Impact of the eruption of Mt Pinatubo on the chemical composition of the stratosphere

Abstract. This article describes the volcanic effect of the Mt Pinatubo eruption in June 1991 on the ozone (O3) and methane (CH4) distribution in the stratosphere, as simulated with the chemistry–climate model EMAC (ECHAM/MESSy Atmospheric Chemistry: ECHAM5, version 5.3.02; MESSy, version 2.51). In this study, the effects of volcanic heating and heterogeneous chemistry on the chemical composition, caused by the volcanic aerosol, are separated. Global model simulations over the relevant period of the eruption from 1989 to 1997 with EMAC in T42L90MA resolution with specified dynamics and interactive chemistry were performed. The first simulation (VOL) contains the volcanic perturbation as an additional aerosol load and thus simulates the interaction of the aerosol with the chemistry and the radiation. The second simulation (NOVOL) neglects the eruption and represents the undisturbed atmosphere. In the third simulation (CVOL) the volcanic aerosol only interacts with the heterogeneous chemistry, such that volcanic heating is omitted. The differences between the simulation results VOL−NOVOL describe the total effect of the Mt Pinatubo eruption on the chemical composition, VOL−CVOL the stratospheric heating effect, and CVOL−NOVOL the chemical effect of the aerosol on the heterogeneous chemistry. The post-volcanic stratosphere shows a decrease in the O3 column in the tropics and an increase in the midlatitudes and polar regions, lasting roughly 1 year. This change in the ozone column is solely a result of the heating effect. The subsequent decrease in the ozone column is related to the chemical effect. The contribution of the catalytic loss cycles (NOx, HOx, ClOx, and BrOx) on the depletion of O3 is analysed in detail. In the tropics, CH4 increases in the upper stratosphere because of stronger vertical transport.

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Impact of the eruption of Mt. Pinatubo on the chemical composition of the stratosphere

10.5194/acp-2020-147 ◽

2020 ◽

Author(s):

Markus Kilian ◽

Sabine Brinkop ◽

Patrick Jöckel

Keyword(s):

Chemical Composition ◽

Climate Model ◽

Chemical Effect ◽

Heterogeneous Chemistry ◽

Volcanic Aerosol ◽

Heating Effect ◽

Subsequent Decrease ◽

Pinatubo Eruption ◽

The Tropics ◽

Ozone Column

Abstract. This article describes the volcanic effect of the Mt. Pinatubo eruption in June 1991 on the ozone (O3) and methane (CH4) distribution in the stratosphere, as simulated with the chemistry-climate model EMAC (ECHAM5 version 5.3.02, MESSy version 2.51). For the first time, the effects of volcanic heating and heterogeneous chemistry on the chemical composition, caused by the volcanic aerosol, are separated. Global model simulations over the relevant period of the eruption from 1989 to 1997 with EMAC in T42L90MA resolution with specified dynamics and interactive chemistry were performed. The first simulation (VOL) contains the volcanic perturbation as additional aerosol load and thus simulates the interaction of the aerosol with the chemistry and the radiation. The second simulation (NOVOL) neglects the eruption and represents the undisturbed atmosphere. In the third simulation (CVOL) the volcanic aerosol only interacts with the heterogeneous chemistry, such that volcanic heating is omitted. The differences between the simulation results VOL-NOVOL describe the total effect of the Mt. Pinatubo eruption on the chemical composition, VOL-CVOL the stratospheric heating effect and CVOL-NOVOL the chemical effect of the aerosol on the heterogeneous chemistry. The post volcanic stratosphere shows a decrease of the O3 column in the tropics, and an increase in the mid-latitudes and polar regions, lasting roughly one year. This change in the ozone column is solely a result of the heating effect. The subsequent decrease of the ozone column is related to the chemical effect. The contribution of the catalytic loss cycles (NOx, HOx, ClOx and BrOx on the depletion of O3 is analysed in detail. In the tropics, CH4 increases in the upper stratosphere because of stronger vertical transport.

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Ship-borne lidar measurements showing the progression of the tropical reservoir of volcanic aerosol after the June 1991 Pinatubo eruption

10.5194/essd-2020-81 ◽

2020 ◽

Cited By ~ 1

Author(s):

Juan-Carlos Antuña-Marrero ◽

Graham W. Mann ◽

Philippe Keckhut ◽

Sergey Avdyushin ◽

Bruno Nardi ◽

...

