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31.
A detailed examination of a high-temperature catalytic oxidation method for liquid samples in the analysis of total nitrogen dissolved in seawater is reported. The nitrogenous compounds in liquid samples are oxidized on a platinum catalyzer at 680°C under oxygen atmosphere and the generated NO2 is absorbed into a chromogenic reagent, followed by a spectrophotometric determination. The results of this method are much higher than those of wet oxidation methods. Molecular size dependency of the results clearly indicates that the above discrepancy is caused by the low oxidation capacity of the wet oxidation method against high-polymer organic matter dissolved in seawater. The results revealed that the concentration of total nitrogen in seawater is nearly constant from surface to bottom, ranging from 30 to 40 μM 1?1, which organic nitrogen concentration higher in the surface layer, and a rapid decrease with depth. An examination of molecular size distribution indicates that the concentration of high-polymer organic nitrogen decreases rapidly from surface to deeper layers, with molecular sizes ranging from 5 × 103 to 3 × 104. Because of the well-defined principle of the oxidation process, its reliability, ease of sample handling and of analytical procedure on board or in the land laboratory, the present method is much more suitable for the marine analytical chemistry of total and organic nitrogen than the other previous methods. 相似文献
32.
A model for the hydrogen coma of a comet on the basis of the Monte Carlo method is presented. In this model isotropic ejections of H atoms produced by photodissociation of H2O and OH, thermalization of the H atoms due to collisions with ambient H2O molecules, and the solar radiation pressure have been taken into account. A production spectrum of H atoms from OH is evaluated by using the predissociation rates and the level populations of OH, confirming that the spectrum has a sharp peak around 8.0 km sec?1 with the standard deviation of 0.1 km sec?1. Including the above effects, velocity distribution functions of the H atoms at various positions in the coma for the first time, as well as their density and outflow velocity profiles, have been calculated. It is pointed out that the collisional thermalization process in the inner coma is an important factor at small heliocentric distances in determining the density profiles and the velocity distributions. It is shown that thermalization leads to an increase in the H density in the inner coma larger than those expected from other models such as the vectorial model, in which collision is not taken into account. Lyman α isophotes and its line profiles in the optically thin region are computed by using the velocity distribution function. 相似文献
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34.
Journal of Oceanography - The authors examine small-scale spatiotemporal variability of the layer nearly 2000-m depth, which is the “bottom” of the present Argo observation system,... 相似文献
35.
36.
Irikawa A Casareto BE Suzuki Y Agostini S Hidaka M van Woesik R 《Marine pollution bulletin》2011,62(8):1702-1707
This ten-year study examined the morphological, physiological, and ecological characteristics of coral growth anomalies on Acropora cytherea on Amuro Island, Okinawa, Japan. The objectives of the study were to assess whether the growth anomalies, identified as diffuse disruptions on the skeleton: (i) were more prevalent on large colonies than on small colonies, (ii) were more common near the center of the colonies than peripherally, (iii) affected colony growth and mortality, and (iv) affected coral-colony fecundity and photosynthetic capacity. We hypothesized that the growth anomalies were signs of the onset of aging. The growth anomalies were more prevalent on colonies >2 m diameter, and were concentrated near the central (older) portions of the colonies. The growth anomalies were also associated with reduced productivity and dysfunctional gametogenesis. Still, the growth anomalies did not appear to affect colony survival. The contact experiments showed that the growth anomalies were not contagious, and were most likely a sign of aging that was exacerbated by thermal stress. 相似文献
37.
The authors have verified a regression model for the evaluation of the daily amplitude of sea surface temperature (ΔSST) proposed
by Kawai and Kawamura (2002). The authors investigated the accuracy of satellite data used for the evaluation and showed that
ΔSST error caused by satellite data error is less than ±0.7 K. The evaluated ΔSSTs were compared with in situ values. Its
root-mean-square error is about 0.3 K or less, except for a coastal region, and it has a bias of more than +0.1 K in the tropics.
This bias can be removed by considering latent heat flux.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
38.
