共查询到20条相似文献，搜索用时 203 毫秒
1.
2.
邢台市大气稳定度和混合层厚度特征研究 总被引：1，自引：0，他引：1
基于1981—2010年邢台市逐日4个时次地面气象观测资料和2014年的同期逐日空气污染API值及气象观测数据,运用修正的Pasquill稳定度分类法和混合层厚度计算方法得出邢台市近30年大气稳定度和混合层厚度变化特征,结果表明:近30年邢台市大气不稳定类呈1.16%/10a增长,中性类呈-1.40%/10a下降,稳定类变化趋势不明显,月变化以中性类和稳定类为主,日变化受太阳辐射强度的影响明显。混合层厚度主要受风速影响,平均厚度460.09m,月变化呈"单峰型"分布。在02:00、08:00、14:00和20:00四个时次上混合层厚度都具有春季大于夏季大于冬季大于秋季的分布特点。经验证发现混合层厚度和不同稳定度等级的出现频率是影响空气质量的重要因子。 相似文献
3.
基于1961-2010年安徽省气象台站的定时观测资料,采用国标法计算安徽省近50年大气稳定度、混合层厚度和大气环境容量系数,并结合合肥市空气质量逐日观测数据初步分析了大气环境容量系数对空气质量的影响。结果表明：安徽省大气稳定度以中性类居多,稳定类其次;近50年来,中性类稳定度呈明显下降趋势,不稳定类和稳定类呈显著上升;不稳定类和稳定类有明显的季节差异,中性类不明显。年平均混合层厚度显著下降;春季混合层厚度在2000年左右发生转折,夏、秋、冬三季下降趋势显著;春、夏季混合层厚度高于秋、冬季,冬季最低,春季最高。安徽省大气环境容量系数以沿淮中部、大别山区南部和沿江中西部最大,淮北大部、大别山区北部和江南南部最小,各地均呈现一致的显著下降趋势,并具有明显的年代际变化特征。年内大气环境容量系数呈"双峰型"分布,秋、冬季为低值时段,大气对污染物容纳能力较差,不利于扩散和清除,空气质量较差。总的来看,1961-2010年安徽省大气稳定度显著增加,混合层厚度较明显下降、风速快速减弱是全省大气环境容量系数变小、大气自净能力减弱的最主要原因。 相似文献
4.
5.
华东区域夏季行星边界层大气稳定度的气候特征及其与气溶胶的联系 总被引：2，自引：1，他引：1
利用1979-2008年夏季（6—8月）逐日NCEP／NACR再分析资料、MODIS卫星的气溶胶资料等,研究了华东区域夏季行星边界层大气稳定度的气候特征与年际变化,分析了大气稳定度和相应的加热场与气溶胶光学厚度（aerosol optical depth,AOD）的联系。结果表明：华东区域夏季行星边界层大气稳定度在空间上分布不均匀,时间上具有明显的年际变化。边界层中的非绝热加热率、大气稳定度及气溶胶光学厚度三者之间可能存在密切联系。利用经验正交函数分析了华东区域总体理查森数Rib的距平场,得到了边界层稳定度分布的3个主要模态,这3个模态所代表的边界层大气稳定度异常与夏季风环流异常密切相关,特别是P-J型遥相关波列和西太平洋副热带高压在中国东部大气边界层稳定度变化中可能起着非常重要的作用。 相似文献
6.
选取青岛2000—2015年逐日地面观测资料和环境监测中心站2011—2015年逐日主要大气污染物浓度资料,分析了青岛大气混合层高度和大气稳定度的变化特征,对青岛日最大混合层高度与空气污染物浓度进行相关分析。结果表明：近16a来,青岛大气混合层高度年际变化呈逐渐减小的趋势,日变化呈现单峰结构;大气稳定度以D类的出现频率最高,深秋到初冬大气较为稳定,4—8月A,B,C类稳定度较其他月份升高;清晨和傍晚大气以中性层结为主,中午弱不稳定发展,夜间稳定层结明显增强。空气污染物质量浓度与日最大混合层高度有明显的负相关关系,污染物质量浓度越大,日最大混合层高度越小;反之,污染物质量浓度越小,日最大混合层高度越大。 相似文献
7.
