In situ measurements of heterogeneous reactions on ambient aerosol particles: Impacts on atmospheric chemistry and climate

2018 ◽  
Author(s):  
Timothy Hugh Bertram
Keyword(s):  
Atmospheric Chemistry ◽  
Aerosol Particles ◽  
In Situ Measurements ◽  
Heterogeneous Reactions ◽  
Ambient Aerosol

scholarly journals Observationally constrained analysis of sea salt aerosol in the marine atmosphere

2019 ◽  
Author(s):  
Huisheng Bian ◽  
Karl Froyd ◽  
Daniel M. Murphy ◽  
Jack Dibb ◽  
Mian Chin ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Atmospheric Chemistry ◽  
Marine Boundary Layer ◽  
Model Simulation ◽  
In Situ Measurements ◽  
Sea Salt ◽  
Boreal Summer ◽  
Integrated Analysis ◽  
Marine Atmosphere

Abstract. Atmospheric sea salt plays important roles in marine cloud formation and atmospheric chemistry. We performed an integrated analysis of NASA GEOS model simulations run with the GOCART aerosol module, in situ measurements from the PALMS and SAGA instruments obtained during the NASA ATom campaign, and aerosol optical depth (AOD) measurements from AERONET Marine Aerosol Network (MAN) sun photometers and from MODIS satellite observations to better constrain sea salt in the marine atmosphere. ATom measurements and GEOS model simulation both show that sea salt concentrations over the Pacific and Atlantic oceans have a strong vertical gradient, varying up to four orders of magnitude from the marine boundary layer to free troposphere. The modeled residence times suggest that the lifetime of sea salt particles with dry diameter less than 3 μm is largely controlled by wet removal, followed next by turbulent process. During both boreal summer and winter, the GEOS simulated sea salt mass mixing ratios agree with SAGA measurements in the marine boundary layer (MBL) and with PALMS measurements above the MBL. However, comparison of AOD from GEOS with AERONET/MAN and MODIS aerosol retrievals indicated that the model underestimated AOD over the oceans where sea salt dominates. The apparent discrepancy of slightly overpredicted concentration and large underpredicted AOD could not be explained by biases in the model RH, which was found to be comparable to or larger than the in-situ measurements. This conundrum is at least partially explained by the sea salt size distribution; where the GEOS simulation has much less sea salt percentage-wise in the smaller particles than was observed by PALMS. Model sensitivity experiments indicated that the simulated sea salt is better correlated with measurements when the sea salt emission is calculated based on the friction velocity and with consideration of sea surface temperature dependence than that parameterized with the 10-m winds.

scholarly journals Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at Cabauw

2010 ◽  
Vol 10 (12) ◽  
pp. 29683-29734 ◽  
Author(s):  
P. Zieger ◽  
E. Weingartner ◽  
J. Henzing ◽  
M. Moerman ◽  
G. de Leeuw ◽  
...  
Keyword(s):  
Optical Properties ◽  
Extinction Coefficient ◽  
In Situ Measurements ◽  
Optical Absorption Spectroscopy ◽  
Aerosol Composition ◽  
Large Variability ◽  
Extinction Coefficients ◽  
Ambient Aerosol ◽  
Wide Range

Abstract. In the field, aerosol in-situ measurements are often performed under dry conditions (relative humidity RH<30–40%). Since ambient aerosol particles experience hygroscopic growth at enhanced RH, also their microphysical and optical properties – especially the aerosol light scattering – are strongly dependent on RH. The knowledge of this RH effect is of crucial importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. Here, we will present results from a four-month campaign which took place in summer 2009 in Cabauw, The Netherlands. The aerosol scattering coefficient σsp(λ) was measured dry and at various, predefined RH conditions between 20 and 95% with a humidified nephelometer. The scattering enhancement factor f(RH,λ) is the key parameter to describe the effect of RH on σsp(λ) and is defined as σsp(RH,λ) measured at a certain RH divided by the dry σsp(dry,λ). The measurement of f(RH,λ) together with the dry absorption measurement (assumed not to change with RH) allows the determination of the actual extinction coefficient σep(RH,λ) at ambient RH. In addition, a wide range of other aerosol properties were measured in parallel. The measurements were used to characterize the effects of RH on the aerosol optical properties. A closure study showed the consistency of the aerosol in-situ measurements. Due to the large variability of air mass origin (and thus aerosol composition) a simple parameterization of f(RH,λ) could not be established. If f(RH,λ) needs to be predicted, the chemical composition and size distribution needs to be known. Measurements of four MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments were used to retrieve vertical profiles of σep(λ). The values of the lowest layer were compared to the in-situ values after conversion of the latter to ambient RH. The comparison showed a good correlation of R2=0.62–0.78, but the extinction coefficients were a factor of 1.5–3.4 larger than the in-situ values. Best agreement is achieved for a few cases characterized by low aerosol optical depths and low planetary boundary layer heights. Differences showed to be dependent on the applied MAX-DOAS retrieval algorithm. The comparison of the in-situ data to a Raman lidar (light detection and ranging) showed a good correlation and higher values measured by the lidar (R2=0.79, slope of 1.81) if the Raman retrieved profile was used to extrapolate the directly measured extinction coefficient to the ground. The comparison improved if only nighttime measurements were used in the comparison (R2=0.93, slope of 1.19).

