首页 | 本学科首页   官方微博 | 高级检索  
     检索      


Transport and Diffusion of Ozone in the Nocturnal and Morning Planetary Boundary Layer of the Phoenix Valley
Authors:Lee  Sang-Mi  Fernando  Harindra JS  Princevac  Marko  Zajic  Dragan  Sinesi  Michela  McCulley  Jennifer L  Anderson  James
Institution:(1) Department of Civil and Environmental Engineering, Environmental Fluid Dynamics Program, Arizona State University, Tempe, AZ 85287-9809, U.S.A;(2) Department of Mechanical and Aerospace Engineering and Aerospace Engineering Environmental Fluid Dynamics Program, Arizona State University, Tempe, AZ 85287-9809, U.S.A.;(3) Departimento di Idraulica Trasporti e Strade, Universita degli Studi di Roma La Sapienza, Via Eudossiana, 18thinsp00184 Roma, Italia
Abstract: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 (sim 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.
Keywords:convective boundary layer  high ozone episode  low level jet  nocturnal boundary layer  recirculation of ozone  thermal circulation  vertical ozone profile
本文献已被 SpringerLink 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号