scholarly journals The effects of deep convection on the concentration and size distribution of aerosol particles within the upper troposphere: A case study

2012 ◽  
Vol 117 (D22) ◽  
pp. n/a-n/a ◽  
Author(s):  
Yan Yin ◽  
Qian Chen ◽  
Lianji Jin ◽  
Baojun Chen ◽  
Shichao Zhu ◽  
...  
Keyword(s):  
Size Distribution ◽  
Deep Convection ◽  
Aerosol Particles ◽  
Upper Troposphere

scholarly journals Cloud-scale modelling of the impact of deep convection on the fate of oceanic bromoform in the troposphere: a case study over the west coast of Borneo

2020 ◽  
Author(s):  
Paul D. Hamer ◽  
Virginie Marécal ◽  
Ryan Hossaini ◽  
Michel Pirre ◽  
Gisèle Krysztofiak ◽  
...  
Keyword(s):  
Boundary Layer ◽  
West Coast ◽  
Deep Convection ◽  
Convective System ◽  
The West ◽  
Upper Troposphere ◽  
Convective Systems ◽  
Mixing Ratios ◽  
The Impact

Abstract. Coastal oceans emit bromoform (CHBr3) that can be transported rapidly to the upper troposphere by deep convection. In the troposphere, the spatial and vertical distribution of CHBr3 and its product gases (PGs) depend on emissions, chemical processing, transport by large scale flow, convection, and associated washout. This paper presents a modelling study on the fate of CHBr3 and its PGs in the troposphere. A case study at cloud scale was conducted along the west coast of Borneo, when several deep convective systems triggered in the afternoon and early evening of November 19th 2011. These systems were sampled by the Falcon aircraft during the field campaign of the SHIVA project. We analyse these systems using a simulation with the cloud-resolving meteorological model C-CATT-BRAMS at 2 × 2 km resolution that describes transport, photochemistry, and washout of CHBr3. We find that simulated CHBr3 mixing ratios and the observed values in the boundary layer and the outflow of the convective systems agree. However, the model underestimates the background CHBr3 mixing ratios in the upper troposphere, which suggests a missing source. An analysis of the simulated chemical speciation of bromine within and around each simulated convective system during the mature convective stage reveals that > 85 % of the bromine derived from CHBr3 and its PGs is transported vertically to the point of convective detrainment in the form of CHBr3 and that the remaining small fraction is in the form of organic PGs, principally insoluble brominated carbonyls produced from the photo-oxidation of CHBr3. The model simulates that within the boundary layer and free troposphere, the inorganic PGs are only present in soluble forms, i.e., HBr, HOBr, and BrONO2, and consequently, within the convective clouds, the inorganic PGs are almost entirely removed by wet scavenging. For the conditions of the simulated case study Br2 plays no significant role in the vertical transport of bromine. This likely results from the small simulated quantities of inorganic bromine involved, the presence of HBr in large excess compared to HOBr and the less soluble BrO, and the relatively quick removal of soluble compounds within the convective column. This prevalence of HBr is a result of the wider simulated regional atmospheric composition whereby background tropospheric ozone levels are exceptionally low.

scholarly journals The influence of deep convection on HCHO and H<sub>2</sub>O<sub>2</sub> in the upper troposphere over Europe

2017 ◽  
Vol 17 (19) ◽  
pp. 11835-11848 ◽  
Author(s):  
Heiko Bozem ◽  
Andrea Pozzer ◽  
Hartwig Harder ◽  
Monica Martinez ◽  
Jonathan Williams ◽  
...  
Keyword(s):  
Large Scale ◽  
Deep Convection ◽  
Trace Gases ◽  
Cloud Droplets ◽  
Data Set ◽  
Transport Efficiency ◽  
Upper Troposphere ◽  
Secondary Formation

Abstract. Deep convection is an efficient mechanism for vertical trace gas transport from Earth's surface to the upper troposphere (UT). The convective redistribution of short-lived trace gases emitted at the surface typically results in a C-shaped profile. This redistribution mechanism can impact photochemical processes, e.g. ozone and radical production in the UT on a large scale due to the generally longer lifetimes of species like formaldehyde (HCHO) and hydrogen peroxide (H2O2), which are important HOx precursors (HOx =  OH + HO2 radicals). Due to the solubility of HCHO and H2O2 their transport may be suppressed as they are efficiently removed by wet deposition. Here we present a case study of deep convection over Germany in the summer of 2007 within the framework of the HOOVER II project. Airborne in situ measurements within the in- and outflow regions of an isolated thunderstorm provide a unique data set to study the influence of deep convection on the transport efficiency of soluble and insoluble trace gases. Comparing the in- and outflow indicates an almost undiluted transport of insoluble trace gases from the boundary layer to the UT. The ratios of out : inflow of CO and CH4 are 0.94 ± 0.04 and 0.99 ± 0.01, respectively. For the soluble species HCHO and H2O2 these ratios are 0.55 ± 0.09 and 0.61 ± 0.08, respectively, indicating partial scavenging and washout. Chemical box model simulations show that post-convection secondary formation of HCHO and H2O2 cannot explain their enhancement in the UT. A plausible explanation, in particular for the enhancement of the highly soluble H2O2, is degassing from cloud droplets during freezing, which reduces the retention coefficient.