Keyword(s):

Lower Layer ◽

Extinction Ratio ◽

Stratospheric Aerosol ◽

Original Text ◽

Aerosol Extinction ◽

Volcanic Aerosol ◽

Tropical Reservoir ◽

Aerosol Cloud ◽

Pinatubo Eruption ◽

The Tropics

Abstract. A key limitation of volcanic forcing datasets for the Pinatubo period, is the large uncertainty that remains with respect to the extent of the optical depth of the Pinatubo aerosol cloud in the first year after the eruption, the saturation of the SAGE-II instrument restricting it to only be able to measure the upper part of the aerosol cloud in the tropics. Here we report the recovery of stratospheric aerosol measurements from two ship-borne lidars, both of which measured the tropical reservoir of volcanic aerosol produced by the June 1991 Mount Pinatubo eruption. The lidars were on-board two Soviet vessels, each ship crossing the Atlantic, their measurement datasets providing unique observational transects of the Pinatubo cloud across the tropics from Europe to the Caribbean (~ 40° N to 8° N) from July to September 1991 (the Prof Zubov ship) and from Europe to south of the Equator (8° S to ~ 40° N) between January and February 1992 (the Prof Vize ship). Our philosophy with the data recovery is to follow the same algorithms and parameters appearing in the two peer-reviewed articles that presented these datasets in the same issue of GRL in 1993, and here we provide all 48 lidar soundings made from the Prof. Zubov, and 11 of the 20 conducted from the Prof. Vize, ensuring we have reproduced the aerosols backscatter and extinction values in the Figures of those two papers. These original approaches used thermodynamic properties from the CIRA-86 standard atmosphere to derive the molecular backscattering, vertically and temporally constant values applied for the aerosol backscatter to extinction ratio and the correction factor of the aerosols backscattering wavelength dependence. We demonstrate this initial validation of the recovered stratospheric aerosol extinction profiles, providing full details of each dataset in this paper's Supplement S1, the original text files of the backscatter ratio, the calculated aerosols backscatter and extinction profiles. We anticipate the data providing potential new observational case studies for modelling analyses, including a 1-week series of consecutive soundings (in September 1991) at the same location showing the progression of the entrainment of part of the Pinatubo plume into the upper troposphere and the formation of an associated cirrus cloud. The Zubov lidar dataset illustrates how the tropically confined Pinatubo aerosol cloud transformed from a highly heterogeneous vertical structure in August 1991, maximum aerosol extinction values around 19 km for the lower layer and 23–24 for the upper layer, to a more homogeneous and deeper reservoir of volcanic aerosol in September 1991. We encourage modelling groups to consider new analyses of the Pinatubo cloud, comparing to the recovered datasets, with the potential to increase our understanding of the evolution of the Pinatubo aerosol cloud and its effects. Data described in this work are available at https://doi.pangaea.de/10.1594/PANGAEA.912770 (Antuña-Marrero et al., 2020).

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Impact of heterogeneous chemistry on the distribution of Glyoxal and Methylglyoxal in the troposphere

10.5194/egusphere-egu21-10780 ◽

2021 ◽

Author(s):

Ramiro Checa-Garcia ◽

Didier Didier Hauglustaine ◽

Yves Balkanski ◽

Paola Formenti

Keyword(s):

Atmospheric Chemistry ◽

Climate Models ◽

Climate Model ◽

Global Climate ◽

Global Climate Model ◽

Experimental Simulation ◽

Heterogeneous Chemistry ◽

Closed Set ◽

Sensitivity Studies ◽

The Tropics

<p>Glyoxal (GL) and methylglyoxal (MGL) are the smallest di-carbonyls present in the atmosphere. They hydrate easily, a process that is followed by an oligomerisation. As a consequence, it is considered that they participate actively in the formation of secondary organic aerosols (SOA) and therefore, they are being introduced in the current climate models with interactive chemistry to assess their importance on atmospheric chemistry. In our study we present the introduction of glyoxal in the INCA global model. A new closed set of gas-phase&#160; reactions is analysed first with a box model. Then the simulated global distribution of glyoxal by the global climate model is compared with satellite observations. We show that the oxidation of volatile organic compounds and acetylene, together with the photolysis of more complex di-carbonyls allows us to reproduce well glyoxal seasonal cycle in the tropics but it requires an additional sink in several northern hemispheric regions. Additional sensitivity studies are being conducted by introducing &#160;GL and MGL interactions with dust and SOA according to new uptake &#160;coefficients obtained by dedicated experiments in the CESAM instrument (Chamber of Experimental Simulation of Atmospheric Multiphases). The effects of these heterogeneous chemistry processes will be quantified in the light of the new chamber measurements &#160;and also evaluated in terms of optical properties of aged dust aerosol &#160;and the changes in direct radiative effects &#160;of the involved aerosol species.</p>

