成都市混合层高度与气溶胶层高度关系的研究

混合层高度(MLH)和气溶胶层高度(ALH)作为表征污染物在大气垂直结构上的最大高度,两者在某些情况下可近似相等,为探究成都市MLH和ALH是否可以等价替换使用,该文利用2017-2019年四川省环保厅超级监测站(西南交通大学站)以及同期成都温江探空站的监测数据,对成都市MLH和ALH的相关性和差异性进行分析研究。结果表明,MLH和ALH在数据分布上具有较大差异性,且MLH和ALH两者在数据上具有较弱的负相关关系。对成都市ALH和MLH的时间变化规律进行分析和研究表明,ALH在一般情况下明显高于MLH,但在白天,温度和辐射较强的时间段,ALH会低于MLH。因此在使用成都市MLH数据时,不能简单地将MLH用ALH进行替换。

合肥春季气溶胶结构层探测研究

为了分析造成合肥上空春季自由对流层气溶胶浓度分布高于其它季节的原因,本文对偏振激光雷达2005～2008年期间春季常规测量和加密测量的数据结果进行再分析,从中提取了137组气溶胶结构层进行统计研究,并对2008年3月2日的观测结果作了个例分析。结果表明,特殊气溶胶结构层大多源于沙尘源区气溶胶粒子的远距离传输,其影响高度70%分布在2～4 km范围内,退偏振比大于0.1的结构层占据85%,这些结果可用于解释合肥春季自由对流层的气溶胶浓度分布偏高的原因。

大气气溶胶多层结构的激光雷达探测

目的探测大气气溶胶的垂直分布,表征气溶胶的垂直结构和各层气溶胶的性质。方法使用金华站点激光雷达观测数据进行个例分析,用梯度法对边界层进行反演,利用退偏振比、颜色比和光学厚度对大气中不同高度的气溶胶层进行分析。结果大气垂直结构会出现多层不同性质的气溶胶层,激光雷达可以准确地探测气溶胶随时间变化的垂直结构特征。选取0点至8点进行分析表明,在1.5km高度上下出现两层气溶胶层,上下两层气溶胶层呈现出不同的性质,且其性质会随时间变化而改变。结论大气边界层以外气溶胶分布较为复杂,利用激光雷达探测的气溶胶消光系数、退偏振比、颜色比和光学厚度等参数能够较好地表征气溶胶的垂直结构和各层气溶胶的性质。

气溶胶影响混合相对流云降水的数值模拟研究

利用一种新的异质冰相核化参数化方案，研究了当气溶胶同时作为云凝结核和冰核时，在不同高度输送对混合相对流云和降水的影响。结果发现，对于本文研究的理想混合相对流云，气溶胶在边界层的输送导致液滴数浓度明显增加，有效半径减小，霰粒的生长受到抑制，引起霰粒质量浓度降低；而气溶胶在对流层中层4～6km输送时，导致冰晶和霰粒数浓度明显增加。由于较多的冰晶引起更加快速的贝吉隆过程，使霰粒的质量浓度增加；气溶胶在对流层中层2～4km高度输送时冰相形成作用相对较弱，并引起霰粒的数浓度略微增加，由于霰粒的有效半径减小导致其质量浓度下降。气溶胶在不同高度的输送都导致液态和固态降水率降低，随着背景气溶胶数浓度的增加，气溶胶在0～2km、2～4km以及4～6km的输送分别导致累积降水量减少28％～64％、4％～44％和3％～46％，并且对降水的抑制效应及所在高度不同引起的降水差异随着背景气溶胶数浓度的增加而减小。

Simulated Impacts of Sulfate and Nitrate Aerosol Formation on Surface-Layer Ozone Concentrations in China