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.

scholarly journals The influence of deep convection on HCHO and H<sub>2</sub>O<sub>2</sub> in the upper troposphere over Europe

2017 ◽  
Author(s):  
Heiko Bozem ◽  
Andrea Pozzer ◽  
Hartwig Harder ◽  
Monica Martinez ◽  
Jonathan Williams ◽  
...  
Keyword(s):  
Large Scale ◽  
Deep Convection ◽  
Trace Gases ◽  
Cloud Droplets ◽  
Data Set ◽  
Transport Efficiency ◽  
Upper Troposphere ◽  
Secondary Formation

Abstract. Deep convection is an efficient mechanism for vertical trace gas transport from the Earth's surface to the upper troposphere (UT). The convective redistribution of short-lived trace gases emitted at the surface typically results in a C-shaped profile. This redistribution mechanism can impact photochemical processes, e.g. ozone and radical production in the UT on a large scale due to the generally longer lifetimes of species like formaldehyde (HCHO) and hydrogen peroxide (H2O2), which are important HOx precursors (HOx = OH + HO2 radicals). Due to the solubility of HCHO and H2O2 their transport may be suppressed as they are efficiently removed by wet deposition. Here we present a case study of deep convection over Germany in the summer of 2007 within the framework of the HOOVER II project. Airborne in-situ measurements within the in- and outflow regions of an isolated thunderstorm provide a unique data set to study the influence of deep convection on the transport efficiency of soluble and insoluble trace gases. Comparing the in- and outflow indicates almost undiluted transport of insoluble trace gases from the boundary layer to the UT. The ratios of out/inflow of CO and CH4 are 0.94 ± 0.04 and 0.99 ± 0.01, respectively. For the soluble species HCHO and H2O2 these ratios are 0.55 ± 0.09 and 0.61 ± 0.08, respectively, indicating partial scavenging and washout. Chemical box model simulations show that post-convection secondary formation of HCHO and H2O2 cannot explain their enhancement in the UT. A plausible explanation, in particular for the enhancement of the highly soluble H2O2, is degassing from cloud droplets during freezing, which reduces the retention coefficient.

scholarly journals Implications of GNSS-Inferred Tropopause Altitude Associated with Terrestrial Gamma-Ray Flashes

2021 ◽  
Vol 13 (10) ◽  
pp. 1939
Author(s):  
Tao Xian ◽  
Gaopeng Lu ◽  
Hongbo Zhang ◽  
Yongping Wang ◽  
Shaolin Xiong ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Thermal Structure ◽  
Deep Convection ◽  
Caribbean Sea ◽  
Negative Bias ◽  
Upper Troposphere ◽  
Cold Anomaly ◽  
The Caribbean ◽  
Geographic Distributions

The thermal structure of the environmental atmosphere associated with Terrestrial Gamma-ray Flashes (TGFs) is investigated with the combined observations from several detectors (FERMI, RHESSI, and Insight-HXMT) and GNSS-RO (SAC-C, COSMIC, GRACE, TerraSAR-X, and MetOp-A). The geographic distributions of TGF-related tropopause altitude and climatology are similar. The regional TGF-related tropopause altitude in Africa and the Caribbean Sea is 0.1–0.4 km lower than the climatology, whereas that in Asia is 0.1–0.2 km higher. Most of the TGF-related tropopause altitudes are slightly higher than the climatology, while some of them have a slightly negative bias. The subtropical TGF-producing thunderstorms are warmer in the troposphere and have a colder and higher tropopause over land than the ocean. There is no significant land–ocean difference in the thermal structure for the tropical TGF-producing thunderstorms. The TGF-producing thunderstorms have a cold anomaly in the middle and upper troposphere and have stronger anomalies than the deep convection found in previous studies.

scholarly journals A Case Study of Mass Transport during the East-West Oscillation of the Asian Summer Monsoon Anticyclone

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Jiali Luo ◽  
Jiayao Song ◽  
Hongying Tian ◽  
Lei Liu ◽  
Xinlei Liang
Keyword(s):  
Lower Stratosphere ◽  
Asian Summer Monsoon ◽  
Chemical Transport ◽  
Upward Motion ◽  
High Concentration ◽  
Upper Troposphere ◽  
Asian Summer ◽  
Mode Tm ◽  
East West

We use ERA-Interim reanalysis, MLS observations, and a trajectory model to examine the chemical transport and tracers distribution in the Upper Troposphere and Lower Stratosphere (UTLS) associated with an east-west oscillation case of the anticyclone in 2016. The results show that the spatial distribution of water vapor (H2O) was more consistent with the location of the anticyclone than carbon monoxide (CO) at 100 hPa, and an independent relative high concentration center was only found in H2O field. At 215 hPa, although the anticyclone center also migrated from the Tibetan Mode (TM) to the Iranian Mode (IM), the relative high concentration centers of both tracers were always colocated with regions where upward motion was strong in the UTLS. When the anticyclone migrated from the TM, air within the anticyclone over Tibetan Plateau may transport both westward and eastward but was always within the UTLS. The relative high concentration of tropospheric tracers within the anticyclone in the IM was from the east and transported by the westward propagation of the anticyclone rather than being lifted from surface directly. Air within the relative high geopotential height centers over Western Pacific was partly from the main anticyclone and partly from lower levels.

scholarly journals Where Do Aerosol Particles in the Antarctic Upper Troposphere Come from?

1989 ◽  
Vol 67 (5) ◽  
pp. 889-906 ◽  
Author(s):  
Koji Yamazaki ◽  
Kikuo Okada ◽  
Yasunobu Iwasaka
Keyword(s):  
Aerosol Particles ◽  
Upper Troposphere ◽  
The Antarctic
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