This paper presents the estimation of the hygroscopic growth parameter of atmospheric aerosols retrieved with a multi-wavelength lidar, a micro-pulse lidar (MPL) and daily radiosoundings in the coastal region of Barcelona, Spain. The hygroscopic growth parameter, γ, parameterizes the magnitude of the scattering enhancement in terms of the backscatter coefficient following Hänel parameterization. After searching for time-colocated lidar and radiosounding measurements (performed twice a day, all year round at 00:00 and 12:00 UTC), a strict criterion-based procedure (limiting the variations of magnitudes such as water vapor mixing ratio (WMVR), potential temperature, wind speed and direction) is applied to select only cases of aerosol hygroscopic growth. A spectral analysis (at the wavelengths of 355, 532 and 1064 nm) is performed with the multi-wavelength lidar, and a climatological one, at the wavelength of 532 nm, with the database of both lidars. The spectral analysis shows that below 2 km the regime of local pollution and sea salt γ decreases with increasing wavelengths. Since the 355 nm wavelength is sensitive to smaller aerosols, this behavior could indicate slightly more hygroscopic aerosols present at smaller size ranges. Above 2 km (the regime of regional pollution and residual sea salt) the values of γ at 532 nm are nearly the same as those below 2 km, and its spectral behavior is flat. This analysis and others from the literature are put together in a table presenting, for the first time, a spectral analysis of the hygroscopic growth parameter of a large variety of atmospheric aerosol hygroscopicities ranging from low (pure mineral dust, γ <0.2) to high (pure sea salt, γ > 1.0) hygroscopicity. The climatological analysis shows that, at 532 nm, γ is rather constant all year round and has a large monthly standard deviation, suggesting the presence of aerosols with different hygroscopic properties all year round. The annual γ is 0.55 ± 0.23. The height of the layer where hygroscopic growth was calculated shows an annual cycle with a maximum in summer and a minimum in winter. Former works describing the presence of recirculation layers of pollutants injected at various heights above the planetary boundary layer (PBL) may explain why γ, unlike the height of the layer where hygroscopic growth was calculated, is not season-dependent. The subcategorization of the whole database into No cloud and Below-cloud cases reveals a large difference of γ in autumn between both categories (0.71 and 0.33, respectively), possibly attributed to a depletion of inorganics at the point of activation into cloud condensation nuclei (CCN) in the Below-cloud cases. Our work calls for more in situ measurements to synergetically complete such studies based on remote sensing.

中文翻译：

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测量报告：西班牙巴塞罗那多波长激光雷达测量气溶胶吸湿增长的光谱和统计分析

本文介绍了西班牙巴塞罗那沿海地区使用多波长激光雷达、微脉冲激光雷达 (MPL) 和日常无线电探空反演的大气气溶胶吸湿生长参数的估计。吸湿生长参数，γ，根据 Hänel 参数化后的反向散射系数参数化散射增强的幅度。在搜索时间同地激光雷达和无线电探空测量（每天执行两次，全年 00:00 和 12:00 UTC）后，一个严格的基于标准的程序（限制水汽混合比（WMVR）等量级的变化)、潜在温度、风速和风向) 仅用于选择气溶胶吸湿增长的情况。使用多波长激光雷达进行光谱分析（波长为 355、532 和 1064 nm），并使用两个激光雷达的数据库进行气候分析，波长为 532 nm。光谱分析表明，在 2 公里以下，局部污染和海盐γ随着波长的增加而减少。由于 355 nm 波长对较小的气溶胶敏感，因此这种行为可能表明在较小尺寸范围内存在的吸湿性稍强的气溶胶。在 2 km 以上（区域污染和残留海盐状况）， 532 nm 处的γ值与 2 km 以下几乎相同，其光谱行为是平坦的。该分析和文献中的其他分析汇总在一个表格中，首次对从低（纯矿物粉尘，γ <0.2）到高的各种大气气溶胶吸湿性的吸湿生长参数进行光谱分析（纯海盐，γ  >  1.0）吸湿性。气候分析表明，在 532 nm 处，γ 全年相当稳定，每月标准偏差较大，表明全年存在具有不同吸湿性的气溶胶。年γ为 0.55  ±  0.23。计算吸湿生长的层高显示了一个年度循环，夏季最大，冬季最小。以前的作品描述了在行星边界层 (PBL) 上方不同高度注入的污染物再循环层的存在，这可以解释为什么γ与计算吸湿性增长的层的高度不同，它不依赖于季节。将整个数据库细分为无云和云下案例揭示了秋季的γ在两个类别之间（分别为 0.71 和 0.33），这可能是由于在云下情况下，无机物在活化点消耗为云凝结核 (CCN)。我们的工作需要更多的原位测量，以协同完成基于遥感的此类研究。