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NORIYUKI NASU SHOJI FUJII KANTARO FUJIOKA CHIAKI IGARASHI HOTAKA KAWAHATA HARUNA MAPPA KENJI KONISHI TAKEO TANAKA TAKASHI SHIMODA 《Boreas: An International Journal of Quaternary Research》1983,12(1):13-16
Tree stumps in a standing position have been discovered in 20 to 40 meters of water in Toyama Bay, Japan. Radiocarbon dated samples from two of these stumps yielded ages of 8.480±70 and 9.060±80 years B.P., indicating that the stumps are remnants of a forest that existed during thc early Holocene. 相似文献
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This paper provides some additional evidence supporting the necessary (but insufficient) condition for the formation of stream meandering proposed by Nakagawa: where Me is a non-dimensional parameter, τs, and τb are the average bank and bed shear stress respectively, ps and pb are the average bank and bed wetted perimeter of a half-channel respectively, and K?0.2 is the critical value of the parameter estimated from experimental data. Provided the criterion is satisfied, the main thread of the stream meanders in the non-erodible channel, and the maximum amplitude amax, the angle a between the channel central axis and oblique crest line of the surface wave, and the mean wavelength L of the main thread decrease as the non-dimensional parameter Me increases. 相似文献
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实时 G P S可降水量资料的变分同化个例研究 总被引:1,自引:1,他引:1
用实时GPS可降水量(Precipitable Water, PW)资料GPSPW,针对2007年7月2-3日发生在日本九州南部地区的一次梅雨锋降水过程,设计控制试验和4个同化试验,利用WRF和WRF-Var模式进行三维变分同化研究,并用ETS评分客观评价各方案的预报效果.结果表明:实时GPSPW同化能有效地改进模式初始时刻水汽场以及预报时间内(0~6 h)的PW.背景误差水平尺度调节系数的大小对水汽场的调整范围和PW的改进程度有一定影响.GPSPW的实时性能提高降水预报业务的实时性. 相似文献
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非海相双壳类江西蛤(Jiangxiella)首次发现于日本 总被引:2,自引:0,他引:2
首次报道日本西南部发现的晚三叠世非海相双壳类江西蛤(Jiangxiella),并讨论这一发现的意义。认为原产于湘、赣、粤地区的江西蛤是地理分布极有限的土著属,它在日本西南部的发现表明当时该区与华南东部的古地理关系极为密切,可能原属同一地块。 相似文献
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TAKEO NAKAGAWA 《Sedimentology》1983,30(1):117-127
ABSTRACT An account of stream meandering and river morphology is given for five experiments, each having different conditions at the wetted perimeter of the channel.
On the basis of the present experiments, it is proposed that a necessary (but insufficient) condition for the formation of stream meandering is an appropriately small ratio of total bank shear force to total bed shear force, both per unit length downstream . In mathematical form, the criterion is expressed by τs and τs are an average bank stress and bed stress, respectively, and p s and p b b are an average bank wetted perimeter and bed wetted perimeter of a half-channel, respectively. The value of α is evaluated by Kinoshita's (1957) experiment and others.
It is also found that the flow pattern, channel morphology and sand waves on the bed are dependent upon the boundary conditions at the wetted perimeter. 相似文献
On the basis of the present experiments, it is proposed that a necessary (but insufficient) condition for the formation of stream meandering is an appropriately small ratio of total bank shear force to total bed shear force, both per unit length downstream . In mathematical form, the criterion is expressed by τ
It is also found that the flow pattern, channel morphology and sand waves on the bed are dependent upon the boundary conditions at the wetted perimeter. 相似文献
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By HIROSHI TANIMOTO KEIICHI SATO TIM BUTLER MARK G. LAWRENCE JENNY A. FISHER MONIKA KOPACZ ROBERT M. YANTOSCA YUGO KANAYA SHUNGO KATO TOMOAKI OKUDA SHIGERU TANAKA JIYE ZENG 《Tellus. Series B, Chemical and physical meteorology》2009,61(2):394-407
The summer of 2003 was an active forest fire season in Siberia. Several events of elevated carbon monoxide (CO) were observed at Rishiri Island in northern Japan during an intensive field campaign in September 2003. A simulation with a global chemistry-transport model is able to reproduce the general features of the baseline levels and variability in the observed CO, and a source attribution for CO in the model suggests that the contribution from North Asia dominated, accounting for approximately 50% on average, with contributions of 7% from North America and 8% from Europe and 30% from oxidation of hydrocarbons. With consideration of recent emission estimates for East Asian fossil fuel and Siberian biomass burning sources, the model captures the timing and magnitude of the CO enhancements in two pollution episodes well (17 and 24 September). However, it significantly underestimates the amplitude during another episode (11–13 September), requiring additional CO emissions for this event. Daily satellite images from AIRS reveal CO plumes transported from western Siberia toward northern Japan. These results suggest that CO emissions from biomass burning in western Siberia in 2003 are likely underestimated in the inventory and further highlight large uncertainties in estimating trace gas emissions from boreal fires. 相似文献