To accurately achieve side scan sonar (SSS) image target detection, a novel target detection algorithm based on a neutrosophic set (NS) and diffusion maps (DMs) is proposed in this paper. Firstly, the neutrosophic subset images were obtained by transforming the input SSS image into the NS domain. Secondly, the shadowed areas of the SSS image were detected using the single gray value threshold method before the diffusion map was calculated. Lastly, based on the diffusion map, the target areas were detected using the improved target scoring equation defined by the diffusion distance and texture feature. The experiments using SSS images of single clear and unclear targets, with or without shadowed areas, showed that the algorithm accurately detects targets. Experiments using SSS images of multiple targets, with or without shadowed areas, showed that no false or missing detections occurred. The target areas were also accurately detected in SSS images with complex features such as sand wave terrain. The accuracy and effectiveness of the proposed algorithm were assessed.

Two phytoplankton blooms triggered by the tropical cyclone (TC) Hibaru were studied in the Bay of Bengal. Hibaru occurred in southeastern Sri Lanka in January 2005. After the passage of Hibaru, two strong phytoplankton blooms appeared in the study area (3.5° N-6° N, 83.5° E-88.5° E). In this study, the dynamic mechanisms were investigated with remote sensing, multisource reanalysis products and Argo float data. The first bloom on January 19 to 20 was induced by upwelling with the upper cyclonic eddy and mixed entrainment caused by Hibaru, where the maximum chlorophyll a (Chl-a) concentration was 0.235 mg•m–3. Sea surface cooling and heavy rainfall also occurred. The second bloom from January 27 to 28 was triggered by the interaction of the upper cyclonic eddy and submarine anticyclonic eddy after the passage of Hibaru, where the maximum of the Chl-a concentration was 0.124 mg•m–3. With the submarine anticyclonic eddy and weakened barrier layer thickness (BLT), the subsurface horizontally converged chlorophyll and nutrient water was uplifted with upwelling. This study contributes to the assessment of the ecological impact of ocean eddies during the passage of TC in the Bay of Bengal.

This chapter presents a new application of scanning interferometric synthetic aperture radar (ScanSAR) interferometry in monitoring land surface deformation caused by large earthquakes. To make better use of the ScanSAR data and obtain a wider deformation observation, this research studied and analyzed certain key elements of ScanSAR interferometry, including coherence, co-registering, methods of removing orbit errors, correction of atmosphere effects, and geoid undulation. The wide swath mode (WSM) is also known as the ScanSAR mode by which synthetic aperture time is shared by adjacent sub-swaths and azimuth resolution that is traded off for a wider coverage. So, it is possible to monitor a larger area of earthquake deformation. In this study, we obtained ScanSAR and Image Mode (IM) data and analyzed coherence, co-registering, methods of removing orbit errors, correction of atmosphere effects, and geoid undulation to monitor land surface deformation caused by large earthquakes in the 405 × 405 km field of the Wenchuan earthquake and Yutian earthquake, respectively, in China. The results obtained agree well with that of the investigations of the crustal motion in the study areas.