Journal cover Journal topic
Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

IF value: 3.668
IF 5-year value: 3.707
IF 5-year
CiteScore value: 6.3
SNIP value: 1.383
IPP value: 3.75
SJR value: 1.525
Scimago H <br class='widget-line-break'>index value: 77
Scimago H
h5-index value: 49

  21 Sep 2020

21 Sep 2020

Review status: a revised version of this preprint was accepted for the journal AMT and is expected to appear here in due course.

Accounting for the photochemical variation of stratospheric NO2 in the SAGE III/ISS solar occultation retrieval

Kimberlee Dubé1, Adam Bourassa1, Daniel Zawada1, Doug Degenstein1, Robert Damadeo2, David Flittner2, and William Randel3 Kimberlee Dubé et al.
  • 1Institute of Space and Atmospheric Studies, University of Saskatchewan, Saskatchewan, Canada
  • 2NASA Langley Research Center, Hampton, VA, USA
  • 3National Center for Atmospheric Research, Boulder, CO, USA

Abstract. The Stratospheric Aerosol and Gas Experiment (SAGE) III has been operating on the International Space Station (ISS) since mid 2017. Nitrogen dioxide (NO2) number density profiles are routinely retrieved from SAGE III/ISS solar occultation measurements in the middle atmosphere. Although NO2 density varies throughout the day due to photochemistry, the standard SAGE NO2 retrieval algorithm neglects these variations along the instrument's line of sight by assuming that the number density has a constant gradient within a given vertical layer of the atmosphere. This assumption will result in a retrieval bias for a species like NO2 that changes rapidly across the terminator. In this work we account for diurnal variations in retrievals of NO2 from the SAGE III/ISS measurements, and determine the impact of this algorithm improvement on the resulting NO2 number densities. The diurnal correction is applied by first undoing the SAGE III/ISS retrieval using publicly available SAGE III/ISS products to obtain an optical depth profile. The retrieval is then performed with a new matrix that applies photochemical scale factors for each point along the line of sight according to the changing solar zenith angle. In general NO2 that is retrieved by accounting for these diurnal variations is more than 10 % lower than the standard algorithm below 30 km. This effect is greatest in winter at high latitudes, and generally greater for sunrise occultations than sunset. Comparisons with coincident profiles from the Optical Spectrograph and InfraRed Imager System (OSIRIS) show that NO2 from SAGE III/ISS is generally biased high, however the agreement improves by up to 20 % in the mid stratosphere when diurnal variations are accounted for in the retrieval. We conclude that diurnal variations along the SAGE III/ISS line of sight are an important term to consider for NO2 analyses at altitudes below 30 km.

Kimberlee Dubé et al.

Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement

Kimberlee Dubé et al.

Kimberlee Dubé et al.


Total article views: 281 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
223 55 3 281 7 5
  • HTML: 223
  • PDF: 55
  • XML: 3
  • Total: 281
  • BibTeX: 7
  • EndNote: 5
Views and downloads (calculated since 21 Sep 2020)
Cumulative views and downloads (calculated since 21 Sep 2020)

Viewed (geographical distribution)

Total article views: 188 (including HTML, PDF, and XML) Thereof 185 with geography defined and 3 with unknown origin.
Country # Views %
  • 1
Latest update: 20 Jan 2021
Publications Copernicus