一次冰雹云演变过程的卫星遥感监测与分析

针对2003年9月21日的一次区域性冰雹云强对流天气过程,结合天气实况、环流场特征和雷达资料,利用NOAA卫星数据,从天气分析、能量转换以及云在可见光、中红外波段的反射特性,分析了冰雹云的演变及特征。结果表明,伴随着大气能量的转换,当日青海湖以北的对流冷云单体在东移过程中,结合了西南部暖舌带来的暖湿气流,午后受地面增温出现了爆发性发展。(1)17：00云团发展最旺盛,云顶温度最低值达到-44℃,并确定冰雹发生的云顶温度临界值为-39．2℃,云顶亮温为221K;(2)冰雹云温度水平梯度介于20～35℃／50km之间,表现为有雹无灾的冰雹强度特征;(3)卫星数据表明,此时雹云与其它云团不同,具有粒子有效半径较大,气溶胶光学厚度也大的特点。     

河北秋季层状云物理结构及适播性分析

利用2006-2010年河北省人工影响天气办公室对29块云体9架次飞机探测(或作业)资料,统计分析了河北地区秋季层状云气溶胶粒子、云凝结核CCN、小云粒子、大云粒子、降水粒子浓度和云粒子有效直径等物理特征。结果表明,河北地区适宜增雨作业的云系为中、低或高、中、低搭配的层状云,过冷层催化有利于云体发展,促使气流流入形成正反馈。适宜催化的作业层指标有:云层高度为4582 m,云内平均含水量≥0.1 g·m-3,所对应温度为-8.0℃,小云粒子浓度为236.5 cm-3。     

The influence of clouds on surface UV erythemal irradiance

The purpose of this study is to examine the effect of clouds on the ultraviolet erythemal irradiance. The study was developed at three stations in the Iberian Peninsula: Madrid and Murcia, using data recorded in the period 2000–2001, and Zaragoza, using data recorded in 2001. In order to determine the cloud effect on ultraviolet erythemal irradiance, we considered a cloud modification factor defined as the ratio between the measured values of ultraviolet erythemal irradiance and the corresponding clear-sky ultraviolet erythemal irradiance, which would be expected for the same time period and atmospheric conditions. The dependence of this cloud modification factor on total cloud amount, cloud type and solar elevation angle was investigated. The results suggest that the effect of cloud on ultraviolet erythemal irradiance can be parameterized in a simple way in terms of the cloud amount. Our results suggest that the same cloud modification factor model can be used at the three analysed locations estimating the ultraviolet erythemal irradiance with mean bias deviation (MBD) in the range of the expected experimental errors. This cloud modification factor is lower than that associated to the whole solar spectral range, indicating that the attenuation for the ultraviolet erythemal irradiance is lower than that associated to other solar spectral ranges. The cloud modification factor for ultraviolet erythemal irradiance presents dependence with solar elevation, with opposite dependencies with solar elevation for overcast and partial cloud cover conditions, a fact that can be explained in terms of the influence of reflection-enhancement of the ultraviolet irradiance in the last case. Concerning the influence of cloud type, a limited study of two cloud categories, low and medium level and high level, indicated that for overcast conditions, lower clouds presents an attenuation of ultraviolet erythemal irradiance 20% greater than that associated to high level clouds.     

基于星载微波雷达和激光雷达探测的夏季云顶高度及云量差异分析

云是天气与气候变化的重要影响因子,准确估量云顶高度和云量对分析云特性、降水及强天气预报、估算云辐射强迫等都具有重要意义。利用2006-2010年6-8月CloudSat卫星搭载的微波云廓线雷达（CPR,简称微波雷达）和CALIPSO卫星搭载的云-气溶胶偏振激光雷达（CALIOP,简称激光雷达）的探测资料,分析了全球云顶高度及云量的空间分布特征。结果表明,热带地区微波雷达探测云顶高度平均比激光雷达低约4 km,但均超过12 km;副热带洋面云顶高度在4 km以下,且两部雷达探测的云顶高度差异存在地域性。微波雷达对薄云、云砧及云顶高度低于2.5 km的低云存在漏判,对厚云的云顶高度偏低估;微波雷达探测的全球总云量均值为51.1%,比激光雷达少23.3%;两者给出的云量分布也存在显著的海-陆差异,其中洋面云量差异更大,如微波雷达测出局部洋面云量为80%,而激光雷达的探测结果却超过90%。由于激光雷达发射波长短,对云顶微小粒子比较敏感,而微波雷达波长较长,对相对较小粒子的探测存在局限性。因此,激光雷达对云顶高度的探测优于微波雷达。此结果不仅加强了对激光雷达和微波雷达探测原理的认识,而且进一步理解了云的气候特征。     

