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1.
An insight into the formation of severe ozone episodes: modeling the 21/03/01 event in the ESCOMPTE region 总被引：1，自引：0，他引：1
High ozone concentrations are observed more and more frequently in the lower troposphere. The development of such polluted episodes is linked to a complex set of chemical, physical and dynamical parameters that interact with each other. To improve air quality, it is necessary to understand and quantify the role of all these processes on the intensity of ozone formation. The ESCOMPTE program, especially dedicated to the numerical simulation of photochemical episodes, offers an ideal frame to investigate details of the roles of many of these processes through 3D modeling. This paper presents the analysis, with a 3D eulerian model, of a severe and local episode of ozone pollution that occurred on the 21st of March 2001 in the ESCOMPTE region. This episode is particularly interesting due to the intensity of the observed ozone peaks (450 μg/m3 during 15 mn) but also because it did not occur in summer but at the beginning of spring. As part of the premodeling work of the ESCOMPTE program, this study focuses on the sensitivity of the simulated ozone peaks to various chemical and physical phenomena (long-range transport, industrial emissions, local dynamic phenomena…) to determine their influence on the rise of high local photooxidant concentrations and to better picture the photochemistry of the ESCOMPTE region. Through sensitivity tests to dynamical calculation resolution and emissions, this paper shows how the combination of sea and pond breezes with emissions of reactive VOCs can generate local intense ozone peaks. 相似文献
2.
Ozone tendencies due to chemistry and transport are calculated by a mesoscale model using a fine horizontal resolution (3 km × 3 km),
over South-Eastern France. Over that region where the anthropogenic emissions are very strong, ozone pollution is highlighted
during two intensive observations periods of the ESCOMPTE campaign, when the sea breeze penetrates far into the Durance and
Rhone valleys and the up-slope breezes are developed. From a fine analysis of time series of ozone concentration at different
ground stations along these valleys and from numerical results, it is possible to discriminate the tendency due to chemistry
from the tendency due to dynamical processes. We can distinguish both processes, either local chemical production/loss or
dynamical increase/decrease (transport, deposition) on maps of ozone budget according to the meteorological conditions. In
particular, we show that the variations due to transport can be have the same order of magnitude than those due to chemistry,
reaching 20 ppbv h−1, whereas those due to chemistry are around 30 ppbv h−1. 相似文献
3.
Interaction between local and regional pollution during Escompte 2001: impact on surface ozone concentrations (IOP2a and 2b) 总被引：2，自引：0，他引：2
Escompte, a European programme which took place in the Marseille region in June–July 2001, has been designed as an exhaustive database to be used for the development and validation of air pollution models. The air quality Mesoscale NonHydrostatic Chemistry model (Meso-NH-C) is used to simulate 2 days of an Intensive Observation Period (IOP) documented during the Escompte campaign, June 23 and 24, 2001. We first study the synoptic and local meteorological situation on June 23 and 24, using surface and aircraft measurements. Then, we focus on the pollution episode of June 24. This study emphasizes the deep impact of synoptic and local dynamics on observed ozone concentrations. It is shown that ozone levels are due both to regional and local factors, with highlights of the importance of ozone layering. More generally this confirms, even in an otherwise predominant local sea-breeze regime, the need to consider larger scale regional pollutant transport. 相似文献
4.
利用2015—2019年辽宁城市逐小时地面O3浓度观测数据,结合各城市逐小时气象要素观测数据,分析了辽宁地区近5 a的O3污染状况及影响O3的相关气象条件。结果表明：除环辽东湾部分城市O3浓度呈下降趋势外,辽宁地区其他城市的O3浓度均呈明显的上升趋势,O3正取代PM2.5成为影响辽宁地区的首要大气污染物。O3浓度具有夏季高、冬季低,下午高、早晨低的时间分布特征。除受污染排放源直接影响外,高温、高湿、强辐射、小风和地面低气压都有利于O3的局地生成;在亚洲夏季风的影响下,上游地区（如京津冀地区）的污染气团会随大气环流向东北地区输送,对辽宁地区夏季O3污染产生重要影响。 相似文献
5.
神经网络方法在环渤海能见度预报中的应用分析 总被引：1，自引：1，他引：0
本文基于2001—2015年中国气象局地面常规气象观测数据及NECP再分析资料,采用BP神经网络方法构建环渤海沿海城市能见度预报模型,利用2016年ECMWF集合预报数据基于预报模型进行能见度预报实验,并与ECMWF集合预报产品中现有能见度预报结果进行对比分析。分析表明:该方法对于环渤海沿海城市能见度预报的预报效果明显高于ECMWF集合预报中的能见度预报,12～72 h预报时效中,最小值对应1 km以下能见度的TS评分为0. 36～0. 43; 10 km以下能见度预报误差显著降低,与离散度的对应关系较好。因此,该方法对低能见度天气过程的能见度预报具有指示意义。 相似文献
6.
