Reduced volatility of aerosols from surface emission to the top of planetary boundary layer

Abstract. Aerosols from surface emission can be transported upwards through convective mixing in the planetary boundary layer (PBL), subsequently interacting with clouds, serving important sources to nucleate droplets or ice particles. However, the evolution of aerosol composition during this vertical transport has yet to be explicitly understood. In this study, simultaneous measurements of detailed aerosol compositions were conducted at both sites of urban Beijing (50 m a.s.l.) and HaiTuo mountain (1344 m a.s.l.) during wintertime, representing the anthropogenically polluted surface environment and the top of PBL respectively. The pollutants from surface emissions were observed to reach the mountain site on daily basis through daytime PBL connective mixing. From surface to the top of PBL, we found efficient transport or formation for lower-volatile species (black carbon, sulphate and low-volatile organic aerosol, OA); however notable reduction of semi-volatile substances, such as the fractions of nitrate and semi-volatile OA reduced by 74 % and 76 % respectively, during the upward transport. This implied the evaporation process may have occurred, in repartitioning the condensed semi-volatile substances to gas-phase, when aerosols were transported and exposed to a cleaner environment. Combining with the oxidation processes, these led to enhanced oxidation state of OA at the top of the PBL compared to surface environment, with an increase of oxygen to carbon atomic ratio by 0.2. Such reduction of aerosol volatility during vertical transport may be important in modifying its viscosity, nucleation activity and atmospheric lifetime.

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Reduced volatility of aerosols from surface emissions to the top of the planetary boundary layer

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-14749-2021 ◽

2021 ◽

Vol 21 (19) ◽

pp. 14749-14760

Author(s):

Quan Liu ◽

Dantong Liu ◽

Yangzhou Wu ◽

Kai Bi ◽

Wenkang Gao ◽

...

Keyword(s):

Boundary Layer ◽

Planetary Boundary Layer ◽

Daily Basis ◽

Atomic Ratio ◽

Vertical Transport ◽

Aerosol Composition ◽

Surface Emission ◽

Convective Mixing ◽

Upward Transport ◽

Surface Environment

Abstract. Aerosols from surface emission can be transported upwards through convective mixing in the planetary boundary layer (PBL), which subsequently interact with clouds, serving as important sources to nucleate droplets or ice particles. However, the evolution of aerosol composition during this vertical transport has yet to be explicitly understood. In this study, simultaneous measurements of detailed aerosol compositions were conducted at two sites, namely urban Beijing (50 m above sea level – a.s.l.) and Haituo mountain (1344 m a.s.l.) during wintertime, representing the anthropogenically polluted surface environment and the top of the PBL, respectively. The pollutants from surface emissions were observed to reach the mountain site on daily basis through daytime PBL convective mixing. From the surface to the top of PBL, we found efficient transport or formation of lower-volatility species (black carbon, sulfate, and low-volatile organic aerosol, OA); however, a notable reduction in semivolatile substances, such as the fractions of nitrate and semivolatile OA reduced by 74 % and 76 %, respectively, during the upward transport. This implies that the mass loss of these semivolatile species was driven by the evaporation process, which repartitioned the condensed semivolatile substances to the gas phase when aerosols were transported and exposed to a cleaner environment. In combination with the oxidation processes, these led to an enhanced oxidation state of OA at the top of the PBL compared to surface environment, with an increase of oxygen to carbon atomic ratio by 0.2. Such a reduction in aerosol volatility during vertical transport may be important in modifying its viscosity, nucleation activity, and atmospheric lifetime.

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Supplementary material to "Reduced volatility of aerosols from surface emission to the top of planetary boundary layer"

10.5194/acp-2021-362-supplement ◽

2021 ◽

Author(s):

Quan Liu ◽

Dantong Liu ◽

Yangzhou Wu ◽

Kai Bi ◽

Wenkang Gao ◽

...

Keyword(s):

Boundary Layer ◽

Planetary Boundary Layer ◽

Surface Emission ◽

Supplementary Material

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Sensitivity of tropospheric chemical composition to halogen-radical chemistry using a fully coupled size-resolved multiphase chemistry/global climate system – Part 1: Halogen distributions, aerosol composition, and sensitivity of climate-relevant gases

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-13-6067-2013 ◽

2013 ◽

Vol 13 (3) ◽

pp. 6067-6129 ◽

Cited By ~ 1

Author(s):

M. S. Long ◽

W.C. Keene ◽

R. C. Easter ◽

R. Sander ◽

X. Liu ◽

...

