Sink, Source or Something In‐Between? Net Effects of Precipitation on Aerosol Particle Populations

Khadir, Théodore; Riipinen, Ilona; Talvinen, Sini; Heslin‐Rees, Dominic; Pöhlker, Christopher; Rizzo, Luciana; Machado, Luiz A. T.; Franco, Marco A.; Kremper, Leslie A.; Artaxo, Paulo; Petäjä, Tuukka; Kulmala, Markku; Tunved, Peter; Ekman, Annica M. L.; Krejci, Radovan; Virtanen, Annele

doi:10.1029/2023gl104325

Cited by 6 publications

(3 citation statements)

References 79 publications

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“…8b). Prior studies have observed both an increase and decrease in the number concentration of Aitken-mode particles with precipitation accumulated along air mass trajectories (Khadir et al, 2023;Tunved et al, 2012). During rapid boundary layer growth under CAO conditions, entrainment is also likely to play a role (Tornow et al, 2022).…”

Section: Scavenging By Precipitationmentioning

confidence: 95%

“…Since the removal of aerosol particles has been linked to precipitation that occurs locally at a specific site in addition to along a calculated trajectory (Khadir et al, 2023;Tunved et al, 2012), we also examined the relationship of aerosol number concentration to local precipitation accumulated within the previous 24 hours at Andenes (Fig. 8b-d).…”

Section: Scavenging By Precipitationmentioning

confidence: 99%

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Aerosol Size Distribution Properties Associated with Cold-Air Outbreaks in the Norwegian Arctic

Williams,

Dedrick,

Russell

et al. 2024

Preprint

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Abstract. The aerosol particles that provide cloud condensation and ice nuclei contribute to key cloud processes associated with cold-air outbreak (CAO) events but are poorly constrained in climate models due to sparse observations. Here we retrieve aerosol size distribution modes from measurements at Andenes, Norway during the Cold-Air Outbreaks in the Marine Boundary Layer Experiment (COMBLE) and at Zeppelin Observatory, approximately 1000 km upwind in Svalbard. During CAO events at Andenes, the sea spray mode number concentration is correlated to strong over-ocean winds with a mean of 8±4 cm-3 that is 71 % higher than during non-CAO conditions. Additionally during CAO events at Andenes, the mean Hoppel minimum diameter is 6 nm smaller than during non-CAO conditions though the estimated supersaturation is lower and the number concentration of particles that likely activated in-cloud is 109±61 cm-3 (similar to non-CAO conditions). For CAO trajectories between Zeppelin Observatory and Andenes, the upwind-to-downwind change in number concentration is largest for the accumulation mode with a mean decrease of 93±95 cm-3, likely attributable primarily to precipitation scavenging. These characteristic properties of aerosol size distributions during CAO events provide guidance for evaluating CAO aerosol-cloud interaction processes in models.

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Section: Scavenging By Precipitationmentioning

confidence: 95%

Section: Scavenging By Precipitationmentioning

confidence: 99%

Aerosol Size Distribution Properties Associated with Cold-Air Outbreaks in the Norwegian Arctic

Williams,

Dedrick,

Russell

et al. 2024

Preprint

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“…The central Amazon is one of the few continental places where the atmospheric aerosol population, along with aerosol-cloud interactions, approaches conditions without significant anthropogenic impacts during particular periods of the wet season (February to May) (Martin et al, 2010;Pöhlker et al, 2016Pöhlker et al, , 2018Andreae et al, 2022). Cloud and precipitation formation are directly linked to the concentration and properties of atmospheric aerosols, which greatly affects the hydrological cycle of the basin (Andreae et al, 2001;Andreae, 2007;Artaxo et al, 2022;Khadir et al, 2023). In the Amazon, biogenic emissions, such as organic gases and aerosols, combined with the high concentration of water vapor and intense solar radiation, result in an atmosphere particularly susceptible to different external forcings that may change its composition (Pöhlker et al, 2012;Carslaw et al, 2013;Artaxo et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Vertically resolved aerosol variability at the Amazon Tall Tower Observatory under wet season conditions

