The Drinking Water State Revolving Fund Helps Ground Water Systems Deliver Public Health Protection     

Peter E. Shanaghan  Howard E. Rubin  Ian P. Kline  Rudd W. Coffey 《Ground Water Monitoring & Remediation》2006,26(3):46-50

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一种多前缘多阈值的波形重构算法   总被引：5，自引：0，他引：5       下载免费PDF全文

常晓涛  李建成  郭金运  黄金维 《地球物理学报》2006,49(6):1629-1634

为了改善近海测高精度,本文对近海测高波形的特征进行了研究,并在现有算法的基础上提出基于波前缘识别算法的多前缘多阈值波形重构方法.然后将该方法用于中国近海的卫星测高波形数据的处理,得到精度与分辨率更好的海面高数据.作为验证,将此海面高数据换算为重力异常并与船测重力进行比较,结果显示该方法可以明显提高卫星测高精度.  相似文献   

Joint NANCAY RADIOHELIOGRAPH AND LASCO OBSERVATIONS OF CORONAL MASS EJECTIONS – II. The 9 July 1996 Event     

M. Pick  D. Maia  A. Kerdraon  R. Howard  G. E. Brueckner  D. J. Michels  S. Paswaters  R. Schwenn  P. Lamy  A. Llebaria  G. Simnett  L. J. Lanzerotti  H. Aurass 《Solar physics》1998,181(2):455-468

The development of a coronal mass ejection on 9 July 1996 has been analyzed by comparing the observations of the LASCO/SOHO coronagraphs with those of the Nancay radioheliograph. The spatial and temporal evolution of the associated radioburst is complex and involves a long-duration continuum. The analysis of the time sequence of the radio continuum reveals the existence of distinct phases associated with distinct reconnection processes and magnetic restructuring of the corona. Electrons are accelerated in association with these reconnection processes. An excellent spatial association is found between the position and extension of the radio source and the CME seen by LASCO. Furthermore, it is shown that the topology and evolution of the source of the radio continuum involve successive interactions between two systems of loops. These successive interactions lead to magnetic reconnection, then to a large scale coronal restructuring. Thus electrons of coronal origin may have access to the interplanetary medium in a large range of heliographic latitudes as revealed by the Ulysses observations.  相似文献   

Fast integration of low orbiter's trajectory perturbed by the earth's non-sphericity     

C. Hwang  M.-J. Lin 《Journal of Geodesy》1998,72(10):578-585

A fast algorithm is proposed to integrate the trajectory of a low obiter perturbed by the earth's non-sphericity. The algorithm uses a separation degree to define the low-degree and the high-degree acceleration components, the former computed rigorously, and the latter interpolated from gridded accelerations. An FFT method is used to grid the accelerations. An optimal grid type for the algorithm depends on the trajectory's permissible error, speed, and memory capacity. Using the non-spherical accelerations computed from EGM96 to harmonic degree 360, orbit integrations were performed for a low orbiter at an altitude of 170 km. For a separation degree of 50, the new algorithm, together with the predict-pseudo correct method, speeds up the integration by 145 times compared to the conventional algorithm while keeping the errors in position and velocity below 10⁻⁴ m and 10⁻⁷ m/s for a 3-day arc. Received: 28 July 1997 / Accepted: 1 April 1998  相似文献   

Post-Palaeozoic evolution of weathered landsurfaces in Uganda by tectonically controlled deep weathering and stripping     

R. G. Taylor  K. W. F. Howard 《Geomorphology》1998,25(3-4)

A model for the evolution of weathered landsurfaces in Uganda is developed using available geotectonic, climatic, sedimentological and chronological data. The model demonstrates the pivotal role of tectonic uplift in inducing cycles of stripping, and tectonic quiescence for cycles of deep weathering. It is able to account for the development of key landforms, such as inselbergs and duricrust-capped plateaux, which previous hypotheses of landscape evolution that are based on climatic or eustatic controls are unable to explain. Development of the Ugandan landscape is traced back to the Permian. Following late Palaeozoic glaciation, a trend towards warmer and more humid climates through the Mesozoic enabled deep weathering of the Jurassic/mid-Cretaceous surface in Uganda during a period of prolonged tectonic quiescence. Uplift associated with the opening South Atlantic Ocean terminated this cycle and instigated a cycle of stripping between the mid-Cretaceous and early Miocene. Deep weathering on the succeeding Miocene to recent (African) surface has occurred from Miocene to present but has been interrupted in the areas adjacent to the western rift where development of a new drainage base level has prompted cycles of stripping in the Miocene and Pleistocene.  相似文献   

Atmospheric effects in the remote sensing of phytoplankton pigments   总被引：3，自引：0，他引：3  

