El Niño-Southern Oscillation influence on tropospheric mercury concentrations

The El Nino-Southern Oscillation (ENSO) affects the tropospheric concentrations of many trace gases. Here we investigate the ENSO influence on mercury concentrations measured in the upper troposphere during Civil Aircraft for the Regular Investigation of the atmosphere Based on an instrumented Container flights and at ground at Cape Point, South Africa, and Mace Head, Ireland. Mercury concentrations cross-correlate with Southern Oscillation Index (SOI) with a lag of 8 +/- 2 months. Highest mercury concentrations are always found at the most negative SOI values, i.e., 8 months after El Nino, and the amplitude of the interannual variations fluctuates between similar to 5 and 18%. The time lag is similar to that of CO whose interannual variations are driven largely by emissions from biomass burning (BB). The amplitude of the interannual variability of tropospheric mercury concentrations is consistent with the estimated variations in mercury emissions from BB. We thus conclude that BB is a major factor driving the interannual variation of tropospheric mercury concentrations

Trapping, chemistry, and export of trace gases in the South Asian summer monsoon observed during CARIBIC flights in 2008

The CARIBIC (Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrument Container) passenger aircraft observatory performed in situ measurements at 10–12 km altitude in the South Asian summer monsoon anticyclone between June and September 2008. These measurements enable us to investigate this atmospheric region (which so far has mostly been observed from satellites) using the broad suite of trace gases and aerosol particles measured by CARIBIC. Elevated levels of a variety of atmospheric pollutants (e.g. carbon monoxide, total reactive nitrogen oxides, aerosol particles, and several volatile organic compounds) were recorded. The measurements provide detailed information about the chemical composition of air in different parts of the monsoon anticyclone, particularly of ozone precursors. While covering a range of 3500 km inside the monsoon anticyclone, CARIBIC observations show remarkable consistency, i.e. with distinct latitudinal patterns of trace gases during the entire monsoon period. Using the CARIBIC trace gas and aerosol particle measurements in combination with the Lagrangian particle dispersion model FLEXPART, we investigated the characteristics of monsoon outflow and the chemical evolution of air masses during transport. The trajectory calculations indicate that these air masses originated mainly from South Asia and mainland Southeast Asia. Estimated photochemical ages of the air were found to agree well with transport times from a source region east of 90–95° E. The photochemical ages of the air in the southern part of the monsoon anticyclone were systematically younger (less than 7 days) and the air masses were mostly in an ozone-forming chemical mode. In its northern part the air masses were older (up to 13 days) and had unclear ozone formation or destruction potential. Based on analysis of forward trajectories, several receptor regions were identified. In addition to predominantly westward transport, we found evidence for efficient transport (within 10 days) to the Pacific and North America, particularly during June and September, and also of cross-tropopause exchange, which was strongest during June and July. Westward transport to Africa and further to the Mediterranean was the main pathway during July

Mercury plumes in the global upper troposphere observed during flights with the CARIBIC observatory from May 2005 until June 2013

Tropospheric sections of flights with the CARIBIC (Civil Aircraft for Regular Investigation of the Atmosphere Based on an Instrumented Container) observatory from May 2005 until June 2013, are investigated for the occurrence of plumes with elevated Hg concentrations. Additional information on CO, CO, CH, NO, O, hydrocarbons, halocarbons, acetone and acetonitrile enable us to attribute the plumes to biomass burning, urban/industrial sources or a mixture of both. Altogether, 98 pollution plumes with elevated Hg concentrations and CO mixing ratios were encountered, and the Hg/CO emission ratios for 49 of them could be calculated. Most of the plumes were found overEast Asia, in the African equatorial region, over South America and over Pakistan and India. The plumes encountered over equatorial Africa and over South America originate predominantly from biomass burning, as evidenced by the low Hg/CO emission ratios andelevated mixing ratios of acetonitrile, CHCl and particle concentrations. The backward trajectories point to the regions around the Rift Valley and the Amazon Basin, with its outskirts, as the source areas. The plumes encountered over East Asia and over Pakistan and India are predominantly of urban/industrial origin, sometimes mixed with products of biomass/biofuel burning. Backward trajectories point mostly to source areas in China andnorthern India. The Hg/CO and Hg/CH emission ratios for several plumes are also presented and discussed

Investigation of chlorine radical chemistry in the Eyjafjallajkull volcanic plume using observed depletions in non-methane hydrocarbons

As part of the effort to understand volcanic plume composition and chemistry during the eruption of the Icelandic volcano Eyjafjallajkull, the CARIBIC atmospheric observatory was deployed for three special science flights aboard a Lufthansa passenger aircraft. Measurements made during these flights included the collection of whole air samples, which were analyzed for non-methane hydrocarbons (NMHCs). Hydrocarbon concentrations in plume samples were found to be reduced to levels below background, with relative depletions characteristic of reaction with chlorine radicals (Cl). Recent observations of halogen oxides in volcanic plumes provide evidence for halogen radical chemistry, but quantitative data for free halogen radical concentrations in volcanic plumes were absent. Here we present the first observation-based calculations of Cl radical concentrations in volcanic plumes, estimated from observed NMHC depletions. Inferred Cl concentrations were between 1.3 × 10 and 6.6 × 10 Cl cm. The relationship between NMHC variability and local lifetimes was used to investigate the ratio between OH and Cl within the plume, with [OH]/[Cl] estimated to be ∼37. Copyright 2011 by the American Geophysical Union

EFAS upgrade for the extended model domain

This publication is a Technical report by the Joint Research Centre (JRC), the European Commission’s science and knowledge service. It aims to provide evidence-based scientific support to the European policymaking process. The scientific output expressed does not imply a policy position of the European Commission. Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use that might be made of this publication.JRC.E.1-Disaster Risk Managemen

EFAS upgrade for the extended model domain

This publication is a Technical report by the Joint Research Centre (JRC), the European Commission’s science and knowledge service. It aims to provide evidence-based scientific support to the European policymaking process. The scientific output expressed does not imply a policy position of the European Commission. Neither the European Commission nor any person acting on behalf of the Commission is responsible for the use that might be made of this publication.JRC.E.1-Disaster Risk Managemen

Latest developments for the IAGOS database: Interoperability and metadata

In-service Aircraft for a Global Observing System (IAGOS, http://www.iagos.org) aims at the provision oflong-term, frequent, regular, accurate, and spatially resolved in situ observations of the atmospheric composition.IAGOS observation systems are deployed on a fleet of commercial aircraft. The IAGOS database is an essentialpart of the global atmospheric monitoring network. Data access is handled by open access policy based on thesubmission of research requests which are reviewed by the PIs. Users can access the data through the followingweb sites: http://www.iagos.fr or http://www.pole-ether.fr as the IAGOS database is part of the French atmosphericchemistry data centre ETHER (CNES and CNRS)