Three-dimensional Temperature And Salinity Reconstruction Method Of Ocean Eddies Based On Multi-source Data

As an important physical process in the ocean,the three-dimensional structure of mesoscale eddy has attracted more and more scholars’ attention.Mesoscale eddy can affect circulation,temperature and salt distribution,and then affect the marine environment.Therefore,it is very important to study mesoscale eddy for understanding the ocean.Sea surface salinity(SSS),as an important physical quantity to study ocean changes and mesoscale eddy structure,is of great significance to the marine ecological environment and sustainable development of the ocean.Due to frequent air-sea activities such as monsoons and circulation,the western Pacific has become a key area affecting short-term climate anomalies in my country.To this end,the inversion of sea surface salinity and the analysis of sea surface characteristics have been carried out in the Western Pacific.With the increasing demand for scientific research and development,on-site observations of sea surface salinity alone are far from enough in time and space,and on-site observations cannot capture smaller-scale spatiotemporal changes.Therefore,there is an urgent need to find new methods and techniques to obtain sea surface salinity.In fact,satellite remote sensing technology can meet the requirements of large-scale continuous observation and smaller-scale spatiotemporal changes,and higher spatial coverage and resolution can be achieved through satellites.In this study,using the brightness temperature data observed by the L-band microwave radiometer of the remote sensing satellite,and considering the influence of wind,wave and other factors,a newton’s method-based sea surface salinity inversion model was established,and the inversion salinity was compared with Argo salinity.comparing.On this basis,combined with the WOA2018 climate temperature and salinity data for many years and the inversion data of sea surface salinity,sea surface temperature and sea surface height,the three-dimensional temperature and salt field was reconstructed,and then the Argo observation profile data was used to test the three-dimensional The reliability and validity of the thermo-salt field,and the structural characteristics of the mesoscale eddy below the sea surface are characterized by the structural characteristics and changes of the three-dimensional thermo-salt field.In order to better understand the structural characteristics of the mesoscale eddies below the sea surface,the WOA2018 temperature and salinity profile data in the western Pacific Ocean was interpolated to form the standard climate temperature and salinity data required for the experiment,and the regression statistical analysis method was used to construct a empirical regression model of sea surface temperature anomaly and sea surface height anomaly was combined to construct a three-dimensional temperature profile,and then the three-dimensional temperature field of the region was reconstructed using satellite remote sensing sea surface temperature and SSH data.In addition,an empirical regression model of salinity was established by the same method,and the traditional method was improved by adding constraints such as inversion of sea surface salinity and sea surface temperature into the model,and reconstructed the three-dimensional salt in this area.degree field.The main results are as follows:(1)An effective method for inversion of sea surface salinity is established.The average deviation of the retrieved sea surface salinity is between 0.115 and 0.167,of which the average deviation in September is the smallest;the root mean square error is between 0.134 and 0.195,and the standard deviation is between 0.127 and 0.177.It can be seen that the salinity data of the two tend to be consistent.The results verify the validity of the salinity inversion model based on Newton’s method.In order to further verify the validity of the inversion results,compared with the SMAP salinity products,it was found that the inversion results were smaller than the SMAP salinity data in terms of root mean square error and standard deviation,and the correlation was more significant.From the inversion results,the sea surface salinity and Argo salinity in the0°N～5°N sea area have a large deviation,which is not only related to the radio frequency interference of the nearby islands,but also affected by the large precipitation.(2)Combined with remote sensing satellite sea surface temperature data,a two-dimensional temperature and salinity field in the western Pacific Ocean was constructed.Judging from the spatial distribution of the two-dimensional temperature-salt field in the western Pacific,it has obvious geographical features of latitudinal distribution.With the increase of latitude,the sea surface salinity first decreased and then increased gradually,showing an overall upward trend.Sea surface salinity is relatively high because evaporation is higher than precipitation in subtropical seas.In addition,the distribution of sea surface temperature gradually decreases from low latitude to high latitude.(3)Based on the improvement of the traditional method,the three-dimensional temperature and salt field is reconstructed.Through the comparative study with the measured profile data of the western Pacific Argo,the results show that the error of the reconstructed three-dimensional temperature field of the ocean surface temperature is about 0.2～0.6℃,and the error of the temperature in the thermocline is 0.4～0.8,and the temperature error below 500 m is not more than0.2.The error of ocean surface salinity in the reconstructed three-dimensional salinity field is about0.1-0.15 psu,and the change at each depth is not as obvious as that of temperature.From the perspective of different months,compared with the traditional method,the accuracy of the reconstructed three-dimensional salinity field in this experiment is improved by 0.08～0.108 psu,and the closer it is to the sea surface,the more obvious the improvement is.(4)Combined with the eddy data,the three-dimensional temperature and salt field of the eddy was reconstructed.Under the influence of the cold eddy,the temperature value in the vertical direction within the observation range decreased significantly,and the salinity change showed a trend of increasing first and then decreasing.The reconstructed eddy 3D temperature profile and the Argo temperature profile tend to be consistent in vertical distribution.The reconstructed eddy3 D temperature profile near the eddy center is slightly higher than the Argo temperature profile.The reconstructed eddy 3D salinity profile is slightly higher than the Argo temperature profile.and the Argo salinity profile error does not exceed 0.1.The experimental results clearly reflect the vertical structure and mesoscale eddy characteristics of the eddy 3D temperature-salt profile,and accurately demonstrate the structural characteristics of the 3D temperature-salt field under the influence of the cold eddy.The thesis has 33 figures,7 tables,and 71 references.