Air–Sea/Land Interaction in the Coastal Zone     

Andrey A. Grachev  Laura S. Leo  Harindra J. S. Fernando  Christopher W. Fairall  Edward Creegan  Byron W. Blomquist  Adam J. Christman  Christopher M. Hocut 《Boundary-Layer Meteorology》2018,167(2):181-210

Atmospheric turbulence measurements made at the U.S. Army Corps of Engineers Field Research Facility (FRF) located on the Atlantic coast near the town of Duck, North Carolina during the CASPER-East Program (October–November 2015) are used to study air–sea/land coupling in the FRF coastal zone. Turbulence and mean meteorological data were collected at multiple levels (up to four) on three towers deployed at different landward distances from the shoreline, with a fourth tower located at the end of a 560-m-long FRF pier. The data enable comparison of turbulent fluxes and other statistics, as well as investigations of surface-layer scaling for different footprints, including relatively smooth sea-surface conditions and aerodynamically rough dry inland areas. Both stable and unstable stratifications were observed. The drag coefficient and diurnal variation of the sensible heat flux are found to be indicators for disparate surface footprints. The drag coefficient over the land footprint is significantly greater, by as much as an order of magnitude, compared with that over the smooth sea-surface footprint. For onshore flow, the internal boundary layer in the coastal zone was either stable or (mostly) unstable, and varied dramatically at the land-surface discontinuity. The offshore flow of generally warm air over the cooler sea surface produced a stable internal boundary layer over the ocean surface downstream from the coast. While the coastal inhomogeneities violate the assumptions underlying Monin–Obukhov similarity theory (MOST), any deviations from MOST are less profound for the scaled standard deviations and the dissipation rate over both water and land, as well as for stable and unstable conditions. Observations, however, show a poor correspondence with MOST for the flux-profile relationships. Suitably-averaged, non-dimensional profiles of wind speed and temperature vary significantly among the different flux towers and observation levels, with high data scatter. Overall, the statistical dependence of the vertical gradients of scaled wind speed and temperature on the Monin–Obukhov stability parameter in the coastal area is weak, if not non-existent.  相似文献   

Investigation of Hydraulic Fracture Propagation Using a Post-Peak Control System Coupled with Acoustic Emission     

Li-Hsien Chen  Wei-Chih Chen  Yao-Chung Chen  Leo Benyamin  An-Jui Li 《Rock Mechanics and Rock Engineering》2015,48(3):1233-1248

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Thermal reservoir modeling in petroleum geomechanics     

Shunde Yin  Maurice B. Dusseault  Leo Rothenburg 《国际地质力学数值与分析法杂志》2009,33(4):449-485

Thermal oil recovery processes involve high pressures and temperatures, leading to large volume changes and induced stresses. These cannot be handled by traditional reservoir simulation because it does not consider coupled geomechanics effects. In this paper we present a fully coupled, thermal half‐space model using a hybrid DDFEM method. A finite element method (FEM) solution is adopted for the reservoir and the surrounding thermally affected zone, and a displacement discontinuity method is used for the surrounding elastic, non‐thermal zone. This approach analyzes stress, pressure, temperature and volume change in the reservoir; it also provides stresses and displacements around the reservoir (including transient ground surface movements) in a natural manner without introducing extra spatial discretization outside the FEM zone. To overcome spurious spatial temperature oscillations in the convection‐dominated thermal advection–diffusion problem, we place the transient problem into an advection–diffusion–reaction problem framework, which is then efficiently addressed by a stabilized finite element approach, the subgrid‐scale/gradient subgrid‐scale method. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

HIV and AIDS in Africa: a geographic analysis at multiple spatial scales   总被引：1，自引：0，他引：1  

