Analysis Of The Structure Of Ocean Vertical Modes In The North Pacific Through Argo Profile Data

The ocean vertical mode structures in the North Pacific (10°～40°N) have been analyzed through the most updated Argo profile data of temperature and salinity. The analysis shows the real vertical mode structures in the ocean. Combined with the Levitus98 climatology data, the relative importance of various vertical modes has also been presented. The results show the dominant vertical modes in different ocean regions at different times, and the distribution patterns of these vertical modes. The analysis of the first and second baroclinic vertical modes structure features, their respective controlling areas and the effects of North Pacific Subtropical Mode Waters (STMW)on the ocean vertical modes structures are preferably analyzed in this paper.The analysis of the effective Argo profile data in the North Pacific(10°～40°N) shows that the wave signal in the western part of the North Pacific is much stronger than that in the eastern part, validating the previous research conclusions from altimeter data. The analysis of the vertical modes structures of these strong signal profiles exhibits that the presence of ocean vertical stratification makes the ocean vertical mode structure deviate from the normal sine or cosine waves. The results of the analysis of the relative importance of various vertical modes shows that in most areas of the Subtropical North Pacific, the first baroclinic modes are predominant, which is consistent with the distribution of sea surface height anomaly through the TOPEX/POSEIDON altimeter data; while in the recirculation area south of Kuroshio Extension, the second baroclinic vertical modes become dominant, which is considered to be closely related to the formation and distribution of mode water there.The ocean vertical modes structures in the North Pacific (10°～40°N) during each month throughout 2004 have been thoroughly analyzed using all effective Argo profile data within each month. The results show that the first baroclinic vertical mode movement is significant in most of the research areas, while the controlled areas of the second baroclinic vertical mode are mainly focused in the recirculation area south of the Kuroshio Extension, which is consistent with the results through the analysis of strong wave signal profile. In order to specify the relationship between the second baroclinic vertical modes and the STMW, the main formation area of the STMW in the year 2004 is examined. It shows that the recirculation area south of Kuroshio Extension coincides well with the formation area of STMW for the year 2004, which to some extent testifies what we propose as the second baroclinic vertical modes are closely related to the subduction of STMW and gives a support to the correctness of the results with only analyzing the strong wave signal profile. Although the second baroclinic vertical mode controls the main formation area of STMW, the range of this controlled area varies with time. At the same time, the analysis also shows that in some regions, especially in the mid and high latitudes, the barotropic vertical modes also exhibit strong signal and become dominant.By using the Argo temperature and salinity profile data and its time series, the paper examines the ocean vertical structure in the main formation area of STMW(140°～155°E,30°～35°N)through the year 2004～2006 and analyzes the evolution of the dominant vertical modes in this area. The results show that this region is mainly controlled under the second baroclinic vertical modes, validating the previous results in this paper. However, the range of the controlled area indeed varies as time goes, but invariably focuses on the center of the formation area of STMW. Near the boundary of STMW formation area, or somewhat distant to the center of the STMW formation area, the barotropic vertical modes are evidently dominant. The first baroclinic vertical modes also present its dominance in some other regions. Although the whole research area is considered to be the main formation area of STMW, it does not mean every point in this region is under the second baroclinic vertical modes'control, which is thought to be related with the intensity, thickness and the water properties of STMW. Of course, this proposal needs further analysis and certification.The creative aspects of this research are shown as follows:By using the most updated Argo temperature and salinity profile data featured as high quality, high resolution, and broad coverage, the paper successfully examines the ocean vertical modes structures, getting the new way to study the ocean vertical movements. It also reproduces the real ocean vertical modes structures through the observational data. With the combination of Levitus98 climatology data, the relative importance of various vertical modes is also presented, showing the dominant vertical modes in various ocean regions and at varied times. Besides, it also provides the distribution patterns of various vertical modes with special attention to the first and the second baroclinic vertical modes. The results of the analysis through observational data validate the theoretical improvements very well and it also brings forward new challenges.