气溶胶对降水系统影响的观测研究

发布时间：2018-06-21 18:30

本文选题：气溶胶 + 云降水系统　；参考：《中国气象科学研究院》2016年硕士论文

【摘要】：气溶胶-云-降水相互作用是目前天气和气候模式中最大的不确定性因子之一。本研究利用长期的三维立体气溶胶-云-降水多源观测数据、再分析数据、以及地面观测数据集探究了气溶胶对降水的影响。在详细讨论降水系统的时空分布特性及其与大气环流系统中动力、热力因子强迫的关系的基础上,试图寻找气溶胶影响云降水系统垂直结构的观测证据,从而提高我们对气溶胶间接效应的认识。主要研究了如下三方面内容:首先,基于2001-2012年MODIS获取的青藏高原积雪面积比例(SCF)数据,利用统计方法分析了SCF时空分布特征及其变化趋势。发现每年10月至次年4月是青藏高原持续性积雪较多的月份,其中2月持续性积雪面积最大,7月最低;且其年平均持续性积雪面积呈3年左右的周期振荡;不同海拔、坡度、坡向的SCF呈现不同的季节变化特征。基于2007-2012年TRMM卫星上搭载的降水雷达产品,给出了全球热带海洋地区浅对流单体、层云、对流云降水系统对区域累积降水面积以及区域累积降水量贡献率的空间分布情况。发现热带海洋地区平均降水率的时空分布与400hPa垂直速度(ω400hPa)的时空分布存在一个显著的负相关;4个子研究区内区域累积降水面积贡献率以层云降水为主,对流云降水次之,累积降水量贡献率则以对流云降水为主,层云降水次之;对流云降水雨顶高度、雷达反射率重心以及30dBZ回波顶高随ω400hPa/850hPa相对湿度(RH850hPa)的下降/增加有一个明显抬升,随下对流层稳定度(LTS)的减小也略有抬升,说明ω400hPa和RH850h Pa与对流云降水系统垂直结构的发展有密切关系。其次,利用TRMM 3B42降水率数据,结合时空匹配的MODIS/Aqua提供的AOD数据,计算了全球热带海洋地区平均降水率随AOD的变化规律,深入分析了不同气象条件下不同类型降水对气溶胶的响应。我们发现,受输送影响,赤道地区大陆周围海域存在一个AOD高值区(类似于降水分布);降水率随AOD的增加呈现一个先增加后减小的趋势,该变化独立于气象条件而存在;相应降水率峰值点对应的AOD约为0.4,但受到气象条件的影响;气象因素(尤其是ω400hPa和RH850h Pa)对降水变率的影响是主要的,气溶胶的影响是次要的,但也是不可忽略的。最后,为了更好地探究气溶胶影响降水的微物理过程,我们以珠三角地区(22°N-24°N,113°E-115°E)为例,结合卫星雷达数据、ECMWF再分析数据与地面观测PM10质量浓度数据,在不同气象条件下深入探究了气溶胶对降水垂直结构的影响,以期获得气溶胶影响降水的直接观测证据。分析结果表明:在大气由清洁转为轻度污染的条件下(PM1045μg/m3):浅对流单体降水系统无明显变化;层云以及对流云降水系统的雷达反射率因子大值区随PM10浓度的增加迅速增大。在大气由清洁转为重度污染的条件下:浅对流单体降水和层云降水倾向于较弱降水过程的发生发展,且其30dBZ回波顶高较低;但较强的对流降水呈现出进一步增强的稳定趋势,且其30dBZ回波顶高较高。总体来说,气溶胶对浅云和层云降水呈现一个抑制效应,而对对流降水呈现一个明显的促进作用。最后,讨论了不同气象条件下(上升气流、风切变、下对流层稳定度、水汽通量散度)气溶胶对降水的影响,未对上述结论产生颠覆性影响,进一步支持了上述观测现象确是由于气溶胶影响了降水系统所致。
[Abstract]:Aerosol cloud precipitation interaction is one of the largest uncertainties in the current weather and climate models. This study uses long-term three-dimensional aerosol cloud precipitation multisource observation data, reanalysis data, and ground observation data sets to explore the effects of aerosol on precipitation. The temporal and spatial distribution of precipitation systems is discussed in detail. On the basis of its relationship with the dynamic and thermal factor forcing in the atmospheric circulation system, we try to find the observation evidence that aerosol affects the vertical structure of the cloud precipitation system, thus improving our understanding of the indirect effect of the aerosol. The following three aspects are mainly studied: first, the snow surface of the Qinghai Tibet Plateau obtained on the basis of 2001-2012 year MODIS The SCF data is used to analyze the spatial and temporal distribution characteristics of SCF and its variation trend. It is found that every year from October to April the following year is the month of continuous snow accumulation on the Qinghai Tibet Plateau, in which the maximum snow area in February is the largest and the lowest in July; and the annual average snow area of the Qinghai Tibet Plateau is 3 years of periodic oscillation; On the basis of the precipitation radar products on the 2007-2012 year TRMM satellite, the spatial distribution of the spatial distribution of the cumulative precipitation area and the cumulative precipitation in the region of the global tropical ocean area is given, based on the precipitation radar products carried on the 2007-2012 year TRMM satellite. There is a significant negative correlation between the spatial and temporal distribution of precipitation rate and the spatial and temporal distribution of the 400hPa vertical velocity (omega 