The effects of vertical shear and stratification on stationary rossby waves     

C. B. Fandry  L. M. Leslie 《地球物理与天体物理流体动力学》2013,107(1-4):305-332

Abstract

The generation of stationary Rossby waves by sources of potential vorticity in a westerly flow is examined here in the context of a two-layer, quasi-geostrophic, β-plane model. The response in each layer consists of a combination of a barotropic Rossby wave disturbance that extends far downstream of the source, and a baroclinic disturbance which is evanescent or wave-like in character, depending on the shear and degree of stratification. Contributions from each of these modes in each layer are strongly dependent on the basic flows in each layer; the degree of stratification; and the depths of the two layers. The lower layer response is dominated by an evanescent baroclinic mode when the upper layer westerlies are much larger than those in the lower layer. In this case, weak stationary Rossby waves of large wavelengths are confined to the upper layer and the disturbance in the lower layer is confined to the source region.

Increasing the upper layer flow (with the lower layer flow fixed) increases the Rossby wavelength and decreases the amplitude. Decreasing the lower layer flow (with the upper layer flow fixed) decreases the wavelength and increases the amplitude. Stratification increases the contribution from the barotropic wave-like mode and causes the response to be confined to the lower layer.

The finite amplitude response to westerly flow over two sources of potential vorticity is also considered. In this case stationary Rossby waves induced by both sources interact to reinforce or diminish the downstream wave pattern depending on the separation distance of the sources relative to the Rossby wavelength. For fixed separation distance, enhancement of the downstreatm Rossby waves will only occur for a narrow range of flow variables and stratification.  相似文献   

Combining a Detailed Building Energy Model with a Physically-Based Urban Canopy Model     

Bruno Bueno  Leslie Norford  Grégoire Pigeon  Rex Britter 《Boundary-Layer Meteorology》2011,140(3):471-489

A scheme that couples a detailed building energy model, EnergyPlus, and an urban canopy model, the Town Energy Balance (TEB), is presented. Both models are well accepted and evaluated within their individual scientific communities. The coupled scheme proposes a more realistic representation of buildings and heating, ventilation and air-conditioning (HVAC) systems, which allows a broader analysis of the two-way interactions between the energy performance of buildings and the urban climate around the buildings. The scheme can be used to evaluate the building energy models that are being developed within the urban climate community. In this study, the coupled scheme is evaluated using measurements conducted over the dense urban centre of Toulouse, France. The comparison includes electricity and natural gas energy consumption of buildings, building façade temperatures, and urban canyon air temperatures. The coupled scheme is then used to analyze the effect of different building and HVAC system configurations on building energy consumption, waste heat released from HVAC systems, and outdoor air temperatures for the case study of Toulouse. Three different energy efficiency strategies are analyzed: shading devices, economizers, and heat recovery.  相似文献   

Australian east coast rainfall decline related to large scale climate drivers   总被引：1，自引：0，他引：1  

Milton Samuel Speer  Lance M. Leslie  Alexandre O. Fierro 《Climate Dynamics》2011,36(7-8):1419-1429

Rainfall on the subtropical east coast of Australia has declined at up to 50?mm per decade since 1970. Wavelet analysis is used to investigate eight station and four station-averaged rainfall distributions along Australia??s subtropical east coast with respect to the El Ni?o-Southern Oscillation (ENSO), the inter-decadal Pacific oscillation (IPO) and the southern annular mode (SAM). The relationships are examined further using composite atmospheric circulation anomalies. Here we show that the greatest rainfall variability occurs in the 15?C30?year periodicity of the 1948?C1975 or ??cool?? phase of the IPO when the subtropical ridge is located sufficiently poleward for anomalous moist onshore airflow to occur together with high ENSO rainfall variability and high, negative phase, SAM variability. Thus, the mid-latitude westerlies are located at their most equatorward position in the Australian region. This maximizes tropospheric interaction of warm, moist tropical air with enhanced local baroclinicity over the east coast, and hence rainfall.  相似文献   

