多层云的卫星检测及其辐射效应

发布时间：2018-01-22 19:38

本文关键词： 主动卫星多层云辐射效应重叠云层间相互作用青藏高原云重叠参数大气动力参数　出处：《兰州大学》2017年博士论文　论文类型：学位论文

【摘要】：多层云能够通过改变大气温度、大气辐射加热率/冷却率和潜热显著影响地气系统的能量收支、大气环流及水汽循环过程。然而过去由于探测手段的限制和地面观测资料的稀缺,我们对多层云的发生频率、辐射效应、以及云层间的相互作用缺乏全面的认识。并且气候模式对云重叠(与多层云紧密相关)的不合理描述也是气候变化预测的一个重要不确定性源。近年来主动卫星基于对云垂直结构的检测优势发展了多套遥感产品,并被广泛应用到各个研究领域。因此,本论文主要利用主动卫星遥感产品系统开展了与多层云相关的研究工作。研究结果将为加深理解全球云的辐射反馈机制提供必要的研究基础,并为改进模式中的云重叠参数化方案提供观测依据。研究内容及主要研究结论如下:(1)本文利用大气辐射观测计划(ARM)的多个观测站和兰州大学半干旱气候与环境观测站(SACOL)的地面辐射资料评估了主动卫星辐射通量产品(2B-FLXHR-LIDAR)的地表向下辐射通量。研究表明:晴空时,主动卫星反演的地表向下短波辐射通量与站点观测值有较好的一致性,偏差在20~50 W/m~2。而云天时,主动卫星反演的地表向下短波辐射通量则显著高于站点的地面观测值,偏差在70~180 W/m~2。这说明,主动卫星反演的地表向下短波辐射通量仍不能全面考虑云的影响且存在相对较大不确定性。相比之下,卫星反演的昼夜地表向下长波辐射通量无论在晴空还是云天时都与站点观测值有比较好的一致性。此外,我们发现时空尺度对地表向下辐射通量偏差的影响较小,而云相态则对该偏差有显著影响。(2)基于2007~2010四年主动卫星的辐射通量产品(2B-FLXHR-LIDAR)和云分类产品(2B-CLDCLASS-LIDAR),本文定量分析了全球尺度多层和单层云系统的云量、权重云辐射强迫、云辐射加热率及其差异。研究表明:多层云主要盛行于赤道附近,其全球云量平均值(24.9%)低于单层云(46.6%);多层云大气层顶、地面以及大气内净权重云辐射强迫贡献率达40.2%、42.4%和57%。多层和单层云系统的云辐射加热率也存在明显差异。就短波云辐射加热率而言,单层云和多层云的最大加热率(分别为0.35 K/d和0.60 K/d)出现在9.75 km和7.5 km,且单层云与多层云的差异呈现随高度由正值转为负值。就长波云辐射加热率而言,多层云的最大冷却率(-0.42 K/d)出现在8 km,而单层云则出现在2km(-0.45 K/d),并且单层云与多层云的差异随高度由负值转为正值。总的来说,单层云和多层云的净云辐射加热率的差异主要集中在对流层7.5 km以下,且均为负值。(3)通过匹配2007~2010年主动卫星云分类产品(2B-CLDCLASS-LIDAR)和被动卫星CERES瞬时辐射数据(CERES-SSF),本文评估了单层不同云类型的云特性及大气层顶云辐射强迫,并进一步统计分析了双层云类型(高云与其他云类型重叠)的云层间相互作用如何影响上下云层的宏、微观物理特性及大气层顶的辐射平衡。研究表明:所有单层云类型的短波(长波)云辐射强迫绝对值随云光学厚度增加而增加,其相关系数绝对值不小于0.78(0.84)。当高云重叠时,云层间的辐射相互作用显著改变上下云层的云特性,表现为:双层云类型的高云比单层高云有更蔽光和更厚的云体;而底层云类型则相比其单层云状态有更透光和更薄的云体。对比单层云类型与其被高云重叠的双层云类型之间的净云辐射强迫,结果表明:除单层的积云外,所有单层云类型对地气系统的冷却效应强于其被高云重叠的双层云类型。(4)通过利用主动卫星云几何廓线产品(2B-GEOPROF-LIDAR),ECMWF-AUX辅助产品及ERA-Interim再分析资料四年(2007~2010)的数据,本文反演了青藏高原地区云的重叠参数,并评估了大气动力参数(譬如:风切变和湿对流条件不稳定度)对云重叠参数的影响。研究表明:对于垂直不连续的云层而言,随机重叠方案能够较好的描述云的重叠特性。然而对于垂直连续的云层而言,云重叠参数随着云层间距逐渐从最大重叠向随机重叠趋近,当云层间距大于1.5km后,云的重叠参数出现负值,意味着高原的云开始趋于最小重叠方案。我们的统计结果表明,青藏高原地区负的云重叠参数样本占总样本量的41%,明显不同于早期研究所提出的全球平均的结果。这种特征与高原独特的大气动力特性紧密相关。我们发现在高原地区大气稳定度和风切变能够明显影响云的重叠特性,并进一步将与云重叠参数相关的退相干指数参数化为大气稳定度和风切变的函数。新的参数化公式与其他公式模拟的总云量对比结果表明其预测的总云量有较小的偏差。因此,我们的研究建议模式云重叠参数化方案应考虑大气动力参数的影响以改进区域总云量的模拟。
[Abstract]:Cloud through changing the atmospheric temperature, atmospheric radiative heating / cooling rate and heat rate significantly affect the energy budget of the earth atmosphere system, atmospheric circulation and water vapor cycle process. However, due to the limitation of past detection and ground observation data are scarce, we to cloud the frequency, radiation effects, and interactions among the clouds a lack of understanding. And the climate model of cloud overlap (closely related to multi cloud) an important source of uncertainty prediction unreasonable description is also climate change. In recent years, active satellite detection advantage of cloud vertical structure based on the development of a number of sets of remote sensing products, and is widely applied to various fields of study. Therefore in this paper, using the active satellite remote sensing system to carry out the related research work and the multilayer cloud. The results will deepen the understanding of the global radiation cloud and feedback mechanism The necessary research foundation, and provide the basis for improving the observation mode in the overlapping parameterization scheme. Conclusion the research contents and the main research are as follows: (1) the atmospheric radiation observation program (ARM) of the multi stations and Lanzhou University semi arid climate and environment Observatory (SACOL) ground radiation data evaluation initiative satellite radiation products (2B-FLXHR-LIDAR) surface downward radiative fluxes. The results show that: the sky, surface active satellite downward shortwave radiation flux and site observations are consistent, the deviation in 20~50 W/m~ 2. and the sky, surface active satellite downward shortwave radiation flux is significantly higher than the value of ground stations in 70~180 W/m~2., deviation of the surface active satellite downward shortwave radiation flux is still not fully consider the effects of clouds and there are relatively large uncertainty compared. Under the surface, day and night satellite downward longwave radiation flux in clear sky or cloudy sky and site observation has good consistency. In addition, we found that the influence of spatial and temporal scales on the surface downward radiation flux deviation, and cloud phase have remarkable influence on the deviation. (2) 2007~2010 radiation flux four years of active satellite based cloud classification (2B-FLXHR-LIDAR) and