Particle Size Distributions within Arctic Polar Stratospheric Clouds to Complement Particle Composition and Scattering Measurements

要从数量上更全面地了解极地平流层臭氧的损失，需要在若干领域开展进一步的工作。极地平流层云（PSC）中粒子的成核、生长、组成和沉降的微物理学就是其中之一。PSC颗粒为激活氯所需的异质化学物质提供了场所，然后破坏臭氧。PSC颗粒所起的关键作用在北极最为明显，那里的臭氧损失基本上每年都受到温度（PSC的替代物）的调节。PSC发生的频率、持续时间和时间决定了平流层极涡中氯活化和反硝化的程度，从而决定了臭氧损失的数量。去除一些目前的不确定性PSC形成温度，颗粒组成，和颗粒相将允许更仔细的建模的量的氯处理的PSC和脱氮的程度。氯的活化和最终的臭氧损失取决于所有这些因素。这项工作利用了来自几个欧洲同事的邀请，在2000/2001和2001/2002年冬季合作进行PSC颗粒的联合测量。欧洲的机构及其测量结果是：海德堡的马克斯-普朗克核物理研究所，粒子组成，巴黎的CNRS动力气象学实验室，气相水蒸气浓度;罗马的CNR大气物理研究所，气溶胶后向散射和去极化;哥本哈根的丹麦气象研究所，气溶胶后向散射和微物理/中尺度建模。在以前的支持下，这四个仪器，加上在这项工作中使用的粒子计数器，已被集成到一个气球吊舱，将同时测量，在现场，PSC颗粒组成，浓度，大小，去极化，后向散射，和气相浓度的水。该吊舱于2000年1月首次在北极地区飞行。该赠款将使用这套独特的仪器完成另外四次北极PSC测量。将使用两台仪器测量12个尺寸等级中半径为0.15 - 10.0毫米的凝结核和气溶胶的环境浓度。根据这些测量结果，可以估计尺寸分布。为了提供PSC中冷凝硝酸和水的体积的估计，将包括第二个气溶胶计数器以测量平流层气溶胶的背景。该仪器将配备一个入口加热器，从而在采样前将气溶胶暴露在250 K的入口壁温下约0.1 s后对气溶胶进行采样。除了为联合测量提供气溶胶粒度分布和冷凝体积估计值外，工作将继续侧重于推断颗粒折射率的方法，折射率是组成的函数，通过将我们的尺寸分布测量与在多个波长处的原位光学散射测量进行比较。从这些比较中得出的粒子折射率估计数将用于解释粒子组成的测量结果，这些新的联合测量将在2000年1月利用这种仪器配置进行的第一组成功测量之后进行。2000年1月的测量构成了PSC内的单颗粒组成的第一次直接测量，与气溶胶的大小，浓度，相位和光学特性的表征相一致。这些测量揭示了由散布有硝酸水合物层的液滴层组成的PSC。各种仪器在捕捉云的精细分层结构方面的一致性令人印象深刻。云的许多层都符合我们对PSC的热力学理解，同时观察到一些新的富含HNO 3的颗粒类型。

Deshler OPP-0095158A more complete quantitative understanding of polar stratospheric ozone loss requires further work in several areas. The microphysics of the nucleation, growth, composition, and sedimentation of particles in polar stratospheric clouds (PSCs) is one of these areas. PSC particles provide sites for the heterogeneous chemistry required to activate chlorine, which then destroys ozone. The pivotal role played by PSC particles is most evident in the Arctic where ozone loss is essentially modulated by temperature, a surrogate for PSCs, from year to year. The frequency, duration, and timing of PSC occurrence determines the extent of chlorine activation and denitrification in the stratospheric polar vortex, and thus the amount of ozone loss. Removing some of the present uncertainties concerning PSC formation temperatures, particle composition, and particle phase will permit more careful modeling of the amount of chlorine processed by PSCs and the extent of denitrification. The activation of chlorine and ultimately ozone loss is dependent on all of these factors.This work takes advantage of invitations from several European colleagues to collaborate on joint measurements of PSC particles during the winters of 2000/2001 and 2001/2002. The European institutions and their measurements are: Max-Planck-Institut fur Kernphysik - Heidelberg, particle composition CNRS-Laboratoire de Meteorologie Dynamique - Paris, gas phase water vapor concentration; CNR - Istituto di Fisica dell'Atmosfera - Rome, aerosol backscatter and depolarization; and Danish Meteorological Institute - Copenhagen, aerosol backscatter and microphysical/mesoscale modeling. Under previous support these four instruments, plus the particle counters used in this work, have been integrated onto one balloon gondola which will simultaneously measure, in situ, PSC particle composition, concentration, size, depolarization, backscattering, and gas phase concentrations of water. This gondola was flown for the first time in January 2000 in the Arctic.This grant will complete four more Arctic PSC measurements with this unique set of instruments. Two instruments will be used to measure the ambient concentration of condensation nuclei and of aerosol with radii =0.15 - 10.0 mm in 12 size classes. From these measurements size distributions can be estimated. To provide estimates of the volume of the condensed nitric acid and water in the PSCs, a second aerosol counter will be included to measure the background stratospheric aerosol. This instrument will be fitted with an inlet heater, thus sampling aerosol after they have been exposed to an inlet wall temperature of 250 K for ~ 0.1 s prior to sampling.In addition to providing aerosol size distributions and estimates of condensed volume for the joint measurements, the work will continue to focus on methods to infer particle index of refraction, which is a function of composition, through comparisons of our size distribution measurements with in situ optical scattering measurements at a number of wavelengths. Estimates of particle index of refraction which result from these comparisons will be used in the interpretation of particle composition measurements.These new joint measurements will follow the first successful set of measurements by this configuration of instruments in January 2000. The January 2000 measurements constituted the first direct measurements of single particle composition within a PSC, coincident with a characterization of aerosol size, concentration, phase, and optical properties. These measurements revealed a PSC composed of layers of liquid droplets interspersed with layers of nitric acid hydrates. The agreement amongst the various instruments in capturing the fine layered structure of the cloud was impressive. Many layers of the cloud fit well within our thermodynamic understanding of PSCs while some new HNO3 rich particle types were observed.