Seasonal Change of the Ozone Layer State over Yakutia
  The ozone layer state in the stratosphere over Yakutia depending on the year time is considered. It is shown that the layer thickness is maximum in February-March (450 Dobson's units) and it is minimum in July-September (300 - 350 DU). Measurements indicate that the ozone layer thickness was significantly decreased in the 1990's. A problem of change of ozone layer state is discussed. 
A.A. Mikhailov, P.P. Ammosov, G.A. Gavrilyeva, N.N. Efremov, S.V.   Nikolashkin