JCOPE-FGO: an eddy-resolving quasi-global ocean reanalysis product

Abstract

In the present research, we provide a brief description and assessment of the oceanic fields analyzed in the newly developed eddy-resolving quasi-global ocean reanalysis product, named the Japan Coastal Ocean Predictability Experiments-Forecasting Global Ocean (JCOPE-FGO). This product covers the quasi-global ocean with a horizontal resolution of 0.1° × 0.1°. Validations of analyzed temperature and salinity fields by JCOPE-FGO against in situ observations revealed that our product can capture various aspects of observed hydrographic structures in the world ocean, including frontal structures near the surface and thermohaline properties of water masses, as well as their spatiotemporal variability. Furthermore, we have assessed dynamical fields analyzed in JCOPE-FGO using satellite altimeters and surface drifters, and found that our product can represent the mean state and variability of the upper ocean circulation in many regions. A notable feature of JCOPE-FGO is the inclusion of an updated global river runoff, and impacts of river forcing have been assessed by an additional reanalysis experiment without river forcing. We found that the removal of continental river discharge leads to dramatic changes in the near-surface salinity and related fields around river mouths of large rivers, but large changes are mostly confined to narrow regions near the coast. As an example of the substantial impact of river runoff, we discuss the dispersion of low-salinity water from the Mississippi river to the Gulf of Mexico: a comparison between the analyzed salinity fields from both reanalysis products with those from satellite observations demonstrated that the inclusion of river runoff is essential for an accurate representation of its seasonal variability. Several key issues that warrant further improvements are discussed for future development.

Anomalous Nutricline Drives Marked Biogeochemical Contrasts During the Kuroshio Large Meander

“…Furthermore, marine industries may benefit from decadal predictions of biogeochemical states, as the decadal variability of the Kuroshio LM is expected to strengthen in the future due to the stronger decadal variability of the Kuroshio Extension (Joh et al, 2022) that is closely linked to the LM occurrence (Usui et al, 2013). Such biogeochemical implementation into a decadal ocean prediction system (e.g., Kido et al, 2022Kido et al, , 2023 has great potential in supporting long-term adaptation planning for future large meanders that may last longer than the ongoing record-breaking event, as demonstrated by our model simulations (Figure 2a).…”

Skillful Multiyear Prediction of the Kuroshio and Gulf Stream Jets and Eddy Activity

“…In this study, the Japan Coastal Ocean Predictability Experiments‐Forecasting Global Ocean (JCOPE‐FGO) system, a quasi‐global eddy‐resolving ocean reanalysis system, was used to obtain the initial conditions for the prediction experiments. This system provided estimates of SSH, three‐dimensional temperature, salinity, and horizontal/vertical components of the velocity fields of the quasi‐global ocean (75°S–75°N) from January 1993 to the present, with a horizontal resolution of 0.1° (Kido et al., 2022). This was achieved by assimilating various kinds of observations (e.g., satellite sea surface temperature and SSH and temperature and salinity profiles obtained from Argo float in‐situ observations) into an eddy‐resolving OGCM (JCOPE‐T) (Varlamov & Miyazawa, 2021) using the three‐dimensional variational scheme (Miyazawa et al., 2009).…”

“…Indeed, temporal variations in the speeds and latitudinal positions of both WBC jets were correctly captured in the reanalysis field of the JCOPE-FGO system (Figure S2 in Supporting Information S1). More details on the configurations and assessments of the JCOPE-FGO system can be found in Kido et al, 2022.…”

Sea surface temperature budget in Indonesian seas: the role of vertical turbulent flux and its east–west variations

“…Rivers with annual discharges larger than 500 m 3 s -1 were selected to be incorporated into the model. This river selection criterion was similar to that used in the latest Japan Agency for Marine-Earth Science and Technology (JAMSTEC) ocean reanalysis product [24]. JRA55-do was notably suitable for a large-scale ocean modeling experiment given its long-term coverage, high resolution (spatial-temporal; 0.5625°/0.25° and three-hourly/daily for atmospheric/river discharge data), and internally consistent features [25].…”