Stratospheric gravity wave potential energy and tropospheric parameters relationships over South America: a study using COSMIC-2 and METOP radio occultation measurements

Using COSMIC-2 and METOP radio occultation measurements during the years 2020 and 2021, the study presents the first direct and independent relationship between the potential energy (E p ) in the stratosphere, precipitable water vapour (PWV), tropopause heights (TPH), and cold-point heights (CPH) over South America. The South American continent comprises the tropical region, the Andes Mountain range, and mid-latitude climates. The seasonal mean of the potential energy (E p ), the PWV, and the tropopause parameters height (TPH and CPH) were obtained to investigate the relationship between the stratospheric gravity wave (SGW) E p and the tropospheric parameters (PWV, TPH, and CPH). Around the Andes Mountains to the east, there is significantly less water vapour (PWV < 10 mm) and a relatively high gravity wave E p (E p > 8 kJ kg − 1 ). A good correlation of variability was found between the PWV and the lower SGW E p in summer over the tropical region (± 20 ◦ ). Generally, good and strong correlations were observed in the summer and spring, with negative/no correlations in the winter in 2020 and 2021. Also, good and strong correlations between SGW, PWV, and TPH were observed in the summer at 20^oN - 10^oN in 2020 and 2021. Our result demonstrated the possibility that convective activity was a major driver of the tropical gravity waves over South America. In the subtropical (30 ^∘ –40 ^∘ ) region, especially in the winter, the tropospheric parameters make little or no contribution to gravity wave activity in the region. The CPH generally showed a no/negative with SGW over the South American tropics. The SGW activities in the tropical region showed an impact on the structure of the tropopause parameters, which could be a result of the convective activity in this region. Graphical Abstract