辽东湾地区大气边界层扩散特征探讨

利用辽东湾地区近地层三轴风速仪资料,分别计算了不同稳定度下的大气扩散参数及湍流强度。并对不同情况下的大气扩散参数及湍流强度进行了比较。结果表明,在地形相对平坦的辽东湾地区,在不同的稳定度下,σy和σx值均略大于同级Briggs公式的计算值,但小于地形相对复杂的本溪地区。在不稳定条件(C、B类)下,湍强值最大。     

牙克石地区大气扩散试验分析

利用牙克石电厂野外平衡球观测资料分别计算了不同稳定度下的大气扩散参数,并与其他结果进行了比较,揭示了牙克石地区大气湍流扩散特征。试验结果仅适用于远距离的高架源排烟计算。     

沿海地区大气边界层扩散特征探讨

利用辽东湾近地层三轴风速仪资料分别计算不同稳定度的大气扩散参数及湍流强度。并将不同情况下的大气扩散参数及湍流强度进行了比较。结果表明 :在地形相对平坦的辽东湾 ,在不同的稳定度下 ,σy 和σz值均略大于同级布里格斯公式的计算值。在不稳定条件 (C、B类 )下 ,湍强值最大。     

沿海地区大气边界层扩散特征探讨

利用辽东湾近地层三轴风速仪资料分别计算不同稳定度的大气扩散参数及湍流强度。并将不同情况下的大气扩散参数及湍流强度进行了比较。结果表明：在地形相对平坦的辽东湾,在不同的稳定度下,σy和σx值均略大于同级布里格斯公式的计算值。在不稳定条件(C、B类)下,湍强值重大。     

局地山区地形对大气扩散参数影响初探

本文通过特殊喇叭口山谷地形下实测的平衡球资料对大气扩散参数的估算,表明在一定的地形条件下,稳定稳定度下的垂直扩散参数σz 可大于中性稳定度下的σz。得出在山区某些特殊地形的局部区域,不能用现有的同类稳定度的扩散参数提级的办法来代替该地区该稳定度下的扩散参数。而用平衡球资料估算扩散参数这种粗糙的方法,也要比用现有的扩散参数精确。     

玛纳斯电厂冬季大气扩散的试验研究

在进行大气环境质量的评价和预测时,对大气扩散规律的分析是十分重要的.目前普遍采用的方法之一是用观测平衡气球轨迹的方法计算扩散参数.本文对1989年冬季,在玛纳斯电厂用平衡气球轨迹法进行的大气湍流扩散试验资料作了分析计算,并与P-G(帕斯圭尔一吉福德)结果进行了比较,提出了厂区不同稳定度条件下的大气湍流扩散参数σ_y和σ_z,为研究和摸清该区大气污染物的扩散能力提供了依据.     

基于欧拉观测的大气扩散参数计算方法

利用超声风速仪对吉林省敦化市大石头镇进行了夏、冬季各10 d的观测。根据大气湍流扩散参数统计理论,利用欧拉观测的风速资料求解正态扩散模式中的大气扩散参数。结果表明:2005年夏季和2007年冬季B—F类稳定度的σy和σz均呈减小趋势,横轴y方向的总体扩散水平大于垂直方向z轴的总体扩散水平。夏季的σy在B—D类明显高于冬季的σy,且随着水平距离的增加更为明显;E—F类,夏季的σy在x=100 m处,略低于冬季,但随着水平距离的增加,夏季的σy比冬季的σy增加更快;夏季的σz在B—F类均高于冬季的σz,且随着水平距离的增加更为明显。该计算方法具有可操作性和实用性,可作为研究该地区大气湍流扩散规律和污染模式选取参数的依据。     

济南市东郊高架源扩散规律的试验研究

本文分析了济南市东郊的高架源扩散试验资料,其中包括SF_6试验、平衡气球试验和烟羽观测试验。SF_6的横向浓度分布为多峰分布,垂直浓度分布为正态分布,浓度轴向上抬升,沿平均风向的浓度分布呈多峰分布;在示踪物(SF_6)由郊区进入城区不远处,浓度出现相对低值。 上述三项试验所得的扩散参数相近。水平扩散参数σ_y较同类试验的值偏大,在粗糙度不连续处无跃变现象;垂直扩散参数σ_y反映了粗糙度较小地区的垂直分布情况。所计算的最大落地浓度距离与实测值相当接近。     

扩散参数的风速订正及短期扩散浓度的分布概率

本文对扩散参数σ_y、σ_z的随机波动性进行了若干物理分析,得出结论为:(1)风速对σ_y,σ_z随下风距离的变化规律有较大影响;(2)短期浓度模式计算中,扩散参数的随机波动不可忍略。利用1983年10月南京大厂地区的实测资料验证了上述结论,对扩散参数随下风距离的变化规律作了风速订正。本文并试图通过风速的概率分布来获得扩散参数的概率,从而进一步探讨以概率的形式来表示短期扩散浓度的分布。     

