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首页> 外文期刊>Atmospheric Chemistry and Physics Discussions >Physical and optical properties of 2010 Eyjafjallaj??kull volcanic eruption aerosol: ground-based, Lidar and airborne measurements in France
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Physical and optical properties of 2010 Eyjafjallaj??kull volcanic eruption aerosol: ground-based, Lidar and airborne measurements in France

机译：2010年Eyjafjallaj？kull火山喷发气溶胶的物理和光学特性：法国的地面，激光雷达和机载测量

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pstrongAbstract./strong During the Eyjafjallaj??kull eruption (14 April to 24 May 2010), the volcanic aerosol cloud was observed across Europe by several airborne in situ and ground-based remote-sensing instruments. On 18 and 19 May, layers of depolarizing particles (i.e. non-spherical particles) were detected in the free troposphere above the Puy de D?′me station, (PdD, France) with a Rayleigh-Mie LIDAR emitting at a wavelength of 355 nm, with parallel and crossed polarization channels. These layers in the free troposphere (FT) were also well captured by simulations with the Lagrangian particle dispersion model FLEXPART, which furthermore showed that the ash was eventually entrained into the planetary boundary layer (PBL). Indeed, the ash cloud was then detected and characterized with a comprehensive set of in situ instruments at the Puy de D?′me station (PdD). In agreement with the FLEXPART simulation, up to 65 ??g msupa??3/sup of particle mass and 2.2 ppb of SOsub2/sub were measured at PdD, corresponding to concentrations higher than the 95 percentile of 2 yr of measurements at PdD. Moreover, the number concentration of particles increased to 24 000 cmsupa??3/sup, mainly in the submicronic mode, but a supermicronic mode was also detected with a modal diameter of 2 ??m. The resulting optical properties of the ash aerosol were characterized by a low scattering ??ngstr??m exponent (0.98), showing the presence of supermicronic particles. For the first time to our knowledge, the combination of in situ optical and physical characterization of the volcanic ash allowed the calculation of the mass-to-extinction ratio (?·) with no assumptions on the aerosol density. The mass-to-extinction ratio was found to be significantly different from the background boundary layer aerosol (max 1.57 g msupa??2/sup as opposed to 0.33 ?± 0.03 g msupa??2/sup). Using this ratio, ash mass concentration in the volcanic plume derived from LIDAR measurements was found to be 655 ?± 23 ??g msupa??3/sup when the plume was located in the FT (3000 m above the sea level a?? a.s.l.). This ratio could also be used to retrieve an aerosol mass concentration of 579 ?± 60 ??g msupa??3/sup on 19 April, when LIDAR observations detected the ash cloud at 3000 m a.s.l. in correspondence with model simulations (FLEXPART). On 22 April, another ash plume entered the BL, and although it was more diluted than during the May episode, the French research aircraft ATR42 that passed over Clermont-Ferrand in the PBL confirmed the presence of particles with a supermicronic mode, again with a modal diameter at 2 ??m. This data set combining airborne, ground-based and remote sensing observations with dispersion model simulations shows an overall very good coherence during the volcanic eruption period, which allows a good confidence in the characteristics of the ash particles that can be derived from this unique data set./p.
机译：> >摘要。在Eyjafjallaj火山喷发（2010年4月14日至5月24日）期间，欧洲各地的几种机载原位和地面遥感仪器观测到了火山气溶胶云。 5月18日至19日，在Puy de D？me站（法国，PdD）上方的自由对流层中，通过Rayleigh-Mie LIDAR以355波长发射的光，检测到了去极化粒子（即非球形粒子）层平行和交叉偏振通道。通过使用拉格朗日粒子色散模型FLEXPART进行的模拟，还可以很好地捕获自由对流层（FT）中的这些层，这进一步表明，灰分最终被夹带到了行星边界层（PBL）中。的确，然后在Puy de D'me站（PdD）上使用一套综合的现场仪器对烟灰云进行了检测和表征。与FLEXPART模拟一致，在PdD处测得的颗粒质量高达65 ?? gm a ?? 3 和2.2 ppb SO 2 ，对应于高于PdD的2年测量值的95％。此外，颗粒的数量浓度主要在亚微米模式下增加到24000cm ，但是也检测到超微模式，其模态直径为2μm。灰雾气溶胶的最终光学特性的特征在于低散射ΔngstrΔm指数（0.98），表明存在超微粒子。据我们所知，火山灰的原位光学和物理表征相结合，可以在不假设气溶胶密度的情况下计算质量消光比（η·）。发现质量消光比与背景边界层气溶胶有显着差异（最大1.57 gm a ?? 2 而不是0.33？±0.03 gm a ?? 2 <2 / sup>）。使用该比率，当烟羽位于FT时（距离烟台高3000 m），根据LIDAR测量得出的火山烟流中的烟灰质量浓度为655±±23 ?? gm a ?? 3 。海平面a ?? asl）。当LIDAR观测到3000 m a.s.l.处的灰云时，该比率也可用于在4月19日恢复579？±60 ?? g m a ?? 3 的气溶胶质量浓度。与模型仿真（FLEXPART）相对应。 4月22日，又有一个烟灰柱进入BL，尽管比5月时更稀薄，但法国研究飞机ATR42越过了PBL的克莱蒙·费朗，确认存在超微粒子模式的颗粒，再次是模态直径为2 ?? m。该数据集将机载，地面和遥感观测与弥散模型模拟相结合，显示出火山喷发期间总体上非常良好的连贯性，这使人们对可从该独特数据集得出的灰烬颗粒特征具有很好的信心。 。

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