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671.
Transport and Diffusion of Ozone in the Nocturnal and Morning Planetary Boundary Layer of the Phoenix Valley 总被引:2,自引:0,他引:2
Lee Sang-Mi Fernando Harindra J.S. Princevac Marko Zajic Dragan Sinesi Michela McCulley Jennifer L. Anderson James 《Environmental Fluid Mechanics》2003,3(4):331-362
The evolution of ozone (O
3) in the nocturnal and morning-transitional planetary boundary layer (PBL) of the Phoenix valley was measured as a part of the `Phoenix Sunrise Experiment 2001' of the U.S. Department of Energy conducted in June 2001. The goal of the field program was to study the transport, distribution and storage of ozone and its precursors in the urban boundary layer over a diurnal cycle. The ground level O
3 as well as mean meteorological variables and turbulence were measured over the entire period, and vertical profiling (using a tethered balloon) was made during the morning transition period. Approximately half of the observational days showed the usual diurnal cycle of high O
3 during the day and low O
3 at night, with nitrogen oxides (NO
x = NO
2 + NO) showing an out of phase relationship with O
3. The rest of the days were signified by an anomalous increase of O
3 in the late evening ( 2200 LST), concomitant with a sudden drop of temperature, an enhancement of wind speed and Reynolds stresses, a positive heat flux and a change of wind direction. NO
x measurements indicated the simultaneous arrival of an `aged' air mass, which was corroborated by the wind predictions of a mesoscale numerical model. In all, the results indicate that the recirculation of O
3 rich air masses is responsible for the said high-O
3 events. Such air masses are produced during the transport of O
3 precursors by the upslope flow toward mountainous suburbs during the day, and they return back to the city at night via downslope winds (i.e. mountain breeze). The corresponding flow patterns, and hence the high-O
3 events, are determined by background meteorological conditions. The vertical profiling of O
3 and flow variables during the morning transition points to a myriad of transport, mixing and chemical processes that determine the fate of tropospheric O
3. How well such processes are incorporated and resolved in predictive O
3 models should determine the accuracy of their predictions. 相似文献
672.
城市地表覆盖材料的热反应 总被引:12,自引:1,他引:12
董靓 《城市环境与城市生态》1995,8(2):18-20
本文对几种地表覆盖材料在具有“火炉”之称的山城重庆典型夏季气候条件下的热反应进行了实测研究,以期为生态城市设计提供有益的参考数据。 相似文献
673.
A numerical model based on a Finite Volume formulation of the Navier–Stokes equations is used to simulate a range of scenarios leading to a thermal bar formed by a river inflow to an idealised deep lake. The results presented here show that small riverine salinity increases have a profound effect on the dynamics of the thermal bar, suppressing horizontal propagation of the plume and raising the possibility of a thermal bar which is capable of sinking to great depths. This finding is particularly relevant to Lake Baikal in Siberia, where the vigorous deep-water renewal is still not fully understood. An analysis of the buoyancy forces governing the depth of penetration of the thermal bar plume shows that realistic salinity gradients are an important factor in determining the circulation of Baikal waters. Observations of the saline curtailment of the thermal bar's horizontal propagation also reveal a potential for reduced productivity in the ecosystem of any temperate river delta during the Spring renewal period. 相似文献
674.
Small bottom slope, inviscid solutions are found for a model of the temperature and circulation structure of the thermal bar system. This model includes Coriolis effects, a vertically non-uniform heat input and is axisymmetric. The model also includes general topography and time dependent heating. These solutions include inertial oscillations that have a significant effect on the circulation, especially for the case when the heating is instantaneously applied. 相似文献
675.
城市热岛的遥感研究 总被引:24,自引:0,他引:24
赵俊华 《城市环境与城市生态》1994,7(4):40-43
随着城市建设事业的发展以及人为热释放的增多,城市热岛效应呈现不断增强趋势。将遥感技术与常规城市热岛监测方法结合起来,才能深入进行城市热岛监测研究。通过回归分析建立一定模式,将遥感手段获得的辐射温度(亮温)转换为常规方法所用的空气温度(气温)是城市热岛遥感研究的主要思路和方法。以武汉市城市热岛分析为例,本文探讨了城市覆盖层与边界层的热岛形成因子,城市热岛效应直接或间接对城市其他气候要素产生多种影响,并对城市居民生产生活和健康带来有利和不利的因素。 相似文献
676.
677.
678.
铂、钯蜂窝催化剂高温老化对甲醇深度氧化的影响 总被引:1,自引:0,他引:1
本研究对铂、钯蜂窝催化剂及分别添加助化剂CeO_2或WO_3,并于500℃、700℃、900℃或1100℃下经受热老化4h后,考察催化剂比表面、晶相结构及其对甲醇深度氧化活性、产物分布及反应动力学网络变化的情况。实验证明,添加CeO_2后,降低了铂催化剂的耐高温性能,但对钯催化剂无明显影响。添加WO_3,降低了钯催化剂对甲醇的氧化活性。经X-线衍射分析证明,在1100℃高温下,WO_3与堇青石载体中的氧化镁和氧化钙发生强相互作用,生成了相应的钨酸盐。甲醇氧化反应动力学研究表明,甲醇在新鲜和高温热老化的铂催化剂上,反应动力学网络表示式是有区别的。 相似文献
679.
废旧轮胎热解资源化研究 总被引:8,自引:1,他引:8
废旧轮胎热解资源化是近年来世界各国关注的热点。热解温度控制在400~800℃便能得到燃料油、炭黑、钢丝和燃料气。热解工艺简单,操作方便,投产18个月能收回全部投资,经济效益可观,同时减轻废旧轮胎对环境的压力。废旧轮胎必将成为一种既有能源价值,更有资源价值的新兴资源,补充世界各国对资源的需求。 相似文献
680.
Sarauskiene D 《Environmental monitoring and assessment》2002,79(1):1-12
The hydrothermal regime of the Lake Druksiai has changedwhen it became a cooler for the Ignalina NPP. For 18 years, 1981–1998, the hydrologists from Lithuanian Energy Institute have been investigating thermal state of the lake. The water temperature data owned by the laboratory is unique as it has been collected sequentially during 18 yr under wide range of different weather and INPP capacity conditions. Gathered information consists of lake surface temperature, related meteorological data and INPP operating capacity data. This information enables not only to state that the relationship between hydrological and meteorological/INPP capacity data exists(that is already known) but also to analyze its character. The aim of this study was to build computer database for data analysis and management as well as to create digital maps for further modelling and forecasting. ArcView software package wasused for data set management and visualization. 相似文献