Study On Marine Performance Evaluation Method Of Shipborne Sea Surface Radiometer

The sea surface skin temperature is one of the most important parameters on the air-sea interface.It is a global climate thermometer and plays an irreplaceable role in environmental science,agriculture and fisheries,energy development and even the military.At home and abroad,satellite remote sensing measurement is widely used to obtain a wide range of sea surface skin temperature,but it is greatly affected by the environment.Therefore,it is necessary to modify the measurement results with shipborne measurement data.At present,people pay more and more attention to the temperature measurement performance of shipborne radiometers,therefore,the perfect sea surface temperature evaluation method is indispensable.First of all,based on the vertical structure of the sea surface temperature and the advantages and disadvantages of the contact measurement and the non-contact measurement,this paper proposed the use of high-precision contact sensors to evaluate the temperature performance of shipborne radiometers.According to the current contact sensor technology,it measured the sea surface bulk temperature rather than accurate sea surface temperature.Therefore,the need to use contact temperature measurement equipment to evaluate shipboard radiometer temperature performance at sea,the contact sensor data must be processed before use as a comparison benchmark.In order to obtain the true sea surface skin temperature,a method based on the sea surface skin temperature model and the warm layer model is proposed,which can calculate the temperature difference between sea surface skin temperature and bulk temperature.In this way,the sea surface bulk temperature measured by the contact sensor can be converted into sea surface skin temperature,and then the temperature measurement performance of the shipborne radiometer can be evaluated.Secondly,determine the parameters in the evaluation model.The sea surface skin temperature model and the warm layer model in the evaluation model all need to calculate the heat flux at ocean-air interface.By analyzing the defects of the ocean-air interface heat flux calculated by the current bulk parameter method.Then,the neural network algorithm in solving the non-linear mapping superiority is used to calculate the heat flux and improve the calculation accuracy of the evaluation model.The selection of the empirical coefficients in the sea surface skin temperature model is optimized,and different values are taken under different wind speed conditions according to field tests.The deviation between the sea surface skin temperature calculated by the model and measured at the field can be reduced,so that the model precision is higher.At last,the accuracy of the model is verified through field experiments and the temperature measuring performance of the radiometer is evaluated.The temperature of all layers in the sea surface should be fully homogenized by means of a sea mixing device so as to eliminate the temperature gradient produced by each layer in the sea surface.Under the open mixing device,the sea surface bulk temperature measured by the CTD was converted to the sea surface skin temperature by the evaluation model and compared with the real sea surface temperature measured by the quartz thermometer.The results show that the proposed method is accurate and can be used to evaluate the temperature performance of the radiometer.The evaluation results show that the temperature measurement performance of the shipborne radiometer is better than 0.3K.