Research with model data

In addition to observational data of stratospheric trace gases, simulations of chemistry-transport- and chemistry-climate-models are used for further analyses. This allows globally resolved studies of dynamical and chemical processes in the stratosphere in past, present and future.

One application of these model results is the validation of newly developed theoretical concepts in various regions of the atmosphere to conclude if and how similar studies could be realized using observations.  For instance, it is investigated how the stratospheric halogen budget und chemical depletion are influenced by tropospheric mixing ratios of ozone depleting substances (e.g. CFCs and halons). For this to happen, so-called age spectra are being used amongst others, which depict statistical distributions of transit times of stratospheric air. Unfortunately, those spectra can only be calculated in models and not be measured directly in reality. To solve this problem, methods are developed to derive stratospheric age spectra from trace gas measurements.

These distributions are an important tool to research the stratospheric meridional circulation. In reality, changes in this meridional transport are mainly tracked by observed vertical profiles of chemically inert trace gases from which the mean age of air can be deduced. Using this quantity, conclusions can be drawn on how the overall strength of the stratospheric transport will evolve in the future. This is an important field of research, since model and observational studies show divergent results regarding this temporal evolution.

With the possibility to derive age spectra from measurements, those could be applied to investigate the shift of single branches of the circulation and could lead to a larger understanding of the underlying processes.