The ability of islands to modulate the temperature of the marine current field has important implications for marine habitat use, especially for the behavior of marine organisms during summer heat waves. The influence of islands on the temperature field is usually studied in large-scale space by remote sensing and assimilation modeling. In this paper, we carried out in-situ observations in small-scale space, and measured the dynamical and environmental parameters (including flow velocity, temperature and salinity, chlorophyll and turbidity) at the range of the wake influence zone of the Dajin Island in the Huangmao Sea, west of the Pearl River Estuary. The results of the analysis indicate that the water column temperature was strongly stratified during the observation period, with surface and bottom temperatures ranging from 34 degrees to 22 degrees Celsius. The flow near the island wake recirculation zone and the vortex area exhibits strong three-dimensional characteristics with high mixing intensity, with cold bottom water being mixed into the upper layers and low temperatures in the mid-surface layer. The tidal flood and ebb flow lead to a north-south shift in the spatial and temporal distribution of the wake. Since there are bays and headlands along the island shoreline, a recirculation zone and a low-temperature area are also formed in the northern part of the island during the ebb tide. Dajin Island is part of the Taishan Chinese White Dolphin Nature Reserve, and the location and time of the white dolphin's appearance coincide with the location and time of the low-temperature zone, indicating that the temperature modulation of the island wake has an important influence on the selection of the Chinese white dolphin's habitat, and that the influence of the island wake should be taken into account in the delineation of the protected area.
 

island wake,Pearl River estuary,in-situ observation,boundary layer separation,Chinese white dolphin