Diurnal sea surface temperature variation and its impact on the atmosphere and ocean: A review 总被引:9,自引:1,他引:9
The importance of the diurnal variability of sea surface temperature (SST) on air-sea interaction is now being increasingly
recognized. This review synthesizes knowledge of the diurnal SST variation, mainly paying attention to its impact on the atmosphere
or the ocean. Diurnal SST warming becomes evident when the surface wind is weak and insolation is strong. Recent observations
using satellite data and advanced instruments have revealed that a large diurnal SST rise occurs over wide areas in a specific
season, and in an extreme case the diurnal amplitude of SST exceeds 5 K. The large diurnal SST rise can lead to an increase
in net surface heat flux from the ocean of 50–60 Wm−2 in the daytime. The temporal mean of the increase exceeds 10 Wm−2, which will be non-negligible for the atmosphere. A few numerical experiments have indicated that the diurnal SST variation
can modify atmospheric properties over the Pacific warm pool or a coastal sea, but the processes underlying the modification
have not yet been investigated in detail. Furthermore, it has been shown that the diurnal change of ocean mixing process near
the surface must be considered correctly in order to reproduce SST variations on an intraseasonal scale in a numerical model.
The variation of mixed-layer properties on the daily scale is nonlinearly related to the intraseasonal variability. The mixed-layer
deepening/shoaling process on the daily scale will also be related to biological and material circulation processes. 相似文献
39.
Research and development of the New Generation Sea Surface Temperature for Open Ccean (NGSST-O) product and its demonstration operation 总被引:1,自引:0,他引:1
Futoki Sakaida Hiroshi Kawamura Shin Takahashi Teruhisa Shimada Yoshimi Kawai Kohtaro Hosoda Lei Guan 《Journal of Oceanography》2009,65(6):859-870
Real-time generation and distribution of the New Generation Sea Surface Temperature for Open Ocean (NGSST-O) product began
in September 2003 as a demonstration operation of the Global Ocean Data Assimilation Experiment (GODAE) High-Resolution Sea
Surface Temperature Pilot Project. Satellite sea surface temperature (SST) observations from infrared radiometers (AVHRR,
MODIS) and a microwave radiometer (AMSR-E) are objectively merged to generate the NGSST-O product, which is a quality-controlled,
cloud-free, high-spatial-resolution (0.05° gridded), wide-coverage (13–63° N, 116–166° E), daily SST digital map. The NGSST-O
demonstration operation system has been developed in cooperation with the Japanese Space Agency (JAXA) and has produced six
years of continuous data without gaps. Comparison to in situ SSTs measured by drifting buoys indicates that the root mean-square error of NGSST-O has been kept at approximately 0.9°C. 相似文献
40.
Atsushi Inagaki Marieta Cristina L. Castillo Yoshimi Yamashita Manabu Kanda Hiroshi Takimoto 《Boundary-Layer Meteorology》2012,142(2):207-222
Instantaneous flow structures “within” a cubical canopy are investigated via large-eddy simulation. The main topics of interest
are, (1) large-scale coherent flow structures within a cubical canopy, (2) how the structures are coupled with the turbulent
organized structures (TOS) above them, and (3) the classification and quantification of representative instantaneous flow
patterns within a street canyon in relation to the coherent structures. We use a large numerical domain (2,560 m × 2,560 m ×
1,710 m) with a fine spatial resolution (2.5 m), thereby simulating a complete daytime atmospheric boundary layer (ABL), as
well as explicitly resolving a regular array of cubes (40 m in height) at the surface. A typical urban ABL is numerically
modelled. In this situation, the constant heat supply from roof and floor surfaces sustains a convective mixed layer as a
whole, but strong wind shear near the canopy top maintains the surface layer nearly neutral. The results reveal large coherent
structures in both the velocity and temperature fields “within” the canopy layer. These structures are much larger than the
cubes, and their shapes and locations are shown to be closely related to the TOS above them. We classify the instantaneous
flow patterns in a cavity, specifically focusing on two characteristic flow patterns: flushing and cavity-eddy events. Flushing
indicates a strong upward motion, while a cavity eddy is characterized by a dominant vortical motion within a single cavity.
Flushing is clearly correlated with the TOS above, occurring frequently beneath low-momentum streaks. The instantaneous momentum
and heat transport within and above a cavity due to flushing and cavity-eddy events are also quantified. 相似文献