Articles | Volume 8, issue 8
Atmos. Meas. Tech., 8, 3407–3418, 2015
Atmos. Meas. Tech., 8, 3407–3418, 2015

Research article 24 Aug 2015

Research article | 24 Aug 2015

Comparison of ozone retrievals from the Pandora spectrometer system and Dobson spectrophotometer in Boulder, Colorado

J. Herman1, R. Evans2, A. Cede4, N. Abuhassan1, I. Petropavlovskikh3, and G. McConville3 J. Herman et al.
  • 1University of Maryland Baltimore County UMBC-JCET Joint Center for Earth Systems and Technology and NASA Goddard Space Flight Center Greenbelt, Greenbelt, MD 20771, USA
  • 2NOAA Earth System Research Laboratory, 325 Broadway, Boulder, CO 80305, USA
  • 3Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder 80309, USA
  • 4Goddard Earth Sciences Technology & Research (GESTAR) Columbia, Columbia, MD 21046, USA

Abstract. A comparison of retrieved total column ozone (TCO) amounts between the Pandora #34 spectrometer system and the Dobson #061 spectrophotometer from direct-sun observations was performed on the roof of the Boulder, Colorado, NOAA building. This paper, part of an ongoing study, covers a 1-year period starting on 17 December 2013. Both the standard Dobson and Pandora TCO retrievals required a correction, TCOcorr = TCO (1 + C(T)), using a monthly varying effective ozone temperature, TE, derived from a temperature and ozone profile climatology. The correction is used to remove a seasonal difference caused by using a fixed temperature in each retrieval algorithm. The respective corrections C(TE) are CPandora = 0.00333(TE-225) and CDobson = -0.0013(TE-226.7) per degree K. After the applied corrections removed most of the seasonal retrieval dependence on ozone temperature, TCO agreement between the instruments was within 1 % for clear-sky conditions. For clear-sky observations, both co-located instruments tracked the day-to-day variation in total column ozone amounts with a correlation of r2 = 0.97 and an average offset of 1.1 ± 5.8 DU. In addition, the Pandora TCO data showed 0.3 % annual average agreement with satellite overpass data from AURA/OMI (Ozone Monitoring Instrument) and 1 % annual average offset with Suomi-NPP/OMPS (Suomi National Polar-orbiting Partnership, the nadir viewing portion of the Ozone Mapper Profiler Suite).

Short summary
Measurements of total column ozone have been obtained by the Dobson #061 spectrophotometer and the Pandora spectrometer system from the roof of the NOAA building in Boulder, Colorado. A comparison of 1 year (17 Dec 2013 to 18 Dec 2014) of ozone data shows that the two instruments are in close agreement after a separate correction was applied to the retrieved ozone data from each instrument. Good agreement was also obtained between Pandora and two satellite data sets, AURA OMI and SUOMI OMPS.