Dataset

Global PALSAR-2/PALSAR/JERS-1 Mosaic and Forest/Non-Forest Map

1. Updates

Apr. 08, 2021
PALSAR-2 global mosaic map in 2020 was released.

Dataset description document has been updated (Ver. K).

Forest/non-forest information is not included in Year 2020 dataset, yet.
Mar. 31, 2021

PALSAR-2 global mosaic map in 2019 was released.

Dataset description document has been updated (Ver. J).

Forest/non-forest information is not included in Year 2019 dataset, yet.
Dec. 27, 2019

PALSAR-2 global mosaic map in 2018 is released.

Dataset description document has been updated (Ver. I).
Forest/non-forest information is not included in Year 2018 datasets, yet.
May. 07, 2018 PALSAR-2 global mosaic and forest/non-forest map (2017 global dataset, and low resolution dataset of 2015-2017) are released.
Dataset description document has been updated (Ver. H).
Apr. 27, 2018 Dataset description document has been updated (Ver. G).
Apr. 19, 2018 PALSAR-2 global mosaic and forest/non-forest map (2015 and 2016 dataset around Japan) are released.
Dataset description document has been updated (Ver. F).
Oct. 2, 2017 Dataset description document has been updated (Ver. E).
Jun. 20, 2017 Replaced 9 tiles of 2015 dataset. The replaced tiles are as follows:
N16E145,N16E146,N17E145,N17E146,N18E145,N18E146,N19E145,N19E146,N20E145
May. 24, 2017 About data utilization has been added.
Apr. 27, 2017: PALSAR-2 global mosaic and forest/non-forest map in 2016 are released. Reprocessed version of PALSAR-2 global mosaic and forest/non-forest map in 2015 are released. Dataset description document has been updated (Ver.D).
* The data around Japan will be available in the near future.
Jan. 11, 2017 JERS-1 SAR yearly mosaic for tropical regions from 1993 to 1998 are released. Dataset description document has been updated (Ver. C).
Oct. 31, 2016 JERS-1 SAR global mosaic in 1996 are released. Dataset description document has been updated (Ver. B).
May. 10, 2016 Dataset description document has been updated (Ver. A).
Apr. 6, 2016 (Correction) of a figure 1 used in [Global 25m Resolution PALSAR-2/PALSAR Mosaic and Forest/Non-Forest Map]
Mar. 28, 2016 PALSAR-2 global mosaic and forest/non-forest map for Japan in 2015 are released.
Mar. 28, 2016 Low resolution forest/non-forest maps (0.25 degrees and 1km) are released.
Jan. 25, 2016 PALSAR-2 global mosaic and forest/non-forest map in 2015.
* Data for Japan (using polarimetry mode) will be available soon.
Jan. 16, 2014 PALSAR global mosaic and forest/non-forest map in 2007, 2008, 2009 and 2010.

2. Overview

Global 25m resolutions PALSAR-2/PALSAR mosaic and forest/non-forest map are free and open dataset generated by applying JAXA's powerful processing and sophisticated analysis method/techniques to a lot of images obtained with Japanese L-band Synthetic Aperture Radars (PALSAR and PALSAR-2) on Advanced Land Observing Satellite (ALOS) and Advanced Land Observing Satellite-2 (ALOS-2).

For understanding and responding to global environmental changes such as global warming and loss of biodiversity, timely assessment of deforestation and forest degradation is essential. Global monitoring with satellite remote sensing is one of the most effective approaches to detect land surface changes because satellites can provide wall-to-wall images covering wide areas periodically. L-band Synthetic Aperture Radars (SAR) on ALOS and ALOS-2 can observe the land surface even under clouds, and therefore the L-band SAR data have been providing useful information about forest changes in tropical region.

The global 25m resolutions PALSAR/PALSAR-2 mosaic is a global SAR image created by mosaicking the SAR images in backscattering coefficients measured by PALSAR/PALSAR-2. Correction of geometric distortion specific to SAR (ortho-rectification) and topographic effects on image intensity (slope correction) are applied to make forest classification easy. The size of one pixel is approximately 25 meters by 25 meters. The temporal interval of the mosaic is generally 1 year. Global 25m resolution JERS-1 (Japanese Earth Resources Satellite-1) SAR mosaic dataset has been added since October 31, 2016. The original data of the mosaic were mainly acquired in 1996. The mosaic was generated with the same method as the PALSAR-2/PALSAR mosaic.


From the 2019 product, the following changes have been made to the processing method and output format compared to the products before 2018;

  • Use GDAL for mosaicking process to improve the absolute geometric accuracy and processing speed.
  • Balancing of backscatter intensity between neighboring paths are not applied when mosaicking the SAR images. SAR intensity value itself after applying orthorectification and slope correction are stored.
  • Products after 2019 are in compliance with CARD4L (CEOS Analysis Ready Data for Land) specifications (under reviewing). Data format changed from binary image file + header file to GeoTiff + XML metadata.
  • Annual data are only used for mosaicking and not used past year’s data for filling gaps.

