NUMERICAL SIMULATION OF ATMOSPHERIC POLLUTANTS DURING THE ONSET STAGE OF SOUTH CHINA SEA SUMMER MONSOON IN 2011

Using the 2006 Global Emissions Data and 2011 NCEP Final Analysis data as the initial and boundary condition, we simulated the three-dimensional distribution of atmospheric chemical pollutants (such as sea salt, PM10, COx, SO2, NOx, O3, etc) during the onset stage of South China Sea (SCS) summer monsoon from 25 April to 25 May in 2011 over the monsoon area of 70°–160°E, 0°–40°N. Simulation results shows that, many changes have taken place in the distribution of atmospheric chemical pollutants near 950 hPa and 400 hPa due to the enhancement of the westerlies and southerlies over the SCS as a result of the monsoon outbreak. Especially, the concentration of pollutants over the SCS is much higher than that over other places because of the strong wind convergence near the surface in situ. Moreover, the vertical distribution of pollutants is also greatly affected by the westerlies and southerlies in the onset process of SCS summer monsoon. Meanwhile, the concentration over land is much greater than that at sea in pre-monsoon period, while the difference between land and sea in the concentration of most pollutants decreases greatly with the onset of SCS summer monsoon.     

霾与雾的区别和灰霾天气预警建议

霾与雾的区分是目前一个非常现实 ,又迫切需要解决的问题。而过去东南沿海各省不成文规定的用相对湿度区分的标准普遍偏低 ,区分霾和雾 ,应该根据影响天气系统的变化 ,结合各种判据来确定。考虑到近几年对气溶胶研究的新成果 ,大气中 0 .1μm以下的水溶性粒子主要是 (NH4) 2 SO4等组成的 ,>1μm的粒子主要是NaCl等组成的。这些物质的相变湿度大都在 80 %左右。建议将相对湿度<80 %时的大气混浊视野模糊导致的能见度恶化的天气现象确定为霾 ,相对湿度 >90 %时的大气混浊视野模糊导致的能见度恶化确定为雾 ,相对湿度介于 80～ 90 %之间时的大气混浊视野模糊导致的能见度恶化是霾和雾的混合物共同造成的 ,但其主要成分应该是霾。建议尽快制定灰霾指数和预警办法 ,开展灰霾天气预测预报预警方法的研究和业务平台建设 ,拓展气象服务领域 ,使环境气象产品更好地为社会公众服务 ,为政府实行动态调控的环保措施的决策服务。     

2010年广州亚运限行减排对大气环境的影响

通过对亚运会、亚残运会期间限行减排各个阶段的广州和相邻城市监测到的污染物浓度以及同期的天气背景进行分析,探讨污染源、城市的地理位置、天气条件和限行减排对亚/亚残运会期间广州大气环境的影响,结果表明:由于人为限行减排、城市的地理位置和气象扩散条件等各种因素综合作用,使得亚运会期间广州统计平均的能见度基本大于10 km;机动车的限行减排对PM10的削减作用不如PM2.5和PM1明显;限行减排对广州O3浓度控制"不敏感",但是会导致浓度峰值时间相对广东东莞出现1小时左右时间"滞后";珠江三角洲(简称珠三角)的大气环境问题呈现区域性,而且污染程度不容乐观,将来对该区域的大气环境治理需要进行长期持续的联防联控。     

西藏羊卓雍错湖面遥感监测模型及近期变化

羊卓雍错作为西藏高原三大圣湖之一和藏南重要的高原特色风景旅游景区, 其水域变化受到当地老百姓和各级政府部门的关注. 应用高分辨率陆地资源卫星等遥感数据可以方便、 准确地获取湖泊面积、 周长等信息, 但是由于Landsat 等高分辨率陆地资源卫星影像受到卫星重复周期和卫星过顶时多云天气的影响, 无法实现湖泊面积变化的常规业务化连续监测. 为此, 以Landsat 等高分辨率陆地资源卫星为主要遥感信息源, 结合羊卓雍错水位观测资料, 建立了羊卓雍错湖泊面积变化与水位波动之间的相关模型. 在此基础上, 利用该湖泊面积遥感监测模型, 结合近期水位观测资料分析了羊卓雍错湖面面积变化特征与趋势.     

南岭山地浓雾的宏微观物理特征综合分析

通过对南岭山地进行的雾野外观测资料以及数值试验的综合分析,得到了南岭山地浓雾和能见度的季节分布特征、雾滴谱微观特征与浓雾形成的物理概念图像。在秋末和冬春季节,南岭山地恶劣能见度出现的频率很高,能见度≤200 m浓雾过程的出现频率平均为24.7%,最高可达41.8%;冬春季节南岭山地出现的雾是复杂的微物理过程、局地地形、水汽输送与影响天气系统等宏微观相互作用的结果,属于平流雾、爬坡雾类型,与辐射雾明显不同,局地山地抬升冷却凝结对雾的形成起重要的作用,迎风坡对雾的形成有利,在海拔较低的迎风坡也可能出现浓雾,从而导致低能见度;南岭山地的雾以小滴谱为主,数密度比城市雾小,小粒子段谱型基本呈下降趋势;在多个微观变量中,含水量与能见度的反相关性最好;雾含水量等微结构特征量的起伏变化,与雾体本身的微物理过程有关外,雾体随环境风的平移过程中,不规则的爬坡、翻越山坡的运动是造成雾体微结构不均匀、振荡起伏变化的重要原因。     

