Investigating African trace gas sources, vertical transport, and oxidation using IAGOS-CARIBIC measurements between Germany and South Africa between 2009 and 2011
Atmospheric movements
; Biomass
; Boundary layers
; Factorization
; Fighter aircraft
; Fossil fuels
; Gas emissions
; Troposphere
; Africa
; Aircraft observations
; Biomass-burning
; NMHC
; Trace gas emissions
; UTLS
; Gases
; acetylene
; benzene
; biofuel
; butane
; carbon monoxide
; ethane
; fossil fuel
; halocarbon
; hydrocarbon
; methane
; ozone
; propane
; toluene
; water
; biomass burning
; boundary layer
; emission
; fossil fuel
; intertropical convergence zone
; ozone
; photochemistry
; pollutant transport
; savanna
; source apportionment
; Southern Hemisphere
; trace gas
; troposphere
; aerosol
; air
; air pollution
; air sampling
; airborne particle
; altitude
; Article
; background air
; biomass
; biomass burning
; boundary layer
; burn
; compressed air
; controlled study
; dilution
; exhaust gas
; Germany
; limit of detection
; Northern Hemisphere
; oxidation
; photochemistry
; positive matrix factorization
; priority journal
; savanna
; South Africa
; stratosphere
; thermodynamics
; tropical rain forest
; troposphere
; vertical transport
; Africa
; Germany
Scopus学科分类:
Environmental Science: Water Science and Technology
; Earth and Planetary Sciences: Earth-Surface Processes
; Environmental Science: Environmental Chemistry
英文摘要:
Between March 2009 and March 2011 a commercial airliner equipped with a custom built measurement container (IAGOS-CARIBIC observatory) conducted 13 flights between South Africa and Germany at 10–12�km altitude, traversing the African continent north-south. In-situ measurements of trace gases (CO, CH4, H2O) and aerosol particles indicated that strong surface sources (like biomass burning) and rapid vertical transport combine to generate maximum concentrations in the latitudinal range between 10�N and 10�S coincident with the inter-tropical convergence zone (ITCZ). Pressurized air samples collected during these flights were subsequently analyzed for a suite of trace gases including C2-C8 non-methane hydrocarbons (NMHC) and halocarbons. These shorter-lived trace gases, originating from both natural and anthropogenic sources, also showed near equatorial maxima highlighting the effectiveness of convective transport in this region. Two source apportionment methods were used to investigate the specific sources of NMHC: positive matrix factorization (PMF), which is used for the first time for NMHC analysis in the upper troposphere (UT), and enhancement ratios to CO. Using the PMF method three characteristic airmass types were identified based on the different trace gas concentrations they obtained: biomass burning, fossil fuel emissions, and “background” air. The first two sources were defined with reference to previously reported surface source characterizations, while the term “background” was given to air masses in which the concentration ratios approached that of the lifetime ratios. Comparison of enhancement ratios between NMHC and CO for the subset of air samples that had experienced recent contact with the planetary boundary layer (PBL) to literature values showed that the burning of savanna and tropical forest is likely the main source of NMHC in the African upper troposphere (10–12�km). Photochemical aging patterns for the samples with PBL contact revealed that the air had different degradation histories depending on the hemisphere in which they were emitted. In the southern hemisphere (SH) air masses experienced more dilution by clean background air whereas in the northern hemisphere (NH) air masses are less diluted or mixed with background air still containing longer lived NMHC. Using NMHC photochemical clocks ozone production was seen in the BB outflow above Africa in the NH. � 2017 The Authors
Max Planck Institute for Chemistry, Mainz, Germany; School of Environmental Sciences, University of East Anglia, Norwich, United Kingdom; Royal Netherlands Meteorological Institute (KNMI), De Bilt, Netherlands; Leibniz Institute for Tropospheric Research, Leipzig, Germany; now Federal Maritime and Hydrographic Agency, Hamburg, Germany; National Centre for Atmospheric Science, University of East Anglia, Norwich, United Kingdom; Karlsruhe Institute of Technology, Karlsruhe, Germany
Recommended Citation:
Thorenz U,R,, Baker A,et al. Investigating African trace gas sources, vertical transport, and oxidation using IAGOS-CARIBIC measurements between Germany and South Africa between 2009 and 2011[J]. Atmospheric Environment,2017-01-01,158