Retrieval of Sea Surface Temperature from TRMM VIRS     

Lei Guan  Hiroshi Kawamura  Hiroshi Murakami 《Journal of Oceanography》2003,59(2):245-249

The Visible and Infrared Scanner (VIRS) aboard the Tropical Rainfall Measuring Mission (TRMM) is a five-channel radiometer with wavelength from 0.6 to 12 μm. Daily 0.125° sea surface temperature (SST) data from VIRS were first produced at the National Space Development Agency (NASDA) for comparison with SST from TRMM Microwave Imager (TMI). In order to obtain accurate high spatial resolution SST for the merging of SST from infrared and microwave measurements, new SST retrieval coefficients of the Multichannel SST (MCSST) algorithm were generated using the global matchups from VIRS brightness temperature (BT) and Global Telecommunications System (GTS) SST. Cloud detection was improved and striping noise was eliminated. One-year global VIRS level-1B data were reprocessed using the MCSST algorithm and the advanced cloud/noise treatments. The bias and standard deviation between VIRS split-window SST and in situ SST are 0.10°C and 0.63°C, and for triple-window SST, are 0.06°C and 0.48°C. The results indicate that the reprocessing algorithm is capable of retrieving high quality SST from VIRS data. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Verification of vertically generalized production model and estimation of primary production in Sagami Bay,Japan     

Joji Ishizaka  Eko Siswanto  Tetsuya Itoh  Hiroshi Murakami  Yukuya Yamaguchi  Naho Horimoto  Takashi Ishimaru  Shinji Hashimoto  Toshiro Saino 《Journal of Oceanography》2007,63(3):517-524

The Vertically Generalized Production Model (VGPM) was verified by the primary production data of the Sagami Bay, Japan. The VGPM with open ocean parameters including P ^B _opt , maximum primary production per unit of chlorophyll a in the water column, explained only 40% of the variability of integrated primary production. Formulations of the open ocean P ^B _opt showed no correlation with in situ P ^B _opt . Adjustment of the parameters of chlorophyll a and temperature dependent P ^B _opt improved the estimation of integrated primary production to 47% of the variation. Vertical integration parameters of VGPM also have to be adjusted to improve the estimation. Integrated primary production calculated with a stronger light dependency and with the adjusted P ^B _opt model can explain 74% of the variation. This model was used to estimate primary production of the Sagami Bay during 2003 with satellite data. In situ measurements on cloudy days indicate that the use of satellite data from sunny days only overestimates primary production.  相似文献   

Dispersion and accumulation of radionuclide in sediment of Urazoko Bay-II     

Kiyoshi Nakamura  Yutaka Nagaya 《Journal of Oceanography》1977,33(1):1-5

Further studies on the transport in sea water and accumulation in marine sediment of the radionuclides, released from a nuclear power plant, on Urazoko Bay, Fukui Prefecture were reported.The partition of radionuclides among the particle size fractions of a sediment sample indicated that the accumulation of⁶⁰Co,¹³⁷Cs and⁵⁴Mn in the sediment were dominated substantially by the sorption on the particle surface in sea water, and the patterns of their sorption were considerably similar to each other.In regard to the⁶⁰Co contamination of marine sediments in an area of about 13 km² around the nuclear power plant, 60% of the⁶⁰Co contamination were retained in Urazoko Bay, which occupies only 7% of the bottom surface of the region.It is clear that a part of⁶⁰Co accumulated in the sediment of Urazoko Bay gradually moved to the outerward.  相似文献   

Relations between Sea Surface Temperature and Air-Sea Heat Flux at Periods from 1 Day to 1 Year Observed at Ocean Buoy Stations around Japan     

