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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >EXTINCTION COEFFICIENT (1 MU-M) PROPERTIES OF HIGH-ALTITUDE CLOUDS FROM SOLAR OCCULTATION MEASUREMENTS (1985-1990) - EVIDENCE OF VOLCANIC AEROSOL EFFECT
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EXTINCTION COEFFICIENT (1 MU-M) PROPERTIES OF HIGH-ALTITUDE CLOUDS FROM SOLAR OCCULTATION MEASUREMENTS (1985-1990) - EVIDENCE OF VOLCANIC AEROSOL EFFECT

机译：太阳能职业测量中高海拔云团的消光系数（1 MU-M）特性（1985-1990）-火山气溶胶效应的证据

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The properties of the 1-mu m volume extinction coefficient of two geographically different high-altitude cloud systems have been examined for the posteruption period (1985-1990) of the April 1982 El Chichon volcanic event with emphasis on the effect of volcanic aerosols on clouds. These two high-altitude cloud systems are the tropical clouds in the tropopause region observed by the Stratospheric Aerosol and Gas Experiment (SAGE) II and the polar stratospheric clouds (PSCs) sighted by the Stratospheric Aerosol Measurement (SAM) II. The results indicate that volcanic aerosols alter the frequency distributions of these high-altitude clouds in such a manner that the occurrence of clouds having high extinction coefficients (6x10(-3) - 2x10(-2) km(-1)) is suppressed, while that of clouds having low extinction coefficients (2x10(-3) - 6x10(-2) km(-1)) is enhanced. This influence of the volcanic aerosols appears to be opposite to the increase in the extinction coefficient of optically thick clouds observed by the faith Radiation Budget Experiment (ERBE) during the initial posteruption period of the June 1991 Pinatubo eruption. A plausible explanation of this difference, based on the Mie theory, is presented. The Mie calculation indicates that there are two possible types of response of cloud extinction coefficient to changes in aerosol concentration depending on the primary effective radius (r(e)) of cloud systems observed by the instrument. These two types of response are separated by the cloud particle effective radius of about 0.8 mu m. When r(e) is smaller than 0.8 mu m, the cloud extinction coefficient decreases in response to increases of aerosol concentration, and when r(e) is greater than 0.8 mu m, the opposite happens. As a consequence, the effective radius of most, if not all, of the high-altitude clouds, measured by the SAGE series of satellite instruments must be less than about 0.8 mu m. This mean cloud particle size implied by the satellite extinction-coefficient data at a single wavelength (1 mu m) is further substantiated by the particle size analysis based on cloud extinction coefficient at two wavelengths (0.525 and 1.02 mu m) obtained by the SAGE II observations. Most of the radiation measured by ERBE is reflected by cloud systems comprised of particles having effective radii much greater than 1 mu m. A reduction in the effective radius of these clouds due to volcanic aerosols is expected to increase their extinction-coefficient values, opposite the effect observed by SAGE II and SAM II. This work further illustrates the capability of the solar occultation satellite sensor to provide particulate extinction-coefficient measurements important to the study of the aerosol-cloud interactions. Finally, the June 1991 Mount Pinatubo major eruption put 3 times more material into the stratosphere than that of the 1982 El Chichon volcanic event. It is important to examine the variations of the extinction coefficient of these two high-altitude cloud systems for the posteruption years of the Pinatubo volcanic event for further evidence of the impact of volcanic aerosols on high-altitude clouds. [References: 81]
机译：在1982年4月El Chichon火山事件的后撤期（1985-1990年）中，研究了两个地理上不同的高空云系统的1-μm体积消光系数的特性，重点是火山气溶胶对云的影响。这两个高空云系统是平流层气溶胶和气体实验（SAGE）II观测到的对流层顶区域的热带云，以及平流层气溶胶测量（SAM）II观测到的极地平流层云（PSC）。结果表明，火山气溶胶改变了这些高海拔云的频率分布，从而抑制了具有高消光系数（6x10（-3）-2x10（-2）km（-1））的云的出现，而消光系数较低的云（2x10（-3）-6x10（-2）km（-1））的云则得到增强。火山气溶胶的这种影响似乎与1991年6月皮纳图博火山喷发的初始后喷发时期的信念辐射预算实验（ERBE）观测到的光学厚云的消光系数增加相反。提出了一种基于米氏理论对此差异的合理解释。 Mie计算表明，根据仪器观测到的云系统的主要有效半径（r（e）），云消光系数对气溶胶浓度变化有两种可能的响应类型。这两种类型的响应被约0.8微米的云粒子有效半径分开。当r（e）小于0.8μm时，云雾消光系数随着气溶胶浓度的增加而降低，而当r（e）大于0.8μm时，相反的情况发生。结果，由SAGE系列卫星仪器测得的大多数（如果不是全部）高空云的有效半径必须小于约0.8微米。通过基于SAGE II获得的两个波长（0.525和1.02μm）下的云消光系数的粒度分析，进一步证实了在单个波长（1μm）下的卫星消光系数数据所隐含的平均云粒径。观察。 ERBE测量的大部分辐射被云系统反射，该云系统由有效半径远大于1微米的粒子组成。与火山气溶胶引起的这些云的有效半径减小，有望增加其消光系数值，这与SAGE II和SAM II观察到的效果相反。这项工作进一步说明了太阳掩星卫星传感器提供颗粒消光系数测量的能力，这些测量对于研究气溶胶-云相互作用至关重要。最终，1991年6月的皮纳图博火山大爆发使平流层中的物质多于1982年El Chichon火山事件的三倍。重要的是要检查这两个高空云系统在皮纳图博火山事件的后撤年代的消光系数的变化，以进一步证明火山气溶胶对高空云的影响。 [参考：81]

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