New Results on Joint Classification of Vertical Structure of Ocean Properties at a Global Scale

Yang Fu,Xiwang Guo,Mengchu Zhou,Haitao Yuan,Zeyu Zheng

doi:10.1109/access.2020.2985527

Abstract

Ocean temperature, salinity, and electric conductivity are essential ocean properties. Their structure and changes directly impact physical, chemical and biological processes in oceans. Since the 1970s, numerous researches have focused on the morphological analysis of vertical profiles in oceanography. However, due to the complexity of an ocean environment, most of them are conducted at local scales or only focus on single elements, e.g., ocean temperature or salinity. This work aims to achieve the joint classification of the vertical structure of ocean properties at a global scale and present two-dimension regional characteristics. Based on 150 seawater profiles from the National Oceanographic Data Center, this work explores such characteristics of ocean temperature, salinity and electric conductivity in the deep sea and achieves global-scale joint classification. We demonstrate that their vertical features have clear regional characteristics and can be classified into four types, i.e., bidirectional gradient, homo-dromous contravariant, homo-dromous gradient, and homodromous gradient (salinity) ones. In addition, our results prove that there exist the power-law distributions of these three factors in intermediate water, which may be explained through the self-organization theory. Moreover, the `up-tail' phenomenon is widely discovered in the vertical structure of electric conductivity, and it may be considered as a combined effect caused by temperature, pressure, and salinity.

Highlights

Ocean temperature, salinity, and electric conductivity are three critical oceanic environmental factors and can directly reflect the physicochemical, thermal, and electric properties of seawater [1], [2]
FOUR CLASSES OF OCEANIC FACTOR VERTICAL STRUCTURES Based on vertical profiles of temperature, salinity, and electric conductivity, their vertical structures can be divided into four classes: bidirectional gradient, homodromous contravariant, homodromous gradient, and homodromous gradient ones as shown in Figs. 2 and 3
The temperature minimum (Tmin) and conductivity minimum (Cmin) layer, temperature and conductivity slowly increase toward the bottom, where the temperature increases in abyssal region due to adiabatic compression

Summary

Introduction

Salinity, and electric conductivity are three critical oceanic environmental factors and can directly reflect the physicochemical, thermal, and electric properties of seawater [1], [2]. As they participate in the physical, chemical and biological processes of seawater, their structure and changes potentially affect marine dynamics, marine primary production, and the interactions between the marine system and climate changes [3]. Numerous work has been conducted to analyze a vertical cross-section of oceanic factors at local scales [6].

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Results

Discussion

Conclusion