Aerodynamic Scaling for Estimating the Mean Height of Dense Canopies   总被引：1，自引：1，他引：0  

Taro Nakai  Akihiro Sumida  Kazuho Matsumoto  Ken’ichi Daikoku  Shin’ichi Iida  Hotaek Park  Mie Miyahara  Yuji Kodama  Alexander V. Kononov  Trofim C. Maximov  Hironori Yabuki  Toshihiko Hara  Takeshi Ohta 《Boundary-Layer Meteorology》2008,128(3):423-443

We used an aerodynamic method to objectively determine a representative canopy height, using standard meteorological measurements. The canopy height may change if the tree height is used to represent the actual canopy, but little work to date has focused on creating a standard for determining the representative canopy height. Here we propose the ‘aerodynamic canopy height’ h _a as the most effective means of resolving the representative canopy height for all forests. We determined h _a by simple linear regression between zero-plane displacement d and roughness length z ₀, without the need for stand inventory data. The applicability of h _a was confirmed in five different forests, including a forest with a complex canopy structure. Comparison with stand inventory data showed that h _a was almost equivalent to the representative height of trees composing the crown surface if the forest had a simple structure, or to the representative height of taller trees composing the upper canopy in forests with a complex canopy structure. The linear relationship between d and z ₀ was explained by assuming that the logarithmic wind profile above the canopy and the exponential wind profile within the canopy were continuous and smooth at canopy height. This was supported by observations, which showed that h _a was essentially the same as the height defined by the inflection point of the vertical profile of wind speed. The applicability of h _a was also verified using data from several previous studies.  相似文献   

Lithostratigraphy and biostratigraphy of the Campanian–Maastrichtian Toyajo Formation in Wakayama, southwestern Japan     

Akihiro Misaki  Haruyoshi Maeda 《Cretaceous Research》2009,30(6):1398-1414

The Upper Cretaceous Toyajo Formation is distributed around the Mt. Toyajo in the Aridagawa area, Wakayama, southwestern Japan. The formation is subdivided into three newly defined members, the Nakaibara Siltstone Member, Hasegawa Muddy Sandstone Member, and Buyo Sandstone Member, in ascending order. Close field observation elucidated the detailed biostratigraphy of the Toyajo Formation, and high-precision biostratigraphic correlation was made with the Yezo Group in Hokkaido (northern Japan) and Sakhalin and the Izumi Group in southwestern Japan.The Toyajo Formation contains diversified lower Campanian to upper Campanian heteromorph ammonoid assemblages, including Eubostrychoceras and Scaphites. Discovery of the heteromorph fauna demonstrates that scaphitid ammonoids survived until Campanian time in the northwestern Pacific region. Although Eubostrychoceras elongatum has been known in the northeastern Pacific region, the occurrence of this species in the northwestern Pacific region has been uncertain before. The rich occurrence of E. elongatum in the Aridagawa area indicates that this species was distributed widely in the northern Pacific realm.The Toyajo Formation is similar to the Izumi Group in various geologic features, and may indicate that the Toyajo Formation was deposited in a strike-slip basin along the Chichibu Belt formed by the movement along the Kurosegawa Tectonic Zone in the latest Cretaceous, like the Izumi Group, along the Median Tectonic Line.  相似文献   

国际全球变化研究发展态势文献计量评价   总被引：1，自引：0，他引：1  

张志强  王雪梅 《地球科学进展》2007,22(7):0-765

-全球变化研究是国际上地球系统综合研究的重大跨学科研究领域。随着全球环境问题的日益突出，国际上先后组织发起了全球环境变化研究的四大科学计划WCRP、IGBP、IHDP、DIVERSITAS及其组成的地球系统科学联盟ESSP，开展对全球变化和地球系统科学的研究。当前，全球变化问题不仅是科学界关注和研究的问题，也是政治界、经济界都关注的重大问题。 科技文献能够反映科学前沿的发展动态。对SCIE和SSCI数据库收录的全球变化研究文献进行统计，从文献计量学的角度，分析国际全球变化研究领域的发展态势，了解中国全球变化研究的国际影响力。可以看出：国际上全球变化研究的论文数量一直呈增长趋势，以地球科学多学科、生态学、环境科学、自然地理学、植物学等学科领域为主。中国自2000年以来在该领域的发文数量增长较快，特别是中国科学院的发文量已进入国际前列，但中国在该研究领域尚缺少高影响力的论文。  相似文献   