Keyword(s):

Boundary Layer ◽

Planetary Boundary Layer ◽

Atmospheric Chemistry ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Tropospheric Chemistry ◽

Oxidation Products ◽

Aerosol Composition ◽

Mixing Ratios

Abstract. Observations and model studies suggest a significant but highly non-linear role for halogens, primarily Cl and Br, in multiphase atmospheric processes relevant to tropospheric chemistry and composition, aerosol evolution, radiative transfer, weather, and climate. The sensitivity of global atmospheric chemistry to the production of marine aerosol and the associated activation and cycling of inorganic Cl and Br was tested using a size-resolved multiphase coupled chemistry/global climate model (National Center for Atmospheric Research's Community Atmosphere Model (CAM); v3.6.33). Simulation results showed strong meridional and vertical gradients in Cl and Br species. The simulation reproduced most available observations with reasonable confidence permitting the formulation of potential mechanisms for several previously unexplained halogen phenomena including the enrichment of Br− in submicron aerosol, and the presence of a BrO maximum in the polar free troposphere. However, simulated total volatile Br mixing ratios were generally high in the troposphere. Br in the stratosphere was lower than observed due to the lack of long-lived organobromine species in the simulation. Comparing simulations using chemical mechanisms with and without reactive Cl and Br species demonstrated a significant temporal and spatial sensitivity of primary atmospheric oxidants (O3, HOx, NOx), CH4, and non-methane hydrocarbons (NMHC's) to halogen cycling. Simulated O3 and NOx were globally lower (65% and 35%, respectively, less in the planetary boundary layer based on median values) in simulations that included halogens. Globally, little impact was seen in SO2 and non-sea-salt SO42− processing due to halogens. Significant regional differences were evident: the lifetime of nss-SO42− was extended downwind of large sources of SO2. The burden and lifetime of DMS (and its oxidation products) were lower by a factor of 5 in simulations that included halogens, versus those without, leading to a 20% reduction in nss-SO42− in the Southern Hemisphere planetary boundary layer based on median values.

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Aerosol optical properties in the southeastern United States in summer – Part 1: Hygroscopic growth

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-4987-2016 ◽

2016 ◽

Vol 16 (8) ◽

pp. 4987-5007 ◽

Cited By ~ 46

Author(s):

Charles A. Brock ◽

Nicholas L. Wagner ◽

Bruce E. Anderson ◽

Alexis R. Attwood ◽

Andreas Beyersdorf ◽

...

Keyword(s):

United States ◽

Boundary Layer ◽

Planetary Boundary Layer ◽

Layer Structure ◽

Southeastern United States ◽

Organic Aerosol ◽

Hygroscopic Growth ◽

Aerosol Composition ◽

Optical Extinction ◽

Southeastern Us

Abstract. Aircraft observations of meteorological, trace gas, and aerosol properties were made during May–September 2013 in the southeastern United States (US) under fair-weather, afternoon conditions with well-defined planetary boundary layer structure. Optical extinction at 532 nm was directly measured at relative humidities (RHs) of ∼  15, ∼  70, and ∼  90 % and compared with extinction calculated from measurements of aerosol composition and size distribution using the κ-Köhler approximation for hygroscopic growth. The calculated enhancement in hydrated aerosol extinction with relative humidity, f(RH), calculated by this method agreed well with the observed f(RH) at ∼  90 % RH. The dominance of organic aerosol, which comprised 65 ± 10 % of particulate matter with aerodynamic diameter <  1 µm in the planetary boundary layer, resulted in relatively low f(RH) values of 1.43 ± 0.67 at 70 % RH and 2.28 ± 1.05 at 90 % RH. The subsaturated κ-Köhler hygroscopicity parameter κ for the organic fraction of the aerosol must have been <  0.10 to be consistent with 75 % of the observations within uncertainties, with a best estimate of κ  =  0.05. This subsaturated κ value for the organic aerosol in the southeastern US is broadly consistent with field studies in rural environments. A new, physically based, single-parameter representation was developed that better described f(RH) than did the widely used gamma power-law approximation.

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Efficient Vertical Transport of Black Carbon in the Planetary Boundary Layer

Geophysical Research Letters ◽

10.1029/2020gl088858 ◽

2020 ◽

Vol 47 (15) ◽

Cited By ~ 1

Author(s):

Dantong Liu ◽

Kang Hu ◽

Delong Zhao ◽

Shuo Ding ◽

Yunfei Wu ◽

...

Keyword(s):

Boundary Layer ◽

Black Carbon ◽

Planetary Boundary Layer ◽

Vertical Transport

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Vertical profiling of aerosol hygroscopic properties in the planetary boundary layer during the PEGASOS campaigns

Atmospheric Chemistry and Physics ◽

10.5194/acp-16-7295-2016 ◽

2016 ◽

Vol 16 (11) ◽

pp. 7295-7315 ◽

Cited By ~ 7

Author(s):

Bernadette Rosati ◽

Martin Gysel ◽

Florian Rubach ◽

Thomas F. Mentel ◽

Brigitta Goger ◽

...

