A New Method for Tropopause Folding Detection and Its Application in Middle-Latitude Disastrous Weather Forecasting

Tropopause folding is an important mid-latitude atmosphere phenomenon occurring within the upper troposphere and lower stratosphere that always correspond to cyclogenesis, rainstorm and convection generation, and precipitation enhancement. Because the atmospheric environment for these above-mentioned weather phenomena is very complicated, preexisting popular schemes that do not consider water vapor may not be suitable for detecting the accompanying tropopause folding. Regarding the merits and demerits of the pattern recognition scheme on the basis of satellite and numerical data, a dynamic new scheme based on FY-2E geostationary weather satellite data is presented to detect tropopause folding related to rainstorms. The core concept of this scheme is based on the statistical relationship between tropopause folding and the water vapor at the high-level troposphere, general moist potential vorticity, ozone, and upper-level jet while simultaneously considering the auxiliary effect of the height of the dynamic tropopause. After accuracy verification using the total amount of ozone and ozone profile operational products retrieved by FY-3A and FY-3B and the potential vorticity calculated by the European Center for Medium-range Weather Forecasting (ECMWF) Interim data, this scheme is applied to analyze two typical middle-latitude weather processes. One is the famous Beijing extreme rainfall of July 21, 2012, and the other is the South China rainstorm that occurred during May 14-17, 2013. A good application effect of both cases suggests that our new method for tropopause folding detection is feasible and can be helpful in middle-latitude disastrous weather monitoring and forecasting.