粤东复杂地形上空的大气湍流强度及扩散参数

在具有复杂下垫面的粤东梅州市采用追踪平衡球的双经纬仪观测和美制ＧＩＬＬ三轴风速仪观测，分别测定了该地区拉格朗日系统和欧拉系统的湍流脉动量。然后用不同参照系的泰勒公式，分别计算出大气的水平和垂直的湍流强度及扩散参数，并与ＰＧ法之计算值和ＢＮＬ实验结果比较，发现距地面１００ｍ以上高空在各类稳定度层结条件下大气扩散参数均比ＰＧ值和ＢＮＬ值偏大。     

上甸子本底站气溶胶散射系数变化特征的初步分析

根据上甸子大气成分本底站从2004～2006年的连续观测数据,分析了区域大气粒子光散射系数的变化特点,以了解本底地区大气气溶胶粒子的基本特征.卜甸子地区3年数据比较表明,散射系数平均水平较低,但在2006年有所升高,主要表现在受春季沙尘天气的影响,污染次数增多.其次,散射系数日变化规律表现为白大低夜间高,午后出现最低值,此变化与大气层结的日变化趋势一致.从季节变化看,冬季和春季的散射系数相对较低,而夏季和秋季的值较高,这与气象条件及内外源的影响都有关系.天气对粒子变化的影响表现为,晴天无云时的大气状况有利于污染物的重直输送,散射系数远远低于阴天时的数值.另一方面,风向对本底站粒子浓度影响也较明显.来自东北东方向的空气较干净,散射系数值通常较低,而西南西风向通常会引起散射系数值的增大,说明位于西南方向上的北京等城镇的污染输送对上甸子本底站的大气状况有一定影响.最后,通过拟和散射系数小时平均值出现频率曲线,对上甸子地区本底浓度值作了初步估算,其范围在10~20 Mm~(-1).     

Calibration of Four Species of Tillandsia as Air Pollution Biomonitors

Many organisms have been used as bioindicators of atmospheric contamination, with moss and lichen species being the most common. However, studies using epiphytic vascular species of Tillandsia have shown a good correlation between the presence of pollutants and the bioindicator's response. Therefore, the aim of our investigation was to calibrate and compare the response of four Tillandsia species of Argentina to ascertain whether they could be used as atmospheric contamination biomonitors. For this, we analysed the correlation between the levels of heavy metals in total atmospheric deposition samples and: a) their rate of enrichment; b) the physiological response of the plant samples. Tillandsia samples collected from a non contaminated area in the province of Córdoba were transplanted to four areas in the capital city with different sources of pollution (industrial or traffic emissions). They were exposed for a period of 3 to 6 months after which the concentrations of Pb, Ni, Fe, Zn, Cu and S as well as the physiological parameters of foliar damage were determined. Simultaneously samples of total atmospheric deposition were also taken.The highest level of metal enrichment was found in T. capillaris followed by T. tricholepis, T. permutata and T. retorta. Also, the use of a foliar damage index proved to be effective and could be a useful tool to evaluate different levels of atmospheric quality in these species. The rate of heavy metal deposition was higher in the industrial area for all metals except for Zn whose values were higher in areas with high levels of traffic.     

Uncertainties in climate stabilization

The atmospheric composition, temperature and sea level implications out to 2300 of new reference and cost-optimized stabilization emissions scenarios produced using three different Integrated Assessment (IA) models are described and assessed. Stabilization is defined in terms of radiative forcing targets for the sum of gases potentially controlled under the Kyoto Protocol. For the most stringent stabilization case (“Level 1” with CO₂ concentration stabilizing at about 450 ppm), peak CO₂ emissions occur close to today, implying (in the absence of a substantial CO₂ concentration overshoot) a need for immediate CO₂ emissions abatement if we wish to stabilize at this level. In the extended reference case, CO₂ stabilizes at about 1,000 ppm in 2200—but even to achieve this target requires large and rapid CO₂ emissions reductions over the twenty-second century. Future temperature changes for the Level 1 stabilization case differ noticeably between the IA models even when a common set of climate model parameters is used (largely a result of different assumptions for non-Kyoto gases). For the Level 1 stabilization case, there is a probability of approximately 50% that warming from pre-industrial times will be less than (or more than) 2°C. For one of the IA models, warming in the Level 1 case is actually greater out to 2040 than in the reference case due to the effect of decreasing SO₂ emissions that occur as a side effect of the policy-driven reduction in CO₂ emissions. This effect is less noticeable for the other stabilization cases, but still leads to policies having virtually no effect on global-mean temperatures out to around 2060. Sea level rise uncertainties are very large. For example, for the Level 1 stabilization case, increases range from 8 to 120 cm for changes over 2000 to 2300.     

