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81.
82.
During the period between 18 August and 22 September 2006, an ultraviolet
photometric O3 analyzer, a NO-NO2-NOx chemiluminescence
analyzer, and a quartz micro-oscillating-scale particle concentration
analyzer were simultaneously used for monitoring at three different heights
each at Beijing (325-m tower) and Tianjin (255-m tower). These towers belong
to the Institute of Atmospheric Physics (IAP) of the Chinese Academy of
Sciences (CAS) and to the Tianjin Municipal Meteorological Bureau,
respectively. These measurements were used to continuously measure the
atmospheric O3 and NOx volume-by-volume concentrations and the
PM2.5 mass concentration within a vertical gradient. When combined with
meteorological data and information on the variation of vertical
characteristics of the various atmospheric pollutants in the two cities,
analysis shows that these two cities were seriously polluted by both
PM2.5 and O3 during summer and autumn. The highest daily-average
concentrations of PM2.5 near the ground in Beijing and Tianjin reached
183 μg m-3 and 165 μg m-3, respectively, while the O3 concentrations reached 52 ppb and 77 ppb, and NOx concentrations
reached 48 ppb and 62 ppb for these two cities, respectively. The variations
in the daily-average concentrations of PM2.5 between Beijing and
Tianjin were demonstrated to be consistent over time. The concentrations of
PM2.5 measured in Beijing were found to be higher than those in
Tianjin. However, the overall O3 concentrations near the ground in
Tianjin were higher than in Beijing. NOx concentrations in Tianjin were
consistently lower than in Beijing. It was also found that PM2.5
pollution in Beijings atmosphere may also be affected by the pollutants
originating in and delivered from Tianjin, and that Ti 相似文献
83.
针对京津冀地区主要大气污染物NOx(氮氧化物)和PM2.5(大气中粒径小于或等于2.5μm的颗粒物),应用柴油车尾气净化技术及中小锅炉烟气脱硝技术,并根据2015年和2030年我国能源规划,设计3种技术应用情景,采用WRF-CAMx耦合模式,对京津冀地区大气中NOx和PM2.5进行了应用情景模拟。结果表明,单独应用柴油车尾气净化技术后(方案1),北京、天津地区大气中的NOx浓度降低幅度达20%,河北地区降低5%;PM2.5的浓度降低幅度约10%;应用柴油车尾气净化技术和2015年能源规划情景(方案2),京津冀地区大气中NOx和PM2.5浓度的降低幅度均超过20%;应用柴油车尾气净化技术和2030年能源规划情景(方案3),该地区NOx浓度降低幅度与之相当,PM2.5浓度降低幅度超过30%。可见脱硝技术和清洁能源利用的有效性依赖于其应用比例。二次气粒转化的化学过程形成的硝酸盐、硫酸盐和铵盐对该地区空气中PM2.5浓度的贡献很大,冬、春、秋季硝酸盐最大贡献高达60%,夏、秋季硫酸盐最大贡献超过70%,铵盐四季最大贡献约25%。这说明PM2.5的主要前体物NOx、SO2、NH3、VOCs (Volatile Organic Compounds)、CO等均大幅度削减才能有效降低该地区空气中PM2.5浓度。 相似文献
84.
10~30 d延伸期预报在气象业务发展和国民经济服务中具有重要的作用。本文回顾了关于延伸期预报的相关理论和技术研究进展,概要介绍了国内外开展延伸期预报业务现状;结合目前气象科技发展水平,进一步分析和阐述了现阶段我国开展延伸期预报业务亟待解决的关键技术问题,旨在共同探讨和推动延伸期预报业务的发展。 相似文献
85.
Particle composition and size distributions in and around a deep-pit swine operation,Ames, IA 总被引:1,自引:0,他引:1
Randal S. Martin Philip J. Silva Kori Moore Mark Erupe Vishal S. Doshi 《Journal of Atmospheric Chemistry》2008,59(2):135-150
The contribution of emissions from agricultural facilities is rapidly becoming a major concern for local and regional air
quality. Characterization of particle properties such as physical size distribution and chemical composition can be valuable
in understanding the processes contributing to emissions and ultimate fate of particulate matter from agricultural facilities.
