A cloud-by-cloud approach for studying aerosol-cloud interaction in satellite observations

IF 3.2 3区地球科学 Q2 METEOROLOGY & ATMOSPHERIC SCIENCES

Atmospheric Measurement Techniques Pub Date : 2023-11-23 DOI:10.5194/egusphere-2023-2773

Fani Alexandri, Felix Müller, Goutam Choudhury, Peggy Achtert, Torsten Seelig, Matthias Tesche

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引用次数: 0

Abstract

Abstract. The effective radiative forcing (ERF) due to aerosol-cloud interactions (ACI) and rapid adjustments (ERFaci) still causes the largest uncertainty in the assessment of climate change. It is understood only with medium confidence and studied primarily for warm clouds. Here, we present a novel cloud-by-cloud (C×C) approach for studying ACI in satellite observations that combines the concentration of cloud condensation nuclei (n_CCN) and ice nucleating particles (n_INP) from polar-orbiting lidar measurements with the development of the properties of individual clouds from tracking them in geostationary observations. We present a step-by-step description for obtaining matched aerosol-cloud cases. The application to satellite observations over Central Europe and Northern Africa during 2014 together with rigorous quality assurance leads to 399 liquid-only clouds and 95 ice-containing clouds that can be matched to surrounding n_CCN and n_INP, respectively, at cloud level. We use this initial data set for assessing the impact of changes in cloud-relevant aerosol concentrations on the cloud droplet number concentration (N_d) and effective radius (r_eff) of liquid clouds and the phase of clouds in the regime of heterogeneous ice formation. We find a Δ ln N_d/Δ ln n_CCN of 0.13 to 0.30 which is at the lower end of commonly inferred values of 0.3 to 0.8. The Δ ln r_eff/Δ ln n_CCN between -0.09 and -0.21 suggests that r_eff decreases by -0.81 to -3.78 nm per increase in n_CCN of 1 cm^-3. We also find a tendency towards more cloud ice and more fully glaciated clouds with increasing n_INP that cannot be explained by the increasingly lower cloud-top temperature of super-cooled liquid, mixed-phase, and fully glaciated clouds alone. Applied to a larger amount of observations, the C×C approach has the potential to enable the systematic investigation of warm and cold clouds. This marks a step change in the quantification of ERFaci from space.

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在卫星观测中研究气溶胶-云相互作用的逐云方法

摘要。气溶胶-云相互作用(ACI)和快速调整(ERFaci)引起的有效辐射强迫(ERF)仍然是气候变化评估中最大的不确定性。人们对它的了解只有中等置信度，研究主要针对暖云。在这里，我们提出了一种新的逐云(C×C)方法来研究卫星观测中的ACI，该方法将极地轨道激光雷达测量的云凝结核(nCCN)和冰核粒子(nINP)的浓度与地球静止观测中跟踪单个云的特性的发展结合起来。我们提出了一步一步的描述，以获得匹配的气溶胶-云的情况。2014年中欧和北非的卫星观测应用，加上严格的质量保证，导致399个纯液体云和95个含冰云，分别可以在云水平上与周围的nCCN和nINP相匹配。我们使用这个初始数据集来评估与云相关的气溶胶浓度变化对云滴数浓度(Nd)和液体云的有效半径(reff)的影响，以及在非均质冰形成状态下云的相位。我们发现Δ ln Nd/Δ ln nCCN为0.13至0.30，这是通常推断值0.3至0.8的下端。Δ ln reff/Δ ln nCCN在-0.09 ~ -0.21之间，表明nCCN每增加1 cm-3, reff降低-0.81 ~ -3.78 nm。我们还发现，随着nINP的增加，云冰和完全冰川云的数量也有增加的趋势，这不能仅仅用过冷液体、混合相和完全冰川云的云顶温度越来越低来解释。应用于更大量的观测，C×C方法有可能使系统地研究冷暖云成为可能。这标志着从太空对ERFaci的量化迈出了一步。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Atmospheric Measurement Techniques METEOROLOGY & ATMOSPHERIC SCIENCES-

CiteScore

7.10

自引率

18.40%

发文量

331

审稿时长

3 months

期刊介绍： Atmospheric Measurement Techniques (AMT) is an international scientific journal dedicated to the publication and discussion of advances in remote sensing, in-situ and laboratory measurement techniques for the constituents and properties of the Earth’s atmosphere. The main subject areas comprise the development, intercomparison and validation of measurement instruments and techniques of data processing and information retrieval for gases, aerosols, and clouds. The manuscript types considered for peer-reviewed publication are research articles, review articles, and commentaries.