The authors quantify the impacts of sulfate and nitrate aerosol formation on surface-layer 03 concentrations over China using the one-way nested-grid capa- bility of the global three-dimensional Goddard Earth Ob- serving System chemical transport model （GEOS-Chem）. Chemical reactions associated with sulfate formation are simulated to generally increase 03 concentrations in China. Over the North China Plain （NCP） and the Si- chuan Basin （SCB）, where simulated sulfate concentra- tions are the largest, ozone concentrations show maximum increases in spring by 1.8 ppbv （3.2%） in the NCP and by 2.6 ppbv （3.7%） in the SCB. On the contrary, nitrate formation is simulated to reduce 03 concentrations by up to 1.0 ppbv in eastern China, with the largest reduc- tions of 1.0 ppbv （1.4%） in summer over the NCE Ac- counting for the formation of both sulfate and nitrate, the surface-layer O3 concentrations over a large fraction of eastern China are simulated to increase in winter, spring, and autumn, dominated by the impact of sulfate forma- tion, but to decrease in summer because of the dominant contribution from nitrate formation.

An Empirical Method for Estimating Background Stratospheric Aerosol Extinction Profiles over China

The current paper introduces an empirical method for estimating the vertical distribution of background stratospheric aerosol extinction profiles covering the latitude bands of 50±5°N,40±5°N,30±5°N,and 20±5°N and the longitude range of 75 135°E based on Stratospheric Aerosol and Gas Experiment (SAGE) II aerosol extinction measurements at wavelengths of 1020 nm,525 nm,452 nm,and 386 nm for the volcanically calm years between 1998 2004.With this method,the vertical distribution of stratospheric aerosol extinction coefficients can be estimated according to latitude and wavelength.Comparisons of the empirically calculated aerosol extinction profiles and the SAGE II aerosol measurements show that the empirically calculated aerosol extinction coefficients are consistent with SAGE II values,with relative differences within 10% from 2 km above the tropopause to 33 km,and within 22% from 33 km to 35 km.The empirically calculated aerosol stratospheric optical depths (vertically integrated aerosol extinction coefficient) at the four wavelengths are also consistent with the corresponding SAGE II optical depth measurements,with differences within 2.2% in the altitude range from 2 km above the tropopause to 35 km.

Stratospheric Aerosol Extinction Profile Retrieval from SCIAMACHY Limb Measurements

Stratospheric aerosol extinction profiles are retrieved from Scanning Imaging Absorption Spectrometer for Atmospheric Cartography(SCIAMACHY) limb scatter measurements.In the process of retrieval,the SCIATRAN radiative transfer model is used to simulate the limb scattering radiation received by the SCIAMACHY instrument,and an optimal estimation algorithm is used to calculate the aerosol extinction profiles.Sensitivity analyses are performed to investigate the impact of the surface albedo on the accuracy of the retrieved aerosol extinction profiles in the northern midlatitudes.It is found that the errors resulting from the bias of the assumed surface albedo in the retrieval are generally below 6%.The retrieved SCIAMACHY aerosol extinction profiles are compared with corresponding Stratospheric Aerosol and Gas Experiment(SAGE) II measurements,and the results indicate that for the zonal mean profiles,the SCIAMACHY retrievals show good agreement with SAGE II measurements,with the absolute differences being less than 2.3×10-5 km-1 from 14–25 km,and less than 5.9×10-6 km-1 from 25–35 km;and the relative differences being within 20% over the latitude range of 14–35 km.

Anthropogenic Direct Radiative Forcing of Tropospheric Ozone and Aerosols in 1850 and 2000 Estimated with IPCC AR5 Emissions Inventories