the product (2B-CLDCLASS-LIDAR), this paper quantitatively analyzes the global scale multi-layer and single-layer cloud systems, cloud cover, the weight of cloud radiative forcing, cloud radiative heating rate and difference. The study shows that the cloud is popular in the vicinity of the equator, the global cloud cover (24.9%) is lower than the average value of a single stratus cloud (46.6%); the top of the atmosphere, forcing the contribution rate of 40.2% and net weights of cloud ground atmospheric radiation, cloud radiation heating and 42.4% 57%. multilayer and single layer cloud rate of the system also has the obvious difference Different. Short wave radiation heating rate, the maximum heating rate (single and multilayer cloud were 0.35 K/d and 0.60 K/d) were 9.75 km and 7.5 km, and single and multi stratus stratus showed differences with height transfer from positive to negative. The long wave cloud radiative heating rate, the maximum cloud the cooling rate (-0.42 K/d) at 8 km, and the single cloud appeared in 2km (-0.45 K/d), and the difference between single and multi stratus clouds with height changed from negative to positive. In general, single and multilayer cloud net cloud radiative heating rate were mainly concentrated in the convection layer below 7.5 km. And are negative. (3) by matching 2007~2010 active cloud classification products (2B-CLDCLASS-LIDAR) and passive satellite CERES instantaneous radiation data (CERES-SSF), this paper evaluates the cloud characteristics and different types of single atmosphere cloud top cloud radiative forcing, and further statistical analysis of the double Stratus type (high cloud and other cloud types overlap) cloud interaction effects on how cloud macro and micro physical properties and radiation balance at the top of the atmosphere. The study shows that all types of clouds (longwave) shortwave cloud radiation increases with the increase of the absolute value of force cloud optical thickness, the absolute value of correlation coefficient is not less than 0.78 (0.84). When the clouds overlap, cloud radiation interactions significantly alter cloud properties, on the clouds as follows: cloud layer type clouds have more dark and thicker than single-layer cloud clouds; and the underlying cloud type is compared with the single state is more transparent and stratus cloud a thinner. Net cloud radiative contrast between single-layer cloud types and cloud layer is high cloud overlap type force, the results show that the addition of single cumulus, stratus all single types of cooling effect on the climate system is stronger than the double high clouds Cloud type. (4) through the use of active satellite cloud geometrical profile (2B-GEOPROF-LIDAR), ECMWF-AUX products and ERA-Interim reanalysis data for four years (2007~2010) data, the inversion overlap parameter in Tibet Plateau cloud, and evaluate the atmospheric dynamical parameters (such as wind shear and moist convective instability conditions the degree of influence on cloud overlap) parameters. It is shown that the vertical discontinuous clouds, random overlapping scheme can better describe the characteristics of overlapping clouds. However for the vertical continuous clouds, clouds overlap with the clouds gradually from the maximum distance parameter overlap to a random overlapping approach, when the spacing is greater than 1.5km, overlapping parameters the clouds appear negative, means that the plateau began to cloud the minimum overlap scheme. Our results show that the negative cloud over the Tibetan Plateau overlap parameters of sample total sample were 41%, Different from the one proposed in earlier research results. The average global atmospheric dynamics of the plateau characteristics and unique closely related. We found that can overlap characteristics significantly affect cloud in Plateau Atmospheric stability and wind shear, and further with the cloud overlap parameters related to the decoherence index parameter for atmospheric stability and wind shear function. Results total cloud parameterization formula of the new formula with other simulation shows that the total cloud cover its forecast to have a smaller deviation. Therefore, our study suggests that cloud pattern overlapping parameterization scheme should be simulated considering the influence of atmospheric dynamic parameters to improve the total cloud.

【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：P407

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