Supplementary material to "Role of black carbons mass size distribution in the direct aerosol radiative forcing"

Abstract. Large uncertainties exist when estimating radiative effects of ambient black carbon (BC) aerosol. Previous studies about the BC aerosol radiative forcing mainly focus on the BC aerosols' mass concentrations and mixing states, while the effects of BC mass size distribution (BCMSD) were not well considered. In this paper, we developed a method of measuring the BCMSD by using a differential mobility analyzer in tandem with an Aethalometer. A comprehensive method of multiple charging corrections was proposed and implemented in measuring the BCMSD. Good agreement was obtained between the BC mass concentration integrated from this system and that measured in the bulk phase, demonstrating the reliability of our proposed method. Characteristics of the BCMSD and corresponding radiative effects were studied based on a field measurement campaign conducted in the North China Plain by using our own measurement system. Results showed that the BCMSD had two modes and the mean peak diameters of the modes were 150 and 503 nm. The BCMSD of the coarser mode varied significantly under different pollution conditions with peak diameter varying between 430 and 580 nm, which gave rise to significant variation in aerosol bulk optical properties. The direct aerosol radiative forcing was estimated to vary by 8.45 % for different measured BCMSDs of the coarser mode, which shared the same magnitude with the variation associated with assuming different aerosol mixing states (10.5 %). Our study reveals that the BCMSD as well as its mixing state in estimating the direct aerosol radiative forcing matters. Knowledge of the BCMSD should be fully considered in climate models.

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Role of black carbons mass size distribution in the direct aerosol radiative forcing

10.5194/acp-2019-385 ◽

2019 ◽

Author(s):

Gang Zhao ◽

Jiangchuan Tao ◽

Ye Kuang ◽

Chuanyang Shen ◽

Yingli Yu ◽

...

Keyword(s):

Size Distribution ◽

Radiative Forcing ◽

Climate Models ◽

Field Measurements ◽

Radiative Effects ◽

Aerosol Radiative Forcing ◽

Mass Size Distribution ◽

Mass Size ◽

Mixing States ◽

Aerosol Radiative

Abstract. Large uncertainties exist when estimating radiative effects of ambient black carbon (BC) aerosol. Previous studies about the BC aerosol radiative forcing mainly focus on the BC aerosols’ mass concentrations and mixing states, while the effects of BC mass size distribution (BCMSD) were not well considered. In this paper, we developed a method by measuring the BCMSD by using a differential mobility analyzer in tandem with an aethalometer. A comprehensive method of multiple charging corrections is proposed and implemented in measuring the BCMSD. Good agreement is obtained between the BC mass concentration integrated from this system and that measured in bulk phase, demonstrating the reliability of our proposed method. Characteristics of the BCMSD and corresponding radiative effects are studied based on field measurements conducted in the North China Plain by using our own designed measurement system. Results show that the BCMSD have two modes and the mean peak diameters of the two modes are 150 nm and 503 nm respectively. The BCMSD of coarser mode varies significantly under different pollution conditions with peak diameter varying between 430 nm and 580 nm, which gives rise to significant variation in aerosol buck optical properties. The aerosol direct aerosol radiative forcing is estimated to vary by 22.5 % for different measured BCMSDs, which shares the same magnitude to the variation associated with assuming different aerosol mixing states (21.5 %). Our study reveals that the BCMSD matters as well as their mixing state in estimating the direct aerosol radiative forcing. Knowledge of the BCMSD should be fully considered in climate models.

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Supplementary material to "The global aerosol-climate model ECHAM6.3-HAM2.3 – Part 2: Cloud evaluation, aerosol radiative forcing and climate sensitivity"

10.5194/gmd-2018-307-supplement ◽

2019 ◽

Author(s):

David Neubauer ◽

Sylvaine Ferrachat ◽

Colombe Siegenthaler-Le Drian ◽

Philip Stier ◽

Daniel G. Partridge ◽

...

Keyword(s):

Climate Sensitivity ◽

Radiative Forcing ◽

Climate Model ◽

Aerosol Radiative Forcing ◽

Supplementary Material ◽

Aerosol Radiative

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The role of highly oxygenated organic molecules in the Boreal aerosol-cloud-climate system

Nature Communications ◽

10.1038/s41467-019-12338-8 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 11

Author(s):

Pontus Roldin ◽

Mikael Ehn ◽

Theo Kurtén ◽

Tinja Olenius ◽

Matti P. Rissanen ◽

...

Keyword(s):

Boreal Forest ◽

Radiative Forcing ◽

Organic Molecules ◽

Cloud Condensation Nuclei ◽

Aerosol Radiative Forcing ◽

Rapid Formation ◽

Primary Driver ◽

Climate Cooling ◽

Aerosol Radiative

Abstract Over Boreal regions, monoterpenes emitted from the forest are the main precursors for secondary organic aerosol (SOA) formation and the primary driver of the growth of new aerosol particles to climatically important cloud condensation nuclei (CCN). Autoxidation of monoterpenes leads to rapid formation of Highly Oxygenated organic Molecules (HOM). We have developed the first model with near-explicit representation of atmospheric new particle formation (NPF) and HOM formation. The model can reproduce the observed NPF, HOM gas-phase composition and SOA formation over the Boreal forest. During the spring, HOM SOA formation increases the CCN concentration by ~10 % and causes a direct aerosol radiative forcing of −0.10 W/m2. In contrast, NPF reduces the number of CCN at updraft velocities < 0.2 m/s, and causes a direct aerosol radiative forcing of +0.15 W/m2. Hence, while HOM SOA contributes to climate cooling, NPF can result in climate warming over the Boreal forest.

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