卷云与水云的短波透射与反射特性

利用矩阵算法计算了对不同太阳天顶角下不同光学厚度的卷云与水云,在4π空间内0～360o的不同方位与0～90o不同天顶角下的波长为1.39 μm太阳短波波段的透射与反射,其天顶角间隔为5.6o,方位角间隔为5.0o。可以看出两种云透射和反射辐射的差别及它们随着光学厚度变化而变化的情况。同时,将其与波长为0.55 μm的可见光波段的透射和反射进行了比较。     

DETECTION OF MULTILAYER CIRRUS CLOUD USING FY-1C DATA

There are ten channels in the FY-1C polar-orbiting meteorological satellite of China.Thesechannels cover visible,near-infrared and infrared spectral bands.Based on simulating analysis ofsingle layer and multilayer clouds that cirrus clouds possibly overlap low water clouds,the casestudy using FY-1C data is performed.Results show that FY-1C data can be used to analyzemultilayer clouds,especially for the ease of low water cloud overlaid by cirrus.     

中国地区卷云分布特征的星载激光雷达遥感

利用2006年6月至2008年5月CALIOP(Cloud-Aerosol LIdar with Orthogonal Polarization)水平分辨率25 km云层产品来研究中国地区的卷云分布特征.所采用的3条基于卷云气候态的质量控制标准能够有效的剔除CALIOP云种分类产品中判别误差.通过卷云水平分布的研究发现...     

热带深对流云对CO、NO、NOx和O3的垂直输送作用

利用2005年11月至2006年2月ACTIVE (Aerosol and Chemical Transport in tropIcal conVEction) 外场试验期间在澳大利亚北部达尔文地区取得的CO、O3、NO和NOx飞机探测资料, 并结合HYSPLIT后向轨迹模式结果, 分析这几种气体成分在对流卷云砧内外的分布情况, 并探讨热带深对流云对于污染气体的垂直输送作用。分析结果显示, 在孤立对流云卷云砧中, 云砧内部O3、NO、NOx浓度均大于云外; 而CO则不同, 只有在近地面浓度高时才如此, 在近地面浓度较小时, 卷云砧内部的浓度反而小于云外。进一步分析造成这两类气体分布差异的原因, 发现CO主要借助深对流云将对流层下层以及对流云周围环境中的CO夹卷并动力垂直输送到对流云顶部卷云砧中, 而对于O3、NO和NOx来说, 除了上述作用以外, 还可能与对流云内部其他物理机制(如闪电), 造成新的O3、NO和NOx有关, 这些新生气体随着风暴内部强烈的上升气流被最终输送进云砧中。     

半干旱地区卷云特征的激光雷达探测

利用兰州大学半干旱气候与环境观测站( SACOL) 2007年4～1 1月微脉冲激光雷达(MPL-4 B)观测资料,统计分析了卷云的高度、厚度及其变化特征.采用透过率方法计算了卷云光学厚度,得到了卷云光学厚度与卷云厚度和云底高度的相关关系.结果表明,SACOL卷云出现的平均海拔高度为10.16±1.32 km;卷云厚度...     

Cloud-base distribution and cirrus properties based on micropulse lidar measurements at a site in southeastern China

The cloud fraction(CF) and cloud-base heights(CBHs), and cirrus properties, over a site in southeastern China from June 2008 to May 2009, are examined by a ground-based lidar. Results show that clouds occupied the sky 41% of the time.Significant seasonal variations in CF were found with a maximum/minimum during winter/summer and similar magnitudes of CF in spring and autumn. A distinct diurnal cycle in the overall mean CF was seen. Total, daytime, and nighttime annual mean CBHs were 3.05 ± 2.73 km, 2.46 ± 2.08 km, and 3.51 ± 3.07 km, respectively. The lowest/highest CBH occurred around noon/midnight. Cirrus clouds were present ～36.2% of the time at night with the percentage increased in summer and decreased in spring. Annual mean values for cirrus geometrical properties were 8.89 ± 1.65 km, 9.80 ± 1.70 km, 10.73 ± 1.86 km and 1.83 ± 0.91 km for the base, mid-cloud, top height, and the thickness, respectively. Seasonal variations in cirrus geometrical properties show a maximum/minimum in summer/winter for all cirrus geometrical parameters. The mean cirrus lidar ratio for all cirrus cases in our study was ～ 25 ± 17 sr, with a smooth seasonal trend. The cirrus optical depth ranged from 0.001 to 2.475, with a mean of 0.34 ± 0.33. Sub-visual, thin, and dense cirrus were observed in ～12%, 43%, and 45%of the cases, respectively. More frequent, thicker cirrus clouds occurred in summer than in any other season. The properties of cirrus cloud over the site are compared with other lidar-based retrievals of midlatitude cirrus cloud properties.     