Keyword(s):

Boundary Layer ◽

Chemical Composition ◽

The Netherlands ◽

Planetary Boundary Layer ◽

Aerosol Particles ◽

Time Of Day ◽

Hygroscopic Growth ◽

Aerosol Composition ◽

Hygroscopic Properties ◽

Direct Measurements

Abstract. Vertical profiles of the aerosol particles hygroscopic properties, their mixing state as well as chemical composition were measured above northern Italy and the Netherlands. An aerosol mass spectrometer (AMS; for chemical composition) and a white-light humidified optical particle spectrometer (WHOPS; for hygroscopic growth) were deployed on a Zeppelin NT airship within the PEGASOS project. This allowed one to investigate the development of the different layers within the planetary boundary layer (PBL), providing a unique in situ data set for airborne aerosol particles properties in the first kilometre of the atmosphere. Profiles measured during the morning hours on 20 June 2012 in the Po Valley, Italy, showed an increased nitrate fraction at ∼  100 m above ground level (a.g.l.) coupled with enhanced hygroscopic growth compared to ∼  700 m a. g. l. This result was derived from both measurements of the aerosol composition and direct measurements of the hygroscopicity, yielding hygroscopicity parameters (κ) of 0.34  ± 0.12 and 0.19  ± 0.07 for 500 nm particles, at ∼  100 and ∼  700 m a. g. l., respectively. The difference is attributed to the structure of the PBL at this time of day which featured several independent sub-layers with different types of aerosols. Later in the day the vertical structures disappeared due to the mixing of the layers and similar aerosol particle properties were found at all probed altitudes (mean κ ≈ 0.18  ± 0.07). The aerosol properties observed at the lowest flight level (100 m a. g. l.) were consistent with parallel measurements at a ground site, both in the morning and afternoon. Overall, the aerosol particles were found to be externally mixed, with a prevailing hygroscopic fraction. The flights near Cabauw in the Netherlands in the fully mixed PBL did not feature altitude-dependent characteristics. Particles were also externally mixed and had an even larger hygroscopic fraction compared to the results in Italy. The mean κ from direct measurements was 0.28 ± 0.10, thus considerably higher than κ values measured in Italy in the fully mixed PBL.

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Lagrangian simulation of the passive tracer in the convective planetary boundary layer

Proceeding of THMT-15. Proceedings of the Eighth International Symposium On Turbulence Heat and Mass Transfer ◽

10.1615/ichmt.2015.thmt-15.1460 ◽

2015 ◽

Author(s):

Boris B. Ilyushin ◽

I.V Mitin ◽

Dmitrii Ph. Sikovsky

Keyword(s):

Boundary Layer ◽

Planetary Boundary Layer ◽

Passive Tracer ◽

Lagrangian Simulation ◽

Convective Planetary Boundary Layer

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Sensitivity of an Idealized Tropical Cyclone to the Configuration of the Global Forecast System–Eddy Diffusivity Mass Flux Planetary Boundary Layer Scheme

Atmosphere ◽

10.3390/atmos12020284 ◽

2021 ◽

Vol 12 (2) ◽

pp. 284

Author(s):

Evan A. Kalina ◽

Mrinal K. Biswas ◽

Jun A. Zhang ◽

Kathryn M. Newman

Keyword(s):

Boundary Layer ◽

Planetary Boundary Layer ◽

Weather Prediction ◽

Intensity Change ◽

Rapid Intensification ◽

Forecast System ◽

Stability Functions ◽

Non Local ◽

The Stability ◽

Heat And Moisture

The intensity and structure of simulated tropical cyclones (TCs) are known to be sensitive to the planetary boundary layer (PBL) parameterization in numerical weather prediction models. In this paper, we use an idealized version of the Hurricane Weather Research and Forecast system (HWRF) with constant sea-surface temperature (SST) to examine how the configuration of the PBL scheme used in the operational HWRF affects TC intensity change (including rapid intensification) and structure. The configuration changes explored in this study include disabling non-local vertical mixing, changing the coefficients in the stability functions for momentum and heat, and directly modifying the Prandtl number (Pr), which controls the ratio of momentum to heat and moisture exchange in the PBL. Relative to the control simulation, disabling non-local mixing produced a ~15% larger storm that intensified more gradually, while changing the coefficient values used in the stability functions had little effect. Varying Pr within the PBL had the greatest impact, with the largest Pr (~1.6 versus ~0.8) associated with more rapid intensification (~38 versus 29 m s−1 per day) but a 5–10 m s−1 weaker intensity after the initial period of strengthening. This seemingly paradoxical result is likely due to a decrease in the radius of maximum wind (~15 versus 20 km), but smaller enthalpy fluxes, in simulated storms with larger Pr. These results underscore the importance of measuring the vertical eddy diffusivities of momentum, heat, and moisture under high-wind, open-ocean conditions to reduce uncertainty in Pr in the TC PBL.

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