White-light optical particle spectrometer for in situ measurements of condensational growth of aerosol particles

2005 ◽  
Vol 44 (22) ◽  
pp. 4693 ◽  
Author(s):  
Alexei Kiselev ◽  
Heike Wex ◽  
Frank Stratmann ◽  
Alexandre Nadeev ◽  
Dmitry Karpushenko
Keyword(s):  
White Light ◽  
Aerosol Particles ◽  
In Situ Measurements ◽  
Condensational Growth

scholarly journals Ground-based FTIR retrievals of SF<sub>6</sub> on Reunion Island

2018 ◽  
Vol 11 (2) ◽  
pp. 651-662 ◽  
Author(s):  
Minqiang Zhou ◽  
Bavo Langerock ◽  
Corinne Vigouroux ◽  
Pucai Wang ◽  
Christian Hermans ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Atmospheric Chemistry ◽  
Michelson Interferometer ◽  
In Situ Measurements ◽  
Annual Growth Rate ◽  
Reunion Island ◽  
Individual Layer ◽  
Infrared Measurements ◽  
Réunion Island

Abstract. SF6 total columns were successfully retrieved from FTIR (Fourier transform infrared) measurements (Saint Denis and Maïdo) on Reunion Island (21∘ S, 55∘ E) between 2004 and 2016 using the SFIT4 algorithm: the retrieval strategy and the error budget were presented. The FTIR SF6 retrieval has independent information in only one individual layer, covering the whole of the troposphere and the lower stratosphere. The trend in SF6 was analysed based on the FTIR-retrieved dry-air column-averaged mole fractions (XSF6) on Reunion Island, the in situ measurements at America Samoa (SMO) and the collocated satellite measurements (Michelson Interferometer for Passive Atmospheric Sounding, MIPAS, and Atmospheric Chemistry Experiment Fourier Transform Spectrometer, ACE-FTS) in the southern tropics. The SF6 annual growth rate from FTIR retrievals is 0.265±0.013 pptv year−1 for 2004–2016, which is slightly weaker than that from the SMO in situ measurements (0.285±0.002 pptv year−1) for the same time period. The SF6 trend in the troposphere from MIPAS and ACE-FTS observations is also close to the ones from the FTIR retrievals and the SMO in situ measurements.

scholarly journals Supplementary material to "Ambient aerosol properties in the remote atmosphere from global-scale in-situ measurements"

2021 ◽  
Author(s):  
Charles A. Brock ◽  
Karl D. Froyd ◽  
Maximilian Dollner ◽  
Christina J. Williamson ◽  
Gregory Schill ◽  
...  
Keyword(s):  
Global Scale ◽  
In Situ Measurements ◽  
Ambient Aerosol ◽  
Supplementary Material ◽  
Aerosol Properties

scholarly journals High number concentrations of transparent exopolymer particles (TEP) in ambient aerosol particles and cloud water – A case study at the tropical Atlantic Ocean

2021 ◽  
Author(s):  
Manuela van Pinxteren ◽  
Tiera-Brandy Robinson ◽  
Sebastian Zeppenfeld ◽  
Xianda Gong ◽  
Enno Bahlmann ◽  
...  
Keyword(s):  
Atlantic Ocean ◽  
Water Samples ◽  
Sea Water ◽  
Aerosol Particles ◽  
Cloud Water ◽  
Tropical Atlantic ◽  
Ambient Aerosol ◽  
Bubble Bursting ◽  
In Situ Formation