A measurement campaign was conducted at an Iowa, deep-pit, three-barn swine finishing facility to characterize near-source
ambient particulate matter. Size-specific mass concentrations were determined using minivol samplers, with additional size
distribution information obtain using optical particle counters. Particulate composition was determined via ion chromatographic
analysis of the collected filters. A thermal-CO2 elemental/organic carbon analyzer measured particulate carbon. The chemical composition and size distribution of sub-micron
particles were determined via real-time aerosol mass spectrometry. Primary particulate was not found to be a major emission
from the examined facility, with filter-based impactor samples showing average near-source increases (~15–50 m) in ambient
PM10 of 5.8 ± 2.9 μg m−3 above background levels. PM2.5 also showed contribution attributable to the facility (1.7 ± 1.1 μg m−3). Optical particle counter analysis of the numerical size distributions showed bimodal distributions for both the upwind
and downwind conditions, with maximums around 2.5 μm and below the minimum quantified diameter of 0.3 μm. The distributions
showed increased numbers of coarse particles (PM10) during periods when wind transport came from the barns, but the differences were not statistically significant at the 95%
confidence level. The PM10 aerosols showed statistically increased concentrations of sulfate, nitrate, ammonium, calcium, organic carbon, and elemental
carbon when the samplers were downwind from the pig barns. Organic carbon was the major constituent of the barn-impacted particulate
matter in both sub-micron (54%) and coarse size (20%) ranges. The AMS PM1 chemical speciation showed similar species increases, with the exception of and Ca+2, the latter not quantified by the AMS. 相似文献
86.
Large-scale air pollution transport (LSAPT) in the Yellow Sea region and their inflow onto the Korean Peninsula were observed
through satellite images and ground measurements. LSAPT includes regional continental air-masses saturated with pollutants
originating from China and subsequently landing on or passing through the Korean Peninsula. It is also possible to identify
the distribution and transport patterns of LSAPT over the Yellow Sea. The ground concentrations for PM10, PM2.5 and CO measured
at Cheongwon, located in the centre of south Korea, were compared with NOAA satellite images. Notably, the episodes observed
of the LSAPT show a PM2.5 to PM10 ratio of 74% of the daily maximum concentrations. However, cases of duststorms were clearly
distinguished by much higher PM10 concentrations and a ratio of 30% of PM2.5 to PM10 for daily maximum concentrations. For
the episode on January 27, 2006, the inflow of a regionally polluted continental air-mass into the central and southwestern
regions of the Korean Peninsula was observed sequentially at various ground observatories as well as by satellite. The north
airflow dissipated the clouds over Mt. Halla on Jeju Island and further downwind, reducing air pollution and creating a von
Kármán vortex. 相似文献
87.
Emilia K. Jin James L. Kinter III B. Wang C.-K. Park I.-S. Kang B. P. Kirtman J.-S. Kug A. Kumar J.-J. Luo J. Schemm J. Shukla T. Yamagata 《Climate Dynamics》2008,31(6):647-664
The overall skill of ENSO prediction in retrospective forecasts made with ten different coupled GCMs is investigated. The coupled GCM datasets of the APCC/CliPAS and DEMETER projects are used for four seasons in the common 22 years from 1980 to 2001. As a baseline, a dynamic-statistical SST forecast and persistence are compared. Our study focuses on the tropical Pacific SST, especially by analyzing the NINO34 index. In coupled models, the accuracy of the simulated variability is related to the accuracy of the simulated mean state. Almost all models have problems in simulating the mean and mean annual cycle of SST, in spite of the positive influence of realistic initial conditions. As a result, the simulation of the interannual SST variability is also far from perfect in most coupled models. With increasing lead time, this discrepancy gets worse. As one measure of forecast skill, the tier-1 multi-model ensemble (MME) forecasts of NINO3.4 SST have an anomaly correlation coefficient of 0.86 at the month 6. This is higher than that of any individual model as well as both forecasts based on persistence and those made with the dynamic-statistical model. The forecast skill of individual models and the MME depends strongly on season, ENSO phase, and ENSO intensity. A stronger El Niño is better predicted. The growth phases of both the warm and cold events are better predicted than the corresponding decaying phases. ENSO-neutral periods are far worse predicted than warm or cold events. The skill of forecasts that start in February or May drops faster than that of forecasts that start in August or November. This behavior, often termed the spring predictability barrier, is in part because predictions starting from February or May contain more events in the decaying phase of ENSO. 相似文献
88.