基于CloudSat和ISCCP资料的中国及周边地区云量分布的对比分析

利用2006年7月至2007年6月的CloudSat 2B-GEOPROF-LIDAR产品资料和国际卫星云气候计划(ISCCP)D2月平均云量数据, 统计分析了中国及周边地区午间、凌晨年平均总云量的分布特征, 并对两种探测手段得到的年平均总云量及其昼夜变化进行了对比分析。结果表明, ISCCP与CloudSat总云量的分布形势在午间和凌晨均具有较好的一致性, 即相对多云与少云中心的位置吻合较好。但是, 两种资料得到的总云量在量值上存在一定差异。对于整个研究区域而言, 午间ISCCP较CloudSat平均总云量偏低8.9%, 凌晨偏低15.1%。除了中国北方少云带和日本岛以北海域等区域ISCCP云量高于CloudSat云量外, 其他区域ISCCP云量普遍低于CloudSat云量, 且在青藏高原、帕米尔高原、横断山脉、云贵高原以及印度半岛南端和热带部分岛屿等区域尤其显著。进一步对比表明, ISCCP与CloudSat云量差值总体上随CloudSat云量的增大而呈线性变化, 在CloudSat少云区ISCCP略有偏高, 而在多云区则显著偏低。此外, 对云量昼夜变化的对比分析发现, 青藏高原地区ISCCP云量昼夜变化量显著大于CloudSat。     

Effects of organic aerosol constituents on extinction and absorption coefficients and liquid water contents of fogs and clouds

We have speculated on the influence of organic material on extinction and absorption coefficients and liquid water content of fogs and of clouds immediately after their condensational stage. It results therefore, that the reduction of the speed of growth from fog to cloud droplets due to the presence of organic films largely reduces the properties mentioned. Compared to that their increase coming from the surface tension reduction due to organic material being dissolved or building up films is expected to be less effective.     

北京密云县泥石流沟危险性的云模型评价

为了解决泥石流危险性评价过程中定性与定量相互转换的问题, 本文基于云模型理论建立了泥石流危险性评价的模型。首先根据泥石危险性的10个评价因子等级的分类标准获得各因子每个等级的数字特征, 将实测泥石流沟各项指标的数据利用正向云发生器进行整合计算, 得出各沟在各危险级别所对应的确定度。将评价因子的权重代入, 计算出泥石流沟在对应各个等级的综合确定度, 因此来确定泥石流沟的危险性等级。本文通过实测北京市密云县4条泥石流沟的实测值进行了云模型的危险性评价, 将云模型评价结果与可拓学评价结果进行了对比分析, 发现两者的评价结果基本一致, 认为云模型对泥石流危险性评价结果能够较准确地反映出泥石流的危险性水平, 其评价结果具有一定的合理性和可靠性。     

Glaciation of a mixed-phase boundary layer cloud at a coastal arctic site as depicted in continuous lidar measurements

The dynamic seeding and glaciation of a mixed-phase cloud by ice crystals injected from above at Ny Ålesund, Svalbard, Norway is described using continuous lidar measurements and thermodynamic data. Glaciation of this cloud was caused by ice crystal growth and sedimentation due to the preferential differences in saturation vapor pressure over ice versus liquid water and riming. The lidar data suggest that precipitation reached the ground for nearly 4 h as a result. The symbiosis between ice and liquid water hydrometeor presence in the polar troposphere is unique. Thermal perturbations and airmass fluctuations influence microphysical cloud characteristics and radiative balance, which makes the otherwise pristine region sensitive to lower-latitude anthropogenic and biogenic influences and a focal point for observing indirect effects and their influence on climate change. The development of lidar technologies capable of continuous and autonomous measurements is yielding important datasets to study unique atmospheric phenomena.     

江苏省国土资源档案在线协同管理平台关键技术研究

本文在分析江苏省国土资源厅档案管理面临困境的基础上,提出了档案在线协同管理平台的建设构想。、在介绍平台总体框架、功能框架和运行框架的基础上,重点阐述了平台建设的关键技术,并进一步提出平台深化建设、推广应用的设想。     

Experimental evaluation of the coalescence efficiencies of colliding water drops

The coalescence of water drops of sizes comparable to rain drops (200–2500 m diameter) was investigated. The method used provided a good separation between collision and coalescence effects. The result suggests a dependence of the coalescence efficiency on both the size of the large drop and the ratio of the radii of the interacting drops (p-ratio). The coalescence was observed to rapidly decrease due to bouncing and partial coalescence as the angle of impact increased from head-on to grazing angle. However, some bouncing was observed at very low impact angles.The results of the coalescence efficiency were fitted with an empirical equation for use in numerical models of cloud growth and precipitation development.On sabbatical leave (1976–77) from the Department of Geophysics and Planetary Sciences, Tel Aviv University, Ramat Aviv, Israel.The National Center for Atmospheric Research is sponsored by the National Science Foundation.