Investigation on the Performance of Pipe Roof Method Adjacent to the Underground Construction     

Ma  Peng  Shimada  Hideki  Sasaoka  Takashi  Hamanaka  Akihiro  Dintwe  Tumelo K. M.  Pan  Donjiang 《Geotechnical and Geological Engineering》2021,39(6):4677-4687

In this paper, the behaviour of the pipe roof method with different pipe roofs disposition schemes including the pipe roof gate system and L-shaped system is discussed in terms of ground settlement reduction in the condition of underground space construction adjacent to the existing structure by using numerical simulation method. Considering the construction sequences of parallel underground tunnels with rectangular cross sections, the appropriate parameters and ground response characteristics of the corresponding pipe roof methods are evaluated by the ground surface displacement. The results indicated that the construction impacts from new buildings can be reduced by the pipe roof method. However, the theoretical performance of pipe roofs is highly dependent on the spacing between two structures. Generally, the L-shaped system is more effective in case of the distance (D) that is less than or equal to 1/2 width of box culvert (R) under the condition of a new structure constructed nearby the existing building. When two structures are constructed simultaneously, the excavation and the construction of structures influence each other reciprocally. The conclusions could provide a reference for the pipe roof method with the application scenario of adjacent building protection.

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Distribution of manufactured floating marine debris in near-shore areas around Japan     

Shiomoto A  Kameda T 《Marine pollution bulletin》2005,50(11):1430-1432

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Kinetics of nitrate and ammonium uptake by the natural populations of marine phytoplankton in the surface water of the Oyashio region during spring and summer     

Akihiro Shiomoto  Katsuyuki Sasaki  Toru Shimoda  Satsuki Matsumura 《Journal of Oceanography》1994,50(5):515-529

The maximum uptake rate (_max) and affinity constant (K _s) for nitrate and ammonium were estimated in the surface water of offshore Oyashio in May (spring) and September (summer), 1990. The average _max/Chl.a for ammonium was 2.1 times larger than that of nitrate in both seasons. The average _max/Chl.a for both nitrogens were 3.5 times larger in summer than in spring. Water temperature and size composition of phytoplankton population were related to the seasonal difference in the _max/Chl.a. Phytoplankton population showed high affinity for both nitrogens in the spring and summer. In addition, the contribution of new production to total production was estimated by _max[_max–No₃/(_max–NO₃+_max–NH₄)]. The spring value was in the range of 0.26 to 0.45 (mean±SD=0.35±0.092), and the values in spring bloom were especially a little over 0.4. The summer value was in the range of 0.30 to 0.37 (0.34±0.04).  相似文献   

Geographical Variations in Prosome Length and Body Weight of Neocalanus Copepods in the North Pacific     

Toru Kobari  Kazuaki Tadokoro  Akihiro Shiomoto  Shinji Hashimoto 《Journal of Oceanography》2003,59(1):3-10

