Preprints
https://doi.org/10.5194/egusphere-2024-1654
https://doi.org/10.5194/egusphere-2024-1654
19 Jun 2024
 | 19 Jun 2024
Status: this preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).

Signs of climate variability in double tropopause global distribution from radio occultation data

Alejandro de la Torre, Peter Alexander, Torsten Schmidt, Andrea K. Steiner, Florian Ladstädter, Rodrigo Hierro, and Pablo Llamedo

Abstract. In a standard atmosphere, there is a single lapse rate tropopause (in what follows, tropopause) that separates the troposphere below from the stratosphere above. However, in certain situations, such as in regions of strong vertical wind shear or associated with certain weather phenomena, a second tropopause layer may form above the standard tropopause. The presence of a double tropopause (DT) can have implications for atmospheric and climate studies, as it may be associated with dynamic and complex weather patterns. Based on 14 years of temperature profiles retrieved by GNSS radio occultation and the resulting DT, a possible relationship between the spatio-temporal distribution of the relative number of DT to simple tropopauses (NDT) (or dependent variable) and a set of monthly climate indices (or features) is explored with a focus on the methodological approach. A cluster analysis is applied to geographically associate the DT occurrences with the climate indices. Then a multivariate linear regression is constructed using a progression of different models to identify the relevant features for the occurrence of DTs. On a global scale, from a hierarchical cluster analysis six sub-regions with different location and spread characteristics are identified. In addition to the condition of linearity in the residuals, the performance of each model in the train and test populations is evaluated to discard possible overfitting. The required conditions of non-collinearity, stationarity and cross-correlation between the features and the relative number of NDT after the removal of the climatological mean for each month (NDT’) are checked. Mean squared errors, adjusted coefficient of determination (adjusted R2) and number of degrees of freedom (F-statistic) parameters are evaluated for each model obtained. Taking into account the constraints of the present analysis, the most relevant climatic indices for the distribution of NDT' are identified.

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Alejandro de la Torre, Peter Alexander, Torsten Schmidt, Andrea K. Steiner, Florian Ladstädter, Rodrigo Hierro, and Pablo Llamedo

Status: open (until 02 Aug 2024)

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Alejandro de la Torre, Peter Alexander, Torsten Schmidt, Andrea K. Steiner, Florian Ladstädter, Rodrigo Hierro, and Pablo Llamedo
Alejandro de la Torre, Peter Alexander, Torsten Schmidt, Andrea K. Steiner, Florian Ladstädter, Rodrigo Hierro, and Pablo Llamedo

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Short summary
A single tropopause separates the troposphere below from the stratosphere above. In regions of strong vertical wind shear, a second tropopause layer may be associated to complex weather patterns. From GNSS radio occultation data, the distribution of multiple tropopause and its possible relation to the variability of climate indices is explored. A cluster analysis is applied to geographically associate the DT occurrences with the climate indices and a multivariate linear regression is constructed