NO2 vertical profiles retrieved from ground-based measurements during spring 1999 in the Canadian Arctic

Retrieval of stratospheric NO2vertical profiles from ground‐based zenith‐sky DOAS measurements: Results for the MANTRA 1998 field campaign

“…Melo et al (2004) show that, for profiles retrieved using measurements taken in the Arctic, small differences in the assumed reference amount of NO 2 may lead to significant changes in the shape of the retrieved NO 2 profile. However, for the mid-latitude measurements analysed here, we observed that the shape of the profile around the peak altitude range is not affected by varying the reference amount of NO 2 by as much as 20%.…”

“…A detailed description of the retrieval method adopted here, including a rigorous error analysis and validation studies, is given by Preston (1995), Preston et al (1997Preston et al ( , 1998, and its application to a dataset acquired in the High Arctic, using the same UV-visible spectrometer as in this study is presented by Melo et al (2004).…”

“…Since the observed spectrum for a given SZA is ratioed to the reference spectrum, in order to calculate the absolute slant column, the amount of NO 2 in the reference spectrum must be added to the retrieved slant column amount. A detailed discussion of the process used to determine the amount of NO 2 in the reference spectrum is given in Melo et al (2004). In brief, the reference column density (RCD) for NO 2 is calculated as the mean slope of the Langley plots (i.e., the plot of differential NO 2 slant columns measured at SZAs from 80°to 85°on the same day against the corresponding NO 2 air mass factors, hereinafter referred to as AMFs) separately for sunrise and sunset.…”

MANTRA ‐ A Balloon Mission to Study the Odd‐Nitrogen Budget of the Stratosphere

“…It recorded polarized spectra of the sky (from 305 to 311 nm) at right angles to the Sun throughout the day, but signal levels proved to be too low for OH retrievals. However, the instrument worked well on two later flights (MANTRA 2002 and2004) and analysis of these results is in progress.…”

“…The zenith-sky spectrometer and data analysis are described by Bassford et al (this issue). Vertical profiles of NO 2 can also be retrieved, following the approach of Preston (1995) and Preston et al (1997Preston et al ( , 1998, as described by Melo et al (2004) and Melo et al (this issue). The MANTRA 1998 campaign provided an opportunity to deploy this new instrument and to evaluate its performance against simultaneous measurements of ozone and NO 2 made by a number of other instruments.…”