Franco,

Valiati,

Holanda

et al. 2024

Preprint

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Abstract. The wet season atmosphere in the central Amazon resembles natural conditions with minimal anthropogenic influence, making it one of the rare pre-industrial-like continental areas worldwide. Previous long-term studies have analyzed the properties and sources of the natural Amazonian background aerosol. However, the vertical profile of the planetary boundary layer (PBL) has not been assessed systematically. Since 2017, such a profile assessment has been possible with the 325 m high tower at the Amazon Tall Tower Observatory (ATTO), located in a largely untouched primary forest in central Amazonia. This study investigates the variability of submicrometer aerosol concentration, size distribution, and optical properties at 60 and 325 m height in the Amazon PBL. The results show significant differences in aerosol volumes and scattering coefficients in the vertical gradient. The aerosol population was well-mixed throughout the boundary layer during the daytime but became separated upon stratification during nighttime. We also found a significant difference in the spectral dependence of the scattering coefficients between the two heights. The analysis of rainfall and related downdrafts revealed changes in the aerosol populations before and after rain events, with absorption and scattering coefficients decreasing as optically active particles are removed by wet deposition. The recovery of absorption and scattering coefficients is faster at 325 m than at 60 m. Convective events were concomitant with rapid increases in the concentration of sub-50 nm particles, likely associated with downdrafts. We found that the aerosol population near the canopy had a significantly higher mass scattering efficiency than at 325 m. It was also observed a clear spectral dependence, with values for λ = 450, 525 and 635 nm of 7.74±0.12, 5.49±0.11and 4.15±0.11 m2 g−1, respectively, at 60 m, while at 325 m, the values were 5.26±0.06, 3.76±0.05 and 2.46±0.04 m2 g−1, respectively. The equivalent aerosol refractive index results, which were obtained for the first time for the wet season in central Amazon, show a slightly higher scattering (real) component at 60 m compared to 325 m, of 1.33 and 1.27, respectively. In contrast, the refractive index’s absorptive (imaginary) component was identical for both heights, at 0.006. This study shows that the aerosol physical properties at 60 and 325 m height are different, likely due to aging processes, and strongly depend on the photochemistry, PBL dynamics, and aerosol sources. These findings provide valuable insights into the impact of aerosols on climate and radiative balance and can be used to improve the representation of aerosols in global climate models.

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Opinion: The strength of long-term comprehensive observations to meet multiple grand challenges in different environments and in the atmosphere

Kulmala,

Lintunen,

Lappalainen

et al. 2023

Atmos. Chem. Phys.

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Abstract. To be able to meet global grand challenges (climate change; biodiversity loss; environmental pollution; scarcity of water, food and energy supplies; acidification; deforestation; chemicalization; pandemics), which all are closely interlinked with each other, we need comprehensive open data with proper metadata, along with open science. The large data sets from ground-based in situ observations, ground and satellite remote sensing, and multiscale modeling need to be utilized seamlessly. In this opinion paper, we demonstrate the power of the SMEAR (Station for Measuring Earth surface–Atmosphere Relations) concept via several examples, such as detection of new particle formation and the particles' subsequent growth, quantifying atmosphere–ecosystem feedback loops, and combining comprehensive observations with emergency science and services, as well as studying the effect of COVID-19 restrictions on different air quality and climate variables. The future needs and the potential of comprehensive observations of the environment are summarized.

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Sink, Source or Something In‐Between? Net Effects of Precipitation on Aerosol Particle Populations

Cited by 6 publications

References 79 publications

Aerosol Size Distribution Properties Associated with Cold-Air Outbreaks in the Norwegian Arctic

Aerosol Size Distribution Properties Associated with Cold-Air Outbreaks in the Norwegian Arctic

Vertically resolved aerosol variability at the Amazon Tall Tower Observatory under wet season conditions

Opinion: The strength of long-term comprehensive observations to meet multiple grand challenges in different environments and in the atmosphere

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