QBO is one of the most important oscillations in the Stratosphere. Study of the oscillation is important because of extratropical effects of QBO and interaction between stratosphere and troposphere. Role of planetary wave activity in interaction between QBO and polar vortex is very important. Extratropical impacts of this oscillation on polar vortex especially on level of lowermost and middle stratosphere is considered in early winter.
Using NCEP NCAR reanalysis data to compute potential vorticity on potential temperature levels in different phases of QBO is examined. Potential vorticity is depicted on potential temperature 380 and 480 levels as lowermost stratospheric levels, and 500 and 580 levels as middle stratospheric levels. Results show that elongation of potential vorticity on these levels toward the Atlantic, Pacific and Mediterranean storm tracks. Vorticity in westerly phase is more stronger than easterly phase of QBO. Polar vortex edge and surf zone are appeared on these levels and hasmeaningful difference in easterly and westerly phase of QBO. Subtropical edge of polar vortex is stronger in lowermost stratosphere while polar edge of vortex is stronger in middle stratosphere.