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Reassessment of causes of ozone column variability following the eruption of Mount Pinatubo using a nudged CCM

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-9-5423-2009 ◽

2009 ◽

Vol 9 (2) ◽

pp. 5423-5446 ◽

Cited By ~ 1

Author(s):

P. Telford ◽

P. Braesicke ◽

O. Morgenstern ◽

J. Pyle

Keyword(s):

Total Ozone ◽

Global Scale ◽

Heterogeneous Chemistry ◽

Mount Pinatubo ◽

Complementary Approach ◽

The Tropics ◽

The Impact ◽

Enhanced Surface ◽

Ozone Column ◽

Polar Ozone

Abstract. The eruption of Mount Pinatubo produced the largest loading of stratospheric sulphate aerosol in the twentieth century. This heated the tropical lower stratosphere, affecting stratospheric circulation, and provided enhanced surface area for heterogeneous chemistry. These factors combined to produce record low values of extra-polar total ozone column. Though well studied, there remains some uncertainty about the attribution of this low ozone, with contributions from both chemical and dynamical effects. We take a complementary approach to previous studies, nudging the temperature and horizontal winds in the new UKCA CCM to reproduce the atmospheric response and assess the impact on global total ozone. We then combine model runs and observations to attribute the variability to chemical and dynamical effects. To estimate the effects of increased heterogeneous chemistry we compare runs with volcanically enhanced and background surface aerosol density, noting that this causes depletion of global ozone peaking at about 7 DU in early 1993, in good agreement with observations. We subtract this effect from the observed variability and attribute the remaining variability to dynamical effects. We see that the remaining variability is dominated by the QBO. In addition to global averages we examine tropical and mid-latitude ozone, diagnosing contributions from El Niño in the tropics and some dynamically driven low ozone in northern mid-latitudes, which we see as possible evidence of changes in the QBO. We conclude that, on a global scale, the record lows of extra-polar ozone are produced by the increased heterogeneous chemistry, although there is evidence for dynamics having producing low ozone in certain regions, such as northern mid-latitudes.

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Reassessment of causes of ozone column variability following the eruption of Mount Pinatubo using a nudged CCM

Atmospheric Chemistry and Physics ◽

10.5194/acp-9-4251-2009 ◽

2009 ◽

Vol 9 (13) ◽

pp. 4251-4260 ◽

Cited By ~ 47

Author(s):

P. Telford ◽

P. Braesicke ◽

O. Morgenstern ◽

J. Pyle

Keyword(s):

Total Ozone ◽

Climate Model ◽

Potential Temperature ◽

Global Scale ◽

Heterogeneous Chemistry ◽

Mount Pinatubo ◽

Complementary Approach ◽

The Tropics ◽

The Impact ◽

Ozone Column

Abstract. The eruption of Mount Pinatubo produced the largest loading of stratospheric sulphate aerosol in the twentieth century. This heated the tropical lower stratosphere, affecting stratospheric circulation, and provided enhanced surface area for heterogeneous chemistry. These factors combined to produce record low values of "global" total ozone column. Though well studied, there remains some uncertainty about the attribution of this low ozone, with contributions from both chemical and dynamical effects. We take a complementary approach to previous studies, nudging the potential temperature and horizontal winds in the new UKCA chemistry climate model to reproduce the atmospheric response and assess the impact on global total ozone. We then combine model runs and observations to distinguish between chemical and dynamical effects. To estimate the effects of increased heterogeneous chemistry on ozone we compare runs with volcanically enhanced and background surface aerosol density. The modelled depletion of global ozone peaks at about 7 DU in early 1993, in good agreement with values obtained from observations. We subtract the modelled aerosol induced ozone loss from the observed ozone record and attribute the remaining variability to `dynamical' effects. The remaining variability is dominated by the QBO. We also examine tropical and mid-latitude ozone, diagnosing contributions from El Niño in the tropics and identifying dynamically driven low ozone in northern mid-latitudes, which we interpret as possible evidence of changes in the QBO. We conclude that, on a global scale, the record lows of extra-polar ozone are produced by the increased heterogeneous chemistry, although there is evidence for dynamics produced low ozone in certain regions, including northern mid-latitudes.