对1951-2007年辽宁省稳定通过0℃、10℃积温和持续日数变化进行了分析.结果表明:(1)近57年来辽宁省稳定通过0℃和10℃积温和持续日数呈递增趋势,其中稳定通过10℃积温和持续日数递增趋势更明显;(2)各标准气候期稳定通过0℃和10℃积温变化趋势不同,第1个和第2个30年标准气候期呈现递增趋势较弱,最近30年标准气候期呈显著递增趋势;各标准气候期稳定通过0℃和10℃持续日数均为递增趋势,而且后期递增较前期更为显著;(3)中部和沿海城市稳定通过0℃、10℃积温和持续日数递增趋势强于北部和西部;(4)城市化引起的热岛效应是观测到的稳定通过0℃、10℃积温和持续日数递增的重要原因,而区域气候变暖则进一步加强了递增趋势. 相似文献
89.
我们曾论述了地球系统100~108年变化的原因[1], 唯对10-1年(月一年)的地球系统变化未指出其变化原因。经过近年的研究, 现在可以明确地指出, 地球内部有两类流体: 地外核和岩石圈裂隙中地下流体(地气)的活动是引发10-1年地球系统变化的原因。外核的上升运动会使其上部岩石圈产生上抬和压缩, 在地表层就出现3.2 m地温升高和降水减少的“干热异常”, 经过“孕震三步曲”最终引发构造地震。外核的下降运动会使其上部岩石圈产生下沉和拉张作用, 地表层表现为3.2 m地温降低, 同时降水增多的“湿冷异常”, 最终可导致发生陷落地震。外核的脉冲运动是引发岩石圈中形成地热(冷)涡的“源”。地气环流也是旋转地球上的一种流体运动, 其特征速度(地下风速)约为0.2 m/s, 据此可推得“自然气候周期”约为8个月。地气环流是使地气系统得以“流”的动力源。地热(冷)涡的“源”、 “流”相结合是使短期气候呈现纷繁复杂变化的原因。 相似文献
90.
利用北京城区污染观测站2006~2013年夏季可吸入颗粒物PM10逐日浓度检测资料,挑选所有PM10浓度大于150μg/m~3的个例,合成分析华北及北京地区风场变化情况,发现风速在污染当天变化不明显,南风与PM10的相关性普遍为正,污染当天各区南风增加较大,太行山一带甚至增长了5倍。南风异常可能会使河北、山东等地污染物向北京输送,造成北京大气污染。同时我们分析北京夏季空气污染时大气环流特征。在500 h Pa与200 h Pa,北京和内蒙古上空有显著的高压异常。在850 h Pa,环流场表现为东正西负的高度场异常,其中北京在正负异常分界线上。低层气压梯度异常会造成北京和以南地区南风异常。同时,我们发现北京污染天气伴随的高空环流异常具有准定常特征。在污染前4天,蒙古上空存在一个显著的高层高压异常。该高压异常增强并向南延伸,在污染当天控制北京和内蒙古。在污染消退期,该异常也逐渐消退。但在消退后第四天,北京和内蒙古上空依然受高压异常控制。这表明北京夏季污染和高空准定常环流异常有关。 相似文献