This study estimates direct radiative forcing by tropospheric ozone and all aerosols between the years 1850 and 2000, using the new IPCC AR5 （the Intergovernmental Panel on Climate Change Fifth Assessment Report） emissions inventories and a fully coupled chemistry-aerosol general circulation model. As compared to the previous Global Emissions Inventory Activity （GEIA） data, that have been commonly used for forcing estimates since 1990, the IPCC AR5 emissions inventories report lower anthropogenic emissions of organic carbon and black carbon aerosols and higher sulfur and NOx emissions. The simulated global and annual mean burdens of sulfate, nitrate, black carbon （BC）, primary organic aerosol （POA）, secondary organic aerosol （SOA）, and ozone were 0.79, 0.35, 0.05, 0.49, 0.34, and 269 Tg, respectively, in the year 1850, and 1.90, 0.90, 0.11, 0.71, 0.32, and 377 Tg, respectively, in the year 2000. The estimated annual mean top of the atmosphere （TOA） direct radiative forcing of all anthropogenic aerosols based on the AR5 emissions inventories is -0.60 W m^-2 on a global mean basis from 1850 to 2000. However, this is -2.40 W m-2 when forcing values are averaged over eastern China （18-45°N and 95-125°E）. The value for tropospheric ozone is 0.17 W m^-1 on a global mean basis and 0.24 W m^-2 over eastern China. Forcing values indicate that the climatic effect of aerosols over eastern China is much more significant than the globally averaged effect.

Towards a combined SAGE Ⅱ and SCIAMACHY aerosol dataset and implications for stratospheric aerosol trend analysis over East Asia

Scanning Imaging Absorption Spectrometer for Atmospheric Cartography（SCIAMACHY） limb observation data are used to retrieve stratospheric aerosol extinction profiles. The retrieved aerosol profiles are compared with Stratospheric Aerosol and Gas Experiment（SAGE） Ⅱ aerosol data records. The comparisons are made over the period 2003–2004. The results show that the SCIAMACHY aerosol profile retrievals exhibit general agreement with the coincident SAGE Ⅱ data records. In the 15–35 km altitude range, the percentage differences between the SCIAMACHY-retrieved and SAGE Ⅱ–measured zonal mean aerosol extinction profiles are less than 20% for the 20–30°N and 30–40°N latitude zones, and less than 25% for the 40–50°N zone. The stratospheric aerosol optical depths in this altitude range calculated from SCIAMACHY retrievals are in good agreement with SAGE Ⅱ measurements, with present differences less than 6% for the three latitude zones. The aerosol retrievals from SCIAMACHY observations are combined with the SAGE Ⅱ aerosol data records, form a long-term data-set for the period 2000–2010. Using the combined SAGE Ⅱ and SCIAMACHY dataset, the variation trends of the stratospheric aerosol layer over East Asia（20–50°N, 70–150°E） are analyzed. The results indicate that the stratospheric aerosols have a significant trend of increase over East Asia during 2000–2010. The stratospheric aerosol optical depths increase by about 5% per year over the 11-yr period. The increase in stratospheric aerosols is found to be obviously related to moderate volcanic eruptions.

Impact of Different Aerosols on the Evolution of the Atmospheric Boundary Layer

The present work analyzes the effect of aerosols on the evolution of the atmospheric boundary layer (ABL) over Shangdianzi in Beijing.A one-dimensional ABL model and a radiative transfer scheme are incorporated to develop the structure of the ABL.The diurnal variation of the atmospheric radiative budget,atmospheric heating rate,sensible and latent heat fluxes,surface and the 2 m air temperatures as well as the ABL height,and its perturbations due to the aerosols with different single-scattering albedo (SSA) are studied by comparing the aerosol-laden atmosphere to the clean atmosphere.The results show that the absorbing aerosols cause less reduction in surface evaporation relative to that by scatting aerosols,and both surface temperature and 2 m temperature decrease from the clean atmosphere to the aerosol-laden atmosphere.The greater the aerosol absorption,the more stable the surface layer.After 12:00 am,the 2 m temperature increases for strong absorption aerosols.In the meantime,there is a slight decrease in the 2 m temperature for purely scattering aerosols due to radiative cooling.The purely scattering aerosols decrease the ABL temperature and enhance the capping inversion,further reducing the ABL height.