Trace element partitioning in the Fe-S-C system and its implications for planetary differentiation and the thermal history of ureilites     

Leslie A. Hayden  James A. Van Orman  Cyrena A. Goodrich 《Geochimica et cosmochimica acta》2011,75(21):6570-6583

Element partitioning in metal-light element systems is important to our understanding of planetary differentiation processes. In this study, solid-metal/liquid-sulfide, liquid-metal/liquid-sulfide and solid-metal/troilite partition coefficients (D) were determined for 18 elements (Ag, As, Au, Co, Cr, Cu, Ge, Ir, Ni, Os, Pd, Pt, Mo, Mn, Re, Ru, Se and W) in the graphite-saturated Fe-S-C system at 1 atm. Compared at the same liquid S concentration, the solid/liquid partition coefficients are similar to those in the Fe-S system, but there are systematic differences that appear to be related to interactions with carbon dissolved in the solid metal. Elements previously shown to be “anthracophile” generally have larger solid/liquid partition coefficients in the Fe-S-C system, whereas those that are not have similar or smaller partition coefficients in the Fe-S-C system. The partitioning of trace elements between C-rich and S-rich liquids is, in most cases, broadly similar to the partitioning between solid metal and S-rich liquid. The highly siderophile elements Os, Re, Ir and W are partitioned strongly into the C-rich liquid, with D ? 100. The partition coefficients for Pt, Ge and W decrease significantly at the transition to liquid immiscibility, while the partition coefficient for Mo increases sharply. The bulk siderophile element patterns of ureilite meteorities appear to be better explained by separation of S-rich liquid from residual C-rich metallic liquid at temperatures above the silicate solidus, rather than by separation of S-rich liquid from residual solid metal at lower temperatures.  相似文献   

Accounting for model error in risk assessments: Alternatives to adopting a bias towards conservative risk estimates in decision models     

Petros Gaganis  Leslie Smith 《Advances in water resources》2008

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Cross-shelf transport into nearshore waters due to shoaling internal tides in San Pedro Bay, CA     

Marlene Noble  Burt Jones  Peter Hamilton  Jingping Xu  George Robertson  Leslie Rosenfeld  John Largier   《Continental Shelf Research》2009,29(15):1768-1785

In the summer of 2001, a coastal ocean measurement program in the southeastern portion of San Pedro Bay, CA, was designed and carried out. One aim of the program was to determine the strength and effectiveness of local cross-shelf transport processes. A particular objective was to assess the ability of semidiurnal internal tidal currents to move suspended material a net distance across the shelf. Hence, a dense array of moorings was deployed across the shelf to monitor the transport patterns associated with fluctuations in currents, temperature and salinity. An associated hydrographic program periodically monitored synoptic changes in the spatial patterns of temperature, salinity, nutrients and bacteria. This set of measurements show that a series of energetic internal tides can, but do not always, transport subthermocline water, dissolved and suspended material from the middle of the shelf into the surfzone. Effective cross-shelf transport occurs only when (1) internal tides at the shelf break are strong and (2) subtidal currents flow strongly downcoast. The subtidal downcoast flow causes isotherms to tilt upward toward the coast, which allows energetic, nonlinear internal tidal currents to carry subthermocline waters into the surfzone. During these events, which may last for several days, the transported water remains in the surfzone until the internal tidal current pulses and/or the downcoast subtidal currents disappear. This nonlinear internal tide cross-shelf transport process was capable of carrying water and the associated suspended or dissolved material from the mid-shelf into the surfzone, but there were no observation of transport from the shelf break into the surfzone. Dissolved nutrients and suspended particulates (such as phytoplankton) transported from the mid-shelf into the nearshore region by nonlinear internal tides may contribute to nearshore algal blooms, including harmful algal blooms that occur off local beaches.  相似文献   

The lower paleolithic landscape of 'Ayoun Qedim,al‐Jafr Basin,Jordan     

Jason A. Rech  Leslie A. Quintero  Philip J. Wilke  Emily R. Winer 《Geoarchaeology》2007,22(2):261-275

