Wavelet Processing And Analysis Of In-situ Observation Data On Its Periodicity Of Hydrothermal Vents On The Seafloor Of Kueishan Island

At present, most of hydrothermal activity areas are known at deep sea. Research on deep sea hydrothermal activity started earlier and the study was thoroughly compared with shallow sea. However, the location of shallow water eruption is close to people’s living environment; the affect of human activity is not avoided. Component of hydrothermal eruption and physical and chemical properties are different with deep sea hydrothermal liquid. There was not much study on correlation between hydrothermal temperature of shallow sea and tidal periodicity, and the effect of related pressure caused by tidal on hydrothermal vent of shallow sea is more previously.As is known to all, in situ observation data is not easy to get due to the complicated environment of sea floor, manufactured various kinds of survey sensor which can work in hydrothermal environment seems extremely important to hydrothermal research. In our job, the temperature series sensors we used in our job were independent research, the temperature measurement probe is made of Pt100sheathed thermocouple, pressure was measured by pressure transmitter, after magnifying and filter processing, the simulation signal outputted by sensors was transformed to digital signal, together with clock saved in a chip of flash. Using series sensors could make sure that the survey still making once a sensor stops working by accident.From May25to30,2011, a joint research was taken on the hydrothermal vents on the seafloor of Kueishan Island, and a series of sensors were located at a White Spring vent (24.83419N;121.96198E), which lies close to Kueishan Island, to the northeast of Taiwan Island, hundreds of thousands of sets data was got, both temperature and pressure show certain periodicity.In situ observation data were processed with Morlet Wavelet. Wavelet coefficients of temperature and pressure were calculated and variation periodicities of the two factors with time were extracted. The results showed that the characteristic of local tidal were both semi-diurnal periodicity and diurnal periodicity. The periodicity of temperature was inconsistent with the periodicity of pressure, which was explained as there had the same internal cause between strength of hydrothermal eruption and the fluctuation of sea water, but different response to the external gravitational the hydrothermal and the sea water.