AIRCRAFT MEASUREMENTS, MODELLED STRATOSHERIC [NO2]/[NO] RATIO and PHOTOCHEICAL STEADY-STATE APROACH WITHIN THE FRAME of ENVISAT SATELLITE DATA VALDATION

The scientific payload aboard the stratospheric aircraft M55 Geophysica consists of both in-situ and remote sensing instruments deployed to validate the ENVISAT chemical payload - SCIAMACHY, MIPAS-E and GOMOS during dedicated field campaigns: July and October 2002, Forli (Italy) and February-March 2003, Kiruna (Sweden). Along with the precise measurements required for correct validation procedures, it is necessary to provide additional information related to certain relationships between the available geophysical parameters in order to allow us to better interpret retrieved results, both from the space and from the aircraft measurements. In this regard NO2/NO ratio is inferred/tested along the flight tracks and used to verify the existence of a steady state photochemical equilibrium, using the data obtained by GASCOD-A/4pi, FOZAN and SIOUX instruments. The obtained experimental ratio is compared to that derived from model calculations. A short description of the instruments and flight conditions are described also.