Towards a Basin-scale Observing Network for Monitoring Upper-ocean Mass and Temperature Variability

An improved sampling strategy integrating elements of the ocean observing system is needed to monitor seasonal to interannual variations of heat and mass transport in boundary currents (BCs) regions and the ocean interior. Both the Argo Program and the high-resolution XBT (HR-XBT) network provide regular sampling of the subsurface ocean. Argo provides systematic observations of temperature and salinity fields between 2000-m and the surface, but the Argo coverage is not dense enough to resolve seasonal and shorter fluctuations, especially in the near-coastal region. The HR-XBT network on the other hand, has sampling frequency higher than Argo and collects observations closer to the coastline within BC regions, but is limited to fixed transects covering the upper 800-m, and is occupied seasonally. Our project aims to assess the value and synergies of the HR-XBT network and the Argo Program to appropriately monitor the basin-wide mass and heat transport, which are key for understanding the state of the ocean, and to advance our outlook and prediction of climate and weather events. This poster will report on the statistical characteristics of the HR-XBT and Argo profiling density in BC regions and along the trans-basin XBT transects, to improve our understanding of the spatial structure and strength of the BCs, their location, and the trans-basin vertical thermal structure. The ultimate goal is to provide important recommendations geared toward the design of a more effective upper-ocean observing system combining Argo, HR-XBT, and satellite altimetry.