Research On Evaluation Method Of CTD Performance Test Based On Underwater Platform

Underwater platform CTD is a kind of conductivity-temperature-depth profiler based on underwater observation platform,used for long-term continuous observation of hydrological information changes of seawater temperature,salinity and depth.As the "sense organ" of the ocean,CTD can be used to derive the salinity,density and sound velocity of the seawater by using the depth,temperature and conductivity,which can reflect the physical characteristics of the ocean,and provid the most basic prerequisite for marine exploration and scientific research.In view of the problems that China's existing supporting observation system construction and innovation research are insufficient for the evaluation capability of CTD performance test,and CTD performance test evaluation method is single,limitation and confused,this paper proposed CTD performance test evaluation method system based on underwater platform by using OSM(Objective-Strategy-Measurement)model and AHP(Analytical Hieracrchy Process)method considering different observations ways of underwter platform CTD and the variation characteristics of temperature and salinity hydrological parameters.To begin with,by combing the CTD business application process:laboratory verification?marine test,the corresponding performance evaluation method was established from two aspects of static characteristics and marine application characteristics(accuracy,stability and reliability in actual marine application).Then taking into account the different background fields of sea trials,the AHP scoring rules and the technical specifications of deep water stable layers were respectively used to establish the evaluation criteria for CTD horizontal and vertical comparison,to realize the comprehensive and objective evaluation of CTD.The application results of underwater platform CTD performance evaluation system showed that the same batch of CTD had good measurement accuracy,stability and reliability in Chudao Island sea area of Weihai city;and the domestic CTD for underwater glider had good measurement accuracy and reliability,but the consistency of multi-profile long-term measurement was poor,mainly beause that the 1000 m shallow sea test in the South China Sea was the first time for glider CTD to carray out marine application evaluation trial,and the long-term stability technology is still in the immature stage,which needs further to be optimized and improved.