Population decline of the Japanese sardine, Sardinops melanostictus, in relation to sea surface temperature in the Kuroshio Extension

1999 ◽  
Vol 56 (6) ◽  
pp. 973-983 ◽  
Author(s):  
Masayuki Noto ◽  
Ichiro Yasuda
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Population Size ◽  
Kuroshio Extension ◽  
Population Decline ◽  
Sea Surface ◽  
Population Increase ◽  
Japanese Sardine ◽  
The Relationship ◽  
The Kuroshio

The relationship between the population size of the Japanese sardine, Sardinops melanostictus, and sea surface temperature (SST) from 1979 to 1994 was studied. Significant positive correlations were found between the natural mortality coefficient during the period from the postlarval stage to age 1 and winter-spring SST in the Kuroshio Extension and its southern recirculation area (30-35°N, 145-180°E). That is, higher (lower) SST over the possible migration route corresponded to higher (lower) mortality rate. This result is consistent with the high mortality and low population size for the high-SST period of the 1950's and 1960's and the population increase during the low-SST period of the 1970's and 1980's due to a decrease in mortality. The population decline after 1988 possibly occurred as a result of the abrupt increase in SST since 1988 in the Kuroshio Extension region and suggests a close relationship between interdecadal climate-ocean variability and sardine population size. This may also explain the relationship between biomass size and distribution area.

scholarly journals Upper Ocean Thermal Responses to Sea Spray Mediated Turbulent Fluxes during Typhoon Passage

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
Lianxin Zhang ◽  
Changlong Guan ◽  
Chunjian Sun ◽  
Siyu Gao ◽  
Shaomei Yu
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Kuroshio Extension ◽  
Turbulent Fluxes ◽  
Sea Surface ◽  
Sea Spray ◽  
Upper Ocean ◽  
Ocean Temperature ◽  
Turbulent Model ◽  
The Kuroshio

A one-dimensional turbulent model is used to investigate the effect of sea spray mediated turbulent fluxes on upper ocean temperature during the passage of typhoon Yagi over the Kuroshio Extension area in 2006. Both a macroscopical sea spray momentum flux algorithm and a microphysical heat and moisture flux algorithm are included in this turbulent model. Numerical results show that the model can well reproduce the upper ocean temperature, which is consistent with the data from the Kuroshio Extension Observatory. Besides, the sea surface temperature is decreased by about 0.5°C during the typhoon passage, which also agrees with the sea surface temperature dataset derived from Advanced Microwave Scanning Radiometer for the Earth Observing and Reynolds. Diagnostic analysis indicates that sea spray acts as an additional source of the air-sea turbulent fluxes and plays a key role in increasing the turbulent kinetic energy in the upper ocean, which enhances the temperature diffusion there. Therefore, sea spray is also an important factor in determining the upper mixed layer depth during the typhoon passage.

scholarly journals Marine Heatwave of Sea Surface Temperature of the Oyashio Region in Summer in 2010–2016

2021 ◽  
Vol 7 ◽  
Author(s):  
Toru Miyama ◽  
Shoshiro Minobe ◽  
Hanako Goto
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Kuroshio Extension ◽  
Sea Surface ◽  
Boreal Summer ◽  
Ocean Reanalysis ◽  
Oyashio Region ◽  
Seriola Quinqueradiata ◽  
Anticyclonic Eddies ◽  
The Kuroshio

The sea surface temperature (SST) of the Oyashio region in boreal summer abruptly increased in 2010 and high summertime SST repeated every year until 2016. Observations and an ocean reanalysis show that this marine heatwave occurred not only at the surface but also at deeper depths down to 200 m. Furthermore, salinity in summer also increased in parallel with the temperature. The rises in temperature and salinity indicate the strengthening of the Kuroshio water influence. The sea surface height and velocity show that the southward intrusion of the Oyashio near the coast in summer weakened from 2010 accompanied by an increase in anticyclonic eddies from the Kuroshio Extension. The much more frequent existence of anticyclonic eddies to the east of the first intrusion of the Oyashio in summer is closely associated with the weakening of the first intrusion and the strengthening of the second intrusion. It is suggested that the rise in the water temperature could increase a catch of yellowtail (Seriola quinqueradiata) in northern Japan.

scholarly journals Variability in the Sea Surface Temperature Gradient and Its Impacts on Chlorophyll-a Concentration in the Kuroshio Extension

2021 ◽  
Vol 13 (5) ◽  
pp. 888
Author(s):  
Yuntao Wang ◽  
Rui Tang ◽  
Yi Yu ◽  
Fei Ji
Keyword(s):  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Chlorophyll A ◽  
Seasonal Variability ◽  
Kuroshio Extension ◽  
Sea Surface ◽  
Chl A ◽  
Gradient Magnitude ◽  
The Kuroshio ◽  
Sst Gradient

Sixteen years of satellite observational data in the Northwestern Pacific Ocean are used to describe the variability in the sea surface temperature (SST) gradient and its impact on chlorophyll-a concentrations (Chl-a). Spatially, a meridional dependence is identified in which the SST gradient increases to the north in association with elevated Chl-a. Temporally, the seasonal variability shows a large SST gradient and high Chl-a in winter and spring, while the SST gradient and Chl-a are much lower in summer. The seasonal variability in Chl-a leads the variability in the SST gradient by one month. A significant correlation between the SST gradient and Chl-a in the anomalous field is obtained only in the western section of the Kuroshio extension (KE) and the highest correlation is identified without any lags. An index for the section is defined as the proportion of the number of times that the SST gradient magnitude is anomalously large in each year, and the index is highly related to the stability of the KE and has a prominent influence on Chl-a in the region. An anomalously large positive (negative) SST gradient magnitude occurs when the KE is unstable (stable) and the corresponding Chl-a is high (low).

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