[A-OS21] Global ocean observation networks: Current status, results, re-assessments, and future perspectives

[AOS21-04] Classification of Argo Profiles in the Mid-latitude Northwest Pacific Ocean by Unsupervised Clustering and Their Potential Use

★Invited Papers

*Fumika Sambe¹, Toshio Suga^1,2 (1.Graduate School of Science, Tohoku University, 2.JAMSTEC)

Keywords:Mid-latitude Northwest Pacific Ocean, Argo float, Unsupervised Clustering, Data-driven Science, Vertical Structure, Temperature and Salinity Profile

The mid-latitude northwest Pacific Ocean is a region where transport, stirring, and mixing of subtropical and subarctic waters occurs strongly. These physical processes form ocean vertical structures that have different characteristics in each region. Many studies have been conducted on the characteristics and distribution of the vertical structure and the boundaries across which the characteristics of the ocean structure and characteristic water masses change have been defined. However, most of these studies have been conducted based on existing definitions based on spatially and temporally limited data, such as shipboard observations. The basic research framework has not changed significantly, although a large amount of vertical profile data is now available spatially and temporally comprehensively with the expansion of global ocean observation network represented by Argo. We thought that the accumulation of Argo vertical profile data would allow us to objectively recapture the characteristics of ocean structure using data-driven science and applied unsupervised clustering to Argo data on temperature and salinity in the mid-latitude northwest Pacific Ocean.
In a series of previous studies, we applied the Profile Classification Model (PCM) developed by Maze et al. (2017) to 56414 Argo temperature and salinity profiles acquired between 30°N and 60°N and between 140°E and 180°E to classify the vertical structure into five classes. As a result, Class 1, 2, 3, 4, and 5 were distributed to form five regions: the subarctic region, the mixed water region, the subtropical-subarctic intermediate region, the northwest part of the subtropical gyre, and the downstream of the Kuroshio Extension, respectively. The vertical structure of each class showed characteristics that corresponded to the distribution areas described by previous studies. This means that it is possible to know the characteristics and areas of the vertical structure of temperature and salinity without existing knowledge and location and time information. In the presentation, in addition to the details of the above, we will present the results of the variability of distribution and vertical structure of Class 2 and Class 3 in the mixed water region and the analysis incorporating potential vorticity and spiciness.