scholarly journals Aerosol characteristics and particle production in the upper troposphere over the Amazon Basin

2017 ◽  
Author(s):  
Meinrat O. Andreae ◽  
Armin Afchine ◽  
Rachel Albrecht ◽  
Bruna Amorim Holanda ◽  
Paulo Artaxo ◽  
...  
Keyword(s):  
Amazon Basin ◽  
Particle Production ◽  
Aerosol Particles ◽  
Convective Transport ◽  
Oxidation Products ◽  
Condensation Nuclei ◽  
Upper Troposphere ◽  
Convective Clouds ◽  
Tropospheric Aerosol ◽  
Deep Convective Clouds

Abstract. Airborne observations over the Amazon Basin showed high aerosol particle concentrations in the upper troposphere (UT) between 8 and 15 km altitude, with number densities (normalized to standard temperature and pressure) often exceeding those in the planetary boundary layer (PBL) by one or two orders of magnitude. The measurements were made during the German-Brazilian cooperative aircraft campaign ACRIDICON-CHUVA on the German High Altitude and Long Range Research Aircraft (HALO). The campaign took place in September/October 2014, with the objective of studying tropical deep convective clouds over the Amazon rainforest and their interactions with atmospheric trace gases, aerosol particles, and atmospheric radiation. Aerosol enhancements were observed consistently on all flights during which the UT was probed, using several aerosol metrics, including condensation nuclei (CN) and cloud condensation nuclei (CCN) number concentrations and chemical species mass concentrations. The UT particles differed in their chemical composition and size distribution from those in the PBL, ruling out convective transport of combustion-derived particles from the BL as a source. The air in the immediate outflow of deep convective clouds was depleted in aerosol particles, whereas strongly enhanced number concentrations of small particles ( 90 nm) particles in the UT, which consisted mostly of organic matter and nitrate and were very effective CCN. Our findings suggest a conceptual model, where production of new aerosol particles takes place in the UT from volatile material brought up by deep convection, which is converted to condensable species in the UT. Subsequently, downward mixing and transport of upper tropospheric aerosol can be a source of particles to the PBL, where they increase in size by the condensation of biogenic volatile organic carbon (BVOC) oxidation products. This may be an important source of aerosol particles in the Amazonian PBL, where aerosol nucleation and new particle formation has not been observed. We propose that this may have been the dominant process supplying secondary aerosol particles in the pristine atmosphere, making clouds the dominant control of both removal and production of atmospheric particles.

scholarly journals Aerosol characteristics and particle production in the upper troposphere over the Amazon Basin

2018 ◽  
Vol 18 (2) ◽  
pp. 921-961 ◽  
Author(s):  
Meinrat O. Andreae ◽  
Armin Afchine ◽  
Rachel Albrecht ◽  
Bruna Amorim Holanda ◽  
Paulo Artaxo ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Amazon Basin ◽  
Deep Convection ◽  
Aerosol Particles ◽  
Condensation Nuclei ◽  
Upper Troposphere ◽  
Convective Clouds ◽  
Tropospheric Aerosol ◽  
Volatile Organic ◽  
Deep Convective Clouds

Abstract. Airborne observations over the Amazon Basin showed high aerosol particle concentrations in the upper troposphere (UT) between 8 and 15 km altitude, with number densities (normalized to standard temperature and pressure) often exceeding those in the planetary boundary layer (PBL) by 1 or 2 orders of magnitude. The measurements were made during the German–Brazilian cooperative aircraft campaign ACRIDICON–CHUVA, where ACRIDICON stands for Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems and CHUVA is the acronym for Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modeling and to the GPM (global precipitation measurement), on the German High Altitude and Long Range Research Aircraft (HALO). The campaign took place in September–October 2014, with the objective of studying tropical deep convective clouds over the Amazon rainforest and their interactions with atmospheric trace gases, aerosol particles, and atmospheric radiation. Aerosol enhancements were observed consistently on all flights during which the UT was probed, using several aerosol metrics, including condensation nuclei (CN) and cloud condensation nuclei (CCN) number concentrations and chemical species mass concentrations. The UT particles differed sharply in their chemical composition and size distribution from those in the PBL, ruling out convective transport of combustion-derived particles from the boundary layer (BL) as a source. The air in the immediate outflow of deep convective clouds was depleted of aerosol particles, whereas strongly enhanced number concentrations of small particles (< 90 nm diameter) were found in UT regions that had experienced outflow from deep convection in the preceding 5–72 h. We also found elevated concentrations of larger (> 90 nm) particles in the UT, which consisted mostly of organic matter and nitrate and were very effective CCN. Our findings suggest a conceptual model, where production of new aerosol particles takes place in the continental UT from biogenic volatile organic material brought up by deep convection and converted to condensable species in the UT. Subsequently, downward mixing and transport of upper tropospheric aerosol can be a source of particles to the PBL, where they increase in size by the condensation of biogenic volatile organic compound (BVOC) oxidation products. This may be an important source of aerosol particles for the Amazonian PBL, where aerosol nucleation and new particle formation have not been observed. We propose that this may have been the dominant process supplying secondary aerosol particles in the pristine atmosphere, making clouds the dominant control of both removal and production of atmospheric particles.