The 'Ayoun Qedim locality includes seven deflated Acheulian sites within and around a limestone box canyon, Juwit el Ghuweir, in the northern al‐Jafr Basin, Jordan. Survey of these sites identified dense scatters of Acheulian bifaces ( _ 1650) along with debris, cores, and reduction material from their production and maintenance. Although there is a clear Levallois component in the assemblages, reflecting a Late Acheulian occupation, strictly Middle and Upper Paleolithic sites are uncommon in this locality. Analysis of the geology and geomorphology of the northern al‐Jafr Basin indicates the area is strongly influenced by shallow subsurface groundwater flow and discharge, and Juwit el Ghuweir displays classic features of a canyon formed by groundwater seepage and sapping, except for the lack of a perennial spring within the modern canyon. The authors suggest that the extreme density of Lower Paleolithic material at 'Ayoun Qedim is associated with perennial groundwater discharge at Juwit el Ghuweir during the Middle Pleistocene and that the dearth of later Paleolithic material is attributable to the cessation of perennial spring discharge. The cause of the spring's cessation is unknown, but may have been related to local geomorphic factors, such as head migration of adjacent streams, or to more regional geomorphic factors, such as the lowering of theregional water table in the area of al‐Jafr Basin. © 2007 Wiley Periodicals, Inc.  相似文献   

Relational Agriculture: Gender,Sexuality, and Sustainability in U.S. Farming     

Isaac Sohn Leslie  Jaclyn Wypler  Michael Mayerfeld Bell 《社会与自然资源》2019,32(8):853-874

Although 97% of U.S. farms are “family-owned,” little research examines how gender and sexual relationships – inherent in familial dynamics – influence farmers’ practices and livelihoods. Gender and sexual dynamics – shaped by race and class – affect who is considered a farmer, land management decisions, and access to resources like land, subsidies, and knowledge. We use feminist and queer lenses to illuminate how today’s agricultural gender and sexual relations are not “natural,” but when left uninterrogated are constructed in ways that harm women and queer farmers while limiting potential to develop sustainable practices. Women and queer farmers also resist, “re-orienting” gender and sexual relations in ways that expand possibilities for achieving food justice and ecological sustainability. We offer “relational agriculture” as a tool for making visible and re-orienting gender and sexual relations on farms. Relational agriculture brings sexuality into food justice and demonstrates the centrality of gender and sexuality to agricultural sustainability.  相似文献   

Private rights,public benefits: Industry-driven seabed protection     

Jeremy Helson  Stefan Leslie  George Clement  Richard Wells  Ray Wood 《Marine Policy》2010

New Zealand has a large exclusive economic zone (EEZ) that contains a variety of marine habitats and commercially-important species. The commercial fishing industry operating within New Zealand's EEZ is of significant value to the economy and fisheries resources are managed through the extensive use of Individual Transferable Quotas (ITQs). One of the benefits of ITQs has been to better align some of the private incentives of quota owners with the public interest. These incentives contributed to an initiative proposed by the fishing industry to close large areas of New Zealand's EEZ to protect the seabed from trawling. These closed areas are termed benthic protection areas (BPAs) and protect the benthic biodiversity of about 1.1 million square kilometres of seabed—approximately 30% of New Zealand's EEZ. A significant proportion of New Zealand's known seamounts and active hydrothermal vents are protected by these closed areas. We describe and discuss the criteria used to select BPAs and some of the criticism of this marine protection initiative. We argue that the assignment of strong property rights in fishing resources was an important precondition to an industry initiative that has a significant public benefit. Where private and public interests are well aligned, government can adopt an enabling and facilitation role, ceding direct control of processes in order to get the results the align with the public interest.  相似文献   

Sources of molecularly uncharacterized organic carbon in sinking particles from three ocean basins: A coupled ΔC and δC approach     

Leslie A. Roland  Matthew D. McCarthy  Tom Guilderson   《Marine Chemistry》2008,111(3-4):199-213

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