Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
doi:10.5194/acp-2016-704
© Author(s) 2016. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
19 Oct 2016
Review status
A revision of this discussion paper was accepted for the journal Atmospheric Chemistry and Physics (ACP) and is expected to appear here in due course.
Extending methane profiles from aircraft into the stratosphere for satellite total column validation: A comparative analysis of different data sources
Shreeya Verma1, Julia Marshall1, Mark Parrington2, Anna Agusti-Panareda2, Sebastien Massart2, Martyn P. Chipperfield3, Christopher Wilson3, and Christoph Gerbig1 1Max Planck Institute for Biogeochemistry, Jena, Germany
2European Centre for Medium-Range Weather Forecasts, Reading, UK
3National Centre for Earth Observation, School of Earth and Environment, University of Leeds, UK
Abstract. Airborne observations of greenhouse gases are a very useful reference for validation of satellite-based column-averaged dry air mole fraction data. However, since the aircraft data are available only up to about 9–13 km altitude, these profiles do not fully represent the depth of the atmosphere observed by satellites and therefore need to be extended synthetically into the stratosphere. In the near future, observations of CO2 and CH4 made from passenger aircraft are expected to be available through the In-Service Aircraft for a Global Observing System (IAGOS) project. In this study, we analyse three different data sources that are available for the stratospheric extension of aircraft profiles by comparing the error introduced by each of them into the total column and provide recommendations regarding the best approach. First, we analyse CH4 fields from two different models of atmospheric composition – the European Centre for Medium-Range Weather Forecasts (ECMWF) Integrated Forecasting System for Composition (C-IFS) and the TOMCAT/SLIMCAT 3-D chemical transport model. Secondly, we consider scenarios that simulate the effect of using CH4 climatologies such as those based on balloons or satellite limb soundings. Thirdly, we assess the impact of using a-priori profiles used in the satellite retrievals for the stratospheric part of the total column. We find that the models considered in this study have a better estimation of the stratospheric CH4 as compared to the climatology-based data and the satellite a-priori profiles. Both the C-IFS and TOMCAT models have a bias of about −9 ppb at the locations where tropospheric vertical profiles will be measured by IAGOS. The C-IFS model, however, has a lower random error (6.5 ppb) than TOMCAT (12.8 ppb). These values are well within the minimum desired accuracy and precision of satellite total column XCH4 retrievals (10 ppb and 34 ppb, respectively). In comparison, the a-priori profile from the University of Leicester Greenhouse Gases Observing Satellite (GOSAT) Proxy XCH4 retrieval and climatology-based data introduce larger random errors in the total column, being limited in spatial coverage and temporal variability. Furthermore, we find that the bias in the models varies with latitude and season. Therefore, applying appropriate bias correction to the model fields before using them for profile extension is expected to further decrease the error contributed by the stratospheric part of the profile to the total column.

Citation: Verma, S., Marshall, J., Parrington, M., Agusti-Panareda, A., Massart, S., Chipperfield, M. P., Wilson, C., and Gerbig, C.: Extending methane profiles from aircraft into the stratosphere for satellite total column validation: A comparative analysis of different data sources, Atmos. Chem. Phys. Discuss., doi:10.5194/acp-2016-704, in review, 2016.
Shreeya Verma et al.
Interactive discussionStatus: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version      Supplement - Supplement
 
RC1: 'Referee Comment', Anonymous Referee #1, 14 Nov 2016 Printer-friendly Version 
 
RC2: 'Review Report', Anonymous Referee #2, 25 Jan 2017 Printer-friendly Version Supplement 
AC2: 'Authors response', Shreeya Verma, 31 Mar 2017 Printer-friendly Version Supplement 
 
AC1: 'Authors response', Shreeya Verma, 31 Mar 2017 Printer-friendly Version Supplement 
Shreeya Verma et al.
Shreeya Verma et al.

Viewed

Total article views: 543 (including HTML, PDF, and XML)

HTML PDF XML Total BibTeX EndNote
461 58 24 543 18 23

Views and downloads (calculated since 19 Oct 2016)

Cumulative views and downloads (calculated since 19 Oct 2016)

Viewed (geographical distribution)

Total article views: 543 (including HTML, PDF, and XML)

Thereof 540 with geography defined and 3 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 26 May 2017
Publications Copernicus
Download
Short summary
Aircraft profiles are a useful reference for validation of satellite-based column-averaged dry air mole fraction data. However, these are available only up to about 9–13 km altitude and therefore need to be extended synthetically into the stratosphere using other sources. In this study, we analyse three different data sources that are available for extension of CH4 profiles by comparing the error introduced by each into the total column and provide recommendations regarding the best approach.
Aircraft profiles are a useful reference for validation of satellite-based column-averaged dry...
Share