Aircraft based four-channel thermal dissociation laser induced fluorescence instrument for simultaneous measurements of NO2, total peroxy nitrate, total alkyl nitrate, and HNO3

A four-channel thermal dissociation laser induced fluorescence (TD-LIF) instrument has been developed for simultaneous measurements of nitrogen dioxide (NO2), total peroxy nitrate (∑PNs), total alkyl nitrate (∑ANs) and nitric acid (HNO3). NO2 is measured directly by LIF at 532 nm, whereas organic nitrates and nitric acid are thermally dissociated at distinct temperatures in the inlet to form NO2, which is then measured by LIF. The concentrations of each dissociated species are derived by the differences in measured NO2 relative to the reference colder inlet channel. The TD-LIF was adapted to fly on board the UK Facility for Airborne Atmospheric Measurements (FAAM) BAe 146-301 atmospheric research aircraft in summer 2010, and to date has successfully flown in five field campaigns. This paper reports novel improvements in the TD-LIF instrumentations, including (1) the use of a single wavelength laser, which makes the system compact and relatively cheap; (2) the use of a single beam laser that allows easy alignment and optical stability against the vibrational aircraft environment; and (3) the optical assembly of four detection cells that allow simultaneous and fast (time resolution up to 0.1 s) measurements of NO2, ∑PNs, ∑ANs and HNO3. Laboratory-generated mixtures of PNs, ANs and HNO3 in zero air are converted into NO2 and used to fix the dissociation temperatures of each heated inlet to test the selectivity of the instrument and potential interferences due to recombination reactions of the dissociated products. The effectiveness of the TD-LIF was demonstrated during the RONOCO aircraft campaign (summer 2010). A chemiluminescence system that was measuring NO2 and a broadband cavity enhanced absorption spectrometer (BBCEAS) that was measuring one of the PNs (N2O5) were installed on the same aircraft during the campaign. The in-flight intercomparison of the new TD-LIF with the chemiluminescence system for NO2 measurements and the intercomparison between ∑PNs measured by the TD-LIF and N2O5 by the BBCEAS are used to assess the performance of the TD-LIF

Production of peroxy nitrates in boreal biomass burning plumes over Canada during the BORTAS campaign

The observations collected during the BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellites (BORTAS) campaign in summer 2011 over Canada are analysed to study the impact of forest fire emissions on the formation of ozone (O₃) and total peroxy nitrates ∑PNs, ∑ROONO₂). The suite of measurements on board the BAe-146 aircraft, deployed in this campaign, allows us to calculate the production of O₃ and of  ∑PNs, a long-lived NO_<i>x</i> reservoir whose concentration is supposed to be impacted by biomass burning emissions. In fire plumes, profiles of carbon monoxide (CO), which is a well-established tracer of pyrogenic emission, show concentration enhancements that are in strong correspondence with a significant increase of concentrations of ∑PNs, whereas minimal increase of the concentrations of O₃ and NO₂ is observed. The ∑PN and O₃ productions have been calculated using the rate constants of the first- and second-order reactions of volatile organic compound (VOC) oxidation. The ∑PN and O₃ productions have also been quantified by 0-D model simulation based on the Master Chemical Mechanism. Both methods show that in fire plumes the average production of ∑PNs and O₃ are greater than in the background plumes, but the increase of ∑PN production is more pronounced than the O₃ production. The average ∑PN production in fire plumes is from 7 to 12 times greater than in the background, whereas the average O₃ production in fire plumes is from 2 to 5 times greater than in the background. These results suggest that, at least for boreal forest fires and for the measurements recorded during the BORTAS campaign, fire emissions impact both the oxidized NO_<i>y</i> and O_3, but (1 ∑PN production is amplified significantly more than O₃ production and (2) in the forest fire plumes the ratio between the O₃ production and the ∑PN production is lower than the ratio evaluated in the background air masses, thus confirming that the role played by the ∑PNs produced during biomass burning is significant in the O₃ budget. The implication of these observations is that fire emissions in some cases, for example boreal forest fires and in the conditions reported here, may influence more long-lived precursors of O₃ than short-lived pollutants, which in turn can be transported and eventually diluted in a wide area

Impact of Biomass Burning emission on total peroxy nitrates: fire plume identification during the BORTAS campaign

Total peroxy nitrate (Sigma PN) concentrations have been measured using a thermal dissociation laser-induced fluorescence (TD-LIF) instrument during the BORTAS campaign, which focused on the impact of boreal biomass burning (BB) emissions on air quality in the Northern Hemisphere. The strong correlation observed between the Sigma PN concentrations and those of carbon monoxide (CO), a well-known pyrogenic tracer, suggests the possible use of the Sigma PN concentrations as marker of the BB plumes. Two methods for the identification of BB plumes have been applied: (1) Sigma PN concentrations higher than 6 times the standard deviation above the background and (2) Sigma PN concentrations higher than the 99th percentile of the Sigma PNs measured during a background flight (B625); then we compared the percentage of BB plume selected using these methods with the percentage evaluated, applying the approaches usually used in literature. Moreover, adding the pressure threshold (similar to 750 hPa) as ancillary parameter to Sigma PNs, hydrogen cyanide (HCN) and CO, the BB plume identification is improved. A recurrent artificial neural network (ANN) model was adapted to simulate the concentrations of Sigma PNs and HCN, including nitrogen oxide (NO), acetonitrile (CH3CN), CO, ozone (O-3) and atmospheric pressure as input parameters, to verify the specific role of these input data to better identify BB plumes

Il portale GeoNetwork di SHARE. Un catalogo condiviso di metadati a servizio delle ricerche in alta montagna.

The need to share information and data in science finds a ready answer in new technology in the development of Internet access services structured according to standards that guarantee the accessibility to the scientific community. In this context it is being realized at the Ev-K2-CNR Commitee a platform for web services based on the architecture of GeoNetwork Opensource for the realization of the data and metadata catalog dedicated to the high altitude research. This activity is one of the themes of scientific and technological research project SHARE (Stations at High Altitude for Research on the Environment). The first phase of the project was dedicated to the completion of the cataloging system of climate observatories and weather stations in high mountain regions included in the SHARE program that acquire the data, some of which are transmitting from the highest peaks in the world, and available in real time for the SHARE researchers and the scientific community