Adapted ECC ozonesonde for long-duration flights aboard boundary-layer pressurised balloons

Abstract

Abstract. Since the 1970s, the French space agency CNES has developed boundary-layer pressurised balloons (BLPBs) with the capability to transport lightweight scientific payloads at isopycnic level and offer a quasi-Lagrangian sampling of the lower atmosphere over very long distances and durations (up to several weeks).Electrochemical concentration cell (ECC) ozonesondes are widely used under small sounding balloons. However, their autonomy is limited to a few hours owing to power consumption and electrolyte evaporation. An adaptation of the ECC sonde has been developed specifically for long-duration BLPB flights.Compared to conventional ECC sondes, the main feature is the possibility of programming periodic measurement sequences (with possible remote control during the flight). To increase the ozonesonde autonomy, the strategy has been adopted of short measurement sequences (2-3 min) regularly spaced in time (e.g. every 15 min). The rest of the time, the sonde pump is turned off.Results of preliminary ground-based tests are first presented. In particular, the sonde was able to provide correct ozone concentrations against a reference UV-absorption ozone analyser every 15 min for 4 days.Then we illustrate results from 16 BLBP flights launched over the western Mediterranean during three summer field campaigns of the ChArMEx project (http://charmex.lsce.ipsl. fr): TRAQA in 2012, and ADRIMED and SAFMED in 2013. BLPB drifting altitudes were in the range 0.25-3.2 km. The longest flight lasted more than 32 h and covered more than 1000 km. Satisfactory data were obtained when compared to independent ozone measurements close in space and time. The quasi-Lagrangian measurements allowed a first look at ozone diurnal evolution in the marine boundary layer as well as in the lower free troposphere. During some flight segments, there was indication of photochemical ozone production in the marine boundary layer or even in the free troposphere, at rates ranging from 1 to 2 ppbv h −1 , which is slower than previously found in the boundary layer over land in the same region.

O3–NOy photochemistry in boundary layer polluted plumes: insights from the MEGAPOLI (Paris), ChArMEx/SAFMED (North West Mediterranean) and DACCIWA (southern West Africa) aircraft campaigns

“…During SAFMED, the ozone production was also derived from boundary-layer pressurized balloon (BLPB) pseudo-Lagrangian flights over the WMB. 139 The reported range of 1 to 2 ppb h −1 is within the variability of the calculated PSS RO x of 6.1 ± 4.4 ppb h −1 . This production remains by far lower than the estimation of 60 to 80 ppb h −1 made by Coll et al 122 a decade ago downwind the urban area of Marseille and, consequently, closer to gaseous precursor sources.…”

“…During SAFMED, the ozone production was also derived from boundary-layer pressurized balloon (BLPB) pseudo-Lagrangian ights over the WMB. 139 The reported range of 1 to 2 ppb h À1 is within the variability of the calculated PSS RO x of 6.1 AE 4. ights 27 and 33 in favor of a rather NO x -sensitive regime.…”

In situ measurements of desert dust particles above the western Mediterranean Sea with the balloon-borne Light Optical Aerosol Counter/sizer (LOAC) during the ChArMEx campaign of summer 2013

“…The BLPB, after its ascending phase, follows a nearLagrangian trajectory, remaining in the same air mass during its trajectory in the lower atmosphere (Ethé et al, 2002;Gheusi et al, 2016;Doerenbecher et al, 2016). Its float altitude was prescribed before the flight (in the 400-3500 m range) by adjusting the balloon density with the appropriate mixture of air and helium.…”

In situ measurements of desert dust particles above the western Mediterranean Sea with the balloon-borne Light Optical Aerosol Counter/sizer (LOAC) during the ChArMEx campaign of summer 2013

“…The BLPB, after its ascending phase, follows a near-Lagrangian trajectory, remaining in the 155 same air mass during its trajectory in the lower atmosphere (Ethé et al 2002;Gheusi et al, 2016;156 Doerenbecher et al, 2016). Its float altitude was prescribed before the flight (in the 400-3500 m 157 range) by adjusting the balloon density with the appropriate mixture of air and helium.…”

“…Within the project, a 89 large regional field campaign was performed from mid-June to early August 2013 with intensive 90 airborne measurements including in situ balloon-borne aerosol (Mallet et al, 2016) and ozone 91 (Gheusi et al, 2016) from mid-June to early July, the focus was on aerosol-radiation measurements and their modelling 95 (Mallet et al, 2016). During the second SOP entitled Secondary Aerosol Formation in the 96…”