Abstract. Transparent exopolymer particles (TEP) exhibit the properties of gels and are ubiquitously found in the world oceans. Possibly, TEP may enter the atmosphere as part of sea spray aerosol. Here, we report number concentrations of TEP (diameter > 4.5 µm) in ambient aerosol and cloud water samples from the tropical Atlantic Ocean as well as in generated aerosol particles using a plunging waterfall tank that was filled with the ambient sea water. The ambient TEP concentrations ranged between 7 × 102 and 3 × 104 #TEP m−3 in supermicron aerosol particles and correlations to sodium (Na+) and calcium (Ca2+) (R2 = 0.5) suggested some contribution via bubble bursting. Cloud water TEP concentrations were between 4 × 106 and 9 × 106 #TEP L−1 corresponding to equivalent air concentrations of 2–4 × 103 #TEP m−3. The TEP concentrations in the tank-generated aerosol particles, produced from the same waters and sampled with an equivalent system, were significantly lower (4 × 102–2 × 103 #TEP m−3) compared to the ambient concentrations. Based on Na+ concentrations in seawater and in the atmosphere, the enrichment factor for TEP in the atmosphere was calculated. The tank-generated TEP were enriched by a factor of 50 compared to sea water and, therefore, in-line with published enrichment factors for supermicron organic matter in general and TEP specifically. TEP enrichment in the ambient atmosphere was on average 1 × 103 in cloud water and 9 × 103 in ambient aerosol particles and therefore about two orders of magnitude higher than the corresponding enrichment from the tank study. Such high enrichment of supermicron particulate organic constituents in the atmosphere is uncommon and we propose that atmospheric TEP concentrations resulted from a combination of enrichment during bubble bursting transfer from the ocean and TEP in-situ formation in atmospheric phases. Abiotic in-situ formation might have occurred from aqueous reactions of dissolved organic precursors that were present in particle and cloud water samples, while biotic formation involves bacteria, which were abundant in the cloud water samples. The ambient TEP number concentrations were two orders of magnitude higher than recently reported ice nucleating particle (INP) concentrations measured at the same location. As TEP likely possess good properties to act as INP, in future experiments it is worth studying if a certain part of TEP contributes a fraction of the biogenic INP population.

scholarly journals A novel method for calculating ambient aerosol liquid water contents based on measurements of a humidified nephelometer system

2017 ◽  
Author(s):  
Ye Kuang ◽  
Chunsheng Zhao ◽  
Gang Zhao ◽  
Jiangchuan Tao ◽  
Nan Ma ◽  
...  
Keyword(s):  
Light Scattering ◽  
Real Time ◽  
Liquid Water ◽  
Atmospheric Chemistry ◽  
Aerosol Particles ◽  
Atmospheric Environment ◽  
Real Time Monitoring ◽  
Ambient Aerosol ◽  
Novel Method ◽  
Water Contents

Abstract. Water condensed on ambient aerosol particles plays significant roles in atmospheric environment, atmospheric chemistry and climate. So far, no instruments are available for real-time monitoring of ambient aerosol liquid water contents (ALWC). In this paper, a novel method is proposed to calculate ambient ALWC based on measurements of a three-wavelength humidified nephelometer system. A humidified nephelometer system measures aerosol light scattering coefficients and backscattering coefficients at three wavelengths under dry and different relative humidity (RH) conditions, and therefore provides measurements of light scattering enhancement factor f(RH). The proposed method of calculating ALWC includes two steps. The first step is estimating total volume concentration of ambient aerosol particles in dry state (Va (dry)) with a machine learning method based on measurements of the “dry” nephelometer. The estimated Va (dry) agrees well with the measured Va (dry). The second step is estimating the volume growth factor Vg(RH) of ambient aerosol particles due to water uptake using f(RH) and Ångström exponent. The ALWC is calculated from the estimated Va (dry) and Vg(RH). Uncertainty analysis of the estimated Va (dry) and Vg(RH) is conducted. This research have bridged the gap between f(RH) and Vg(RH). The advantage of this new method is that the ambient ALWC can be obtained using only measurements from a three-wavelength humidified nephelometer system. This method will facilitate the real-time monitoring of the ambient ALWC and help for studying roles of aerosol liquid water in atmospheric chemistry, secondary aerosol formation and climate change.

scholarly journals A novel method for calculating ambient aerosol liquid water content based on measurements of a humidified nephelometer system

2018 ◽  
Vol 11 (5) ◽  
pp. 2967-2982 ◽  
Author(s):  
Ye Kuang ◽  
Chun Sheng Zhao ◽  
Gang Zhao ◽  
Jiang Chuan Tao ◽  
Wanyun Xu ◽  
...  
Keyword(s):  
Light Scattering ◽  
Real Time ◽  
Liquid Water ◽  
Atmospheric Chemistry ◽  
Aerosol Particles ◽  
New Method ◽  
Atmospheric Environment ◽  
Real Time Monitoring ◽  
Ambient Aerosol ◽  
Novel Method