400hPa); the contribution rate of accumulated precipitation area in the 4 sub areas is dominated by stratigraphic precipitation, second to the convective cloud precipitation, and the cumulative precipitation contribution rate is mainly to the convective cloud precipitation, and the precipitation top height of the convective clouds, thunder and rain. The center of gravity of the reflectivity and the height of the 30dBZ echo have a distinct uplift with the decrease / increase of the relative humidity of the Omega 400hPa/850hPa (RH850hPa), with the decrease of the lower tropospheric stability (LTS) and a slight uplift, indicating that the Omega 400hPa and RH850h Pa are closely related to the vertical structure of the convective cloud precipitation system. Secondly, the 3B42 precipitation rate data of TRMM is used. Combined with the AOD data provided by the spatio-temporal matching MODIS/Aqua, the variation of the average precipitation rate with the AOD in the global tropical marine area is calculated. The response of different types of precipitation to the aerosol under different weather conditions is deeply analyzed. We find that there is a high value area (similar to water reduction) in the continental circumference of the equatorial region under the influence of the different weather conditions. The precipitation rate increased first and then decreased with the increase of AOD, which was independent of meteorological conditions; the corresponding AOD of corresponding precipitation rate was about 0.4, but influenced by meteorological conditions; the influence of meteorological factors (especially Omega 400hPa and RH850h Pa) on precipitation variability was main, and the effect of aerosol was secondary, But in the end, in order to better explore the microphysical process of aerosol affecting precipitation, we take the Pearl River Delta region (22 N-24 N, 113 E-115 E) as an example, combined with satellite radar data, ECMWF reanalysis data and ground observation PM10 mass concentration data, and explore the aerosol vertical precipitation perpendicular to the precipitation under different weather conditions. The results show that there is no obvious change in the shallow convective monomer precipitation system in the atmosphere from cleanliness to mild pollution (PM1045 mu g/m3), and the large value area of radar anti ejection factor in the stratigraphic and convective cloud precipitation system increases rapidly with the increase of PM10 concentration. In the atmosphere from cleanliness to severe pollution, shallow convective mono precipitation and stratigraphic precipitation tend to develop in weaker precipitation process, and its 30dBZ echo top is low, but the strong convective precipitation shows a further enhancement trend, and its 30dBZ echo top is high. Generally speaking, aerosol to Asabu Wa stratiform precipitation In the end, the effects of aerosols on precipitation are discussed under different weather conditions (updraft, wind shear, lower troposphere stability, and water vapor flux divergence), which do not have a subversive effect on the above conclusion, and further support the above observation phenomenon due to gas. The sols affect the precipitation system.
【学位授予单位】：中国气象科学研究院
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P426.6;X513

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