塔中秋冬季大气稳定度频率分布 总被引：1，自引：0，他引：1
采用温度梯度法、理查逊数法、总体理查逊数法分别分析塔中地区秋、冬季的大气稳定度的差异以及大气稳定度的分布频率特征.结果表明:不同的方法对大气稳定度的计算结果有很大影响,采用Ri法和BRi法能够较好的反映塔中秋冬季大气稳定度的变化;塔中秋、冬季大气层结以稳定层结为主,不稳定层结出现频率次之,中性层结出现的频率最小;秋季、冬季稳定度频率有一定差异,秋季中性层结、稳定层结频率小于冬季,不稳定层结大于冬季. 相似文献
8.
《沙漠与绿洲气象(新疆气象)》2010,(1)
采用温度梯度法、理查逊数法、总体理查逊数法分别分析塔中地区秋、冬季的大气稳定度的差异以及大气稳定度的分布频率特征。结果表明:不同的方法对大气稳定度的计算结果有很大影响,采用Ri法和BRi法能够较好的反映塔中秋冬季大气稳定度的变化;塔中秋、冬季大气层结以稳定层结为主,不稳定层结出现频率次之,中性层结出现的频率最小;秋季、冬季稳定度频率有一定差异,秋季中性层结、稳定层结频率小于冬季,不稳定层结大于冬季。 相似文献
9.
《高原气象》2017,(5)
利用MODIS/Aqua地表温度产品(MYD11A1)分析了2003—2013年环太湖城市地表温度和地表城市热岛的时空变化特征,研究了地表城市热岛与大气稳定度、土地利用类型的关系。结果表明,该区域在2003—2013年日间的不稳定类天数最多,约占总天数50%。不稳定类天数在2003—2010年呈增加趋势,2010年后呈减少趋势;中性类与不稳定类天数年变化的位相相反,与弱不稳定类天数年变化的位相大致相同。受云和降水影响,MODIS图像质量随着不稳定度的降低而降低。日间地表城市热岛在不稳定大气边界层条件下最强,城市热岛强度随着白天边界层不稳定度的降低而减弱。近10年来环太湖城市圈经济发展迅速,城市用地面积增加,2010年环太湖城区的地表温度较2004年普遍升高约1℃,部分新城区的地表温度升高3℃以上,高温范围扩大,形成一条环太湖的高温带,分析地表温度和城市热岛的时空变化对研究城市化带来的区域气候效应具有重要意义。 相似文献
10.
通过分析2010—2018年天津气象塔风、温度资料,对近年来天津城市边界层粗糙度、大气稳定度和逆温特征进行研究。结果表明:随着城市发展,气象塔周边各方向粗糙度和零平面位移明显增高,气象塔周边建筑物对80 m高度以下风场的影响较为明显。受湍流强度日变化影响,各季节中气象塔高层和低层风速日变化特征差异明显。通过温差-风速法计算大气稳定度发现稳定类层结多出现在秋冬季的夜间,稳定层结条件下逆温情况多发,其逆温强度、逆温层厚度和贴地逆温比例也明显高于不稳定和中性层结。天津城市热岛强度的时间分布表现出夜间强于白天,秋冬季强于春夏季的特征。城市热岛强度与大气稳定度时间分布具有一定相关性。 相似文献
11.
Alistair D. Culf 《Boundary-Layer Meteorology》1992,58(1-2):1-18
Profiles of temperature were measured in the atmospheric boundary layer (ABL) over the West African Sahel on eleven days at three different times of the year. The final depth of the mixed layer was shown to vary substantially during the year, but it was often greater than 2.5 km. Measured values of the sensible heat flux at the surface are used to force several simple slab models of the ABL. It is found that these simple models can describe the increases of height and temperature of the ABL during the day. 相似文献
12.
A. K. Georgoulias D. K. Papanastasiou D. Melas V. Amiridis G. Alexandri 《Meteorology and Atmospheric Physics》2009,104(1-2):103-111
The atmospheric boundary layer (ABL) is characterized by the turbulence eddies that transport heat, momentum, gaseous constituents and particulate matter from Earth’s surface to the atmosphere and vice versa. Thus, the determination of its height has a great importance in a wide range of applications like air quality forecasting and management. This study aims at estimating the height of the ABL in a suburban environment and at investigating its temporal variation and its relationship with meteorological variables, like temperature and wind. For this purpose, radiosonde data from the suburban area of Thessaloniki, Greece, are analyzed. The data analysis reveals that ABL height is usually below 200 m in the morning hours during all seasons of the year and that is also low when near-surface temperature and wind speed are low too. Additionally, noon ABL height exhibits a strong seasonal variation, reaching higher values during summer than during winter.Very high values of ABL height, of the order of ~3,000 m, are occasionally observed in Thessaloniki during summer. Moreover, sea breeze development during summer is related to a slight reduction of the ABL height. 相似文献
13.