Using Scintillometry to Estimate Sensible Heat Fluxes over Water: First Insights

An extra large aperture scintillometer (XLAS) was used over several months across the Thau Lagoon (South of France) to retrieve one-wavelength scintillation and, thence, sensible heat flux. We present the experiment with the XLAS, an eddy-covariance station and meteorological stations measuring on or near the Thau Lagoon. Changes implemented to adapt the scintillometry processing schemes to the above water conditions are presented together with a full error budget, including sensitivity tests to the relevant parameters of the scintillometer processing scheme. The XLAS error budget amounts to 16% (systematic part) ±50% (random part). Sensible heat fluxes obtained using the XLAS under unstable atmospheric conditions are then compared to eddy-covariance estimates used as a reference. The scintillometry technique proved to perform satisfactorily in such a watery environment. Some discrepancies observed between the XLAS and eddy-covariance measurements were investigated according to the lagoon fraction of the source area, to discriminate whether they were related to deviations from the Monin–Obukhov similarity theory or to different atmospheric conditions at the respective instrument locations. Local atmospheric conditions agreed well with the Monin–Obukhov similarity theory, especially measurements with source areas largely composed of the lagoon surface. Retaining only the measurements with almost only the lagoon surface in the source area improved the agreement between the XLAS and eddy-covariance measurements. The remaining discrepancies are interpreted as being due to significant location differences between the two instruments, resulting in different atmospheric conditions, and to size differences in the source areas.     

Identification of motion parameters from spatio-temporal atmospheric temperature patterns

In near-calm conditions it is difficult to make direct measurements of atmospheric advection reliably and cheaply, particularly at many points over a large area. An alternative indirect method is examined using time-series measurements of atmospheric temperature (or any other convenient conserved field variable) at points on a spatial grid.System identification methodology is applied to analyze atmospheric temperature data obtained in such near-calm conditions during an experiment with a low-flying helicopter. A three-parameter numerical model of atmospheric advection has been identified in the temperature data, the advection parameters being an eddy diffusion coefficient and horizontal components of the wind velocity. It has been demonstrated by analysis of all the assumptions, and using simulated data, that in this case the standard least-square procedure can be applied to recover sensible parameter estimates, even though the model is of the error-in-variables type and parameters appear to change abruptly at certain moments of time (but by a reasonably small amount). The parameter estimates have been validated against independent data.     

多普勒雷达晴空回波识别与应用

在现有多普勒天气雷达资料质量控制基础上,采用徐州雷达站2009年4月和9月雷达资料,统计并对比几种常见的降水回波与非降水回波特性,找出一种有效地识别晴空回波的方法。该方法在不同径向距离区间(小于25km及25～200km)采用不同的识别参数,能够较好地将非降水回波中对临近预报有用的晴空回波信息保留,而将其他非降水回波信息(地物回波、超折射回波等)剔除。依据该方法识别的晴空回波区域所对应Doppler速度可用于判别大气平流状况,从而为预报工作提供帮助。     

Modeling soil respiration and variations in source components using a multi-factor global climate change experiment

Soil respiration is an important component of the global carbon cycle and is highly responsive to changes in soil temperature and moisture. Accurate prediction of soil respiration and its changes under future climatic conditions requires a clear understanding of the processes involved. Most current empirical soil respiration models incorporate just few of the underlying mechanisms that may influence its response. In this study, a new partially process-based component model that separately treated several source components of soil respiration was tested with data from a climate change experiment that manipulated atmospheric [CO₂], air temperature and soil moisture. Results from this model were compared to results from other widely used models with the parameters fitted using experimental data. Using the component model, we were able to estimate the relative proportions of heterotrophic and autotrophic respiration in total soil respiration for each of the different treatments. The value of the Q ₁₀ parameters for temperature response component of all of the models showed sensitivity to soil moisture. Estimated Q ₁₀ parameters were higher for wet treatments and lower for dry treatments compared to the values estimated using either the data from all treatments or from only the control treatments. Our results suggest that process-based models provide a better understanding of soil respiration dynamics under changing environmental conditions, but the extent and contribution of different source components need to be included in mechanistic and process-based soil respiration models at corresponding scales.     

Maximum fluctuations of wind direction in limited time intervals at the levels up to 300 m from observations at a meteorological tower

On the basis of wind direction measurements with 1-s discreteness at the meteorological tower VMM-310 in the town of Obninsk, maximum fluctuations of wind direction are obtained with 10-s averaging over limited time intervals that correspond to the transport of pollutant puffs at distances about 10 km from the source at altitudes up to 300 m. Average values of maximum fluctuations of wind direction decrease with increasing wind speed, level of measurements, and stratification stability. Examples are presented of distributions of maximum fluctuations of wind direction as dependent of these factors. Parameters are given of distributions of maximum fluctuations of wind direction at six levels under different wind speeds and different atmospheric stability. The empirical distributions are approximated by Weibull distribution, and parameters of the latter are presented for separate levels. The results obtained can be used for estimation of an angular size of an area of possible pollution under different conditions of atmospheric stratification, wind speed, and levels of transport of an instantaneous puff of pollutants for the pollutant cloud motion up to a distance of 10 km from the source.