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391.
392.
JGOFS has revealed the importance of marine biological activity to the global carbon cycle. Ecological models are valuable tools for improving our understanding of biogeochemical cycles. Through a series of workshops, the North Pacific Marine Science Organization (PICES) developed NEMURO (North Pacific Ecosystem Model Understanding Regional Oceanography) a model, specifically designed to simulate the lower trophic ecosystem in the North Pacific Ocean. Its ability to simulate vertical fluxes generated by biological activities has not yet been validated. Here compare NEMURO with several other lower trophic level models of the northern North Pacific. The different ecosystem models are each embedded in a common three-dimensional physical model, and the simulated vertical flux of POM and the biomass of phytoplankton are compared. The models compared are: (1) NEMURO, (2) the Kishi and Nakata Model (Kishi et al., 1981), (3) KKYS (Kawamiya et al., 1995, 2000a, 2000b), and (4) the Denman model (Denman and Peña, 2002). With simple NPZD models, it is difficult to describe the production of POM (Particulate Organic Matter) and hence the simulations of vertical flux are poor. However, if the parameters are properly defined, the primary production can be well reproduced, even though none of models we used here includes iron limitation effects. On the whole, NEMURO gave a satisfactory simulation of the vertical flux of POM in the northern North Pacific. 相似文献
393.
This study presents the results of the decoupling of a free-roll decay test by wavelet transforms. A free-roll decay test was performed to determine the coefficients of damping terms in equations of motion. No motion of the model was restricted during the experiment. A slight yaw motion was found while the model was in the free-roll decay motion. It was necessary to extract a pure roll motion from the experimental data. Wavelet transforms were applied to the signals to extract the pure roll motion. The results were compared to those found through the Fourier transform. Discrete wavelet transforms were able to efficiently decouple the test signals, while the continuous wavelet transform and the Fourier transform could not. 相似文献
394.
Seasonal Variability of Near-Surface Heat Budget of Selected Oceanic Areas in the North Tropical Indian Ocean 总被引:1,自引:0,他引:1
The results obtained from an Ocean General Circulation Model (OGCM), the Modular Ocean Model 2.2, forced with the National
Center for Environmental Prediction/National Center for Atmospheric Research reanalysis data, and observational data have
been utilized to document the climatological seasonal cycle of the upper ocean response in the Tropical Indian Ocean. We address
the various roles played by the net surface heat flux and the local and remote ocean dynamics for the seasonal variation of
near-surface heat budget in the Tropical Indian Ocean. The investigation is based in seven selected boxes in the Arabian Sea,
Bay of Bengal and the Equatorial Indian Ocean. The changes of basin-wide heat budget of ocean process in the Arabian Sea and
the Western Equatorial Indian Ocean show an annual cycle, whereas those in the Bay of Bengal and the Eastern Equatorial Indian
Ocean show a semi-annual cycle. The time tendency of heat budget in the Arabian Sea depends on both the net surface heat flux
and ocean dynamics while on the other hand, that in the Bay of Bengal depends mainly on the net surface flux. However, it
has been found that the changes of heat budget are very different between western and eastern regional sea areas in the Arabian
Sea and the Bay of Bengal, respectively. This difference depends on seasonal variations of the different local wind forcing
and the different ocean dynamics associated with ocean eddies and Kelvin and Rossby waves in each regional sea areas. We also
discuss the comparison and the connection for the seasonal variation of near-surface heat budget among their regional sea
areas.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
395.
Hitoshi Kawabata Hisashi Narita Koh Harada Shizuo Tsunogai Masashi Kusakabe 《Journal of Oceanography》2003,59(5):651-661
Thirteen vertical profiles of 226Ra and 222Rn in the near-surface water were obtained in the western North Pacific in winter, and the gas transfer velocities across
the air-sea interface were estimated. The transfer velocities found by applying a steady state model varied widely from 2.1
to 30.2 m day−1 with a mean of 9.4 m day−1. The mean value is almost 5 times higher than that in summer in other oceans, and the maximum value is a record high for
world oceans. This is partly due to the inadequacy of the steady state model, which overestimates when stronger winds blow
in more recent days than the 222Rn half-life of about 4 days. In fact, a strong low pressure zone passed through the station about 2 days earlier, which was
one of the low pressure zones that with a period of develop once a week or so in the northwestern North Pacific in winter.
