Characteristics of Tropopause and Tropopause Inversion Layer in the Polar Region

Characteristics of the thermal and ozone tropopauses and the tropopause inversion layer (TIL) in the Antarctic and Arctic are investigated using high vertical resolution ozonesonde data. The ozone tropopause is clearly defined even in the Antarctic winter and spring in which the thermal tropopause is ambiguous. The Antarctic ozone tropopause shows a smaller annual variation than the thermal tropopause. While the ozone tropopause is located below the thermal tropopause in the Arctic throughout the year, the ozone tropopause in the Antarctic summer is located at the same height as or slightly above the thermal tropopause. A description of the vertical structure around the tropopause in the ozone tropopause based coordinate presents a sharp and continuous transition from the troposphere to the stratosphere, while the transition in the thermal tropopause based coordinate is sharp but discontinuous. The TIL defined in the ozone tropopause based coordinate almost disappears in the Antarctic winter and spring unlike in summer and fall. In the Arctic, the TIL is observed even in winter, but its maximum value of Brunt-Vaisala frequency squared (N-2) is smaller than summer. The value of N-2 in the TIL is larger in the Antarctic summer than in the Arctic summer.