Due to the above changes, the following phenomena may appear when compared with products before 2018;

  • The color of the mosaic images sometimes differs from path to path, which is due to the change of backscattering intensity caused by change of land cover or soil moisture.
  • Due to the geometric accuracy improvement, misalignment between the published images may occur.

In the future, we plan to reprocess the past data according to this new product format. For details of the changes, please see to the dataset description document.

The global forest/non-forest map (FNF) is generated by classifying the backscattering intensity values in the global 25m resolution PALSAR-2/PALSAR mosaic so that strong and low backscatter in HV-polarization are classified "forest" (colored in green) and "non-forest" (colored in yellow), respectively. Here, the "forest" is defined as the tree covered land with the area larger than 0.5 ha and canopy cover over 10 %, as same to the FAO definition. Since the radar backscatter from the forest depends on the region (climate zone), the classification of Forest/Non-forest is conducted by using the region dependent threshold of backscatter. The classification accuracy is more than 84% according to the comparison with reference data such as in-situ photos and high-resolution optical satellite images. Figure 1 and Figure 2 illustrate global mosaic images and an example of Borneo island.
JAXA plans to update the FNF classification algorithm to improve the accuracy. Please let us know if there are comments or requests for the dataset.

Figure 1: (Left top) PALSAR global mosaic in 2009, (right top) PALSAR forest/non-forest map in 2009
(left bottom) PALSAR-2 global mosaic in 2015, and (right bottom) PALSAR-2 forest/non-forest map in 2015.

Figure 2: Deforestation (red colored areas in the map) in Borneo island during 2010 to 2015.

3. Dataset description

  • SAR processing algorithm:
    • Product up to 2018: Sigma-SAR IMAGE (for orthorectification) and Sigma-SAR MOSAIC (for mosaicking)
    • Product after 2019: Sigma-SAR IMAGE (for orthorectification) and GDAL (for mosaicking)
  • Data format:
    • Product up to 2018: binary image file + header file
    • Product after 2019: Geotiff + XML metadata (in compliance with CARD4L (CEOS Analysis Ready Data for Land) specifications)
  • Resolution: approx. 25 m (original product), 100 m/1 km/0.25 deg. (low resolution product, only forest/non-forest map)
  • Contents: ortho and slope corrected backscattering coefficient (HH and HV polarization), forest/non-forest map, observation date, local incidence angle, processing mask information

For details, please see the dataset description document (Ver. K, PDFfile, 476KB).

4. Download

Please register your information from following URL to download the dataset. It is required your email address.

https://www.eorc.jaxa.jp/ALOS/en/palsar_fnf/registration.htm

This is temporally registration (especially please check your email address again) and will send email you to accept your registration request. After the confirmation of your request, the download information will send by email.
The dataset download site is

https://www.eorc.jaxa.jp/ALOS/en/palsar_fnf/data/index.htm

* If you forget your password, please register again.
* Recommend to use Microsoft Edge, Google Chrome, Mozilla Firefox, Apple Safari.
   However, it may not be available depending on the version.
* Depending on your network environment, the downloaded compressed file may be automatically uncompressed.
* Depending on the time, it may take time to display the page or download the dataset.

5. About data utilization

  • About decompression of data

After login to the download page, clicking on the location of necessary data from the map on the screen display makes it possible to download in latitude / longitude 1 × 1 degree tile or 5 × 5 degree unit.
The downloaded file is compressed into one file by tar.gz and software may be necessary for this decompression. For example, 7-Zip is available as free software.


  • Displaying and using data

Software such as image processing, remote sensing, GIS, etc. is required for display and use of "Global PALSAR-2/PALSAR/JERS-1 Mosaic and Forest/Non-Forest map".
You can use software released free of charge, for example,

QGIS

It is widely used software for the general public.

Please note that the free software introduced here is only an example, and it is not necessarily guaranteed by JAXA. Please understand that JAXA can not answer any questions about software.
Please refer to these and use "Global PALSAR-2/PALSAR/JERS-1 Mosaic and Forest/Non-Forest map".

6. Note for data use

This dataset is available to use with no charge under the "Terms for Use".
To publish images using the dataset as it is, please display "©JAXA" in the image.

7. Contact

ALOS-2/ALOS Science Project

Earth Observation Research Center (EORC)

Japan Aerospace Exploration Agency (JAXA)

E-mail: aprojectjaxa.jp

Please refer to FAQ before sending email.
Please contact us in English or Japanese.

8. References

9. Old Version

  • PALSAR 10m Mosaic Data
    PALSAR mosaic dataset with 10m spatial resolution.
    • 1) Porto Velho, Rondonia, Brazil
    • 2) Riau, Indonesia
    • 3) Congo River