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首页> 外文会议>Fourth Conference on Atmospheric Chemistry: Urban, Regional, and Global Scale Impacts of Air Pollutants, Jan 13-17, 2002, Orlando, Florida >VERTICAL MIXING AND CHEMISTRY OVER AN ARID URBAN SITE: FIRST RESULTS FROM SKYSCRAPER OBSERVATIONS MADE DURING THE PHOENIX SUNRISE CAMPAIGN
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VERTICAL MIXING AND CHEMISTRY OVER AN ARID URBAN SITE: FIRST RESULTS FROM SKYSCRAPER OBSERVATIONS MADE DURING THE PHOENIX SUNRISE CAMPAIGN

机译：干旱城市站点上的垂直混合和化学性质：凤凰城太阳活动期间进行的摩天大楼观测的第一个结果

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We report here on combined meteorological and chemical trace-gas observations made from two levels of a skyscraper in downtown Phoenix, Arizona. These observations were made as part the U.S. Department of Energy's Phoenix Sunrise Campaign in June 2001. The focus of this campaign was to study the early morning chemical and meteorological transition period as an urban atmosphere develops from a stable to a convec-tive state. The measurements to be presented here were designed to evaluate changes to the concentration of NO_x, VOCs, PAN and other photochemically active species at sunrise concurrent with the onset of mixing and chemistry. The Bank One observations were one component of an extensive set of meteorological observations and supporting air chemistry measurements designed to characterize the vertical structure of the lower urban atmosphere (Figure 1), as described in Doran, et al. (2002). Additional measurements were available above the surface through a series of aircraft observations taken at approximately 300, 500, and 700 m AGL. Thus, the Bank One building provided two intermediate sampling levels within a much larger network of observations. The motivation for this campaign developed from studies in other urban areas that found peak ozone values above the surface layer appeared to play an important role in governing the surface ozone concentrations in the early morning. The conceptual model for the design of our field campaign hinged on the development of a nocturnal stable layer via cooling at night. Phoenix was selected as a study site because of its heavy pre-dawn traffic, which is a common occurrence as workers schedule their days to avoid high daytime temperatures. As a result of this traffic we expected to find a rich mixture of emissions trapped close to the ground (below 200 m AGL) at sunrise. This rich mixture would be decoupled from air aloft at sunrise, which was expected to have its own unique chemical mix. With the onset of sunrise and surface warming, these two layers would mix together, diluting surface pollutants into a deeper layer, and bringing air aloft down to the surface. Sampling at two levels of a skyscraper was an ideal way to quantify this process. Measurements were made 24 hours a day, 7 days a week during the period from June 16-30. Observations made during the early morning hours at the 39th floor (～139 m AGL) were expected to be made above the nocturnal stable layer, while measurements made at the 16th floor (at ～73m AGL) would be within this layer at sunrise. We decided not to sample directly at street level so as to avoid contamination from idling vehicles or other very localized sources. As the day developed, we anticipated that observations from the 16th floor would measure changes associated with dilution as the mixed layer became deeper. In contrast, observations from the 39th floor were anticipated to characterize the chemistry above the nocturnal stable layer and the chemistry associated with the subsequent upward mixing of surface emissions.
机译：我们在此报告从亚利桑那州凤凰城市中心的一座摩天大楼的两个楼层进行的气象和化学痕量气体的综合观测。这些观察是作为2001年6月美国能源部凤凰日出运动的一部分进行的。该运动的重点是研究随着城市大气从稳定状态发展为对流状态而进行的化学和气象的清晨过渡期。此处提出的测量值旨在评估日出时与混合和化学作用同时发生的NO_x，VOCs，PAN和其他光化学活性物质浓度的变化。如Doran等人所述，Bank One观测是广泛的气象观测和支持性空气化学测量的一个组成部分，这些测量旨在表征低层城市大气的垂直结构（图1）。 （2002）。通过在大约300、500和700 m AGL进行的一系列飞机观测，可以在地面以上进行其他测量。因此，第一银行大楼在一个更大的观测网络中提供了两个中间采样级别。这项运动的动机是由在其他城市地区进行的研究得出的，这些研究发现在表层之上的臭氧峰值位于似乎在清晨控制表面臭氧浓度方面起着重要作用。我们野战活动设计的概念模型取决于夜间冷却后夜间稳定层的形成。凤凰城之所以被选为研究地点，是因为它的黎明前交通繁忙，这是经常发生的事情，因为工人安排工作时间以避免白天的高温。由于这种交通，我们预计在日出时会发现大量排放物被困在靠近地面（低于200 m AGL）的位置。这种丰富的混合物将在日出时从高空空气中分离出来，预计会有自己独特的化学混合物。随着日出和表面变暖的开始，这两层将混合在一起，将表面污染物稀释到更深的一层，并向上方输送空气。在摩天大楼的两个级别进行采样是量化此过程的理想方法。从6月16日至30日，每周7天，每天24小时进行测量。预计清晨在39层（〜139 m AGL）的观测是在夜间稳定层以上进行的，而在16层（〜73m AGL）的观测则是在日出时在该层内进行的。我们决定不直接在街道上取样，以避免空转的车辆或其他非常局部的污染源。随着一天的发展，我们预计从16楼开始的观察将测量随着混合层变深而与稀释相关的变化。相比之下，从39楼开始的观察预计将表征夜间稳定层上方的化学物质以及与随后向上混合的表面排放物相关的化学物质。

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