Abstract

The status of the tropopause affects weather phenomena and climate change occurring in the Earth’s atmosphere. Investigation of the structure and variation of the tropopause is crucial for the development of an in-depth understanding of water-vapor exchange processes, the concentrations and nature of chemicals within the tropopause, and their role in climate change and the ecosphere. At present, the common methods used for the estimation of tropopause height are limited by their reliance on area, an overdependence on atmospheric temperature, and the use of many different data types, and thus lack strong generality. Therefore, this study directly used atmospheric refractivity data from multiple sources to determine the tropopause height. An objective covariance transform method was applied to identify transitions in a refractivity profile. The refractivity tropopause height was compared with the bending angle tropopause (BAT)/cold-point tropopause (CPT)/lapse-rate tropopause (LRT) height in bending angle profiles and temperature profiles derived from radio occultation and radiosonde temperature profiles. This revealed a good agreement between the tropopause heights obtained by the refractivity method and those obtained from BAT/LRT/CPT. An initial analysis of global tropopause structure and seasonal changes in tropopause height for 2014-2016 using the radio occultation (RO) refractivity method afforded results that were consistent with existing research results.

To obtained a more detailed view, the seasonal variation in tropopause height above China was further analyzed. The validity of the refractivity covariance transform method for determining the tropopause height was proven. The refractivity method was also used to analyze a variety of types of data downloaded from the Constellation Observing System for Meteorology, Ionosphere and Climate (COSMIC) Data Analysis and Archive Center (CDAAC), such as RO products; radiosonde comparison profiles; temperature, pressure and moisture profiles; temperature, pressure and moisture profiles generated from the ERA-Interim model; and a vertical profile obtained through gridded National Centers for Environmental Protection operational analysis of Network Common Data Form files. The results show that this method is not only suitable for the analysis of RO data, but also for the analysis of radiosonde, reanalysis and analysis/forecast data. A series of experiments were used to verify the generality of the refractivity covariance transform method to determine tropopause height. This confirmed the utility of our method, which will be useful for the analysis of long-term variations in tropopause height.

You do not currently have access to this content.