Ezekiel Kalipeni  Leo C. Zulu 《GeoJournal》2012,77(4):505-523

This study offers an alternative method rooted in GIS techniques and spatial analysis to estimate HIV/AIDS prevalence over space from an incomplete surveillance data set and explain the variation of those estimates. The results clearly show that the HIV/AIDS epidemic is complex and that it is interconnected with other geographic, historical, economic and cultural phenomena which help explain its spatial spread and variation. The regression models which were developed in this paper illustrated that variables which measure the historical context of colonialism such as resource exploitation and labor migration, gender, culture, contemporary global forces, poverty and disease burden have all contributed variously to the rapid spread of this disease both in space and time. The policy implication is that concentrating on behavior change or therapy alone may not turn the epidemic around. The attack needs to be multifaceted and interdisciplinary taking into consideration the context and the economic and social realities at multiple spatial scales.  相似文献   

Relationships between tissue concentrations of paralytic shellfish toxins and antioxidative responses of clams, Ruditapes philippinarum     

Choi NM  Yeung LW  Siu WH  So IM  Jack RW  Hsieh DP  Wu RS  Lam PK 《Marine pollution bulletin》2006,52(5):572-578

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“The ESA XMM-Newton Science Operations Centre: Making Basic Space Science Available to the Whole Scientific World”     

Carlos Gabriel  Matteo Guainazzi  Leo Metcalfe 《Astrophysics and Space Science》2006,305(3):315-320

XMM-Newton is a major X-ray observatory of the European Space Agency (ESA). Its observing time is open to astronomers from the whole scientific community on a peer reviewed competitive basis. The Science Operations Centre, located at ESA’s premises in Villafranca del Castillo, Spain, is responsible for the instrument operations, as well as for all the tasks related to facilitating the scientific exploitation of the data which the mission has been producing since its launch in December 1999. Among them, one may list:

•	distribution of scientific data in different formats, from raw telemetry, up to processed and calibrated high-level science products, such as images, spectra, source lists, etc;
•	development and distribution of dedicated science analysis software, as well as of continuously updated instrument calibration;
•	regular organisation of training workshops (free of cost), for potential users of XMM-Newton data, where the procedures and techniques to successfully reduce and analyze XMM-Newton data are introduced;
•	access to the data through state-of-the-art, in-house-developed archival facilities, either through the Internet or via CD-ROM;
•	continuously updated documentation on all aspects of spacecraft and instrument operations, data reduction and analysis;
•	maintenance of a comprehensive set of project web pages;
•	a competent and responsive HelpDesk, providing dedicated support to individual XMM-Newton users.

Everyone can be an XMM-Newton observer. So far, astronomers from 36 countries submitted observing programs. Public data can be accessed by every scientist in the world through the XMM-Newton Science Archive (XSA).Despite all these efforts, one can’t help noticing an asymmetric level of scientific exploitation in the realm of X-ray astronomy between developing and developed countries. The latter have traditionally enjoyed the comparative advantage of deeper know-how, deriving from direct experience in hardware and mission development. The XMM-Newton Science Operations Centre’s efforts act to alleviate this situation through, for example, increasing the usage of the web for data and information dissemination, as well as by supporting actively such initiatives as the COSPAR Capacity-Building Workshops, specifically designed to create long-lasting bridges between researchers in developing and developed countries.  相似文献   

Radio frequency interference measurements in Indonesia     

Taufiq Hidayat  Achmad Munir  Budi Dermawan  Anton Timur Jaelani  Stéphane Léon  Dading Hadi Nugroho  Andriyan Bayu Suksmono  Putra Mahasena  Premana Wardayanti Premadi  Dhani Herdiwijaya  Chatief Kunjaya  Zadrach Ledoufij Dupe  Budi Brahmantyo  Denny Mandey  Muhammad Yusuf  Hesti Retno Tri Wulandari  Falahuddin Arief  Muhammad Irfan  Agus Triono Puri Jatmiko  Evan Irawan Akbar  Hery Leo Sianturi  Jehunias Leonidas Tanesib  Ali Warsito  Judhistira Aria Utama 《Experimental Astronomy》2014,37(1):85-108