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Shipborne lidar measurements showing the progression of the tropical reservoir of volcanic aerosol after the June 1991 Pinatubo eruption

Earth System Science Data ◽

10.5194/essd-12-2843-2020 ◽

2020 ◽

Vol 12 (4) ◽

pp. 2843-2851

Author(s):

Juan-Carlos Antuña-Marrero ◽

Graham W. Mann ◽

Philippe Keckhut ◽

Sergey Avdyushin ◽

Bruno Nardi ◽

...

Keyword(s):

Lower Layer ◽

Extinction Ratio ◽

Stratospheric Aerosol ◽

Aerosol Extinction ◽

Volcanic Aerosol ◽

Tropical Reservoir ◽

Aerosol Cloud ◽

Pinatubo Eruption ◽

The Tropics ◽

Aerosol Backscatter

Abstract. A key limitation of volcanic forcing datasets for the Pinatubo period is the large uncertainty that remains with respect to the extent of the optical depth of the Pinatubo aerosol cloud in the first year after the eruption, the saturation of the SAGE-II instrument restricting it to only be able to measure the upper part of the aerosol cloud in the tropics. Here we report the recovery of stratospheric aerosol measurements from two shipborne lidars, both of which measured the tropical reservoir of volcanic aerosol produced by the June 1991 Mount Pinatubo eruption. The lidars were on board two Soviet vessels, each ship crossing the Atlantic, their measurement datasets providing unique observational transects of the Pinatubo cloud across the tropics from Europe to the Caribbean (∼ 40 to 8∘ N) from July to September 1991 (the Professor Zubov ship) and from Europe to south of the Equator (∼ 40∘ N to 8∘ S) between January and February 1992 (the Professor Vize ship). Our philosophy with the data recovery is to follow the same algorithms and parameters that appear in the two peer-reviewed articles that presented these datasets in the same issue of GRL in 1993, and here we provide all 48 lidar soundings made from the Professor Zubov and 11 of the 20 conducted from the Professor Vize, ensuring we have reproduced the aerosol backscatter and extinction values in the figures of those two papers. These original approaches used thermodynamic properties from the CIRA-86 standard atmosphere to derive the molecular backscattering, vertically and temporally constant values applied for the aerosol backscatter-to-extinction ratio, and the correction factor of the aerosol backscatter wavelength dependence. We demonstrate this initial validation of the recovered stratospheric aerosol extinction profiles, providing full details of each dataset in this paper's Supplement S1, the original profiles of backscatter ratio, and the calculated profiles of aerosol backscatter and extinction. We anticipate these datasets will provide potentially important new observational case studies for modelling analyses, including a 1-week series of consecutive soundings (in September 1991) at the same location showing the progression of the entrainment of part of the Pinatubo plume into the upper troposphere and the formation of an associated cirrus cloud. The Zubov lidar dataset illustrates how the tropically confined Pinatubo aerosol cloud transformed from a highly heterogeneous vertical structure in August 1991, maximum aerosol extinction values around 19 km for the lower layer and 23–24 for the upper layer, to a more homogeneous and deeper reservoir of volcanic aerosol in September 1991. We encourage modelling groups to consider new analyses of the Pinatubo cloud, comparing the recovered datasets, with the potential to increase our understanding of the evolution of the Pinatubo aerosol cloud and its effects. Data described in this work are available at https://doi.org/10.1594/PANGAEA.912770 (Antuña-Marrero et al., 2020).

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Seasonal impact of biogenic VSL bromine on the evolution of mid-latitude lowermost stratospheric ozone during the 21<sup>st</sup> century

10.5194/acp-2019-1091 ◽

2020 ◽

Author(s):

Javer A. Barrera ◽

Rafael P. Fernandez ◽

Fernando Iglesias-Suarez ◽

Carlos A. Cuevas ◽

Jean-Francois Lamarque ◽

...

