Lombok Strait internal wave occurrence frequency derived from Sentinel-1A SAR images

Abstract

Internal wave is one phenomenon that plays an important role in the turbulent process and mixing in the ocean. One area that has been known as a source of internal wave generation is the Lombok Strait. The study of the internal wave characteristics in the Lombok Strait has been carried out using satellite data, radar sensor or Synthetic Aperture Radar (SAR). Although the internal wave parameter well extracted and described from SAR imagery, however, the information related to the frequency of occurrence and its temporal distribution remains unclear because of the limited spatial and temporal resolution of SAR data used in previous studies. The unprecedented availability of SAR C-band images provided by the Sentinel-1A constellation offers the opportunity to propose a new approach of internal wave occurrence frequency distribution in the Lombok Strait. In this work, 4-year consecutive period SAR images from Sentinel-1A satellite examined. Annual and monthly distribution of internal wave occurrence frequency in the Lombok Strait is discussed. It is found that the yearly distribution of SAR-observed internal wave occurrence frequencies varies each year with the maximum frequency of 33% in the year 2015, implying that large-scale processes changing the SAR observed internal wave occurrence. The monthly SAR observed internal wave occurrence frequencies show the monthly variability with the high frequencies are distributed from March to September with a maximum frequency of 55%. The low occurrence frequencies are distributed in October and February with a minimum frequency of 30%.