Monitoring Air Quality in Mountains: Designing an Effective Network

A quantitatively robust yet parsimonious air-quality monitoring network in mountainous regions requires special attention to relevant spatial and temporal scales of measurement and inference. The design of monitoring networks should focus on the objectives required by public agencies, namely: 1) determine if some threshold has been exceeded (e.g., for regulatory purposes), and 2) identify spatial patterns and temporal trends (e.g., to protect natural resources). A short-term, multi-scale assessment to quantify spatial variability in air quality is a valuable asset in designing a network, in conjunction with an evaluation of existing data and simulation-model output. A recent assessment in Washington state (USA) quantified spatial variability in tropospheric ozone distribution ranging from a single watershed to the western third of the state. Spatial and temporal coherence in ozone exposure modified by predictable elevational relationships ( 1.3 ppbv ozone per 100 m elevation gain) extends from urban areas to the crest of the Cascade Range. This suggests that a sparse network of permanent analyzers is sufficient at all spatial scales, with the option of periodic intensive measurements to validate network design. It is imperative that agencies cooperate in the design of monitoring networks in mountainous regions to optimize data collection and financial efficiencies.     

陕南近期两次特大暴雨天气成因的对比分析

采用天气动力诊断分析方法,对陕西秦岭山脉南麓两次小范围特大暴雨（2002年6月8日佛坪特大暴雨与2003年8月29日宁陕特大暴雨） 发生的环流背景、主要影响系统、垂直环流和热力学特征等进行对比分析,指出在相对稳定的环流形势下,高空急流与低空急流耦合形成低层辐合与高空辐散垂直结构与不稳定的大气层结是小范围特大暴雨形成的主要原因之一.     

The GaNE programme in a global perspective

This paper provides the background to this special issue, outlining the extent to which the global atmospheric nitrogen cycle has been modified by human activity and outlining the range of effects. The global total emissions of reduced and oxidized nitrogen, amount to 124 Tg N, and exceed those from natural sources (34 Tg N) by almost a factor of four showing the extent to which anthropogenic activity has taken over the global N cycle. Of the 124 Tg N, 70 Tg N is emitted in the oxidized form, largely as NO and 70% of which results directly from anthropogenic activity. The remaining 54 Tg N is emitted as NH₃, (66% anthropogenic). The enhanced nitrogen emissions are associated with a range of local, regional and global issues including, acidification, eutrophication, climate change, human health and tropospheric O₃. The paper also places the Global Nitrogen Enrichment (GaNE) research programme in the UK in a wider perspective.     

HCFCs和HFCs对流层寿命的预测

利用Ｃ－Ｈ键的Ｍｕｌｌｉｋｏｎ键重叠布局数，对甲烷的不完全氟氯取代物的对流层寿命用公式作了计算。对传统的人工神经网络法－反向传递算法作了改进。在电荷这一量化参数基础上，用ＡＮＮ法对一碳和二碳的ＨＣＦＣｓ和ＨＦＣｓ的对流层寿命作了预测。     

基于卫星观测的青海高原对流层臭氧时空分布特征研究

基于OMI-MLS对流层臭氧总量数据集对2005—2019年青海高原对流层大气臭氧总量进行提取分析,探讨其时空分布格局及气象因子的影响.结果表明：①OMI-MLS对流层臭氧总量数据在青海高原的适用性良好.③海高原的多年平均对流层臭氧总量分布整体呈东北高西南低的态势,受地形和大气环流形势影响较大.海东市的对流层臭氧总量最高,其次是西宁市、格尔木市、德令哈市,玉树市的对流层臭氧总量最低.对流层臭氧总量月变化在一定程度上表现为"倒V"型特点：峰值位于6—7月,谷值位于1月,与气温变化密切相关.对流层臭氧总量季节变化明显,空间异质性强,夏季最高,春季、秋季次之,冬季最低.③近15年青海高原对流层臭氧总量呈显著增加趋势,年平均增加速率为0.22 DU,4个季节的对流层臭氧总量均呈波动上升趋势,冬季的对流层臭氧总量增加速率最快,其次是春季、夏季,秋季增加速率较慢.④影响青海高原对流层大气臭氧总量的主要气象因子是气温和降水,而次要因子表现略有不同.     

