Validation of SCIAMACHY limb NO<sub>2</sub> profiles using solar occultation measurements

Abstract

Abstract. The increasing amounts of reactive nitrogen in the stratosphere necessitate accurate global measurements of stratospheric nitrogen dioxide (NO 2 ). Over the past decade, the SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY) instrument on ENVISAT (European Environmental Satellite) has been providing global coverage of stratospheric NO 2 every 6 days. In this study, the vertical distributions of NO 2 retrieved from SCIAMACHY limb measurements of the scattered solar light are validated by comparison with NO 2 products from three different satellite instruments (SAGE II, HALOE and ACE-FTS). The retrieval algorithm based on the information operator approach is discussed, and the sensitivity of the SCIAMACHY NO 2 limb retrievals is investigated. The photochemical corrections needed to make this validation feasible, and the chosen collocation criteria are described. For each instrument, a time period of two years is analyzed with several hundreds of collocation pairs for each year. As NO 2 is highly variable, the comparisons are performed for five latitudinal bins and four seasons. In the 20 to 40 km altitude range, mean relative differences between SCIAMACHY and other instruments are found to be typically within 20 to 30 %. The mean partial NO 2 columns in this altitude range agree typically within 15 % (both global monthly and zonal annual means). Larger differences are seen for SAGE II comparisons, which is consistent with the results presented by other authors. For SAGE II and ACE-FTS, the observed differences can be partially attributed to the diurnal effect error.

Limb–nadir matching using non-coincident NO<sub>2</sub> observations: proof of concept and the OMI-minus-OSIRIS prototype product

“…OMI-DOMINO data are available at http://www.temis.nl. Gille et al, 2012), and SCIAMACHY (v3.1;Bauer et al, 2012), as well as satellite nadir measurements from OMI (KNMI DOMINO version 2.0, Boersma et al, 2004Boersma et al, , 2011 and SCIAMACHY (KNMI-BIRA TM4NO2A version 2.3; Boersma et al, 2004). Belmonte Rivas et al (2014) found that the limb stratospheric VCDs from SCIAMACHY-limb, MIPAS, and HIRDLS agree to within 0.25 × 10 15 molecules cm −2 , which is better than 10 %, when all observations are adjusted to the HIRDLS local time.…”

Chemical ozone loss and ozone mini-hole event during the Arctic winter 2010/2011 as observed by SCIAMACHY and GOME-2

“…More detailed explanations of the retrieval algorithms and validation results for different species are reported elsewhere: e.g. for the NO 2 retrieval algorithm in , for the O 3 algorithm in Sonkaew et al (2009), O 3 profile validation results are presented in Mieruch et al (2012), BrO profile validation is reported by Rozanov et al (2011a, b), and for NO 2 profile validation see Bauer et al (2012).…”

Validation of ACE-FTS version 3.5 NO<sub><i>y</i></sub> species profiles using correlative satellite measurements

“…This study used v3.1 of the SCIAMACHY level 2 NO 2 profiles, which was validated by Bauer et al (2012). The NO 2 profiles were compared to correlative satellite measurements that were diurnally scaled to the SCIAMACHY local times.…”

“…It was used by Brohede et al (2007b) in producing NO 2 climatologies from OSIRIS measurements, by Kerzenmacher et al (2008) in the validation of ACE-FTS v2.2 NO 2 and by Bauer et al (2012) in the validation of SCIAMACHY v3.1 NO 2 . In the simulation of the diurnal cycle for an ACE-FTS profile, the model is constrained using the corresponding ACE-FTS temperature, pressure, and O 3 profiles.…”

“…The instrument scanned the Earth's limb from the surface up to 100 km with a 2.5 km vertical field of view and a ∼ 3 km vertical sampling. The NO 2 retrieval algorithm, detailed by and summarized by Bauer et al (2012), uses limb-scattered radiances measured from 420 to 470 nm and solves the inverse problem using the DOAS technique and Tikhonov regularization (Tikhonov, 1963). In each profile, the spectra are normalized by the limb radiances nearest 43 km.…”