Validation of burst overlapping for ALOS-2 PALSAR-2 ScanSAR-ScanSAR interferometry

The Phased Array type L-band Synthetic Aperture Radar-2 (PALSAR-2) aboard the Advanced Land Observing Satellite2 (ALOS-2, " DAICHI-2") is the latest L-band spaceborne synthetic aperture radar (SAR). PALSAR-2 observes the world mainly with 10 m resolution /70 km swath Stripmap mode and 25 m resolution /350 km swath ScanSAR mode. The 3-m resolution Stripmap mode is mainly used upon Japan. The 350 km ScanSAR observation could detect large scale deformation e. g., the Mw 7.8 Gorkha, Nepal earthquake and its aftershocks in 2015. ALOS-2 ScanSAR is the first one that supports ScanSAR-ScanSAR interferometry in L-band spaceborne SAR. However, because of the parameter setting error for the orbit estimation, ALOS-2 PALSAR-2 ScanSAR could achieve little number of interferometric pair until the software modification on February 8, 2015. That is, the burst overlap timing required for the interferometric analysis was insufficient and it depends on the observation date. In this paper, we report the investigation results of this case and discuss the current status of the ALOS-2 ScanSAR InSAR. Some archives achieved before February 8, 2015 can be used for interferometric analysis with after Feb. 8. However, most of them have no interferometric pair, due to the burst overlap timing problem. We also report that the archives acquired after February 8, have enough burst overlapping.