Submesoscale Ageostrophic Motions Within and Below the Mixed Layer of the Northwestern Pacific Ocean

Abstract

The oceanic flow is known to be highly turbulent and consists of motions on a wide range of scales. With the great success in satellite altimetry, geostrophic eddies with horizontal scales of a few hundred kilometers can be routinely observed (Chelton et al., 2007;Fu et al., 2010). The mesoscale features and their impacts on the transport of oceanic tracers have been well studied in the past decades (e.g.,

Submesoscale Vertical Heat Transport at the Kuroshio Extension: Characteristics and Mechanisms

“…The vertical heat transport in these four regions is similar in the following aspects (Figure 4): One, RVHT is generally negligible. Two, consistent with previous literature (Balwada et al, 2018;Cao & Jing, 2022;Yu, Naveira Garabato, et al, 2019), SVHT is generally upward, with the peak value occurring around the center of the winter MLD. Three, compared to SVHT, the maximum MVHT generally occurs at a deeper depth.…”

“…Using the decomposition approach from Equation , EVHT can be divided into MVHT, SVHT, and residual vertical heat transport (RVHT): $$$\underset{\text{EVHT}}{\underbrace{{\rho }_{0}{C}_{\mathrm{p}}{w}^{\prime }{T}^{\prime }}}=\underset{\text{MVHT}}{\underbrace{{\rho }_{0}{C}_{\mathrm{p}}\left({{w}_{m}}^{\prime }{T}_{m}^{\prime }\right)}}+\underset{\text{SVHT}}{\underbrace{{\rho }_{0}{C}_{\mathrm{p}}\left({{w}_{s}}^{\prime }{T}_{s}^{\prime }\right)}}+\underset{\text{RVHT}}{\underbrace{{\rho }_{0}{C}_{\mathrm{p}}\left({{w}_{m}}^{\prime }{T}_{s}^{\prime }+{w}_{s}^{\prime }{T}_{m}^{\prime }\right)}},$$$ where w and T denote the vertical velocity and temperature, respectively. Here the density constant ρ 0 is chosen to be 1027.5 kg m −3 and the specific heat capacity of seawater C p is 3,985 J kg −1 K −1 (Cao & Jing, 2022; Siegelman, 2020; Siegelman et al., 2020). RVHT represents the part of vertical heat transport induced by the meso‐ and submeso‐scale coupling; it includes both the transport of submesocale temperature anomaly by mesoscale motions and the transport of mesoscale temperature anomaly by submesoscale motions.…”

Air-Sea Latent Heat Flux Anomalies Induced by Oceanic Submesoscale Processes: An Observational Case Study

“…The effect of air-sea interactions at submesoscales may also be linked to submesoscale dynamics in the ocean interior where submesoscale turbulence is energetic [we reveal upper ocean submesoscale instabilities driven by internal wave shear in a twin study (Song et al, 2022)]. In addition, underwater submesoscale dynamics can be an important dynamic mechanism for vertical heat transport into the deep ocean (Su et al, 2018(Su et al, , 2020Cao and Jing, 2022).…”

Two Key Mechanisms of Large‐Scale Cross‐Shelf Penetrating Fronts in the East China Sea: Flow Convergence and Thermocline Undulation

“…In order to show the role of convergence, Figure 9 shows the divergence of upper 20‐m averaged currents and frontogenesis function at surface layer. The frontogenesis function can be expressed as follows (Calil & Richards, 2010; Cao & Jing, 2022; Hoskins, 1982; Jones et al., 2023). $$\begin{align*}{F}_{s}=\boldsymbol{Q}\cdot \nabla b\end{align*}$$ where $$b=-\frac{g{\rho }^{\prime }}{{\rho }_{0}}$$ is buoyancy, ρ ′ is density anomaly, ρ 0 is reference density, and g is gravitational acceleration.…”