Hiroshi Murakami  Hiroshi Kawamura 《Journal of Oceanography》2001,57(5):565-580

Relations between sea-surface temperature (T _s) and heat flux at the sea surface (F) have been investigated using data from ocean observation buoys located off Shikoku in the Sea of Japan and in the East China Sea. Wavelet transformation decomposed F and T _s to wavelet coefficients (WLC) in the period-time domain. Assuming one-dimensional heat transfer by eddy diffusion in the upper ocean, the phase difference (δθ) defined as the difference between the phase of the temporal change rate of T _s, and the phase of F ranges statistically from 0 to +π/4 when F changes T _s, and is around −π/2 when heat convergence in the sea (Av) forces T _s. The δθ values are distributed from 0 to +π/4 at one-day and one-year periods at all buoys. WLC amplitude (WLCA) of F at periods from 16 to 32 day periods, which may be caused by the atmospheric ridge-trough systems, maintains energy longer than WLCA at periods from 2 to 16 days, which may be caused by monsoonal surges. At periods from 2 to 64 days, δθ values distribute from 0 to +π/4 or around −π/2 at each event, reflecting the surroundings of each ocean, i.e., Kuroshio recirculation in the off-Shikoku area, water-temperature front in the Sea of Japan, and water exchange in the continental shelf edge in the East China Sea. We demonstrate that the wavelet analysis can characterize the correspondence between irregular signals of F and T _s in various time scales and locations. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

Literature review of sand transport by wind on a dry sand surface   总被引：1，自引：0，他引：1  

Kiyoshi Horikawa  Shintaro Hotta  Nicholas C. Kraus 《Coastal Engineering》1986,9(6)

A critical and comprehensive literature survey of sand transport by wind on a dry sand surface is made from the perspective of engineering use. Principal findings are: (1) Most predictive expressions for the sand transport rate show a cubic dependence on the shear velocity, or obey a similar power law. (2) Some difference is found in the value of the multiplicative empirical coefficient in the various formulas, and much of the scatter may be ascribed to relative trap efficiency. (3) Verification of predictive formulas has mainly rested on laboratory measurements, and reliable but limited field verification has not been made until recently. (4) The laboratory and field data indicate that both the Bagnold and the Kawamura formulas are applicable to a well-sorted sand and can be used for estimation of wind-blown sand transport on dry natural beaches. Modifications have been made for a widely distributed sand and for fluctuating wind velocity.  相似文献   

In-water algorithms for ADEOS/OCTS     

Motoaki Kishino  Takashi Ishimaru  Ken Furuya  Tomohiko Oishi  Kiyoshi Kawasaki 《Journal of Oceanography》1998,54(5):431-436

In-water algorithms for OCTS standard products were developed using in situ data and installed for operationally processing at NASDA/EOC. This paper describes the in-water algorithms Version 1.0 for chlorophylla concentration, pigment concentration, and attenuation coefficient at a wavelength of 490 nm. The selected OCTS standard algorithms (Ver. 1.0) are as follows:   相似文献   

Artificial radionuclides in the western Northwest Pacific (II):137Cs and239,240Pu inventories in water and sediment columns observed from 1980 to 1986     

Yutaka Nagaya  Kiyoshi Nakamura 《Journal of Oceanography》1987,43(6):345-355

Concentrations and inventories of¹³⁷Cs and^239,240Pu were determined in sea waters and sediments columns from the western North Pacific from 1980 to 1986.The^239,240Pu/¹³⁷Cs activity ratio in the water column shows a tendency to increase from the surface (10^–3) to bottom waters (10^–1), but the ratio in sediment is within a rather narrow range (10^–2 to 10^–1), indicating more effective removal of plutonium from the water column than¹³⁷Cs. In regions south of 40N, the radionuclide inventories in the water column significantly exceed the estimated global fallout (stratospheric fallout due to the atmospheric nuclear explosion), especially in the case of^239,240Pu. These excess inventories imply that local or close-in fallout derived from nuclear explosions in the equatorial North Pacific are well-preserved and retained in the regions, despite about 20 years since the atmospheric nuclear explosion moratorium. Data suggesting lateral transport of¹³⁷Cs in surface water from north of 40N to southern regions is shown. Some data on⁹⁰Sr contents are also shown.  相似文献   

Validation of ADEOS-II GLI ocean color products using in-situ observations     

Hiroshi Murakami  Kosei Sasaoka  Kohtaro Hosoda  Hajime Fukushima  Mitsuhiro Toratani  Robert Frouin  B. Greg Mitchell  Mati Kahru  Pierre-Yves Deschamps  Dennis Clark  Stephanie Flora  Motoaki Kishino  Sei-Ichi Saitoh  Ichio Asanuma  Akihiko Tanaka  Hiroaki Sasaki  Katsumi Yokouchi  Yoko Kiyomoto  Hiroaki Saito  Cécile Dupouy  Absornsuda Siripong  Satsuki Matsumura  Joji Ishizaka 《Journal of Oceanography》2006,62(3):373-393