Howard R. Gordon  Dennis K. Clark 《Boundary-Layer Meteorology》1980,18(3):299-313

We investigate the accuracy with which relevant atmospheric parameters must be estimated to derive phytoplankton pigment concentrations (chlorophyll a plus phaeophytin a ) of a given accuracy from measurements of the ocean's apparent spectral radiance at satellite altitudes. The analysis is limited to an instrument having the characteristics of the Coastal Zone Color Scanner scheduled to orbit the Earth on NIMBUS-G. A phytoplankton pigment algorithm is developed which relates the pigment concentration (C) to the three ratios of upwelling radiance just beneath the sea surface which can be formed from the wavelengths () 440, 520 and 550 nm. The pigment algorithm explains from 94 to 98% of the variance in log₁₀ C over three orders of magnitude in pigment concentration. This is combined with solutions to the radiative transfer equation to simulate the ocean's apparent spectral radiance at satellite altitudes as a function of C and the optical properties of the aerosol, the optical depth of which is assumed to be proportioned to ^-n . A specific atmospheric correction algorithm, based on the assumption that the ocean is totally absorbing at 670 nm, is then applied to the simulated spectral radiance, from which the pigment concentration is derived. Comparison between the true and derived values of C show that: (1) n is considerably more important than the actual aerosol optical thickness; (2) for C 0299-1 0.2 g l^-1 acceptable concentrations can be determined as long as n is not overestimated; (3) as C increases, the accuracy with which n must be estimated, for a given relative accuracy in C, also increases; and (4) for C greater than about 0.5 g 1^-1, the radiance at 440 nm becomes essentially useless in determining C. The computations also suggest that if separate pigment algorithms are used for C 1gl^-1 and C 1 gl^-1, accuracies considerably better than ±± in log C can be obtained for C 1 g l^-1 with only a coarse estimate of n, while for C 10 gl^-1, this accuracy can be achieved only with very good estimates of n.Contribution No. 387 from the NOAA/ERL Pacific Environmental Laboratory.On leave from Department of Physics, University of Miami, Coral Gables, Florida.  相似文献   

Compositions of Formosan basalts and aspects of their petrogeneses     

Howard H. Lo  Gordon G. Goles 《Lithos》1976,9(2):149-159

Twenty-three basalts from northwestern Formosa were analyzed for Si, Ti, Al, Fe, Mg, Ca, Na, K, Rb, Sr, Hf, Co, Sc, Cr, Th, and 7 REE. Formosan alkalic basalts are generally similar to most alkalic basalts, and Formosan tholeiites are somewhat similar to island arc and continental tholeiites in terms of trends in K/Rb, Rb/Sr, K/Sr, and Ca/Sr ratios. Compared to most submarine tholeiites, Formosan tholeiites are enriched in Rb relative to K and Sr, and enriched in Sr relative to K and Ca. Both types of Formosan basalts show, relative to chondritic proportions, enrichments in light REE which smoothly decrease through the heavy REE. Their REE patterns are similar to those observed in Dogo-Oki alkalic basalts, Hawaiian basalts, and Deccan Plateau basalt, but differ strikingly from those of Japanese tholeiites and oceanic ridge basalts. These relationships and contrasts suggest that Formosan basalts originated in a plagioclase-free portion of the upper mantle and at greater depths that did Japanese tholeiites and oceanic ridge basalts.  相似文献   

Planation surfaces: Peneplains,pediplains, and etchplains: George F. Adams (Editor). Benchmark Papers in Geology Vol. 22, Halstead Press, 1975, 476 pp., $28.00     

Arthur D. Howard 《Quaternary Research》1976,6(3):460-461

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Climatological aspects of the tropical convective boundary layer     

E. B. Kraus  Howard P. Hanson 《Boundary-Layer Meteorology》1974,6(1-2):219-233

The characteristics of a boundary layer depend both on conditions at the surface and in the interior of the medium. In the undisturbed tropics, the latter are largely determined by subsidence and by infrared radiational cooling. One-dimensional models are used to establish relationships between the inversion height, subsidence, upper-air humidity and sea-surface temperature. In particular, it is shown that a universally colder tropical ocean would probably be covered by more extensive clouds.Contribution No. 1700 Rosenstiel School of Marine and Atmospheric Science, University of Miami.  相似文献   

Surface history of some Apollo 17 lunar soils     

Robert L. Fleischer  Howard R. Hart 《Geochimica et cosmochimica acta》1974,38(10):1615-1623

Cosmic ray track densities in Apollo 17 soil samples are used to infer surface exposure times of soils from a trench at Van Serg Crater, from on and near a boulder at Camelot Crater, and from the position of the heat flow and neutron flux experiments (the ALSEP site). The topmost 2 cm of soil at Van Serg was exposed for 11 m.y., the top cm at Camelot for 36 m.y. A layering chronology and average deposition rate are proposed for the trench. For all soils the median track densities imply predispositional irradiation in the top 15 cm of the lunar surface for times that were long compared with the actual residence in the stratigraphic positions from which the soils were collected. Van Serg crater is inferred to have been formed approximately 24 m.y. ago.  相似文献