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排序方式: 共有114条查询结果,搜索用时 729 毫秒
91.
92.
DISTRIBUTION OF AEROSOL EXTINCTION IN THE LOWER TROPOSPHERE BY MICRO-PULSE LIDAR OBSERVATION 下载免费PDF全文
The profiles of aerosol extinction coefficients are investigated by micro-pulse lidar(MPL)combined with the meteorological data in the lower troposphere at Meteorological ResearchInstitute(MRI).Japan.Larger extinction values of aerosol are demonstrated in the nocturnalstable air layer with larger Richardson number,and light wind velocities are favorable for aerosolconcentrating in the planetary boundary layer(PBL).But aerosol extinction coefficients showlarger values over the altitudes of 2.0 to 5.0km where correspond to higher relative humidity(RH).The tops of PBL identified by the aerosol extinction profiles almost agree with ones byradiosonde data.The diurnal variations of aerosol extinction profiles are clearly displayed,intensive aerosol layers usually are formed over the period of mid-morning to 1400 Loeal Time(LT).then elapse in the cloudless late afternoon and nighttime.Thermal eonvection or turbulenttransport from the surfaee probably dominates these temporal and spatial changes of aerosoldistribution. 相似文献
93.
WU Yonghu HU Huanling ZHOU Jun Nobuo TAKEUCHI Akihiro LICHIYAMA Shoji ASANO 《Acta Meteorologica Sinica》2000,14(4):503-508
The profiles of aerosol extinction coefficients are investigated by micro-pulse lidar(MPL) combined with the meteorological data in the lower troposphere at Meteorological Research Institute(MRI).Japan.Larger extinction values of aerosol are demonstrated in the nocturnal stable air layer with larger Richardson number,and light wind velocities are favorable for aerosol concentrating in the planetary boundary layer(PBL).But aerosol extinction coefficients show larger values over the altitudes of 2.0 to 5.0km where correspond to higher relative humidity(RH).The tops of PBL identified by the aerosol extinction profiles almost agree with ones by radiosonde data.The diurnal variations of aerosol extinction profiles are clearly displayed,intensive aerosol layers usually are formed over the period of mid-morning to 1400 Loeal Time(LT).then elapse in the cloudless late afternoon and nighttime.Thermal eonvection or turbulent transport from the surfaee probably dominates these temporal and spatial changes of aerosol distribution. 相似文献
94.
95.
We present the study of the star formation histories (SFHs) of a sample of Local Group dwarf galaxies (LGDGs), via the analysis
and modelling, with the means of an evolutionary stellar population synthesis, of their colour-magnitude (CM) diagrams. It
appears that important parameters to describe the SFHs are star formation rate (SFR) and duration of star formation. We find
a possible correlation between the mass and the SFRs. The correlation might be the origin of the observed luminosity-metallicity
relation in the LGDGs. A well-defined correlation between the durations of star formation and the distance from M31 or the
Galaxy indicates that the current early-type dwarf galaxies should have been transformed from late-type by strong tidal force
of the massive galaxies.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
96.
We investigated the effects of seawater acidification induced by ocean CO2 sequestration on bathypelagic prokaryotes. We simulated acidification conditions by bubbling high-CO2 air or adding chemical buffer solutions to seawater samples in order to examine changes in total cell counts, heterotrophic
production rate, direct viable cell count, and relative abundance of Bacteria and Archaea. Considerable suppression of prokaryotic activities was observed at pH 7.0 or lower, especially in samples enriched with
organic matter. The relative abundance of Archaea increased with increasing CO2 concentration. We found that seawater acidification can potentially alter heterotrophic activities and community structure
of bathypelagic prokaryotes. 相似文献
97.
Characteristics of Tsunamis Propagating over Oceanic Ridges: Numerical Simulation of the 1996 Irian Jaya Earthquake Tsunami 总被引:1,自引:0,他引:1
The 1996 Irian Jaya earthquake tsunami was simulated by using the numerical model based on the linear long wave theory including Coriolis force in the spherical coordinate system. The numerical modeling result at Chichijima is in good agreement with the observed tide gauge data. The distinctive oscillation at Chichijima can be interpreted as the formation of boundary waves, so called ridge waves that are excited on the South-Honshu ridge. The mechanism of tsunami propagation trapped on an oceanic ridge is analyzed with the simple ridge model. The result explains the characteristics of ridge waves excited on theSouth-Honshu ridge. 相似文献
98.
The present study investigates the way an ocean filled with homogeneous warm water is cooled by prescribing cold water formation inside the ocean in the southern part of the southern hemisphere using multi-level numerical models. Cooling of the whole ocean starts with introduction of the cold water from the formation region into the deepest part of the ocean in the equatorial and eastern boundary regions by Kelvin wave-type density currents. The cold water along the eastern boundary extends westward as a Rossby wave-type density current setting up an interior poleward flow, and hits the western boundary to form a northward flowing boundary current in the northern hemisphere. Only then does the western boundary current cross the equator. Cooling of the rest of the ocean basin is accomplished by upwellings in the interior and also along the coasts. During this introduction the cold water is mixed with surrounding warm waters, and the thermocline, rather than forming just below the top level where heating is imposed, tends to spread down to deeper depths. Consequently the circulation at a steady state has a significant vertical structure such that the maximum upwelling in the interior occurs in the mid-depths, and only the deeper part of the deep ocean yields the Stommel and Arons circulation pattern. In the equatorial region higher vertical mode motions dominate, and a set of alternating zonal jets forms along the equator. 相似文献
99.
Nobuo Suginohara 《Journal of Oceanography》1974,30(1):23-33
On the assumption that motions of the barotropic mode are horizontally nondivergent, action of the wind stress with longshore variation on a two-layer ocean adjacent to the meridional east coast is studied. Only the equatorward wind stress is considered. Along the east coast, upwelling is induced by the direct effect of the coast and is confined in a narrow strip with the width of the order of the internal radius of deformation. The upwelling propagates poleward with the internal gravity wave speed. Coastal upwelling induced by the wind stress with longshore variation may be interpreted as the generation and propagation of internal Kelvin waves. Associated with the coastal upwelling, the equatorward flow in the upper layer and the poleward flow in the lower layer are formed as an internal mode of motions. When the bottom topography with the continental shelf and slope is taken into account, occurrence of the poleward undercurrent is delayed by a few days because of the generation of continental shelf waves. And, after the forcing is stopped, the shelf waves propagate poleward away from the upwelling region and the poleward undercurrent fully develops. At the margin of the continental shelf, another upwelling region is induced and propagates poleward. 相似文献
100.
Takayuki Ishikawa Jinro Ukita Kay I. Ohshima Masaaki Wakatsuchi Takashi Yamanouchi Nobuo Ono 《Journal of Oceanography》1996,52(3):389-398
Coastal polynyas off East Queen Maud Land in Antarctica are examined using NOAA AVHRR infrared data. From image analyses, two locations of coastal polynyas in this region are identified; one in Breid Bay and the other along the shelf break. The areal coverage of the Breid Bay polynya is significantly related to the strength of katabatic winds, which maintain their strength over the coastal sea due to land topography favoring for their confluence, thereby being capable of removing newly formed ice. Land fast ice in the eastern part of the bay also plays an additional role in the formation mechanism. It is also found that the areal coverage of coastal polynyas in this region fluctuate coherently. Moreover, these fluctuations correspond to the synoptic index, which measures the strength of the offshore wind, with their peaks closely associated with the areal peaks. These facts strongly suggest the influence of synoptic scale weather on the formation and maintenance of polynyas in this region. 相似文献