Abstract. Water condensed on ambient aerosol particles plays significant roles in atmospheric environment, atmospheric chemistry and climate. Before now, no instruments were available for real-time monitoring of ambient aerosol liquid water contents (ALWCs). In this paper, a novel method is proposed to calculate ambient ALWC based on measurements of a three-wavelength humidified nephelometer system, which measures aerosol light scattering coefficients and backscattering coefficients at three wavelengths under dry state and different relative humidity (RH) conditions, providing measurements of light scattering enhancement factor f(RH). The proposed ALWC calculation method includes two steps: the first step is the estimation of the dry state total volume concentration of ambient aerosol particles, Va(dry), with a machine learning method called random forest model based on measurements of the “dry” nephelometer. The estimated Va(dry) agrees well with the measured one. The second step is the estimation of the volume growth factor Vg(RH) of ambient aerosol particles due to water uptake, using f(RH) and the Ångström exponent. The ALWC is calculated from the estimated Va(dry) and Vg(RH). To validate the new method, the ambient ALWC calculated from measurements of the humidified nephelometer system during the Gucheng campaign was compared with ambient ALWC calculated from ISORROPIA thermodynamic model using aerosol chemistry data. A good agreement was achieved, with a slope and intercept of 1.14 and −8.6 µm3 cm−3 (r2 = 0.92), respectively. The advantage of this new method is that the ambient ALWC can be obtained solely based on measurements of a three-wavelength humidified nephelometer system, facilitating the real-time monitoring of the ambient ALWC and promoting the study of aerosol liquid water and its role in atmospheric chemistry, secondary aerosol formation and climate change.

scholarly journals Comparison of ambient aerosol extinction coefficients obtained from in-situ, MAX-DOAS and LIDAR measurements at Cabauw

2011 ◽  
Vol 11 (6) ◽  
pp. 2603-2624 ◽  
Author(s):  
P. Zieger ◽  
E. Weingartner ◽  
J. Henzing ◽  
M. Moerman ◽  
G. de Leeuw ◽  
...  
Keyword(s):  
Optical Properties ◽  
Extinction Coefficient ◽  
In Situ Measurements ◽  
Optical Absorption Spectroscopy ◽  
Aerosol Composition ◽  
Large Variability ◽  
Extinction Coefficients ◽  
Ambient Aerosol ◽  
Wide Range

Abstract. In the field, aerosol in-situ measurements are often performed under dry conditions (relative humidity RH<30–40%). Since ambient aerosol particles experience hygroscopic growth at enhanced RH, their microphysical and optical properties – especially the aerosol light scattering – are also strongly dependent on RH. The knowledge of this RH effect is of crucial importance for climate forcing calculations or for the comparison of remote sensing with in-situ measurements. Here, we will present results from a four-month campaign which took place in summer 2009 in Cabauw, The Netherlands. The aerosol scattering coefficient σsp(λ) was measured dry and at various, predefined RH conditions between 20 and 95% with a humidified nephelometer. The scattering enhancement factor f(RH,λ) is the key parameter to describe the effect of RH on σsp(λ) and is defined as σsp(RH,λ) measured at a certain RH divided by the dry σsp(dry,λ). The measurement of f(RH,λ) together with the dry absorption measurement (assumed not to change with RH) allows the determination of the actual extinction coefficient σep(RH,λ) at ambient RH. In addition, a wide range of other aerosol properties were measured in parallel. The measurements were used to characterize the effects of RH on the aerosol optical properties. A closure study showed the consistency of the aerosol in-situ measurements. Due to the large variability of air mass origin (and thus aerosol composition) a simple parameterization of f(RH,λ) could not be established. If f(RH,λ) needs to be predicted, the chemical composition and size distribution need to be known. Measurements of four MAX-DOAS (multi-axis differential optical absorption spectroscopy) instruments were used to retrieve vertical profiles of σep(λ). The values of the lowest layer were compared to the in-situ values after conversion of the latter ones to ambient RH. The comparison showed a good correlation of R2 = 0.62–0.78, but the extinction coefficients from MAX-DOAS were a factor of 1.5–3.4 larger than the in-situ values. Best agreement is achieved for a few cases characterized by low aerosol optical depths and low planetary boundary layer heights. Differences were shown to be dependent on the applied MAX-DOAS retrieval algorithm. The comparison of the in-situ extinction data to a Raman LIDAR (light detection and ranging) showed a good correlation and higher values measured by the LIDAR (R2 = 0.82−0.85, slope of 1.69–1.76) if the Raman retrieved profile was used to extrapolate the directly measured extinction coefficient to the ground. The comparison improved if only nighttime measurements were used in the comparison (R2 = 0.96, slope of 1.12).

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