Frontolysis by surface heat flux in the eastern Japan Sea: importance of mixed layer depth

Ohishi, Shun; Aiki, Hidenori; Tozuka, Tomoki; Cronin, Meghan F.

doi:10.1007/s10872-018-0502-0

Cited by 7 publications

(6 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figure 1 shows the climatological absolute value, position and intensity of the SPF calculated from the MSSTG with the seven-year running average based on CoralTemp (the results for the other three products are shown in Figures S2-S4). The characteristics of the SPF calculated by the MSSTG are consistent with the SPF defined by whole horizontal SST gradient (Ohishi et al, 2019). There are three regions along the SPF with large SST gradients (>4°C/100km).…”

Section: Decadal Variations In the Intensity And Position Of The Spfsupporting

confidence: 76%

“…The monsoon also forces the JES with the strong westerly winds from Vladivostok Gap in winter, inducing strong cold currents and pushing cold water equatorward. Ohishi et al (2019) pointed out that the NHF tends to relax the SPF throughout the year, however, the MLD can dampen (enhance) the frontolysis induced by the NHF in winter (summer). The possible mechanisms of the oceanic and atmospheric factors are explored by the frontogenesis rate equation (equation 3).…”

Section: Possible Mechanismsmentioning

confidence: 99%

“…In terms of the seasonal frontogenesis processes, the mixed-layer model and oceanic reanalysis data showed that horizonal advection is dominant throughout the year, especially the geostrophic component (Zhao et al, 2014). With respect to the seasonal frontolysis processes, the surface heat flux has a dominant role in all months, especially in spring and summer (Ohishi et al, 2019), and also causes weakening or even the disappearance of the SPF (Park et al, 2007). In autumn and winter, the mixed-layer gradient damps the frontolysis induced by the surface heat flux (Ohishi et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

“…With respect to the seasonal frontolysis processes, the surface heat flux has a dominant role in all months, especially in spring and summer (Ohishi et al, 2019), and also causes weakening or even the disappearance of the SPF (Park et al, 2007). In autumn and winter, the mixed-layer gradient damps the frontolysis induced by the surface heat flux (Ohishi et al, 2019). However, a detailed description of the decadal variations and mechanisms of the SPF are yet to be addressed, partly due to the limited duration of observations-for example, numerical simulations have shown that the interannual variability of the SPF from 1993 to 2001 was strongly affected by wind stress and transport of the TWC (Choi et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Decadal intensified and slantwise Subpolar Front in the Japan/East Sea

et al. 2022

View full text Add to dashboard Cite

The Subpolar Front in the Japan/East Sea (JES) could far-reaching influence the atmospheric processes over the downstream regions. However its variability on decadal timescale remains less understood. In this study, the decadal trends in the intensity and position of the SPF in the JES during the time period 1985−2020 are analyzed by using four categories of satellite observed high-resolution sea surface temperature products. The results show that there is a significant intensification trend of the SPF at a rate of 0.37°C/100km/decade. The SPF is further divided into three regions based on the meridional sea surface temperature gradient (MSSTG): the eastern (135−138°E), central (130−135°E) and western (128−130°E) regions, respectively. These three regions showed different meridional movements with the eastern SPF moving poleward by 0.08°/decade, the central SPF moving equatorward by −0.11°/decade and the western SPF showing no significant displacements. The reverse meridional movements between the central and eastern SPF increased its skewness. The frontogenesis rate equation is employed to identify the mechanisms of these decadal trends. Results show that the geostrophic advection term, especially its zonal component, had a crucial role in the decadal trends of the intensity and position of the central and eastern SPF. The decadal trend of the central SPF was mainly attributed to the zonal geostrophic advection of the MSSTG associated with the enhancement of the Subpolar Front Current (SFC) in the upstream region, whereas the decadal trend in the eastern SPF was mainly driven by the zonal geostrophic shear advection controlled by the shear of the SFC in the downstream region. Before 2002, the eastern SPF moved poleward at a rate of 0.27°/decade, whereas there was no obvious trend after 2002. Further decomposition showed that this shift was caused by meridional Ekman advection of the MSSTG.

show abstract

Section: Decadal Variations In the Intensity And Position Of The Spfsupporting

confidence: 76%

Section: Possible Mechanismsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Decadal intensified and slantwise Subpolar Front in the Japan/East Sea

et al. 2022

View full text Add to dashboard Cite

show abstract

“…As the J1 jet position is quasi-stationary due to topographic effects (Isoguchi et al 2006;Mitsudera et al 2018), the ensemble spread in the horizontal flow along the J1 jet is not as large as that for the KE. A huge amount of turbulent heat is released around the SST fronts because of strong wind speed and large air-sea humidity and temperature differences (e.g., Ohishi et al 2016Ohishi et al , 2019aTozuka et al 2017); therefore, the perturbed atmospheric forcing may result in the large temperature and salinity spread around the J1 jet. It is beyond the scope of this study to quantitatively investigate the causes of the formation of the large ensemble spread.…”

Section: Lora-wnpmentioning

confidence: 99%

LORA: a local ensemble transform Kalman filter-based ocean research analysis

2023

Self Cite

View full text Add to dashboard Cite

We have produced an eddy-resolving local ensemble transform Kalman filter (LETKF)-based ocean research analysis (LORA) for the western North Pacific (WNP) and Maritime Continent (MC) regions (LORA-WNP and LORA-MC, respectively). This paper describes the system configuration and validation comparisons with Japan Coastal Ocean Predictability Experiment 2M (JCOPE2M) reanalysis and Archiving, Validation, and Interpretation of Satellite Oceanographic Data (AVISO) observational datasets. The results show that the surface horizontal velocity in the LORA-WNP is closer to independent drifter buoy observations in the mid-latitude region, especially along the Kuroshio Extension (KE), and is less close in the subtropical region than the JCOPE2M, although the AVISO is the closest over the whole domain. The sea surface temperatures (SSTs) in the LORA-WNP correspond better to assimilated satellite observations than the JCOPE2M over most of the domain except for coastal regions. The results using an independent buoy south of the KE indicate that better fit of temperature in the LORA-WNP may be limited to the upper 300 m depth, probably because of the prescribed vertical localization cutoff length of 370 m. In the MC region, the surface velocity in the LORA-MC is closer to the independent drifter buoys in the equatorial coastal region and is less close in the offshore region than the AVISO. The SSTs in the LORA-MC correspond better to the assimilated satellite observations in the offshore region than the nearshore region. Therefore, the LORA-WNP and LORA-MC have sufficient accuracy for geoscience research applications as well as for fisheries, marine transport, and environment consultants.

show abstract