Keyword(s):

21St Century ◽

Total Ozone ◽

Stratospheric Ozone ◽

Polar Regions ◽

Total Ozone Column ◽

Seasonal Impact ◽

The Tropics ◽

The Impact ◽

Ozone Column ◽

Modelling Study

Abstract. Biogenic very short-lived bromine (VSLBr) represents, nowadays, ~ 25 % of the total stratospheric bromine loading. Owing to their much shorter lifetime compared to anthropogenic long-lived bromine (LLBr, e.g., halons) and chlorine (LLCl, e.g., chlorofluorocarbons) substances, the impact of VSLBr on ozone peaks at the extratropical lowermost stratosphere, a key climatic and radiative atmospheric region. Here we present a modelling study of the evolution of stratospheric ozone and its chemical losses in extra-polar regions during the 21st century, under two different scenarios: considering and neglecting the additional stratospheric injection of 5 ppt biogenic VSLBr naturally released from the ocean. Our analysis shows that the inclusion of VSLBr result in a realistic stratospheric bromine loading and improves the quantitative 1980–2015 model-satellite agreement of total ozone column (TOC) in the mid-latitudes. We show that the overall ozone response to VSLBr within the mid-latitudes follows the stratospheric abundances evolution of long-lived inorganic chlorine and bromine throughout the 21st century. Additional ozone losses due to VSLBr are maximised during the present-day period (1990–2010), with TOC differences of −8 DU (−3 %) and −5.5 DU (−2 %) for the southern (SH-ML) and northern (NH-ML) mid-latitudes, respectively. Moreover, the projected TOC differences at the end of the 21st century are at least half of the values found for the present-day period. In the tropics, a small (

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Impact of different Asian source regions on the composition of the Asian monsoon anticyclone and of the extratropical lowermost stratosphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-13699-2015 ◽

2015 ◽

Vol 15 (23) ◽

pp. 13699-13716 ◽

Cited By ~ 41

Author(s):

B. Vogel ◽

G. Günther ◽

R. Müller ◽

J.-U. Grooß ◽

M. Riese

Keyword(s):

Chemical Composition ◽

Southeast Asia ◽

Asian Monsoon ◽

Monsoon Season ◽

Intraseasonal Variability ◽

Air Masses ◽

Northern India ◽

Source Regions ◽

The Tropics ◽

Emission Tracers

Abstract. The impact of different boundary layer source regions in Asia on the chemical composition of the Asian monsoon anticyclone, considering its intraseasonal variability in 2012, is analysed by simulations of the Chemical Lagrangian Model of the Stratosphere (CLaMS) using artificial emission tracers. The horizontal distribution of simulated CO, O3, and artificial emission tracers for India/China are in good agreement with patterns found in satellite measurements of O3 and CO by the Aura Microwave Limb Sounder (MLS). Using in addition, correlations of artificial emission tracers with potential vorticity demonstrates that the emission tracer for India/China is a very good proxy for spatial distribution of trace gases within the Asian monsoon anticyclone. The Asian monsoon anticyclone constitutes a horizontal transport barrier for emission tracers and is highly variable in location and shape. From the end of June to early August, a northward movement of the anticyclone and, during September, a strong broadening of the spatial distribution of the emission tracer for India/China towards the tropics are found. In addition to the change of the location of the anticyclone, the contribution of different boundary source regions to the composition of the Asian monsoon anticyclone in the upper troposphere strongly depends on its intraseasonal variability and is therefore more complex than hitherto believed. The largest contributions to the composition of the air mass in the anticyclone are found from northern India and Southeast Asia at a potential temperature of 380 K. In the early (mid-June to mid-July) and late (September) period of the 2012 monsoon season, contributions of emissions from Southeast Asia are highest; in the intervening period (early August), emissions from northern India have the largest impact. Our findings show that the temporal variation of the contribution of different convective regions is imprinted in the chemical composition of the Asian monsoon anticyclone. Air masses originating in Southeast Asia are found both within and outside of the Asian monsoon anticyclone because these air masses experience, in addition to transport within the anticyclone, upward transport at the southeastern flank of the anticyclone and in the tropics. Subsequently, isentropic poleward transport of these air masses occurs at around 380 K with the result that the extratropical lowermost stratosphere in the Northern Hemisphere is flooded by the end of September with air masses originating in Southeast Asia. Even after the breakup of the anticyclonic circulation (around the end of September), significant contributions of air masses originating in India/China are still found in the upper troposphere over Asia. Our results demonstrate that emissions from India, China, and Southeast Asia have a significant impact on the chemical composition of the lowermost stratosphere of the Northern Hemisphere, in particular at the end of the monsoon season in September/October 2012.