粤港澳大湾区NO2污染的时空特征及影响因素分析

利用Aura卫星搭载的臭氧观测仪（OMI）反演的对流层NO₂柱密度数据,分析了自2005年以来粤港澳大湾区（GBA）对流层NO₂柱密度的空间分布特征、时间变化趋势及其影响因素.研究结果表明GBA对流层NO₂柱密度从2005~2018年呈减少的趋势,每年递减约为2.8%.小波系数显示时间演化过程中存在9个月的主振荡周期,冬季浓度较高,夏季较低.人为排放和各种自然因素,导致了GBA对流层NO₂柱浓度月变化在时间和空间上存在明显差异,最小值和最大值分别出现在6和12月,多年平均值分别为3.9665×10¹⁵和12.3423×10¹⁵molec/cm².NO₂在空间分布上呈现明显的空间分异特征,冬季12月最明显.NO₂污染严重的高值区主要出现在中部地区,如广州市、佛山市和中山市,最大的对流层NO₂柱密度可达18.8306×10¹⁵molec/cm²,大约是周边地区的3 倍,且高污染区域向四周逐渐扩散,连成一片.低值区主要在北部的肇庆市和东部的惠州市,多年平均的对流层NO₂柱密度约为7.1400×10¹⁵molec/cm².对流层NO₂柱密度的增长率在不同区域的变化趋势呈现明显的差异,变化范围为-15×10¹⁵~6×10¹⁵molec/cm²,增长率百分比范围为-65%~65%.出现增长的地区主要是肇庆市北部和惠州市东部的低值区;对流层NO₂出现明显减少的区域集中在中部的高值区,减少量最大的地区为广州市、佛山市和中山市交界处.     

The distribution of the chlorinated solvents dichloromethane,perchloroethylene, and trichloroethylene in the global atmosphere

Dichloromethane, perchloroethylene, and trichloroethylene are commercially important chlorinated solvents whose health and environmental impacts are under scrutiny in the industrial world. Their distributions in the global atmosphere have been computed based on data from the Reactive Chlorine Emissions Inventory (RCEI) project using the Global Balance Environment (GLOBE) model, a 3-D radiative-dynamical-chemical model. Their atmospheric lifetimes, scaled to an observed methyl chloroform lifetime of 4.8 years, are 158 days, 105 days, and 4.3 days, respectively. They have strong interhemispheric gradients, with maximum zonal mean surface concentrations in the winter mid-latitude northern hemisphere of approximately 40 ppt, 9 ppt, and 2.5 ppt, respectively. Their spatial distributions show significant seasonal variability, and are sensitive to vertical mixing by cumulus convection and horizontal mixing by synoptic-scale turbulence. While the model interhemispheric exchange time (1.0 years) and computed atmospheric lifetimes are very sensitive to sub-grid scale diffusion, interhemispheric gradients of the chlorinated solvents are not. The simulated results suggest a greater importance for oceanic emissions of perchloroethylene and trichloroethylene than has previously been assumed.     

Retrieval And Monitoring of Atmospheric Trace Gas Concentrations in Nadir and Limb Geometry Using the Space-Borne Sciamachy Instrument

The Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) onboard the European Envisat spacecraft performs continuous spectral observations of reflected, scattered and transmitted sunlight in various observation geometries. A unique feature of SCIAMACHY is the capability of probing the atmosphere in three different observation geometries:The nadir, limb, and occultation measurement modes. In nadir mode, column densities of trace gases are retrieved with a spatial resolution of typically 30× 60 km using the Differential Optical Absorption Spectroscopy (DOAS) technique (Platt and Perner, 1983). Alternating with the nadir measurement, vertical profiles of absorber concentration in the stratosphere are derived in limb and occultation. In this paper we present an overview over some applications of SCIAMACHY data in space-based monitoring of atmospheric pollution. The DOAS algorithms for the retrieval of total column amounts from nadir spectra are briefly described and case studies of pollution events are presented. We also illustrate the technique used to derive stratospheric concentration profiles from limb observations and show comparisons with other remote sensing systems. Special emphasis will be given to techniques, which take advantage of SCIAMACHY's different viewing geometries. In particular, we will discuss the potential and limits of strategies to infer tropospheric abundances of O₃and NO₂.     

Concentrations,Cumulative Exposure and Critical Levels of Ozone in Ireland

Concentrations of tropospheric ozone(O₃) and exceedance of critical levels to vegetationhave been investigated and mapped for Ireland. Hourlyozone concentration data (1995–1997) at 7 sevenmonitoring stations and the CORINE landcover database,supported by a Geographical Information System, wereused. AOT40 (Accumulated exposure Over a Threshold of 40ppb) was calculated for daylight hours for each station,and mapped using surface interpolation. Average O₃concentrations vary from year to year, and were estimatedto be 28 ppb, 26 ppb and 24 ppb for 1995, 1996 and 1997respectively. Ozone concentrations show a large diurnalvariation, with a maximum in the afternoon and a minimumat night-time. The critical level for crops and (semi-)natural vegetation was exceeded in all years examined.The highest exceedance occurred in 1995, where thecritical level was exceeded for almost 35% of the mappedarea. Approximately 15% and 1% of the mapped area wasexposed to exceedance levels during 1996 and 1997respectively. The maximum cumulative exposures (AOT40)were approximately 5000, 3890 and 3230 ppbh in 1995, 1996and 1997 respectively. The critical level for forests wasnot exceeded during the period of investigation.