Particle production in the upper troposphere over the Amazon Basin

2020 ◽  
Author(s):  
Lixia Liu ◽  
Hang Su ◽  
Ulrich Pöschl ◽  
Yafang Cheng
Keyword(s):  
Amazon Basin ◽  
Particle Production ◽  
Cloud Condensation Nuclei ◽  
Aerosol Particles ◽  
Particle Formation ◽  
Dry Season ◽  
New Particle Formation ◽  
High Concentration ◽  
Fine Grid ◽  
Upper Troposphere

&lt;p&gt;Particle production in the upper troposphere has been reported as an important source of aerosol particles and cloud condensation nuclei in pristine environment and tropical regions and exerts significant climate effects. In this work, we develop a new organic nucleation scheme to the WRF-Chem model with extended particle size bins from 1nm to 10&amp;#956;m. We improve on previous coarse-resolution global simulations that approximate the highly oxygenated multifunctional organic compounds (HOMs) in a thermodynamic state by implementing kinetic calculation of HOMs and using fine-grid regional simulations. Sensitivity studies are conducted over the Amazon Basin during the dry season in 2014 to characterize the HOMs-induced new particle formation and identify its key controlling factors in Amazon. The model simulations are evaluated using aircraft observations of profiles of aerosol particles during the 2014 ACRIDICON-CHUVA campaign. We show that the new particle formation occurs mostly at the upper troposphere and modestly in the planetary boundary layer, driven by low temperature and high concentration of biogenic precursors, respectively. Including the HOMs-induced biogenic new particle formation mechanism decreases the model prediction bias of the particle number concentration in the upper troposphere by over 50%, suggesting an important role of the HOMs-induced biogenic new particle formation in the dry season over the Amazon region.&lt;/p&gt;

scholarly journals Ozone mixing ratios inside tropical deep convective clouds from OMI satellite measurements

2008 ◽  
Vol 8 (4) ◽  
pp. 16381-16407
Author(s):  
J. R. Ziemke ◽  
J. Joiner ◽  
S. Chandra ◽  
P. K. Bhartia ◽  
A. Vasilkov ◽  
...  
Keyword(s):  
Radar Data ◽  
Mixing Ratio ◽  
Ozone Monitoring Instrument ◽  
Upper Troposphere ◽  
Mixing Ratios ◽  
Convective Clouds ◽  
Deep Convective Clouds ◽  
A New Technique ◽  
Oceanic Boundary Layer ◽  
Column Ozone

Abstract. We have developed a new technique for estimating ozone mixing ratio inside deep convective clouds. The technique uses the concept of an optical centroid cloud pressure that is indicative of the photon path inside clouds. Radiative transfer calculations based on realistic cloud vertical structure as provided by CloudSat radar data show that because deep convective clouds are optically thin near the top, photons can penetrate significantly inside the cloud. This photon penetration coupled with in-cloud scattering produces optical centroid pressures that are hundreds of hPa inside the cloud. We use the measured column ozone and the optical centroid cloud pressure derived using the effects of rotational-Raman scattering to estimate O3 mixing ratio in the upper regions of deep convective clouds. The data are obtained from the Ozone Monitoring Instrument (OMI) aboard NASA's Aura satellite. Our results show that low O3 concentrations in these clouds are a common occurrence throughout much of the tropical Pacific. Ozonesonde measurements in the tropics following convective activity also show very low concentrations of O3 in the upper troposphere. These low amounts are attributed to vertical injection of ozone poor oceanic boundary layer air during convection into the upper troposphere followed by convective outflow. Over South America and Africa, O3 mixing ratio inside deep convective clouds often exceeds 50 ppbv which is comparable to mean background (cloud-free) concentrations. These areas contain higher amounts of ozone precursors due to biomass burning and lightning. Assuming that O3 is well mixed (i.e. constant mixing ratio with height) up to the tropopause, we can estimate the stratospheric column O3 over clouds. Stratospheric column ozone derived in this manner agrees well with that retrieved independently with the Aura Microwave Limb Sounder (MLS) instrument and thus provides a consistency check of our method.

