Gilles Athier

The YAK-AEROSIB transcontinental aircraft campaigns: new insights on the transport of CO2, CO and O3 across Siberia

Two airborne campaigns were carried out to measure the tropospheric concentrations and variability of CO2, CO and O3 over Siberia. In order to quantify the influence of remote and regional natural and anthropogenic sources, we analysed a total of 52 vertical profiles of these species collected in April and September 2006, every ∼200 km and up to 7 km altitude. CO2 and CO concentrations were high in April 2006 (respectively 385–390 ppm CO2 and 160–200 ppb CO) compared to background values. CO concentrations up to 220 ppb were recorded above 3.5 km over eastern Siberia, with enhancements in 500–1000 m thick layers. The presence of CO enriched air masses resulted from a quick frontal uplift of a polluted air mass exposed to northern China anthropogenic emissions and to fire emissions in northern Mongolia. A dominant Asian origin for CO above 4 km (71.0%) contrasted with a dominant European origin below this altitude (70.9%) was deduced both from a transport model analysis, and from the contrasted ΔCO/ΔCO2 ratio vertical distribution. In September 2006, a significant O3 depletion (∼ –30 ppb) was repeatedly observed in the boundary layer, as diagnosed from virtual potential temperature profiles and CO2 gradients, compared to the free troposphere aloft, suggestive of a strong O3 deposition over Siberian forests.

Instrumentation on commercial aircraft for monitoring the atmospheric composition on a global scale: the IAGOS system, technical overview of ozone and carbon monoxide measurements

This article presents the In-service Aircraft of a Global Observing System (IAGOS) developed for operations on commercial long-range Airbus aircraft (A330/A340) for monitoring the atmospheric composition. IAGOS is the continuation of the former Measurement of OZone and water vapour on Airbus In-service airCraft (MOZAIC) programme (1994–2014) with five aircraft operated by European airlines over 20 yr. MOZAIC has provided unique scientific database used worldwide by the scientific community. In continuation of MOZAIC, IAGOS aims to equip a fleet up to 20 aircraft around the world and for operations over decades. IAGOS started in July 2011 with the first instruments installed aboard a Lufthansa A340-300, and a total of six aircraft are already in operation. We present the technical aircraft system concept, with basic instruments for O3, CO, water vapour and clouds; and optional instruments for measuring either NOy, NOx, aerosols or CO2/CH4. In this article, we focus on the O3 and CO instrumentation while other measurements are or will be described in specific papers. O3 and CO are measured by optimised but well-known methods such as UV absorption and IR correlation, respectively. We describe the data processing/validation and the data quality control for O3 and CO. Using the first two overlapping years of MOZAIC/IAGOS, we conclude that IAGOS can be considered as the continuation of MOZAIC with the same data quality of O3 and CO measurements.

The first regular measurements of ozone, carbon monoxide and water vapour in the Pacific UTLS by IAGOS

We present the features seen in the first 2 months (July and August 2012) of data collected over the Pacific by IAGOS (In-service Aircraft for a Global Observing System)-equipped aircraft. IAGOS is the continuation and development of the well-known MOZAIC (Measurement of Ozone and Water Vapour on Airbus in-service Aircraft) project where scientific instruments were carried on commercially operated A340 aircraft to make measurements of chemical species in the atmosphere. Here, we show data from an aircraft operated by China Airlines on routes from Taipei to Vancouver, which provided the first trans-Pacific measurements by an IAGOS-equipped aircraft. We describe the chemical composition of the extratropical upper troposphere/lower stratosphere (Ex-UTLS) across the Pacific basin in the Northern Hemisphere. The observed concentrations of ozone span a range from 18 to 500 ppbv indicating sources in the marine boundary layer and lowermost stratosphere, respectively. Concentrations of carbon monoxide (CO) greater than 400 ppbv are observed in the Ex-UTLS suggesting that plumes of pollution have been exported from the continent. These low concentrations of ozone and high concentrations of CO were rarely recorded in 8 yr of MOZAIC observations over the Atlantic.

Ozone et pollution atmosphérique à grande échelle: Le réseau de surveillance Paes

Ozone as an environmental concern extends beyond the questions usually covered by the media – stratospheric ozone depletion over the Antartic and urban pollution peaks. Strong exposures to this pollutant are frequent even far from pollution sources, and the background tropospheric content of ozone has been grown fivefold over the last century. In response to this concern at the French national scale, formerly independent monitoring stations have been coordinated since 2004 in a structured network: Paes (French acronym for atmospheric pollution at synoptic scale). The data are put in free access online.

Methodology for Using the MOZAIC Ozone Climatology in Future Comparisons with Data from SCIAMACHY Onboard ENVISAT

The MOZAIC program was designed to collect ozone and water vapour data, using automatic equipment installed on board five long-range Airbus A340 aircraft flying regularly all over the world since August 1994 (Marenco et al. 1998). From ozone data recorded at cruise levels during a 2-year period (September 1994 to August 1996), the first accurate ozone climatology at 9–12 km altitude has been generated (Thouret et al. 1998a). From now on, we are providing different “elaborated” products such as the tropospheric ozone columns and the horizontal climatology with data referred to the tropopause altitude. We have chosen to use the tropopause altitude as the reference to get rid of its seasonal variations. Thus, we have access to the upper tropospheric ozone and to the lower stratospheric ozone distributions. In this first approach, we have chosen only to represent and analyse the measurements recorded at mid northern latitudes. In this study, we defined the tropopause as a mixing zone 30 mb thick centred on the surface PV = 2 PVU. Another set of climatologies is now available for the levels “tropopause ±15 mb” and “tropopause ±45 mb”. In the frame of TROPOSAT, this new set of climatologies demonstrates that we have started a development for future comparisons with the SCIAMACHY instrument, for example. The 8 first years of the MOZAIC program has allowed a first assessment of the inter-annual variability of ozone both in the free troposphere and in the UT/LS to be made. The results are surprisingly high (about 2 %/year). The year 1998 appears as a positive anomaly. Further studies have started to explain such a high increase of ozone in the troposphere and the lower stratosphere at northern mid-latitudes.