Sensitivity of polar stratospheric clouds to the Arctic polar vortex weakening in the lower stratosphere in midwinter

The polar vortex strength and persistence from December to January play an important role in Arctic ozone depletion from late winter to spring. The short-term elongation or displacement of the Arctic polar vortex in midwinter, occurring under the influence of vertically propagating planetary waves, can lead to the local weakening of the dynamical barrier of the vortex edge. The weakening of the vortex edge in winter, accompanied by short-term complete melting of polar stratospheric clouds (PSCs), leads to the fact that the springtime ozone destruction was not observed even under the conditions of the strong polar vortex (in the presence of PSCs). In this work, we showed that complete or almost complete melting of PSCs in midwinter is observed during the local weakening of the dynamic barrier of the Arctic polar vortex edge in the lower stratosphere, characterized by a decrease in zonal and meridional winds below 20 m/s for at least 3 hours in a small section of the vortex edge determined by the geopotential values of about 19.5.10(4) m(2)/s(2) at the 50 hPa pressure level.