Lidar observations of the stratospheric aerosol layer over southern Italy in the period 1991–1995
Lidar observations of the stratospheric aerosol layer over southern Italy in the period 1991–1995
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1991-1995年期间意大利南部平流层气溶胶层的激光雷达观测
DOI：
10.1029/96jd01172
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
R. Velotta
中科院分区：
文献类型：
--
作者：
P. Di Girolamo;G. Pappalardo;N. Spinelli;V. Berardi;R. Velotta
在1991 - 1995年期间，在Napoli（40°50′N‐14°10′E）和Potenza（40°36′N‐15°44′E）进行了平流层气溶胶层的激光雷达测量，涵盖了Pinatubo火山喷发（1991年6月，菲律宾）产生的气溶胶云的历史。测量值用气溶胶后向散射系数βA(z)、气溶胶积分后向散射系数IB和λ = 351 nm和355 nm处气溶胶光学厚度τA表示；βA(z)和τA由单波长弹性回波确定。气溶胶后向散射峰值IB、τA和βmax在1991年12月达到最大值，随后的e -折叠时间分别为237±25、250±111和257±33 d，散射峰值Rmax的衰减时间为235±13 d。消光-后向散射比αA(z)/βA(z)和柱参数τA/IB的测量使我们能够获得气溶胶的尺寸特征。测定了气溶胶云质心高度zc的时间演变规律。平流层气溶胶随时间的向下重力沉降表明，气溶胶颗粒的大小在0.1 ~ 0.3 μm之间。在火山喷发后约1000天，由于冬-夏过渡和对流层中平流层气溶胶层下部的去除，观测到IB和βmax的突变。IB、τA/IB和zc值的变化表明，这种转变的特征是气溶胶平均半径从0.3 μm变化到0.1 μm。
Lidar measurements of the stratospheric aerosol layer have been carried out in Napoli (40°50′ N‐14°10′ E) and Potenza (40°36′ N‐15°44′ E) during the period 1991–1995, covering the history of the aerosol cloud produced by the eruption of Mount Pinatubo (June 1991, Philippines). Measurements are expressed in terms of aerosol backscattering coefficient βA(z), aerosol integrated backscattering IB and aerosol optical thickness τA at λ = 351 nm and 355 nm; βA(z) and τA are determined from a single‐wavelength elastic return. IB, τA, and βmax, the peak aerosol backscattering, reached their maximum value in December 1991, displaying a subsequent decay with e‐folding times of 237 ± 25, 250 ± 111, and 257 ± 33 days, respectively, Rmax, the peak scattering ratio, is characterized by a decay time of 235 ± 13 days. Measurements of the extinction‐to‐backscattering ratio, αA(z)/βA(z), and of the column parameter, τA/IB, allowed us to retrieve aerosol dimensional characteristics. The time evolution of the height, zc, of the aerosol cloud center of mass was also determined. Downward gravitational settling of stratospheric aerosols with time suggests aerosol particles fall within the size range 0.1–0.3 μm. An abrupt change in IB and βmax is observed approximately 1000 days after the eruption as a result of the winter‐summer transition and the tropospheric removal of the lower portion of the stratospheric aerosol layer. Changes in the values of IB, τA/IB, and zc suggest that this transition is characterized by a change in the aerosol mean radius from 0.3 to 0.1 μm.