Geographical variations in prosome length and body weight of Neocalanus copepods (N. cristatus, N. plumchrus and N. flemingeri) were investigated on samples from North-South and East-West transects in the North Pacific during spring to early summer in 1998 and 1999. Southward and eastward increasing patterns were pronounced for water temperature, although no significant pattern was observed for chlorophyll a concentrations. All Neocalanus species showed large geographical variations in prosome length and body weight, being smaller in the southern and eastern waters. Comparing the relationship between prosome length and body weight, large deviations (lower body weight at a given prosome length) were evident for the eastern specimens of N. cristatus and N. plumchrus. In stepwise regression analysis, the geographical variations of prosome length and body weight revealed a significantly negative correlation with temperature variations. These results suggest that temperature is a more important environmental factor than chlorophyll a concentration in its effect on geographical variations in prosome length and body weight of Neocalanus copepods in the North Pacific. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Stability of genetic diversity in an intertidal goby population after exposure to tsunami disturbance          下载免费PDF全文

Shotaro Hirase  Minoru Ikeda  Shun Hayasaka  Wataru Iwasaki  Akihiro Kijima 《Marine Ecology》2016,37(5):1161-1167

Massive tsunami disturbances have potentially detrimental effects on genetic diversity and effective population size of coastal marine species, and evaluating these effects can be useful for devising conservation strategies for coastal marine environments. Local populations of the intertidal goby Chaenogobius annularis, which are distributed on scattered rocky beaches of the Japanese Archipelago, show demographic independence without overlapping generations, making this an ideal species with which to study the effects of tsunami disturbance on genetic diversity. Some of these populations were affected by the tsunami of the 2011 off the Pacific coast of Tohoku Earthquake. Here, we investigated the change in genetic diversity of a local population of this species, which was located close to the epicenter of the earthquake, across the cohorts before and after the tsunami and evaluated the impact of the tsunami disturbance. Genetic diversity was maintained after the tsunami, and no change in the effective population size was observed. Our results suggest that the tsunami disturbance has had no marked impact on the genetic diversity of C. annularis.  相似文献   

Purification of seawater contaminated with undegradable aromatic ring compounds using ozonolysis followed by titanium dioxide treatment   总被引：1，自引：0，他引：1  

Nakamura Y  Kobayashi F  Daidai M  Kurosumi A 《Marine pollution bulletin》2008,57(1-5):53-58

Treatment of aromatic ring compounds, 2,4-dichlorophenoxy acetic acid (2,4-D), 2,4,5-trichloro-phenoxy acetic acid (2,4,5-T), and bisphenol A, in the artificial seawater, i.e. Allen seawater, was carried out by ozonation and titanium dioxide (TiO2) photocatalyst treatment. Each compound was degraded and varnished within 30 min by only ozonolysis at pH 9.0 and at 20 degrees C, while the TOC value of each compound decreased gradually but reached almost constant value, i.e. about 70-80% of the initial value, at even 30 min of ozonation time. Ozonolysis (30 min of ozonation time) followed by TiO2 photocatalyst treatment (50h of reaction time) was a very effective method for decreasing the TOC values of aromatic ring compounds in the artificial seawater. In consequence, TOC values of 2,4-D, 2,4,5-T, and bisphenol A could be reduced to about 28, 21, and 34% of their initial values, respectively.  相似文献   

Primary productivity and solar radiation off Sanriku in May 1997     

Akihiro Shiomoto  Shinji Hashimoto  Takayuki Murakami 《Journal of Oceanography》1998,54(5):539-544

We measured the in situ primary production at four stations from the surface to 80 m off Sanriku in late May 1997. The depth-integrated daily primary production in the upper 80 m was estimated to be 391, 468, and 855 mgC m⁻²d⁻¹ in water from the Oyashio, and 336 mgC m⁻²d⁻¹ in the warm-core ring. The variation in the primary production was primarily due to the variation in phytoplankton activity (chlorophyll α-specific primary production). A combination of previous and present studies in water from the Oyashio and the warm-core ring suggested that phytoplankton activity is proportional to light intensity between 12 and 50 Ein m⁻²d⁻¹ which is close to the usual light condition (61–75 Ein m⁻²d⁻¹) off Sanriku in May and June. Light may be a limiting factor for phytoplankton off Sanriku in late spring and early summer.  相似文献