We report the first measurements of radio frequency spectrum occupancy performed at sites aimed to host the future radio astronomy observatory in Indonesia. The survey is intended to obtain the radio frequency interference (RFI) environment in a spectral range from low frequency 10 MHz up to 8 GHz. The measurements permit the identification of the spectral occupancy over those selected sites in reference to the allocated radio spectrum in Indonesia. The sites are in close proximity to Australia, the future host of Square Kilometre Array (SKA) at low frequency. Therefore, the survey was deliberately made to approximately adhere the SKA protocol for RFI measurements, but with lower sensitivity. The RFI environment at Bosscha Observatory in Lembang was also measured for comparison. Within the sensitivity limit of the measurement equipment, it is found that a location called Fatumonas in the surrounding of Mount Timau in West Timor has very low level of RFI, with a total spectrum occupancy in this measured frequency range being about 1 %, mostly found at low frequency below 20 MHz. More detailed measurements as well as a strategy for a radio quiet zone must be implemented in the near future.  相似文献   

Climate projections over CORDEX Africa domain using the fifth-generation Canadian Regional Climate Model (CRCM5)     

René Laprise  Leticia Hernández-Díaz  Kossivi Tete  Laxmi Sushama  Leo Šeparović  Andrey Martynov  Katja Winger  Michel Valin 《Climate Dynamics》2013,41(11-12):3219-3246

Following the CORDEX experimental protocol, climate simulations and climate-change projections for Africa were made with the new fifth-generation Canadian Regional Climate Model (CRCM5). The model was driven by two Global Climate Models (GCMs), one developed by the Max-Planck-Institut für Meteorologie and the other by the Canadian Centre for Climate Modelling and Analysis, for the period 1950–2100 under the RCP4.5 emission scenario. The performance of the CRCM5 simulations for current climate is discussed first and compared also with a reanalysis-driven CRCM5 simulation. It is shown that errors in lateral boundary conditions and sea-surface temperature from the GCMs have deleterious consequences on the skill of the CRCM5 at reproducing specific regional climate features such as the West African Monsoon and the annual cycle of precipitation. For other aspects of the African climate however the regional model is able to add value compared to the simulations of the driving GCMs. Climate-change projections for periods until the end of this century are also analysed. All models project a warming throughout the twenty-first century, although the details of the climate changes differ notably between model projections, especially for precipitation changes. It is shown that the climate changes projected by CRCM5 often differ noticeably from those of the driving GCMs.  相似文献   

Concepts and science for coastal erosion management - An introduction to the Conscience framework     

Marcel Marchand  Agustin Sanchez-ArcillaMaria Ferreira  Jeremy GaultJosé A. Jiménez  Marina MarkovicJan Mulder  Leo van RijnAdrian St?nic?  Wojciech SuliszJames Sutherland 《Ocean & Coastal Management》2011,54(12):859-866

The main objective of the Conscience project was to develop and test concepts, guidelines and tools for the sustainable management of erosion along the European coastline, based on the best available scientific knowledge and on existing practical experience. Four concepts are potentially capable of providing the nexus between scientific knowledge and management: coastal resilience, coastal sediment cell, favourable sediment status and strategic sediment reservoir. The project has tested the use of these concepts and found that they are useful, provided that they are positioned and linked within a logical structure that we shall call the Conscience “Frame of Reference”, defined in time and space and supported through data and monitoring. Practical experience in six coastal sites in Europe has shown that the use of this Frame of Reference together with these concepts can make management objectives explicit and transparent. It can therefore support the design of an appropriate, resilience based coastal erosion management practice.  相似文献   

Revisiting mobile bed tests for beach profile dynamics     

Agustín Sánchez-Arcilla  Iván Cáceres  Leo van Rijn  Joachim Grüne 《Coastal Engineering》2011

The levels of uncertainty for morphodynamic analysis in the present state of art require field measurements and, whenever possible, large scale mobile bed tests to reproduce what happens in Nature under controlled conditions. Following this idea, the paper will revise the procedure to design reduced scale mobile bed tests, including the criteria for scaling and those for selecting an experimental facility.  相似文献