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Vertical distributions of aerosol optical properties during haze and floating dust weather in Shanghai 
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下载免费PDF全文 A comparative study on the vertical distributions of aerosol optical properties during haze and floating dust weather in Shanghai was conducted based on the data obtained from a micro pulse lidar.There was a distinct difference in layer thickness and extinction coefficient under the two types of weather conditions.Aerosols were concentrated below 1 km and the aerosol extinction coefficients ranged from 0.25 to 1.50km-1 on haze days.In contrast,aerosols with smaller extinction coefficients(0.20 0.35 km-1) accumulated mainly from the surface to 2 km on floating dust days.The seasonal variations of extinction and aerosol optical depth（AOD） for both haze and floating dust cases were similar greatest in winter,smaller in spring,and smallest in autumn.More than 85%of the aerosols appeared in the atmosphere below 1 km during severe haze and floating dust weather.The diurnal variation of the extinction coefficient of haze exhibited a bimodal shape with two peaks in the morning or at noon,and at nightfall,respectively.The aerosol extinction coefficient gradually increased throughout the day during floating dust weather.Case studies showed that haze aerosols were generated from the surface and then lifted up,but floating dust aerosols were transported vertically from higher altitude to the surface.The AOD during floating dust weather was higher than that during haze.The boundary layer was more stable during haze than during floating dust weather. 相似文献
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新一代区域气候模式RegCM4.6引进了Mix积云参数化方案,可以将之前版本中的Emanuel和Grell方案结合在一起,以弥补单个参数化方案的不足。利用2016年MODIS(Moderate-resolution imaging spectroradiometer)数据对RegCM4.6中Mix和Emanuel积云参数化方案模拟的东亚云量(Cloud fraction,CF)、冰水柱含量(Ice water path,IWP)和液水柱含量(Liquid water path,LWP)进行初步评估,计算了相关系数(r)、平均绝对误差(Mean absolute error,MAE)、平均偏差(Mean bias error,MBE)和均方根误差(Root mean square error,RMSE),以便为相关研究选取积云参数化方案提供参考依据。结果表明：(1)模拟的CF的MBE大致以胡焕庸线为界,西北部为轻微高估,东南部通常为低估。2种方案在夏季的模拟效果最好,冬季最差。Mix方案的MAE、MBE和RMSE的绝对值在四季普遍小于Emanuel方案。(2)模式明显低估了东亚的IWP,... 相似文献
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针对具有一定内热源的庭院建筑,采用计算流体力学（CFD）方法,分析了热压自然通风量与庭院内热源和室外风向、风速的关系．结果表明房间的通风量随室外风速、风向的变化而变化,且热压对通风的相对影响作用随室外风速的增大而减弱．在对庭院式建筑进行自然通风系统设计时,这一结论可作为理论设计依据之一． 相似文献
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交通干道地面热力条件对街道内部和附近建筑小区内的流场和浓度场有着重要的影响.本研究采用数值模拟方法,就交通干道地面散热量对街道内部和建筑附近的流场及浓度分布进行分析比较.结果表明,低风速情况下,交通干道地面散热导致街道通风量增加,有利于交通污染物向上空和下风向运移.此外,地面热力条件对污染物浓度分布的影响作用在街道背风区大于迎风区,在街道两侧有建筑物的区域大于两侧无建筑物的区域. 相似文献
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西北典型地域条件下云量的对比分析 总被引：9，自引：1，他引：8
采用NASA地球观测系统（EOS）“云与地球辐射能量系统(CERES)”2002年7月至2004年6月CERES SSF Aqua MODIS Edition 1B云资料,选取我国西北地区不同气候环境条件下的4个典型地域,研究了总云量、低层云和高层云云量的空间分布特征以及季节和年变化特征。结果表明,低层云量的高值区不仅分布在山脉地区,而且也分布在非山脉地区。但高层云的云量高值区只分布在山脉地区;总体来说,云量大小随地域的不同相差相当大,高层云云量年平均值的最大差异发生在祁连山区和塔克拉玛干沙漠之间,两者相差16.4%。而总云量和低层云量年平均值在季风区和塔克拉玛干沙漠地区相差最大,分别可达27.6%和19.5%。季风区和祁连山区云量最大值一般都出现在夏季,天山和塔克拉玛干沙漠地区云量最大值一般都出现在春季,最小值则均出现在秋冬季。总的来说,3个云量参数值在3～9月较高,最低值出现在10～12月。 相似文献
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