Microphysical explanation of the RH-dependent water affinity of biogenic organic aerosol and its importance for climate

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Rastak , N , Pajunoja , A , Navarro , J C A , Ma , J , Song , M , Partridge , D G , Kirkevag , A , Leong , Y , Hu , W W , Taylor , N F , Lambe , A , Cerully , K , Bougiatioti , A , Liu , P , Krejci , R , Petäjä , T , Percival , C , Davidovits , P , Worsnop , D R , Ekman , A M L , Nenes , A , Martin , S , Jimenez , J L , Collins , D R , Topping , D O , Bertram , A K , Zuend , A , Virtanen , A & Riipinen , I 2017 , ' Microphysical explanation of the RH-dependent water affinity of biogenic organic aerosol and its importance for climate ' , Geophysical Research Letters , vol. 44 , no. 10 , pp. 5167-5177 . https://doi.org/10.1002/2017GL073056

Titel: Microphysical explanation of the RH-dependent water affinity of biogenic organic aerosol and its importance for climate
Författare: Rastak, N.; Pajunoja, A.; Navarro, J. C. Acosta; Ma, J.; Song, M.; Partridge, D. G.; Kirkevag, A.; Leong, Y.; Hu, W. W.; Taylor, N. F.; Lambe, A.; Cerully, K.; Bougiatioti, A.; Liu, P.; Krejci, R.; Petäjä, T.; Percival, C.; Davidovits, P.; Worsnop, D. R.; Ekman, A. M. L.; Nenes, A.; Martin, S.; Jimenez, J. L.; Collins, D. R.; Topping, D. O.; Bertram, A. K.; Zuend, A.; Virtanen, A.; Riipinen, I.
Upphovmannens organisation: Department of Physics
Datum: 2017-05-28
Språk: eng
Sidantal: 11
Tillhör serie: Geophysical Research Letters
ISSN: 0094-8276
DOI: https://doi.org/10.1002/2017GL073056
Permanenta länken (URI): http://hdl.handle.net/10138/211403
Abstrakt: A large fraction of atmospheric organic aerosol (OA) originates from natural emissions that are oxidized in the atmosphere to form secondary organic aerosol (SOA). Isoprene (IP) and monoterpenes (MT) are the most important precursors of SOA originating from forests. The climate impacts from OA are currently estimated through parameterizations of water uptake that drastically simplify the complexity of OA. We combine laboratory experiments, thermodynamic modeling, field observations, and climate modeling to (1) explain the molecular mechanisms behind RH-dependent SOA water-uptake with solubility and phase separation; (2) show that laboratory data on IP- and MT-SOA hygroscopicity are representative of ambient data with corresponding OA source profiles; and (3) demonstrate the sensitivity of the modeled aerosol climate effect to assumed OA water affinity. We conclude that the commonly used single-parameter hygroscopicity framework can introduce significant error when quantifying the climate effects of organic aerosol. The results highlight the need for better constraints on the overall global OA mass loadings and its molecular composition, including currently underexplored anthropogenic and marine OA sources. Plain Language Summary The interaction of airborne particulate matter ("aerosols") with water is of critical importance for processes governing climate, precipitation, and public health. It also modulates the delivery and bioavailability of nutrients to terrestrial and oceanic ecosystems. We present a microphysical explanation to the humidity-dependent water uptake behavior of organic aerosol, which challenges the highly simplified theoretical descriptions used in, e.g., present climate models. With the comprehensive analysis of laboratory data using molecular models, we explain the microphysical behavior of the aerosol over the range of humidity observed in the atmosphere, in a way that has never been done before. We also demonstrate the presence of these phenomena in the ambient atmosphere from data collected in the field. We further show, using two state-of-the-art climate models, that misrepresenting the water affinity of atmospheric organic aerosol can lead to significant biases in the estimates of the anthropogenic influence on climate.
Subject: LIQUID PHASE-SEPARATION
CONDENSATION NUCLEI ACTIVITY
DROPLET ACTIVATION KINETICS
SOUTHEASTERN UNITED-STATES
REGIONAL DUST SAMPLES
EARTH SYSTEM MODEL
HYGROSCOPIC GROWTH
MASS-SPECTROMETER
BOREAL FOREST
ATMOSPHERIC AEROSOLS
114 Physical sciences
1171 Geosciences
Referentgranskad: Ja
Licens: cc_by
Användningsbegränsning: openAccess
Parallelpublicerad version: publishedVersion


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