On instrumental errors and related correction strategies of ozonesondes: possible effect on calculated ozone trends for the nearby sites Uccle and De Bilt

Abstract

Abstract. The ozonesonde stations at Uccle (Belgium) and De Bilt (the Netherlands) are separated by only 175 km but use different ozonesonde types (or different manufacturers for the same electrochemical concentration cell (ECC) type), operating procedures, and correction strategies. As such, these stations form a unique test bed for the Ozonesonde Data Quality Assessment (O3S-DQA) activity, which aims at providing a revised, homogeneous, consistent dataset with an altitude-dependent estimated uncertainty for each revised profile. For the ECC ozonesondes at Uccle mean relative uncertainties in the 4-6 % range are obtained. To study the impact of the corrections on the ozone profiles and trends, we compared the Uccle and De Bilt average ozone profiles and vertical ozone trends, calculated from the operational corrections at both stations and the O3S-DQA corrected profiles.In the common ECC 1997-2014 period, the O3S-DQA corrections effectively reduce the differences between the Uccle and De Bilt ozone partial pressure values with respect to the operational corrections only for the stratospheric layers below the ozone maximum. The upper-stratospheric ozone measurements at both sites are substantially different, regardless of the correction methodology used. The origin of this difference is not clear. The discrepancies in the tropospheric ozone concentrations between both sites can be ascribed to the problematic background measurement and correction at De Bilt, especially in the period before November 1998. The Uccle operational correction method, applicable to both ozonesonde types used, diminishes the relative stratospheric ozone differences of the Brewer-Mast sondes in the 1993-1996 period with De Bilt to less than 5 % and to less than 6 % in the free troposphere for the De Bilt operational corrections.Despite their large impact on the average ozone profiles, the different (sensible) correction strategies do not change the ozone trends significantly, usually only within their statistical uncertainty due to atmospheric noise. The O3S-DQA corrections bring the Uccle and De Bilt ozone trend estimates for 1997-2014 closer to each other in the lower stratosphere and lower troposphere. Throughout the whole vertical profile, these trend estimates are, however, not significantly different from each other, and only in the troposphere significantly positive. For the entire Uccle observation period , the operational corrections lead to height-independent and consistent ozone trends for both the troposphere and the stratosphere, with rates of + 2 to +3 % decade −1 and −1 to −2 % decade −1 , respectively.

First Reprocessing of Southern Hemisphere ADditional OZonesondes Profile Records: 3. Uncertainty in Ozone Profile and Total Column

“…Van Malderen et al (2016) applied corrections to the Uccle data set for high-SO 2 interference in the Brewer-Mast ozonesondes using in situ SO 2 measurements from a nearby site. No corrections were necessary during the ECC sonde era (1996 to present) because SO 2 concentrations had diminished to levels that would not impact the ECC measurements.…”

“…Results are plotted in sequence, accounting for the uneven spacing of the years on the x axis. 2015;Smit & ASOPOS, 2014;Sterling et al, 2017;Tarasick et al, 2016;Van Malderen et al, 2016).…”

First Reprocessing of Southern Hemisphere Additional Ozonesondes (SHADOZ) Ozone Profiles (1998–2016): 2. Comparisons With Satellites and Ground‐Based Instruments

“…At present six to eight providers of ozonesonde data, representing~30 stations globally, have adopted the guidelines. Papers describing the reprocessing of Canadian network data (Tarasick et al, 2016) and two European records (van Malderen et al, 2016) have appeared. In the past 2 years we have been reprocessing the SHADOZ profiles for 14 stations that have records of at least 10 years within the period 1998-2016.…”

The NASA Wallops Flight Facility Digital Ozonesonde Record: Reprocessing, Uncertainties, and Dual Launches

“…How do the WFF uncertainty estimates compare to other studies based on records from sondes launched in the midlatitudes? Similarly, van Malderen et al (2016) showed ozone uncertainties at the Uccle, Belgium, site are largely controlled by the conversion efficiency uncertainty term (Figure 8, orange) throughout the profile except around the vicinity of the tropopause where background current uncertainties matter more. The WCCOS simulation by Smit and ASOPOS (2014) of a midlatitude profile estimate a similar range of ΔP O3 values that also maximize in the tropopause region (up to~9%) due to the dominance of the ΔI B / ΔI M term.…”

“…Sections 3 and 4 detail the reprocessing methods and evaluation, respectively, of the July 1995 to July 2018 digital era ozonesonde records followed by a review of the first estimates of ozone uncertainty in section 5. Similar to a number of sonde reprocessing studies (van Malderen et al, 2016;Sterling et al, 2018;Witte et al, 2017Witte et al, , 2018, including Smit12 guidelines, corrections to radiosonde pressure offsets and their uncertainties are not addressed in this study. Dual sonde launches under flight conditions are an integral component in evaluating sonde performance, SOPs, and ozone response to various KI solution recipes in combination with the two lead ECC manufacturers (EN-SCI and SPC).…”