Diurnal Variations of Air Pollution and Atmospheric Boundary Layer Structure in Beijing During Winter 2000／2001 总被引：4，自引：0，他引：4
The diurnal variations of gaseous pollutants and the dynamical and thermodynamic structures of the atmospheric boundary layer (ABE) in the Beijing area from January to March 2001 are analyzed in this study using data from the Beijing City Air Pollution Observation Field Experiment (BECAPEX). A heavy pollution day (22 February) and a good air quality day (24 February) are selected and individually analyzed and compared to reveal the relationships between gaseous pollutants and the diurnal variations of the ABL. The results show that gaseous pollutant concentrations exhibit a double-peak-double-valley-type diurnal variation and have similar trends but with different magnitudes at different sites in Beijing. The diurnal variation of the gaseous pollutant concentrations is closely related to (with a 1-2 hour delay of) changes in the atmospheric stability and the mean kinetic energy in the ABL. 相似文献
14.
复杂地形城市冬季边界层对气溶胶辐射效应的响应 总被引：9，自引：3，他引：6
作者着眼于城市气溶胶辐射效应与大气边界层的相互作用问题,针对地形复杂的兰州市及周边地区,开发应用了WRF(Weather Research and Forecasting,天气研究和预报)模式,使之与包含了大气气溶胶辐射效应和气溶胶粒子扩散的综合大气边界层数值模式嵌套起来.通过个例分析,揭示了冬季气溶胶辐射效应对边界层结构的定量影响.主要特征为夜间气溶胶的长波辐射效应使地面附近的气温增高,增温幅度为0.1～0.3 K/h,使低空(25～300 m)大气层冷却,降温幅度为0.08～0.15 K/h,风速在150 m以下减小;白天气溶胶的短波辐射效应使地面层内明显增温,1 h内升温约0.5 K,增温最大值在混合层顶500～600 m高度.受增温影响,垂直风场和水平风场随之调整,风速在450 m以下增大约0.1 m/s左右,而在450 m以上风速减小0.1 m/s左右. 相似文献
15.
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. 相似文献
16.
The atmospheric boundary layer (ABL) over a given coastal station is influenced by the presence of mesoscale sea breeze circulation, together with the local and synoptic weather, which directly or indirectly modulate the vertical thickness of ABL (z ABL). Despite its importance in the characterization of lower tropospheric processes and atmospheric modeling studies, a reliable climatology on the temporal evolution of z ABL is not available over the tropics. Here, we investigate the challenges involved in determination of the ABL heights, and discuss an objective method to define the vertical structure of coastal ABL. The study presents a two year morphology on the diurnal evolution of the vertical thickness of sea breeze flow (z SBF) and z ABL in association with the altitudes of lifting condensation level (z LCL) over Thiruvananthapuram (8.5° N, 76.9° E), a representative coastal station on the western coastline of the Indian sub-continent. We make use of about 516 balloon-borne GPS sonde measurements in the present study, which were carried out as part of the tropical tropopause dynamics field experiment under the climate and weather of the sun-earth system (CAWSES)–India program. Results obtained from the present study reveal major differences in the temporal evolution of the ABL features in relation to the strength of sea breeze circulation and monsoonal wind flow during the winter and summer monsoon respectively. The diurnal evolution in z ABL is very prominent in the winter monsoon as against the summer monsoon, which is attributed to the impact of large-scale monsoonal flow over the surface layer meteorology. For a majority of the database, the z LCL altitudes are found to be higher than that of the z ABL, indicating a possible decoupling of the ABL with the low-level clouds. 相似文献
17.
