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1.
Infiltration experiments have been performed at three sites along a well-known catena under virgin tropical rain forest using a portable sprinkling infiltrometer. Experimentally determined infiltration curves are presented. Infiltration curves are also simulated on the basis of the Mein-Larson equation. The parameters for this model have been obtained from the infiltration curves (saturated conductivity) and simple soil moisture determinations (fillable porosity). The agreement between experimentally determined and modelled infiltration is reasonable, provided (a) saturated conductivity as derived from the experimental data is corrected, (b) a storage parameter, also derived from the experimental data, is added to the Mein-Larson model, and (c) the decline in soil porosity with depth is either small or occurs abruptly at shallow depth. Comparison of observed infiltration rates with rainfall intensity shows that Horton Overland Flow has to occur naturally at least on the middle and lower section of the catena. Despite the fact that most parameters can be estimated in principle from basic soil data, it remains advisable to obtain sprinkling infiltrometer field measurements, because of soil variability due to dynamic surface conditions, macroporosity, air entrapment, and irregularity of the wetting front. 相似文献
2.
主要介绍卫星天线控制系统中天线旋转定位控制的软硬件设计和实现。该部分的主要功能是:接收红外遥控器的信号;检测前面板上的按键信号;检测传感器反馈的信号;根据所得信号作出相应的动作。 相似文献
3.
A modified method of mine tremors location used in Lubin Copper Mine is presented in the paper. In mines where an intensive exploration is carried out a high accuracy source location technique is usually required. The effect of the flatness of the geophones array, complex geological structure of the rock mass and intense exploitation make the location results ambiguous in such mines. In the present paper an effective method of source location and location's error evaluations are presented, combining data from two different arrays of geophones. The first consists of uniaxial geophones spaced in the whole mine area. The second is installed in one of the mining panels and consists of triaxial geophones. The usage of the data obtained from triaxial geophones allows to increase the hypocenter vertical coordinate precision. The presented two-step location procedure combines standard location methods: P-waves directions and P-waves arrival times. Using computer simulations the efficiency of the created algorithm was tested. The designed algorithm is fully non-linear and was tested on the multilayered rock mass model of the Lubin Copper Mine, showing a computational better efficiency than the traditional P-wave arrival times location algorithm. In this paper we present the complete procedure that effectively solves the non-linear location problems, i.e. the mine tremor location and measurement of the error propagation. 相似文献
4.
Roles of Biogeochemical Processes in the Oceanic Carbon Cycle Described with a Simple Coupled Physical-Biogeochemical Model 总被引:1,自引:0,他引:1
Masahiko?FujiiEmail author Motoyoshi?Ikeda Yasuhiro?Yamanaka 《Journal of Oceanography》2005,61(5):803-815
To evaluate the contribution of biogeochemical processes to the oceanic carbon cycle and to calculate the ratio of calcium
carbonate to organic carbon downward export, we have incorporated biological and alkalinity pumps in the yoked high-latitude
exchange/interior diffusion-advection (YOLDA) model. The biogeochemical processes are represented by four parameters. The
values of the parameters are tuned so that the model can reproduce the observed phosphate and alkalinity distributions in
each oceanic region. The sensitivity of the model to the biogeochemical parameters shows that biological production rates
in the euphotic zone and decomposition depths of particulate matters significantly influence horizontal and vertical distributions
of biogeochemical substances. The modeled vertical fluxes of particulate organic phosphorus and calcium carbonate are converted
to vertical carbon fluxes by the biological pump and the alkalinity pump, respectively. The downward carbon flux from the
surface layer to the deep layer in the entire region is estimated to be 3.36 PgC/yr, which consists of 2.93 PgC/yr from the
biological pump and 0.43 PgC/yr from the alkalinity pump, which is consistent with previous studies. The modeled rain ratio
is higher with depth and higher in the Pacific and Indian Oceans than in the Atlantic Ocean. The global rain ratio at the
surface layer is calculated to be 0.14 to 0.15. This value lies between the lower and higher ends of the previous estimates,
which range widely from 0.05 to 0.25. This study indicates that the rain ratio is unlikely to be higher than 0.15, at least
in the surface waters. 相似文献
5.
