Lagrangian reconstruction of ozone column and profile at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR) throughout the winter and spring of 1997-1998

We present a Lagrangian model-based technique to reconstruct ozone profile and column in support of the interpretation of ozone lidar observations mad e at the Arctic Lidar Observatory for Middle Atmosphere Research (ALOMAR). High-resolution ozone profiles as well. as column ozone are reconstructed l ocally at ALOMAR, several times a day, regularly throughout the winter and spring of 1997/1998. The approach consists of calculating a large number of back trajectories to determine the origin of air parcels above ALOMAR and of using satellite observations to determine their ozone content. The blend of satellite observations with limited spatial and temporal coverage, and global gridded meteorological data is akin to a simplified form of data ass imilation. The usefulness of the approach is demonstrated by a systematic c omparison between reconstructed and observed ozone profiles and column and, in particular, their day-to-day variability. Abrupt changes in reconstruct ed and observed profile shape are caused by polar vortex displacements, dee p intrusions of midlatitude air, or vortex edge filamentation. Prominent la minae are seen in the spring, as the vortex breaks down. Short-lived, large -amplitude total ozone peaks are seen in the model and observations, most p rominently in February and March, when they are in excess of 100 Dobson uni ts. They are shown to result from a combination of a lowering of isentropes in the lowermost stratosphere and of advection of ozone-rich air from the base of the polar vortex.