1961~2005年中国大雾天气气候特征

利用1961～2005年中国541个地面台站观测的能见度和相对湿度资料,分析了中国大雾时空分布特征和趋势变化特征.结果表明:中国大部分地区冬半年大雾日数明显偏多.夏半年明显偏少.其中11月最多,6月最少.在空间分布上,中国东部降水量较多的平原和丘陵年均大雾日数较多,而内蒙古大部和中国西部大部分地区年均大雾日数较少,多在1天以下.长江中下游和黄淮地区一些省市,是大雾天气多发的地区,并且具有明显正变化趋势,年大雾天气日数呈波动增多的趋势,波动的周期大约为1.5年.1982、1987、1989～2000年和2002年是大雾日数较多的年份,而1967年则是大雾日数明显偏少的年份.     

STUDY ON THE CHEMICAL CHARACTERISTICS OF POLLUTING FOG IN GUANGZHOU AREA IN SPRING

Samples of fog water collected in the area of Guangzhou during February, March and April of 2005 are used in this work to study the chemical composition of fog water in polluting fog there. Three typical episodes of polluting fog are analyzed in terms of ionic concentration and their possible sources. It is found that the concentration of various ions in fog water is much higher than those in rainwater. Fog not only blocks visual range but contains liquid particles that result in high degree of pollution and are very harmful to human health. SO₄⁼ is the anion with the highest concentration in fog water, followed by NO₃^-.For the cation, Ca⁺⁺ and NH₄⁺ are the highest in concentration. It is then known that rainwater is more acidic than fog water, indicating that ionic concentration of fog water is much higher than that of rainwater, but there are much more buffering materials in fog water, like NH₄⁺ and Ca⁺⁺. There is significant enrichment of Ca⁺⁺, SO₄⁼, and Mg⁺⁺ in fog water. In the Guangzhou area, fog water from polluting fog is mainly influenced continental environment and human activity. The episodes of serious fog pollution during the time have immediate relationships with the presence of abundant water vapor and large amount of polluting aerosol particles.     

VARIATION OF AEROSOL OPTICAL CHARACTERISTICS IN GUANGZHOU DURING SOUTH CHINA SEA SUMMER MONSOON EVENTS

Variations in Guangzhou’s aerosol optical characteristics and their possible causes are studied against the large-scale background of South China Sea summer monsoons(SCSSM) using aerosol data derived from Panyu Atmospheric Composition Watch Station in Guangzhou and the National Centers for Environmental Prediction/National Center for Atmospheric Research(USA). The data is reanalyzed to develop a composite analysis and perform physical diagnoses. Analysis of the results shows that aerosol extinction in Guangzhou first increases then decreases during the active period of a SCSSM, with variations in the stratification of the planetary boundary layer(PBL) and environmental winds playing important roles in affecting Guangzhou’s aerosol optical characteristics. Regional diabatic heating and anomalous cyclonic circulations excited by monsoon convection induce environmental wind anomalies that significantly modify the stratification of the PBL.     

关于霾与雾的区别和灰霾天气预警的讨论

由于经济规模的迅速扩大和城市化进程的加快,大气气溶胶污染日趋严重,霾与雾的区分成为一个非常现实,又迫切需要解决的问题。而过去东南沿海各省不成规定的用相对湿度区分的标准普遍偏低。区分霾和雾,应该根据影响天气系统的变化,结合各种判据来确定。考虑到近几年对气溶胶研究的新成果,大气中0．1μm以下的水溶性粒子主要是硫酸铵等组成的,大于1μm的粒子主要是氯化钠等组成的。这些物质的相变湿度大都在80％左右。建议将相对湿度小于80％时的大气混浊视野模糊导致的能见度恶化的天气现象确定为霾,相对湿度大于90％时的大气混浊视野模糊导致的能见度恶化确定为雾,相对湿度介于80％～90％之间时的大气混浊视野模糊导致的能见度恶化是霾和雾的混合物共同造成的,但其主要成分应该是霾。建议尽快制定灰霾指数和预警办法,开展灰霾天气预测预报预警方法的研究和业务平台建设,拓展气象服务领域,使环境气象产品更好地为社会公众服务,为政府实行动态调控的环保措施的决策服务。     

一次早春多单体冰雹分析

利用常规气象资料、NCEP再分析资料,结合黄山多普勒雷达观测资料,对2009年2月发生在黄山地区一次冰雹天气个例发生发展过程进行分析。结果显示:①此次降雹是由于高空急流引发的,有一次积云合并过程,具有多雷暴单体的基本特征。②冰雹发生在早春2月,具有明显的季节特征,组合反射率也很高,但由于空气柱气温较低,垂直液态水含量相比初夏的冰雹要小,-20℃高度相比初夏低1～2km。