Atmospheric forcing of the eastern tropical Pacific: A review 总被引:1,自引:8,他引:1
Jorge A. Amador Eric J. Alfaro Omar G. Lizano Victor O. Magaa 《Progress in Oceanography》2006,69(2-4):101
The increase in marine, land surface, atmospheric and satellite data during recent decades has led to an improved understanding of the air–sea interaction processes in the eastern tropical Pacific. This is also thanks to extensive diagnoses from conceptual and coupled ocean–atmosphere numerical models. In this paper, mean fields of atmospheric variables, such as incoming solar radiation, sea level pressure, winds, wind stress curl, precipitation, evaporation, and surface energy fluxes, are derived from global atmospheric data sets in order to examine the dominant features of the low level atmospheric circulations of the region. The seasonal march of the atmospheric circulations is presented to depict the role of radiative forcing on atmospheric perturbations, especially those dominating the atmosphere at low levels.In the tropics, the trade winds constitute an important north–south energy and moisture exchange mechanism (as part of the low level branch of the Hadley circulation), that determines to a large extent the precipitation distribution in the region, i.e., that associated with the Inter-Tropical Convergence Zone (ITCZ). Monsoonal circulations also play an important role in determining the warm season precipitation distribution over the eastern tropical Pacific through a large variety of air–sea–land interaction mechanisms. Westward traveling waves, tropical cyclones, low latitude cold air intrusions, and other synoptic and mesoscale perturbations associated with the ITCZ are also important elements that modulate the annual rainfall cycle. The low-level jets of the Gulf of California, the Intra-Americas Sea (Gulf of Mexico and Caribbean Sea) and Chocó, Colombia are prominent features of the eastern tropical Pacific low-level circulations related to sub-regional and regional scale precipitation patterns. Observations show that the Intra-Americas Low-Level Jet intensity varies with El Niño/Southern Oscillation (ENSO) phases, however its origin and role in the westward propagation and development of disturbances that may hit the eastern tropical Pacific, such as easterly waves and tropical cyclones, are still unclear. Changes in the intensity of the trade winds in the Caribbean Sea and the Gulf of Mexico (associated with eastern tropical Pacific wind jets) exert an important control on precipitation by means of wind–topography interactions. Gaps in the mountains of southern Mexico and Central America allow strong wind jets to pass over the continent imprinting a unique signal in sea surface temperatures and ocean dynamics of the eastern tropical Pacific.The warm pools of the Americas constitute an important source of moisture for the North American Monsoon System. The northeastern tropical Pacific is a region of intense cyclogenetic activity, just west of the coast of Mesoamerica. Over the oceanic regions, large-scale properties of key variables such as precipitation, moisture, surface energy fluxes and wind stress curl are still uncertain, which inhibits a more comprehensive view of the region and stresses the importance of regional field experiments. Progress has been substantial in the understanding of the ocean and atmospheric dynamics of the eastern tropical Pacific, however, recent observational evidence such as that of a shallow meridional circulation cell in that region, in contrast to the classic concept of the Hadley-type deep meridional circulation, suggests that more in situ observations to validate theories are still necessary.This paper is part of a comprehensive review of the oceanography of the eastern tropical Pacific Ocean. 相似文献
6.
平均大潮高潮面的科学定位和现实描述 总被引:4,自引:0,他引:4
在对平均大潮高潮面进行科学定位的基础上,进一步阐明了我国海岸线(岛屿岸线、明礁、灯塔)起算面的定义。引入了三个国标的定义和沿海五省制定的法律条例的规定,结合东海及其岛屿海岸线不同起算面的计算算例,论证了我国海岸线就是平均大潮高潮面形成的实际痕迹线,并以此作为海陆分界线的科学定位和现实意义,澄清了在这一领域存在的一些异议和模糊认识。同时,并就这一重要的基准面进行现实的描述,以期服务于当前我国沿海经济建设、海域使用管理、海岸带开发和有关专项调查以及海洋测绘事业中。 相似文献
7.
8.
9.
Jean Tournadre 《Marine Geodesy》2004,27(1):153-169
New rain flags based on the dual frequency capabilities of the new Jason Poseidon-2 and Envisat RA2 altimeters have been tested, developed and adopted for the operational processing of the altimeter data. Their validation conducted during the calibration/validation phases of the satellites is presented here. The Jason flag is validated by comparison with the TOPEX one, using the Tandem mission. The results show a very good agreement between the two sensors and the two rain flags The Envisat flag is validated by comparison with both Jason and TOPEX using global and collocated data sets. The results show similar performances for the three sensors. The f relations estimated during the calibration-validation period and presented here have been given to the altimeter ground processing facilities for operational use. 相似文献
10.
张训华 《海洋地质与第四纪地质》1994,14(4):95-100
本文简要介绍了局控项目《中国海区1∶50万区域地质编图(大连幅)》重力异常图、磁力异常图的编制过程,给出了一种以计算机为手段、实现编图自动化的新方法,并分析了该方法与以往编图方法的不同和优点,以国际分幅在中国海区开展区域地质编图尚属首次,在既无海区地质调查规范,又无海区地质调查编图规范的情况下,这一工作无异具有开创性。从理论上系统总结出一套切实可行的编图方法,对于编制中国海区区域地质调查编图规范以 相似文献