In this study, we present the observational data of near surface ozone and some meteorological parameters during 2004, at an urban site (36°42′ N, 117°08′ E, 34.5 m a.s.l.) of Jinan, China. Hourly ozone concentrations exceeding the standard value of China, 100 ppbv, were observed for 65 h (in 23 days) from April to October, and values exceeding US NAAQS (National Ambient Air Quality Standard) for 1 h ozone, 120 ppbv, were observed for 15 h (in 7 days) from late May to early July. Ozone formation presented the phenomenon of “weekend effect”, especially in summer. Monthly variation of ozone coincided with temperature except for July and August. The low ozone levels in July and August may be due to the short sunshine duration and much rainfall during this period. Among these meteorological parameters, daily averaged ozone shows a significant correlation with temperature (r = 0.66) in the year and with relative humidity (r = − 0.75) in summer. Throughout the year, high ozone concentrations were mainly associated with the wind from 180 to 247.5°, while high ozone concentration seemed to have no obvious correlation with a given wind direction in summer. An anomalous nocturnal high ozone episode during 23–25 May 2004 was investigated. Growth fractions of ozone during the nighttime episode were 62.2% and 71.1% for 23 and 24 May, respectively. Synoptic analysis shows that favorable synoptic condition had presumably elevated the background ozone level in this region. Backward trajectory analysis shows that the increase of ozone concentration and the relatively constant high ozone concentrations during the night of May 23 might originate from the transport of ozone rich air mass above boundary layer. Transport of ozone from Yangtze Delta and East Central China might be a significant process for the high ozone level during night May 24 at Jinan. 相似文献
7.
海南岛海风演变特征的观测分析 总被引：4，自引：1，他引：3
本文利用2012年海南岛19个常规气象站、5个海岛站的逐时资料以及海口站的探空资料,对海南岛海风的时空演变特征及在不同天气条件下海风发展的特征进行了统计分析,结果表明:2012年全年海南岛的海风多发生于春、秋季,频率分别为40%和33%,冬季最少(约为19%),尤其是一月,大部分站点均不足10%。夏季海风出现时刻较早;南部沿海海风结束时间晚于北部沿海;冬季海风开始得较晚,南部海风结束时间早于北部沿海。海风平均持续时间约为10 h。沿海站的海风风速主要集中在3~6 m·s~(-1),且最大风速值出现在春季,除琼山、海口站外,最大海风强度多出现于春夏季。内陆站中部山区附近海风出现频率较高、开始时刻较早、持续时间较长、强度也较大。海风向内陆的传播距离至少为70 km;海风易发生在阴天,其次为多云天气,少云日的海风最少。 相似文献
8.
Virginie Guemas David Salas-Mélia Masa Kageyama Hervé Giordani Aurore Voldoire Emilia Sanchez-Gomez 《Climate Dynamics》2010,34(4):527-546
This study aims at understanding the summer ocean-atmosphere interactions in the North Atlantic European region on intraseasonal
timescales. The CNRMOM1d ocean model is forced with ERA40 (ECMWF Re-Analysis) surface fluxes with a 1-h frequency in solar
heat flux (6 h for the other forcing fields) over the 1959–2001 period. The model has 124 vertical levels with a vertical
resolution of 1 m near the surface and 500 m at the bottom. This ocean forced experiment is used to assess the impact of the
North Atlantic weather regimes on the surface ocean. Composites of sea surface temperature (SST) anomalies associated with
each weather regime are computed and the mechanisms explaining these anomalies are investigated. Then, the SST anomalies related
to each weather regime in the ocean-forced experiment are prescribed to the ARPEGE Atmosphere General Circulation Model. We
show that the interaction with the surface ocean induces a positive feedback on the persistence of the Blocking regime, a
negative feedback on the persistence of the NAO-regime and favours the transition from the Atlantic Ridge regime to the NAO-regime
and from the Atlantic Low regime toward the Blocking regime. 相似文献
9.
Ground-based remote sensing observation of the complex behaviour of the Marseille boundary layer during ESCOMPTE 总被引：1，自引：0，他引：1
H. Delbarre P. Augustin F. Saïd B. Campistron B. Bnech F. Lohou V. Puygrenier C. Moppert F. Cousin P. Frville E. Frjafon 《Atmospheric Research》2005,74(1-4):403-433
Ground-based remote sensing systems have been used during the ESCOMPTE campaign, to continuously characterize the boundary-layer behaviour through many atmospheric parameters (wind, extinction and ozone concentration distribution, reflectivity, turbulence). This analysis is focused on the comparison of the atmospheric stratification retrieved from a UV angular ozone lidar, an Ultra High Frequency wind profiler and a sodar, above the area of Marseille, on June 26th 2001 (Intensive Observation Period 2b). The atmospheric stratification is shown to be very complex including two superimposed sea breezes, with an important contribution of advection. The temporal and spatial evolution of the stratification observed by the UV lidar and by the UHF radar are in good agreement although the origin of the echoes of these systems is quite different. The complexity of the dynamic situation has only partially been retrieved by a non-hydrostatic mesoscale model used with a 3 km resolution. 相似文献
10.
