Takeshi Motooka

Generation of 10m resolution PALSAR and JERS-SAR mosaic and forest/non-forest maps for forest carbon tracking

The Japan Aerospace Exploration Agency (JAXA) has produced the worlds first 10m resolution L-band SAR global mosaic datasets. These data sets were generated to monitor forest changes from the 1990s to present. SRTM-3 (90m resolution) DEM was used to correct the terrain-induced SAR intensity variations and the ortho-rectification. Both corrections were applied for geometric and radiometric calibration purposes. The data sets are useful to monitor the temporal forest cover and forest change, and were used to derive forest/non-forest information.

PALSAR-2 polarimetric performance and the simulation study using the PI-SAR-L2

This paper describes the performance, calibration method, and observation scenarios for the ALOS-2/PALSAR-2 polarimetry mode. It also describes simulation studies conducted using data from Pi-SAR-L2, JAXAs L-band airborne SAR, for calibration and application studies.

Generation of the first PALSAR-2 global mosaic 2014/2015 and change detection between 2007 and 2015 using the PALSAR and PALSAR-2

Decreasing the carbon emission from the deforestation and forest degradation is one of the issues that the humans need to tag for sustaining the Earth. Monitoring the forest from the space is the recent achievements that the space agencies contribute. Measuring the forest cover change is being conducted by using the high resolution optical and/or SAR images. ALOS-2 has been on-orbit carrying the L-band SAR since May 24, 2014. After more than one year data acquisition and related processing, the first version of the 25-m resolution global PALSAR-2 mosaic dataset from the 2014-2015 acquisitions, forest-non-forest map, and the forest cover change from 2007 to 2015 were generated.

Subsidence estimation of the peatland forest in the central Kalimantan using the PALSAR time series differential interferometry

The spatiotemporal distribution of subsidence at Palangkaraya, Central Kalimantan, Indonesia, was studied by a time-series analysis of PALSAR data obtained over 26 passes of ALOS over the study area. This area consists mainly of peatland and tends to subside because of climate change, i.e., global warming. Applying a moving weighted window to the stacking of a DinSAR dataset, each of which was calibrated using stable points in the image, we quantitatively captured subsidence phenomena and found that the area has subsided at an average rate of 2.02 cm/yr.

Regenerated ALOS-2/PALSAR-2 global mosaics 2016 and 2014/2015 for forest observations

ALOS-2/PALSAR-2 25-m spaced global mosaic has been produced as the L-band SAR forest monitoring dataset selected from the best acquisitions over the global land and year 2014 and 2015, as the resume of the dataset after pausing the ALOS/PALSAR on 2011 April 22, in the end of 2015. Detailed evaluation results showed some image degradations compared to ALOS/PALSAR: visible stripes across the neighboring strips. The possible causes are 1) less overlapping area between two neighboring strips and needs careful area selection for the radiometric balancing, and 2) antenna elevation pattern needed some more calibration. These two points were well recovered as the recalibration processing in 2016. We are creating the new version of the mosaic as of now. In this paper, we will describe the details of recalibrated and regenerated PALSAR-2 mosaic products for 2014/2015 and 2016 using the improved radiometric calibration algorithm.

Accuracy improvement by residue and amplitude based local co-registration method for ALOS-2/PALSAR-2 DInSAR

In the field of Synthetic Aperture Radar (SAR) interferometry, we generally expect that there is only unique dominant scatterer in one pixel. To make a SAR interferogram, we have to observe a place twice. The dominant scatterer in every pixel must be identical in those observations. However, in an actual situation, there are multiple scatterers in one pixel physically, and the dominant one may be changed in the two observations. Slight difference of incident angle may cause the change of the dominant scatterer and the propagation path. The change can generate singular points (SPs) in the inter-ferogram which prevent us from accurate phase unwrapping. Here, we present experimental results in an anechoic chamber which show the mechanism of the singular point generation.