Reconstruction Of 3D Temperature Field Based On Profile Data And Sea Surface Information

The main sources of the profile data are some buoys such as Argo,CTD and XBT.Due to the floating characteristics of the buoy with seawater and the location of the observation point of the measuring instrument is only for a specific marine phenomenon,so temperature observation profile is irregular distributed in time and space,this feature makes the basic research of profile data in marine science and other fields and the application of commercialization have great limitations.Therefore,through the objective analysis method,the profile data is processed to form scientific,reasonable and convenient three-dimensional gridded data.In this paper,an objective analysis method based on temperature gradient and sea surface temperature information will be used to reconstruct the initial temperature field of the three-dimensional grid.When objectively analyzing the profile data,first establish a fitting model of the temperature change with depth,fit the mean value of the RMSE of 0.15?,convert the temperature change process into a temperature gradient change process,and generate temperature gradient grid field from the temperature gradient profile,the sea surface temperature is used as the initial value of the temperature gradient integration,thereby constructing a three-dimensional grid temperature initial field.In order to improve the accuracy of the three-dimensional temperature field,the sea surface height information is used to correct the under surface temperature field.By establishing a mapping relationship between the sea surface height and the lower temperature,the regression coefficient between the two can be obtained.The height information is reflected inside the ocean,and the final three-dimensional grid temperature analysis field is obtained.Based on the analysis of the results of the selected test area,the RMSE with the existing three-dimensional grid temperature data are 0.80?(EN4)and 0.92?(BOA),respectively,and the RMSE is reduced by 0.10? compared with the initial temperature field.The correlation coefficient is increased by 0.05,and the accuracy at different depths is improved.Through the objective analysis method based on temperature gradient and sea surface information,the temperature profile data was used to construct a monthly average threedimensional gridded temperature field in the Northwest Pacific(120°E-180°E,0°-40°N)region from January 2004 to December 2017,The horizontal resolution is 0.5°×0.5°,the vertical depth range is 5-700 m,divided into 52 layers.Error analysis was carried out with the original temperature profile,the existing three-dimensional grid temperature data set(BOA,EN4)and the field observation data(TAO).The RMSEs of the original temperature profile is less than 0.36?,and the correlation coefficients are all greater than 0.97.At a confidence level of 0.01,the credibility above 500 m is more than 55%.The temperature at different depths is compared with the existing data set,the correlation coefficients are all over 0.8,and the error of the 5m layer is the smallest,and the error of the 150 m layer is the largest.Compared with the TAO data,the RMSEs at the depth of 100-200 m exceeds 1.0?,and the temperature deviation at other depths is less than 0.5?.This shows that the constructed threedimensional grid temperature analysis field(ORT)is consistent with the measured data.Finally,the three-dimensional grid temperature analysis field was used to analyze the temperature distribution characteristics and changes in the Northwest Pacific region,which was consistent with the conclusions obtained by the predecessors using historical temperature data analysis.The results show that the constructed monthly temperature analysis field of the threedimensional grid of the Northwest Pacific is credible,compared with the existing temperature data sets,it has more mesoscale signals,which makes it possible to study the complex temperature structure of underwater.And,with the continuous accumulation of profile data,the constructed grid temperature analysis field can also be used as the initial field of the ocean model to improve the simulation accuracy.