Ozone and nitrogen dioxide have been monitored by ground-based visible spectrometry from ESRANGE base at Kiruna in Sweden (68N, 22E) from mid January until early April 1988. Stratospheric winter was exceptionally long and cold this year and spring final warming developed only in March. Ozone column was found to increase slowly during this period from 400 DU to 450 DU in the average. After February 15, several rapid decreases by 30% lasting a few days have been observed in correlation with advection from the North West. They are indicative of the presence of an ozone minimum above polar regions during the period. The diurnal variation amplitude is in agreement with the current NOX photochemistry assuming the NO2 layer centered around 30 km. As already observed in the Southern polar regions, the day to day and seasonal NO2 variations are closely associated with stratospheric temperature. Calculations and comparison with other experimental data show that this behaviour cannot de interpreted with the current photochemistry.