防毒面具浅谈

防毒面具是我军的制式装备。对于现代战争中敌人的核武器、化学武器和生物武器袭击,它是有效的个人防护器材。部队卫生人员在战时要救治遭受核武器、化学武器和生物武器损伤的伤员,在平时也要负责对部队指战员进行'三防'训练,所以必须熟悉防毒面具的性能和使用方法。有些战士、干部以至卫生人员,就是由于不懂防毒面具的使用方法,结果造成了严重的事故。下面,我们简要地介绍一下防毒面具的构造、原理和使用、保管方法。一、防毒面具为什么能防毒?过滤式防毒面具主要由滤毒罐、面罩、面具袋3个部分组成。面具的防毒是在滤毒罐中进行的。各种面具的滤毒罐虽然在形状。

An Empirical Model for Estimating the Zonal Mean Aerosol Extinction Profiles from SAGE II Measurements

This paper presents an empirical model for estimating the zonal mean aerosol extinction profiles in the stratosphere over 10°-wide latitude bands between 60°S and 60°N, on the basis of Stratospheric Aerosol and Gas Experiment(SAGE) II aerosol extinction measurements at 1.02, 0.525, and 0.452 μm during the volcanically quiescent period between 1998–2004. First, an empirical model is developed for calculating the stratospheric aerosol extinction profiles at 1.02 μm. Then, starting from the 1.02 μm extinction profile and an exponential spectral dependence, an empirical algorithm is developed that allows the aerosol extinction profiles at other wavelengths to be calculated. Comparisons of the model-calculated aerosol extinction profiles at the wavelengths of 1.02, 0.525, and 0.452 μm and the SAGE II measurements show that the model-calculated aerosol extinction coefficients conform well with the SAGE II values, with the relative differences generally being within 15% from 2 km above the tropopause to 40 km. The model-calculated stratospheric aerosol optical depths at the three wavelengths are also in good agreement with the corresponding optical depths derived from the SAGE II measurements, with the relative differences being within 0.9% for all latitude bands. This paper provides a useful tool in simulating zonal mean aerosol extinction profiles, which can be used as representative background stratospheric aerosols in view of atmospheric modeling and remote sensing retrievals.

Characterization of Stratospheric Aerosol Distributions during the Volcanically Quiescent Period of 1998–2004

The Stratospheric Aerosol and Gas Experiment （SAGE） II aerosol extinction profiles at 1020 nm were used to study the distribution characteristics of stratospheric aerosols during the volcanically quiescent period of 1998-2004. The stratospheric aerosol distributions exhibited hemispheric asymmetry between the Northern Hemisphere （NH） and the Southern Hemisphere （SH）. In the lower stratosphere below 20 km, the zonal averaged aerosol optical depths in the NH were higher than those of the corresponding SH; whereas at higher altitudes above 20 km, the optical depths in the SH-- except the equatorial region--were higher than those of the NH. At 0-10°N and 10-20°N, the stratospheric aerosol optical depth （SAOD） exhibited larger values in boreal winter and lower values in the spring and summer; at 0-10°S and 10-20°S, the SAOD presented small seasonal variations. At 30-40°N, the SAOD presented larger values in the boreal fall and winter and lower values in the spring and summer; while at 30-40°S, the SAOD exhibited larger values in the austral winter and early spring and lower values in the summer and fall. These characteristics can mainly be attributed to the seasonal cycle of the dynamic transport, and the effects of the buildup and breakdown of the polar vortex. At 50-60°S, the SAOD exhibited extremely high values during austral winter associated with the Antarctic polar vortex boundary; at 50-60°N, the SAOD also exhibited larger values during the boreal winter, but it was much less obvious than that of its southern counterpart.

The Role of the Dipole Interaction of Molecules with Charged Particles in the Polar Stratosphere

Our analysis of published results of experiments in the Polar Regions substantiates and further develops our new approach to the photochemical processes in the polar stratosphere involving the charged particles. The dipole interaction of molecules with charged particles, primarily with ions, leads to the adhesion and disintegration of a number of molecules including ozone. Molecules acquire additional energy on the surface of the charged particles, enabling reactions that are not possible in space. Galactic cosmic rays are the main source of ions in the polar stratosphere, their equilibrium concentration at altitudes of 15 to 25 km can reach up ~ （1-5） ~ 103 ions/cm3. Estimations show that if the ozone destruction in the regime of＂collision＂ with ions then the lifetime of ozone will vary from 10 days to 2 months. We suppose that alongside with the chlorine mechanism of ozone destruction there is a mechanism of ozone decay on a charged particle which can act also at those latitudes and altitudes where chlorine oxide CIO is absent, as well as in the night conditions. Here, we demonstrated the close connection of photochemical processes with the dynamic, electrical and condensational phenomena in the stratosphere, in particular, with the accumulation of unipolar charged particles on the upper and lower boundaries of the polar stratospheric clouds and aerosol layers as a result of the activity of the global electric circuit.

