The Modeling of the North Equatorial Countercurrent in the Community Earth System Model and its Oceanic Component

Sun, Zhikuo; Liu, Hailong; Lin, Pengfei; Tseng, Yu‐Heng; Small, R. Justin; Bryan, Frank O.

doi:10.1029/2018ms001521

Cited by 22 publications

(19 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Because the 10-m wind product from a scatterometer represents the wind relative to the oceanic currents, using this wind with a bulk formula and a parameterization based on prescribed coupling coefficients (n in Figure 11) would, therefore, have a realistic eddy killing effect; however, the large-scale effect might be doubly accounted for, weakening the mean circulation. This has been recently shown to be important by Sun et al (2019) for the North Equatorial Countercurrent. To overcome this issue, one could filter out the CFB imprint (as in f in 11) by using the parameterization based on a predicted s and observed surface currents, for example, from AVISO (k in Figure 11).…”

Section: Summary and Discussionmentioning

confidence: 92%

Recipes for How to Force Oceanic Model Dynamics

Renault

Masson

Arsouze

et al. 2020

J Adv Model Earth Syst

View full text Add to dashboard Cite

The current feedback to the atmosphere (CFB) contributes to the oceanic circulation by damping eddies. In an ocean‐atmosphere coupled model, CFB can be correctly accounted for by using the wind relative to the oceanic current. However, its implementation in a forced oceanic model is less straightforward as CFB also enhances the 10‐m wind. Wind products based on observations have seen real currents that will not necessarily correspond to model currents, whereas meteorological reanalyses often neglect surface currents or use surface currents that, again, will differ from the surface currents of the forced oceanic simulation. In this study, we use a set of quasi‐global oceanic simulations, coupled or not with the atmosphere, to (i) quantify the error associated with the different existing strategies of forcing an oceanic model, (ii) test different parameterizations of the CFB, and (iii) propose the best strategy to account for CFB in forced oceanic simulation. We show that scatterometer wind or stress are not suitable to properly represent the CFB in forced oceanic simulation. We furthermore demonstrate that a parameterization of CFB based on a wind‐predicted coupling coefficient between the surface current and the stress allows us to reproduce the main characteristics of a coupled simulation. Such a parameterization can be used with any forcing set, including future coupled reanalyses, assuming that the associated oceanic surface currents are known. A further assessment of the thermal feedback of the surface wind in response to oceanic surface temperature gradients shows a weak forcing effect on oceanic currents.

show abstract

Section: Summary and Discussionmentioning

confidence: 92%

Recipes for How to Force Oceanic Model Dynamics

Renault

Masson

Arsouze

et al. 2020

J Adv Model Earth Syst

View full text Add to dashboard Cite

show abstract

“…Rather it is due to a weak south equatorial counter current north of the equator and a weak equatorial counter current (not shown). This is at least partly attributed to deficiencies in the representation of wind stress curl in the JRA-55do forcing product (Sun et al 2019). These errors in forcing result in a weak meridional shear north of the equator which in turn leads to reduced instability.…”

Section: Discussionmentioning

confidence: 99%

Modulation of Cross-Isothermal Velocities with ENSO in the Tropical Pacific Cold Tongue

Deppenmeier

Bryan

Kessler

et al. 2021

Journal of Physical Oceanography

View full text Add to dashboard Cite

The tropical Pacific cold tongue (CT) plays a major role in the global climate system. The strength of the CT sets the zonal temperature gradient in the Pacific that couples with the atmospheric Walker circulation. This coupling is an essential component of the El Niño Southern Oscillation (ENSO). The CT is supplied with cold water by the equatorial undercurrent that follows the thermocline as it shoals toward the east, adiabatically transporting cold water towards the surface. As the thermocline shoals, its water is transformed through diabatic processes producing water mass transformation (WMT) that allows water to cross mean isotherms. Here, we examine WMT in the cold tongue region from a global high resolution ocean simulation with saved budget terms that close its heat budget exactly. Using the terms of the heat budget, we quantify each individual component of WMT (vertical mixing, horizontal mixing, eddy fluxes, solar penetration), and find that vertical mixing is the single most important contribution in the thermocline, while solar heating dominates close to the surface. Horizontal diffusion is much smaller. During El Niño events, vertical mixing, and hence cross-isothermal flow as a whole, is much reduced, while during La Niña periods strong vertical mixing leads to strong WMT, thereby cooling the surface. This analysis demonstrates the enhancement of diabatic processes during cold events, which in turn enhances cooling of the CT from below the surface.

show abstract

“…The surface ocean current is strongly determined and dominated by wind pattern distributions, as has been proposed for developing simulation models in previous NECC investigations [31,32]. Therefore, we plotted the average of the zonal component anomalies of wind stress extracted from wind data from 1993 to 2017 (Figure 7).…”

Section: Wind Forcingmentioning

confidence: 99%

Differences in the Reaction of North Equatorial Countercurrent to the Developing and Mature Phase of ENSO Events in the Western Pacific Ocean

Wijaya

Hisaki

2021

Climate

View full text Add to dashboard Cite

The North Equatorial Countercurrent (NECC) is an eastward zonal current closely related to an El Niño Southern Oscillation (ENSO) event. This paper investigated the variations of NECC in the Western Pacific Ocean over 25 years (1993–2017) using satellite data provided by the Copernicus Marine Environment Monitoring Service (CMEMS) and the Remote Sensing System (RSS). The first mode of empirical orthogonal function (EOF) analysis showed that the NECC strengthened or weakened in each El Niño (La Niña) event during the developing or mature phase, respectively. We also found that the NECC shifting was strongly coincidental with an ENSO event. During the developing phase of an El Niño (La Niña) event, the NECC shifted southward (northward), and afterward, when it entered the mature phase, the NECC tended to shift slightly northward (southward). Moreover, the NECC strength was found to have undergone a weakening during the 2008–2017 period.

show abstract

The Modeling of the North Equatorial Countercurrent in the Community Earth System Model and its Oceanic Component

Cited by 22 publications

References 34 publications

Recipes for How to Force Oceanic Model Dynamics

Recipes for How to Force Oceanic Model Dynamics

Modulation of Cross-Isothermal Velocities with ENSO in the Tropical Pacific Cold Tongue

Differences in the Reaction of North Equatorial Countercurrent to the Developing and Mature Phase of ENSO Events in the Western Pacific Ocean

Contact Info

Product

Resources

About