The Global Imager (GLI) aboard the Advanced Earth Observing Satellite-II (ADEOS-II) made global observations from 2 April 2003 to 24 October 2003. In cooperation with several institutes and scientists, we obtained quality controlled match-ups between GLI products and in-situ data, 116 for chlorophyll-a concentration (CHLA), 249 for normalized water-leaving radiance (nLw) at 443 nm, and 201 for aerosol optical thickness at 865 nm (Tau_865) and Angstrom exponent between 520 and 865 nm (Angstrom). We evaluated the GLI ocean color products and investigated the causes of errors using the match-ups. The median absolute percentage differences (MedPD) between GLI and in-situ data were 14.1–35.7% for nLws at 380–565 nm, 52.5–74.8% nLws at 625–680 nm, 47.6% for Tau_865, 46.2% for Angstrom, and 46.6% for CHLA, values that are comparable to the ocean-color products of other sensors. We found that some errors in GLI products are correlated with observational conditions; nLw values were underestimated when nLw at 680 nm was high, CHLA was underestimated in absorptive aerosol conditions, and Tau_865 was overestimated in sunglint regions. The error correlations indicate that we need to improve the retrievals of the optical properties of absorptive aerosols and seawater and sea surface reflection for further applications, including coastal monitoring and the combined use of products from multiple sensors.  相似文献   

Heat and salt balances in the Seto Inland Sea   总被引：1，自引：0，他引：1  

Mayumi Murakami  Yukio Oonishi  Hideaki Kunishi 《Journal of Oceanography》1989,45(3):204-216

Seasonal variations of heat and salt balances are estimated in the Seto Inland Sea with the use of a numerical experiment.The surface effect is dominant with respect to the heat balance. In spring, however, the effect of the horizontal heat transport is the same as or greater than that of the surface heating (or cooling). Annual mean heat transport is 85 cal cm^–2 day^–1 (356 J cm^–2 day^–1) which is supplied from the open ocean and lost through the sea surface in the Inland Sea as a whole. Because of the shallow water depth, heat is supplied through the surface and carried out by the horizontal heat transport in Hiuchi- and Bingo-nada in the annual mean. The heat transport has the opposite sense to that in the whole Seto Inland Sea and annual mean transport is negative (–10 cal cm^–2 day^–1,i.e., –42 J cm^–2 day^–1).The salt balance is primarily controlled by the river discharge and the surface effect (precipitation) in June and July. In the other months, the effects of horizontal salt transport, of river inflow and of sea surface exchange (especially of the evaporation in autumn) are comparable to each other. In the Bungo Channel the river effect is relatively small. Osaka Bay and the Kii Channel are characterized by a smaller surface effect.Contribution No. 446 from Tohoku Regional Fisheries Research Laboratory.  相似文献   

Modification of North Pacific Intermediate Water around Mixed Water Region     

Ryuichiro Inoue  Jiro Yoshida  Yutaka Hiroe  Kousei Komatsu  Kiyoshi Kawasaki  Ichiro Yasuda 《Journal of Oceanography》2003,59(2):211-224

The mixing processes in the Mixed Water Region (MWR) that lead to changes in the properties of North Pacific Intermediate Water (NPIW) have been studied using observational data sets obtained in May–June 1998. Neutral surfaces, the equation of water mass conversion rate on neutral surfaces and the equation of vertical velocity across neutral surfaces have been used to distinguish dominant processes by assuming the horizontal scale to be the streamer scale (under 100 km). The possibility of double diffusive convection is also discussed in relation to the density ratio. These results may be summarized as follows: (1) the difference between the potential density surface and the neutral surface may rise to −0.04 kg/m³ around the source water of NPIW; (2) horizontal diffusion causes strong modifications of the source water of NPIW; (3) the density range within which strong modification of the source water of NPIW occurs becomes dense from the northern part of MWR near the Oyashio Front to the southern part near the Kuroshio Front, and to the eastern part. Our modeling of these processes shows that cabbeling has effects on the density increment of the source water of NPIW in the northern and southern part of MWR. Double diffusive convection has effects on the density increment of the source water of NPIW, mainly in the northern part of MWR. The possible density increment due to cabbeling in these areas is estimated to be 0.01≈0.03 kg/m³. The possible density increment due to double diffusive convection is 0.01≈0.03 kg/m³. The total density increment due to cabbeling and double diffusive convection amounts to 0.06 kg/m³. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献