Previous: Ext. Abst. Next: Technique Up: Ext. Abst.
1. Introduction
A long term monitoring program for NO2 and O3 column by visible spectroscopy in the Antarctic region was initiated in February 1994 by an Agreement between INTA (Spain) and DNA/IAA (Argentina). Three unattended scanning spectrometers operating in short spectral ranges for NO2 and O3 observations were deployed at Ushuaia (55ºS, 68ºW), Marambio (Antarctic Peninsula, 64ºS, 56ºW) and Belgrano (Continental Antarctica, 78ºS, 35ºW) between 1994 and 1995 [Yela et al., 1998]. The stations are representatives of mid latitudes, the edge of the vortex and the core of the vortex, respectively. The observations were extended in 1999 by an ozonesounding program at Belgrano station. The 5-year spectroscopic dataset available are analysed and compared with the Chemical-Transport-Model SLIMCAT [Chipperfield 1999] including heterogeneous chemistry for the same location and observational solar zenith angles.
We will report the main characteristics of the NO2 column seasonal wave, interannual variability, diurnal variation and dependence with the light available. For O3 column, the twilight technique allows to extend the measurements period of few weeks toward the polar night. These measurements provide a valuable datasets in a period when the ozone depletion develops and data are scarce (TOVS-IR only).