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The decrease in mid-stratospheric tropical ozone since 1991

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-4215-2015 ◽

2015 ◽

Vol 15 (8) ◽

pp. 4215-4224 ◽

Cited By ~ 11

Author(s):

G. E. Nedoluha ◽

D. E. Siskind ◽

A. Lambert ◽

C. Boone

Keyword(s):

Atmospheric Chemistry ◽

Concomitant Increase ◽

Using Data ◽

The Tropics ◽

Chemistry Experiment ◽

Long Term Variations ◽

Halogen Occultation Experiment

Abstract. While global stratospheric O3 has begun to recover, there are localized regions where O3 has decreased since 1991. Specifically, we use measurements from the Halogen Occultation Experiment (HALOE) for the period 1991–2005 and the NASA Aura Microwave Limb Sounder (MLS) for the period 2004–2013 to demonstrate a significant decrease in O3 near ~ 10 hPa in the tropics. O3 in this region is very sensitive to variations in NOy, and the observed decrease can be understood as a spatially localized, yet long-term increase in NOy. In turn, using data from MLS and from the Atmospheric Chemistry Experiment (ACE), we show that the NOy variations are caused by decreases in N2O which are likely linked to long-term variations in dynamics. To illustrate how variations in dynamics can affect N2O and O3, we show that by decreasing the upwelling in the tropics, more of the N2O can photodissociate with a concomitant increase in NOy production (via N2O + O(1D) → 2NO) at 10 hPa. Ultimately, this can cause an O3 decrease of the observed magnitude.

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Combined effects of boundary layer dynamics and atmospheric chemistry on aerosol composition during new particle formation periods

10.5194/acp-2018-538 ◽

2018 ◽

Author(s):

Liqing Hao ◽

Olga Garmash ◽

Mikael Ehn ◽

Pasi Miettinen ◽

Paola Massoli ◽

...

Keyword(s):

Boundary Layer ◽

Chemical Composition ◽

Atmospheric Chemistry ◽

Mass Fraction ◽

Organic Aerosols ◽

Organic Aerosol ◽

Sulfate Aerosol ◽

Organic Mass ◽

Night Time ◽

Aerosol Mass

Abstract. Characterizing aerosol chemical composition in response to meteorological changes and atmospheric chemistry is important to gain insights into new particle formation mechanisms. A BAECC (Biogenic Aerosols-Effects on Clouds and Climate) campaign was conducted during the spring 2014 at SMEAR II station (Station for Measuring Forest Ecosystem-Aerosol Relations) in Finland. The particles were characterized by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). A PBL (planetary boundary layer) dilution model was developed to assist interpreting the measurement results. Right before nucleation events, the mass concentrations of organic and sulfate aerosol species were both decreased rapidly along with the growth of PBL heights. However, the mass fraction of sulfate aerosol of the total aerosol mass was increased, in contrast to a decrease for the organic mass fraction. Meanwhile, an increase of LVOOA (low-volatility oxygenated organic aerosol) mass fraction of the total organic mass was observed, in distinct comparison to a reduction of SVOOA (semi-volatile OOA) mass fraction. Our results demonstrate that, at the beginning of nucleation events, the observed sulfate aerosol mass was mainly driven by vertical turbulent mixing of sulfate-rich aerosols between the residual layer and the newly formed boundary layer, while the condensation of sulfuric acid played a minor role in interpreting the measured sulfate mass concentration. For the measured organic aerosols, their temporal profiles were mainly driven by dilution from PBL development, organic aerosol mixing in different boundary layers and/or condensation of organic vapors, but accurate measurements of organic vapor concentrations and characterization on the spatial aerosol chemical composition are required. In general, the observed aerosol particles by AMS are subjected to joint effects of PBL dilution, atmospheric chemistry and aerosol mixing in different boundary layers. During aerosol growth periods in the night time, the mass concentrations of organic aerosols and organic nitrate aerosols were both increased. The increase of SVOOA mass correlated well with the calculated increase of condensed HOMs (highly oxygenated organic molecules) mass. To our knowledge, our results are the first atmospheric observations showing a connection between increase in SVOOA and condensed HOMs during the night time.

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