Numerical analysis for contribution of the Tibetan Plateau to dust aerosols in the atmosphere over the East Asia

Although the Tibetan Plateau is widely thought as a potential dust source to the atmosphere over East Asia,little is known about the temporal changes of Tibetan dust activities and Tibetan dust source strength.In this study,we address these two issues by analyzing dust storm frequencies and aerosol index through remote sensing data and by means of numerical simulation.The findings indicate that monthly dust profiles over the Tibetan Plateau vary significantly with time.Near the surface,dust concentration increases from October,reaches its maximum in February March,and then decreases.In the middle to upper troposphere,dust concentration increases from January,reaches its maximum in May June,and decreases thereafter.Although Tibetan dust sources are important contributors to dust in the atmosphere over the Tibetan Plateau,their contribution to dust in the troposphere over eastern China is weaker.The contribution of Tibetan dust sources to dust in the atmosphere over the Tibetan Plateau decreases sharply with height,from 69% at the surface,40% in the lower troposphere,and 5% in the middle troposphere.Furthermore,the contribution shows seasonal changes,with dust sources at the surface at approximately 80% between November and May and 45% between June and September;in the middle and upper troposphere,dust sources are between 21% from February to March and less than 5% in the other months.Overall,dust aerosols originating from the Tibetan Plateau contribute to less than 10% of dust in East Asia.

Observation analysis on characteristics of formation,evolution and transition of a long-lasting severe fog and haze episode in North China

An unusual fog and haze event lasted for one week took place during 1–7 December,2011 over North China.To investigate the characteristics and mechanism of formation,evolution,and transition of the fog and haze event,we studied the microphysical properties such as aerosol,cloud condensation nuclei(CCN),fog droplet spectrum and liquid water content(LWC),as well as horizontal visibility and boundary layer properties,using the data collected in the Project of Low-Visibility Weather Monitoring and Forecasting in the Beijing-Tianjin region.The results indicate that the long-lasting fog and haze event occurred in a high pressure weather system and calm wind condition.The stable boundary-layer structure resulted from temperature inversions that were built by warm advection and radiation cooling provided a favorable condition for the accumulation of polluted aerosols and the formation and development of the fog and haze event.In particular,the continuous southerly wet flow advection made the process a persistent and long-lasting event.The horizontal visibility was almost below 2 km in the whole process,and the lowest visibility was only 56 m.The average LWC was about 10-3 g m-3,and the maximum LWC reached 0.16 g m-3.The aerosol number concentration was more than 10000 cm-3,and its mass concentration ranged from 50 to 160 -g m-3.The further study shows that the fog and haze event experienced three main processes in different intensities during the whole period,each process could be divided into three main stages:aerosol accumulation,transition and mixture of aerosol and fog,and dissipation.Each stage had different physical features:the aerosol accumulation stage was characterized by the increase of aerosol number concentration in Aitken nuclei and accumulation mode sequentially.In the transition and mixing stage of fog and haze,the latent heating produced by fog droplet condensation process and high aerosol number concentration condition intensified the Brownian coagulation process,which induced the small size of aerosols to become larger ones and enhanced the CCN activation process,thereby promoting the explosive development of the fog event.The ratio of aerosol activated to CCN reached 17%,and the ratio of CCN converted to fog droplet exceeded 100%,showing an explosively broadening of fog droplet spectrum.The decrease and dissipation of the fog was caused by an increased solar radiation heating or the passage of cold frontal system.