Stratospheric nitrogen dioxide in Antarctic regions from ground based and satellite observations during 2001

Abstract

The application of Differential Optical Absorption Spectroscopy (DOAS) methodology to the zenith scattered light data collected with the GASCOD spectrometer developed at the ISAC Institute allow for the detection of stratospheric trace gases involved in the ozone cycle such as NO 2 , OClO, BrO. The instrument was installed in December 1995 in the Italian Antarctic station at Terra Nova Bay (74°26'S, 164°03E', Ross Sea), after several tests both in laboratory and in Antarctic region, for unattended and continuous measurement in extreme high-latitude environment. The GASCOD is still working and producing very interesting data for the study of the denitrification processes during the formation of the so-called ozone hole over the Antarctic region. For the continuous NO 2 monitoring for whole the year, also during winter when the station is unmanned, the [407 - 460] nm spectral region is investigated. The results for Nitrogen Dioxide, obtained by application of DOAS algorithms to the data recorded during the year 2001, are presented. ERS-2 was launched in April 1995 into a near-polar sun-synchronous orbit at a mean altitude of 795 km. The descending node crosses the equator at 10:30 local time. GOME is a nadir-scanning double monochromator covering the 237 nm to 794 nm wavelength range with a spectral resolution of 0.17-0.33 nm. The spectrum is split into four spectral channels, each recorded quasi-simultaneously by a 1024-pixel photodiode array. The global spatial coverage is obtained within 3 days at the equator by a 960 km across-track swath (4.5 s forward scan, 1.5 s back scan). The ground pixel size of the measurements is 320 X 40 km 2 . A comparison of GASCOD and GOME results for NO 2 total column is performed.