基于CloudSat资料对中国低纬度陆地区域卷云物理特征的研究

利用2008年9月—2016年8月的CloudSat卫星资料对发生在我国低纬度陆地区域(5°~36.5°N,78°~124°E)的卷云物理特征进行统计分析,并分别讨论东部沿海、中部、西部3个子区域的卷云物理特征的季节变化。结果表明:卷云的整层发生率西部地区整体低于中部与东部沿海地区。3个子区域整层发生率均在夏季最高、冬季最低。卷云的主要发生高度在5.04~18.71 km,垂直分布中卷云发生率的最大值出现在春季中部地区,为15.34%,高度为9.83 km。冰水路径最大值出现在夏季的东部沿海,液水路径最大值在秋季的西部地区。冰水含量、冰粒数浓度、冰粒有效半径的主要分布高度与卷云的发生高度一致,液水含量、液滴数浓度、液滴有效半径的主要分布高度在5.04~9.35 km。3个子区域卷云冰水含量、冰粒数浓度、冰粒有效半径垂直分布中大多集中在中上部;液水含量垂直分布主要集中在分布高度的中下部。四季卷云雷达反射率因子的最大值在-19.89~-16.78 dBZ,分布高度在7.19~10.55 km。     

The APE-THESEO Tropical Campaign: An Overview

The APE-THESEO campaign was held from 15 February to 15 March 1999 from the Seychelles in the western Indian Ocean. APE-THESEO stands for Airborne Platform for Earth observation — (contribution to) the Third European Stratospheric Experiment on Ozone. The campaign aimed to study processes controlling the low water content of the stratosphere, including the mechanisms of cloud formation in the tropical tropopause region, and transport processes, studied using measurements of long-lived trace gases and ozone.Two aircraft were used: the high-altitude research aircraft, M-55 Geophysica, which can fly up to 21 km, and the Falcon of the Deutsches Zentrum für Luft- und Raumfahrt, a tropospheric aircraft. Seven flights were performed, including the first simultaneous in situ and remote sensing of sub-visible cirrus clouds, the first interception of sub-visible cirrus using in-flight guidance from a path-finding aircraft, and guided descent of a high-altitude research aircraft into the anvil cloud at the top of a tropical cyclone. In this paper we describe the payload used, the objectives for each flight, and the meteorological conditions encountered. First results show that a new type of cloud, which we have dubbed ultra-thin tropical tropopause cloud (UTTC), has been observed frequently, and observed to cover areas of 10⁵ km². The frequent coincidence of the tropopause and hygropause implies that the western Indian Ocean played an important role in the dehydration of the lower tropical stratosphere during the season of the mission. UTTCs, sub-visible cirrus, and visible cirrus, have all been implicated in the observed dehydration. Tracer measurements indicate little mixing of stratospheric air into the upper tropical troposphere.     

DETECTION OF MULTILAYER CIRRUS CLOUD USING FY-1C DATA*

There are ten channels in the FY-1C polar-orbiting meteorological satellite of China.These channels cover visible,near-infrared and infrared spectral bands.Based on simulating analysis of single layer and multilayer clouds that cirrus clouds possibly overlap low water clouds,the case study using FY-1C data is performed.Results show that FY-1C data can be used to analyze multilayer clouds,especially for the ease of low water cloud overlaid by cirrus.     

Cloud-Radiation Studies During the European Cloud and Radiation Experiment (EUCREX)

The dominant role of clouds in modulating and interacting with radiative energy transports within the atmosphere, in providing precipitation, transporting water and influencing air-chemical processes is still not understood well enough to be accurately represented within atmospheric circulation and climate models over all regions of the globe. Also the extraction of real-world cloud properties from satellite measurements still contains uncertainties. Therefore, various projects have been developed within the Global Energy and Water Cycle Experiment (GEWEX), to achieve more accurate solutions for this problem by direct measurements within cloud fields and other complementary studies. They are based on the hypothesis, that most relevant properties of cloud fields can be parametrized on the basis of the prognostic field variables of atmospheric circulation models, and that the cloud microphysical properties can directly be related – with additional parameters on the particle shapes etc. – to the radiative transfer properties.One of these projects has been the European Cloud and Radiation Experiment (EUCREX) with its predecessor ICE (International Cirrus Experiment).The EUCREX and ICE provided a common platform for research groups from France, Germany, Sweden and the United Kingdom to concentrate their efforts primarily on high, cold cirrus. They showed, with data from satellites, that this cloud species enhances the atmospheric greenhouse-effect. Numerical mesoscale models were used in sensitivity studies on cloud developments. In-situ measurements of cloud properties were made during more than 30 aircraft missions, where also in-flight comparisons of various instruments were made to ensure the quality of data sets measured from different aircraft. The particle sampling probes, used for in-cloud measurements, showed a disagreement in total number density in all ranges between about 20–50%, while all other instruments agreed quite satisfactorily. A few measured holographic data provided information on typical ice-crystal shapes, which were used in numerical simulations of their absorption and scattering properties.Several new instruments for both in-situ and remote measurement, such as a polar nephelometer, a chopped pyrgeometer and an imaging multispectral polarimeter (POLDER) for cloud and radiation measurements were tested and improved. New algorithms were developed for cloud classifications in multispectral satellite images and also for simulations of the scattering of radiation by non-spherical particles.This paper primarily summarizes the EUCREX results obtained between 1989 and 1996, and provides examples of the many results which have been obtained so far. It is not a complete review of the world-wide state in this field, but it tries to place the EUCREX results into the world-wide development. Therefore many references are made to the results of other groups, which in turn influenced the work within EUCREX.