Variability in tropopause height and its temperature on different time scales: An observational study over Banqiao, Taiwan

Abstract

Long term variability of cold point tropopause (CPT) height (CPTh) and cold point tropopause temperature (CPTt) using 21 years (1985–2005) of radiosonde observations over Banqiao (25°N, 121.3°E), Taiwan is reported. The time-frequency analysis of CPTh using the Morlet wavelet revealed a pronounced annual cycle (AC) over the entire observational period, whereas the CPTt showed a quasi-biennial oscillation (QBO) signal during some specific time period (1988–1998). It is observed that the CPTh and CPTt vary at different time scales. To examine the origin of observed CPT oscillations, the outgoing longwave radiation (OLR) observations from the National Centers for Environmental Prediction and the National Center for Atmospheric Research (NCEP/NCAR) have been used for the same time period (1985–2005) over the study site. The ozone observations from ozonesonde, which is launched from the Banqiao during the period from 1992 to 2005, are also used. The wavelet spectra of the CPTh, CPTt, OLR and stratospheric ozone obtained in the present analysis reveal that the CPTh and OLR have similar kind of variability, whereas the CPTt and the stratospheric ozone shows correlative interannual variations.