Comparison between LPMA measurements 3D Reprobus modelling using a box model : sensitivity of vertical profiles to time, latitude, longitude and implications on NOy modelling

Mixing ratio profiles of ozone and several NO_y species were measured using the Limb Profile Monitor of the Atmosphere (LPMA) instrument during ascent, occultation and sunset for a balloon flight, which took place on August 21, 2001 from Kiruna (Sweden). These profiles were compared with the Reprobus 3D chemistry transport model (CTM) results for a latitude and a longitude area close to the mean balloon position. Discrepancies between model and measurements are observed particularly for the photochemical variation of NO_2 and NO between ascent and sunset. A more precise comparison, taking into account the variation with time of the position (latitude, longitude) of the probed air mass reduces the disagreement between model and measurements. The box model Reprobus 1D has then been used to study in detail the photochemical variation of NO_2 and NO. A robust interpolation scheme was used to initialize the box model with LPMA. Reprobus 1D reproduced well the photochemical variation of NO_2 and NO measured by LPMA observations. However, a disagreement still remains for the total NO_y burden. The intercomparison procedure and the corresponding results will be presented