Instead of steady-state removal, if half of the radon removal occurred sporadically every 7 days, and the last removal took
place two days before the observation, the transfer velocity would be 26 m day−1. Our mean transfer velocity, which is less than 20% different from the steady state value including both overestimated and
underestimated values, 9.4 ± 4.8 m day−1, seems to represent the mean state of this region in winter. This suggests that the gas exchange fluxes under extremely rough
conditions in the open ocean are larger than those estimated by using a transfer velocity equation with a linear or quadratic
relationship with wind speed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
396.
Since the Intermediate Oyashio Water (IOW) gradually accumulates in Sagami Bay, it can reasonably be supposed that the IOW
also flows out from Sagami Bay, even though it may be altered by mixing with other waters. We have occasionally observed a
water less than 34.2 psu with a potential density of 26.8 at the southeastern area off Izu Peninsula in July 1993 by the training
vessel Seisui-maru of Mie University. Observational data supplied by the Japan Meteorological Agency and the Kanagawa Prefectural
Fisheries Experimental Station show that the IOW of less than 34.1 psu was observed at northern stations of the line PT (KJ)
off the Boso Peninsula and to the east of Oshima in the late spring 1993. Based upon these observations, it is concluded that
the IOW flows out from Sagami Bay into the Shikoku Basin along southeastern area off the Izu Peninsula. The less saline water
(<34.2 psu) was also observed to the west of Miyake-jima during the same cruise, and the westward intrusion of IOW from south
of the Boso Peninsula to the Shikoku Basin through the gate area of the Kuroshio path over the Izu Ridge was detected. This
event indicated that the IOW branched south of the Boso Peninsula and flowed into Sagami Bay and/or into the gate area over
the Izu Ridge. The southward intrusion of IOW into the south of the Boso Peninsula is discussed in relation to the latitudinal
location of the main axes of the Kuroshio and the Oyashio.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
397.
The global community's ability to assess the environmental effects of marine scientific research (MSR) as required by the 1982 United Nations Convention on the Law of the Sea's (UNCLOS) marine environment provisions (MEP) is limited, as shown by experimental activities that intentionally manipulate the marine environment. Such work enhances knowledge of the ocean, but it may also have significant environmental effects. This growing use of the ocean as a laboratory has global scientific, environmental, legal and policy implications. Examined here is the relationship between the MSR and the MEP provisions of UNCLOS. International, science-driven guidelines are proposed. 相似文献
398.
399.
400.
The S/V Shoyo, of the Hydrographic Department, Japan Coast Guard, has conducted high-density expendable bathythermograph (XBT)
measurements along the 32.5°N line in the North Pacific every year from 1990 to 1993 as a part of the Japanese-World Ocean
Circulation Experiment (WOCE). These XBT data are analyzed here, focusing on year-to-year variations of the inventory and
core layer temperature (CLT) of the North Pacific subtropical mode water (NPSTMW). Large year-to-year changes are found in
the NPSTMW CLTs estimated in longitudes between 140°E and 160°E. CLT values were found of 17.4°C in 1990, 17.1°C in 1991,
17.3°C in 1992 and 17.6°C in 1993. Inspection of the wintertime westerlies over the formation area and sea surface temperature
distribution revealed that this change in CLT can be qualitatively attributed to the strength of atmospheric cooling in the
formation area in the previous winter. Although a large year-to-year variation of NPSTMW inventory was also found, it is hard
to state any relationship between CLT and atmospheric forcing. There is a possibility that different observational seasons
may affect the inventory. It has also been found that the thermocline depth in 1991 was shallower in the sea area east of
180° than in 1992 and 1993. Associated with this change, the North Pacific central mode water (NPCMW), characterized by thermostad
with temperatures ranging from 14°C to 11°C, appears in the sea area east of 180° in the 1992 and 1993 cross sections. The
1993 cross section, which ranged from the Japanese coast to the west coast of North America, possessed another thermostad
in the surface layer, with a temperature of about 17°C in the eastern part of the cross section, off California.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献