对中国国家气象中心T639数值预报、德国降水预报和欧洲中心（ECMWF）数值预报中对中国东北地区的降水、温度和环流模式的预报结果,分别进行检验。结果表明：降水预报中,德国降水预报对中国东北地区的晴雨预报、一般性降水预报效果较好,但T639数值预报的漏报率明显低于德国降水预报,而T639数值预报中24-120 h暴雨预报的TS评分明显高于德国降水预报。温度预报中,T639数值预报对中国东北地区温度预报72 h内基本可用;欧洲中心（ECMWF）数值预报在96 h内效果较好。对于24 h的温度预报准确率,T639数值预报稍高于ECMWF数值预报结果。环流模式方面：48h内T639预报效果好于ECMWF,72 h以后ECMWF预报效果好于T639。 相似文献
11.
库车大风天气特征分析及预报指标 总被引：1，自引：0，他引：1
彭江良 《沙漠与绿洲气象(新疆气象)》2003,26(6):15-16,25
应用1997-2001年大风资料和历史天气图、欧洲数值预报资料，分析了库车大风的天气气候特征和地面气压场、高空环流形势和影响系统演变特征及单站要素变化特点，得到了一些有预报意义的指标。 相似文献
12.
`Kanpachi Street Cloud (KSC)' is an unusual small-scalecumulus cloud line visible during calm summer conditions over a major street in the Tokyo metropolitanarea. In order to understand the mechanism leading to the formation of this cloud line,numerical simulations have been performed using the Regional Atmospheric Modelling System.The general characteristics of the simulated KSC agree well with observations. On alarge-scale view, the KSC can be characterized as a cumulus cloud line generated at the convergenceline of two sea breezes on the western side of Tokyo Bay, while on the microscale view, it resemblesBenard-type thermal convection modified longitudinally by wind shear.The location of the convergence line leading to the KSCformation coincides withthe Kanpachi street location, although the street itself does notmake any direct effect on the KSC formation. Additional numerical experiments were performed toidentify causes of the KSC formation in accordance with urbanization, by changing anthropogenicheat impact, land-cover and grid resolution.They confirmed that the formation of the KSC requirestwo meteorological processes at the same time:(1) the convergence of two sea breezes – the localsouth-eastern sea breeze from Tokyo Bay andan extended southern sea breeze from thePacific Ocean, respectively; (2) Forcing due to an urban heat island. It is shown that urbanization couldchange the intensity and position of the KSC through enhancement of local upward motions and changesin the near-surface horizontal pressure gradient between urban and sub-urban areas. Further,fine horizontal grid resolution is needed to be able to resolve these local thermal convection issues. 相似文献
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为探讨ECMWF业务预报模式(以下简称ECMWF)的地面气温预报不一致性问题,本文利用2015年12月1日—2016年11月30日业务预报中常用的地面气温预报数据,研究ECMWF地面气温预报产品在不同季节里的不一致性指数分布及变化特征。结果表明:各个季节不一致性指数有不同的特点,冬季不一致性指数最大,大值区主要分布在除华南和青藏高原外的大部分区域;而夏季不一致性指数最小,在青藏高原地区不一致性指数相对较大;春、秋两季不一致性指数大小均处于冬、夏季之间。此外,研究还发现冬季地面气温预报不一致性指数单日变化较大,而夏季较小。夏季不同起报时间的地面气温预报比较稳定。 相似文献
15.
The leading mode of southern hemisphere (SH) climatic variability, the southern annular mode (SAM), has recently seen a shift towards its positive phase due to stratospheric ozone depletion and increasing greenhouse gas (GHG) concentrations. Here we examine how sensitive the SAM (defined as the leading empirical orthogonal function of SH sea level pressure anomalies) is to future GHG concentrations. We determine its likely evolution for three intergovernmental panel on climate change (IPCC) special report on emission scenarios (SRES) for austral summer and winter, using a multi-model ensemble of IPCC fourth assessment report models which resolve stratospheric ozone recovery. During the period of summer ozone recovery (2000–2050), the SAM index exhibits weakly negative, statistically insignificant trends due to stratospheric ozone recovery which offsets the positive forcing imposed by increasing GHG concentrations. Thereafter, positive SAM index trends occur with magnitudes that show sensitivity to the SRES scenario utilised, and thus future GHG emissions. Trends are determined to be strongest for SRES A2, followed by A1B and B1, respectively. The winter SAM maintains a similar dependency upon GHG as summer, but over the entire twenty-first century and to a greater extent. We also examine the influence of ozone recovery by comparing results to models that exclude stratospheric ozone recovery. Projections are shown to be statistically different from the aforementioned results, highlighting the importance of ozone recovery in governing SAM-evolution. We therefore demonstrate that the future SAM will depend both upon GHG emissions and stratospheric ozone recovery. 相似文献
16.
