Effect of horizontal advection induced by intrusion of the Kuroshio water on plankton biomass in the spring fishing period of shirasu on the Pacific coast of Japan

Abstract This study used a 4-km resolution regional climate model to examine the sensitivity of surface air temperature on the Pacific coast of Japan to sea surface temperature (SST) south of the Pacific coast of Japan during summer. The authors performed a control simulation (CTL) driven by reanalysis and observational SST datasets. A series of sensitivity experiments using climatological values from the CTL SST datasets over a 31-yr period was conducted. The interannual variation in surface air temperature over the Pacific coast was well simulated in CTL. The interannual variation in SST over the Kuroshio region amplified the interannual variation in surface air temperature over the Pacific coast. It was found that 30% of the total variance of interannual variation in surface air temperature can be controlled by interannual variation in SST. The calculated surface air temperature on the Pacific coast increased by 0.4 K per 1-K SST warming in the Kuroshio region. Note that this sensitivity was considerably greater during nighttime than during daytime. Concurrent with the warming in surface air temperature, downward longwave radiation at the surface was also increased. In summer, the increase in latent heat flux was considerably larger than that in sensible heat flux over the ocean because of SST warming, according to the temperature dependence of the Bowen ratio. This implies that the primary factor for the increase in surface air temperature in summer is increased moisture in the lower troposphere, indicating that the regional warming was caused by an increase in H2O greenhouse gas.

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Concentrations and activity ratios of 228Ra and 226Ra in surface seawater along the Pacific coast of Japan

Proceedings in Radiochemistry ◽

10.1524/rcpr.2011.0033 ◽

2011 ◽

Vol 1 (1) ◽

pp. 183-188 ◽

Cited By ~ 2

Author(s):

T. Ohta ◽

Y. Mahara ◽

T. Kubota ◽

J. Sato ◽

T. Gamo

Keyword(s):

Pacific Coast ◽

Tokyo Bay ◽

Surface Seawater ◽

Sagami Bay ◽

Surface Salinity ◽

Shelf Sediment ◽

The Pacific ◽

Activity Ratios ◽

Pacific Coast Of Japan ◽

The Kuroshio

AbstractWe measured the 228Ra/226Ra activity ratios in surface seawater along the Pacific coast of Japan at five ports around the island of Izu-Oshima (n = 29), at Atami in Sagami Bay (n = 13), and at Umizuri Park in Tokyo Bay (n = 14). We also conducted these measurements along a transect from the open Pacific Ocean across the Kuroshio to the mouth of Tokyo Bay (n = 7). The activity ratios decreased with increasing salinity of the sampling sites. The 228Ra/226Ra activity ratios in surface seawater along the coast gradually decreased after at the end of autumn and were lowest in winter and the beginning of spring. The surface salinity along the coast decreased from summer into autumn and increased from winter to the beginning of spring. The activity ratios decreased with the increase of salinity.The variation in activity ratios at the three coastal sites is possibly caused by differing contributions of surface seawater from the Kuroshio and surrounding open ocean. The different patterns and ranges of variation in the 228Ra/226Ra activity ratios in surface seawater at Izu-Oshima, Atami, and Umizuri Park may reflect both the amount of water from the Kuroshio and vicinity, and the local bathymetry, because continental shelf sediment is the source of Ra isotopes in surface seawater.

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