scholarly journals Measurements of CH<sub>3</sub>O<sub>2</sub>NO<sub>2</sub> in the upper troposphere

2014 ◽  
Vol 7 (9) ◽  
pp. 9453-9479
Author(s):  
B. A. Nault ◽  
C. Garland ◽  
S. E. Pusede ◽  
P. J. Wooldridge ◽  
K. Ullmann ◽  
...  
Keyword(s):  
Detection Limit ◽  
Low Temperatures ◽  
Theoretical Calculations ◽  
Thermal Dissociation ◽  
Atmospheric Composition ◽  
Upper Troposphere ◽  
Convective Clouds ◽  
Peroxy Nitrates ◽  
Deep Convective Clouds ◽  
Pernitric Acid

Abstract. The non-acyl peroxy nitrates, HO2NO2 and CH3O2NO2, are predicted to be important for photochemistry at low temperatures characteristic of the upper troposphere. We report the first measurements of methyl peroxy nitrate (CH3O2NO2). During the Deep Convective Clouds and Chemistry (DC-3) and the Studies of Emissions and Atmospheric Composition, Clouds, and Climate Coupling by Regional Surveys (SEAC4RS) experiments, different inlet configurations for the UC Berkeley Thermal Dissociation-Laser Induced Instrument were tested to optimize measurements of CH3O2NO2 from the NASA DC-8. In addition, the inlet modifications were optimized for measurements of NO2 without CH3O2NO2 interferences. The CH3O2NO2 measurements we report have a detection limit (S/N = 2) of 15 pptv (parts per trillion by volume) at 1 min averaging on a background of 200 pptv NO2 and an accuracy of ±40%. Both observations and theoretical calculations were used to constrain the interference of pernitric acid (HO2NO2), which partially decomposes (~ 11%) along with CH3O2NO2 in our heated CH3O2NO2 channel. Evaluation of the accuracy of the CH3O2NO2 measurements is presented.

scholarly journals Supplementary material to "Aerosol characteristics and particle production in the upper troposphere over the Amazon Basin"

2017 ◽  
Author(s):  
Meinrat O. Andreae ◽  
Armin Afchine ◽  
Rachel Albrecht ◽  
Bruna Amorim Holanda ◽  
Paulo Artaxo ◽  
...  
Keyword(s):  
Amazon Basin ◽  
Particle Production ◽  
Upper Troposphere ◽  
Supplementary Material

New MESSy scavenging subroutine to treat aerosol particles gas-phase partitioning in convective clouds

2021 ◽  
Author(s):  
Giorgio Taverna ◽  
Marc Barra ◽  
Holger Tost
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Aerosol Particles ◽  
Phase Partitioning ◽  
Convective Clouds ◽  
Terrestrial Atmosphere ◽  
Deep Convective Clouds ◽  
High Level

&lt;p&gt;The Modular Earth Submodel System (MESSy) has been proven to be successful in the understanding of several processes which characterize the terrestrial atmosphere and climate.&lt;/p&gt;&lt;p&gt;However, the complexity of aerosol particles/gas phase partitioning of species in deep convective clouds together with the inherent problems of modelling sub-grid scale processes, make MESSy results significant underestimated, especially in case of SO&lt;sub&gt;2&lt;/sub&gt;, when compared with available flight observations. For this reason, the subroutine which reproduce the scavenging of these species has been updated to include a more realistic treatment of liquid/phase partitioning of aerosol induced species in high level clouds.&lt;/p&gt;&lt;p&gt;Results obtained are shown in this poster.&lt;/p&gt;

scholarly journals Transport and chemistry of isoprene and its oxidation products in deep convective clouds

Tellus B ◽  
2021 ◽  
Vol 73 (1) ◽  
pp. 1-21
Author(s):  
Roman Bardakov ◽  
Joel A. Thornton ◽  
Ilona Riipinen ◽  
Radovan Krejci ◽  
Annica M. L. Ekman
Keyword(s):  
Oxidation Products ◽  
Convective Clouds ◽  
Deep Convective Clouds
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