利用ECMWF、NCEP和CMC中心的1~3天7种降水集合预报产品,同时结合内蒙古119个气象站同期降水观测资料,对降水预报效果基于晴雨、降水等级划分(包括小雨、中雨、大雨以及暴雨)确定性TS评分以及空间分布特点进行了归纳总结,评估了三大全球集合预报系统在内蒙古地区的降水预报能力,为进一步开发模式预报及应用提供技术支撑。研究结果表明,ECMWF集合预报产品对内蒙古降水预报能力明显优于NEPC和CMC中心的产品。ECMWF集合预报产品24h时效下的晴雨及小雨、中雨、大雨以及暴雨预报都具有良好的预报能力,但是随着预报时效的延长至48h、72h,ECMWF集合预报产品预报能力明显降低,预报能力与NCEP和CMC中心的产品接近。24h的ECMWF集合预报产品在呼伦贝尔市、兴安盟、锡林郭勒盟、巴彦淖尔市西部、阿拉善盟地区预报效果明显较好,三大集合预报系统对内蒙古东部地区的预报能力总体偏高。 相似文献
17.
Impact of the Rhône and Durance valleys on sea-breeze circulation in the Marseille area 总被引：2，自引：0，他引：2
Sophie Bastin Philippe Drobinski Alain Dabas Patricia Delville Oliver Reitebuch Christian Werner 《Atmospheric Research》2005,74(1-4):303-328
Sea-breeze dynamics in the Marseille area, in the south of France, is investigated in the framework of the ESCOMPTE experiment conducted during summer 2001 in order to evaluate the role of thermal circulations on pollutant transport and ventilation. Under particular attention in this paper is the sea-breeze channelling by the broad Rhône valley and the narrow Durance valley, both oriented nearly-north–south, i.e., perpendicular to the coastline, and its possible impact on the sea-breeze penetration, intensity and depth, which are key information for air pollution issues. One situation of slight synoptic pressure gradient leading to a northerly flow in the Rhône valley (25 June 2001) and one situation of a weak onshore prevailing synoptic wind (26 June 2001) are compared. The impact of the Rhône and Durance valleys on the sea-breeze dynamics on these two typical days is generalized to the whole ESCOMPTE observing period.The present study shows by combining simple scaling analysis with wind data from meteorological surface stations and Doppler lidars that (i) the Durance valley always affects the sea breeze by accelerating the flow. A consequence is that the Durance valley contributes to weaken the temperature gradient along the valley and thus the sea-breeze circulation. In some cases, the acceleration of the channelled flow in the Durance valley suppresses the sea-breeze flow by temperature gradient inhibition; (ii) the Rhône valley does not generally affect the sea breeze significantly. However, if the sea breeze is combined with an onshore flow, it leads to further penetration inland and intensification of the low-level southerly flow. In this situation, lateral constriction may accelerate the sea breeze. Simple scaling analysis suggests that Saint Paul (44.35°N, about 100 km from the coastline) is the lower limit where sea breeze can be affected by the Rhône valley. These conclusions have implications in air quality topics as channelled sea breeze may advect far inland pollutants which may be incorporated into long-range transport, particularly in the Durance valley. 相似文献
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利用ECMWF模式降水和极端天气指数资料,以及浙江省68个气象站降水观测资料,评估了ECMWF细网格模式(EC-thin)和降水极端天气指数(EFI)对浙江2018—2020年梅汛期暴雨预报效果。研究表明：对于同一预报时效,随着阈值的增加,EC-thin和降水EFI的暴雨预报评分都呈现“先增加、后减小”的趋势,对于不同预报时效都存在某一阈值使得暴雨预报评分达到最大。从24 h时效到72 h时效,EC-thin的降水预报阈值从45 mm逐渐下降到25 mm,而降水EFI的暴雨预报阈值从07下降到06。EC-thin和降水EFI对暴雨预报的空报率随着阈值的增大而减小,漏报率随着阈值的增大而增大。对于不同预报时效,通过合理组合EC-thin降水阈值和降水EFI阈值,可以得到更好的暴雨预报效果,其评分高于单独使用降水EFI阈值或EC-thin降水阈值得到的评分。 相似文献