A set of atmospheric general circulation model experiments were performed where the Community Atmospheric Model version 3.1 is forced with sea-surface temperatures (SSTs) that have the imprint of tropical instability waves (TIWs) of varying strengths. The presence of TIWs in the SSTs increased the variance in the large-scale circulation in the atmospheric boundary layer (ABL). The impact of TIWs in the SST anomalies is directly seen in enhanced mixing of the air temperature anomalies, thereby diffusing the air temperature gradients setup by the oceanic fronts throughout the ABL. The presence of TIWs transformed the diffusive-natured ABL to advection-dominated regime. This implies that within the ABL, the presence of TIWs leads to the enhanced interactions among the neighboring grid cells and prompts greater horizontal communications among atmospheric variables. However, the advection in the ABL due to the TIWs is not a linear function of increasing TIW strength. Unlike air temperature, zonal, and vertical velocity, the variance in the meridional velocity changes at the top of the ABL due to the momentum mixing across the ABL in the vertical direction. This causes the ABL to be more turbulent beyond seasonal time scales. This analysis also suggests that a simple parameterization is not sufficient to take the account of rectification effects on the atmospheric variables that are missing due to the lack of TIW representation in the coarse-resolution coupled general circulation models. 相似文献
18.
The vertical and horizontal temperature structure of the atmospheric boundary layer (ABL) were studied using aircraft observations made in the lowest 2.4 km above ground level during the summer monsoon.The vertical temperature structure of the ABL in the region may be classified into the following four categories.Category The ABL consisted of two layers of thickness 700–900 m separated by a thin transition layer. The lapse rates in the former two layers were dry adiabatic.Category The lowest layer of the ABL of thickness 400–600 m was adiabatically stratified and the overlying layer was stable with gradients of potential temperature 4–5°C km–1. The stable layer contained a thin adiabatic stratified layer of 200–300 m thickness at a height of 1.5 km.Category The lowest 200–400 m layer of the ABL was adiabatically stratified and the overlying layer was stable with potential temperature gradients of 5–6 °C km1.Category The ABL was mainly stable with potential temperature gradients of 6 °C km–1 or greater. Occasionally thin layers with adiabatic stratification were found embedded in the ABL.The temperature distribution of the horizontal temperature at 900 m was mainly normal. The high-frequency portion of the spectra lying between 0.05 and 0.16 Hz (corresponding to wave length 1 km to 300 m) oscillated around the –\2/3 power law line. The spectral curve showed a significant peak at 0.011 Hz having a wave-length of 5 km.Department of Geoscience, North Carolina State University, Raleigh, NC, 27650, U.S.A. 相似文献
19.
V. N. Kudryavtsev S. A. Grodsky V. A. Dulov V. V. Malinovsky 《Boundary-Layer Meteorology》1996,79(1-2):51-82
Ship borne measurements of atmospheric boundary layer (ABL) parameters, sea-surface temperature and radar signals are analyzed to reveal the effects of the ABL transformation above the Gulf Stream temperature frontal zone. It was found that local changes in vertical gradients of wind speed and air temperature are well correlated with sub-mesoscale (~ 10 km) sea surface temperature variations. These effects are accompanied by appropriate variations in surface wind stresses that were identified from microwave backscatter.For steady atmospheric conditions the same effects were observed on spatial scales of 100 km, demonstrating positive radar signal contrast of the Gulf Stream warm waters with respect to surrounding Sargasso sea and shelf water areas. A simplified model of the ABL, accounting for an effect of spatial inhomogeneity by introducing an internal boundary layer, is used to analyze field observations. The model is able to reproduce both sub-mesoscale and mesoscale ABL evolution. 相似文献
20.
Hrvoje Kozmar 《Theoretical and Applied Climatology》2010,100(1-2):153-162
Precise urban atmospheric boundary layer (ABL) wind tunnel simulations are essential for a wide variety of atmospheric studies in built-up environments including wind loading of structures and air pollutant dispersion. One of key issues in addressing these problems is a proper choice of simulation length scale. In this study, an urban ABL was reproduced in a boundary layer wind tunnel at different scales to study possible scale effects. Two full-depth simulations and one part-depth simulation were carried out using castellated barrier wall, vortex generators, and a fetch of roughness elements. Redesigned “Counihan” vortex generators were employed in the part-depth ABL simulation. A hot-wire anemometry system was used to measure mean velocity and velocity fluctuations. Experimental results are presented as mean velocity, turbulence intensity, Reynolds stress, integral length scale of turbulence, and power spectral density of velocity fluctuations. Results suggest that variations in length-scale factor do not influence the generated ABL models when using similarity criteria applied in this study. Part-depth ABL simulation compares well with two full-depth ABL simulations indicating the truncated vortex generators developed for this study can be successfully employed in urban ABL part-depth simulations. 相似文献