and cross-validation with SAOCOM |
| Bernd Scheuchl | University of California, Irvine | Validation of ALOS-4/PALSAR-3 for glacier and ice sheet applications |
| Bruce Chapman | Jet Propulsion Laboratory, California Institute of Technology | Joint calibration activities between NISAR and ALOS-2/ALOS-4 |
| Cunren Liang | Peking University | InSAR algorithm development and product validation for ALOS-2 and ALOS-4 |
| Konstantinos Papathanassiou | German Aerospace Center | Polarimetric (PolSAR) and Polarimetric interferometric (Pol-InSAR) calibration of ALOS-4 data |
| Malin Johansson | UiT The Arctic University of Norway | Calibration and validation of ALOS-2/ALOS-4 for advanced sea ice and oil slick monitoring |
| Marc Thibeault | CONAE | Crops classification, soil moisture and polarimetry with ALOS-4 |
| Masanobu Shimada | Tokyo Denki University | Calibration and validation of PALSAR-3 |
| Ridha Touzi | Canada Centre for Remote Sensing | Calibration of Polarimetric ALOS-4/PALSAR-3 and validation for peatland and permafrost monitoring in Northern Canada |
| Ryo Natsuaki | University of Tokyo | Validation of PALSAR-3 and PALSAR-2 long-term interferometric analysis |
| Tomokazu Kobayashi | Geospatial Information Authority of Japan (GSI) | ALOS-4-based nationwide monitoring of ground deformation |
| Urs Wegmüller | Gamma Remote Sensing AG | ALOS-4 ionosphere correction and cross-sensor interferometry |
| Yohei Kinoshita | University of Tsukuba | Research and development of small displacement detection technique with time-series L-band SAR analysis and its accuracy improvement |