In addition to microphysical processes, the distribution of PV at the tropopause is also influenced by radiative effects, i.e., due to radiative heating/cooling anomalies in the vicinity of the tropopause, induced by the presence of ice clouds and/or strong vertical humidity gradients (Zierl and Wirth, 1997; Chagnon et al., 2013). Also within the lower stratosphere can radiative effects modify PV and contribute to the formation of intense mesoscale cyclonic PV anomalies, so-called TPVs (Cavallo and Hakim, 2010; Kew et al., 2010). And clearly, for the climate community understanding the processes that influence radiation in the upper troposphere and lower stratosphere is of central importance, also because in this region changes in water vapour strongly affect surface climate and decadal variability of surface temperatures (Forster and Shine, 1997).
High resolution observations of the thermodynamic structure near the tropopause, in and around clouds, will enable the assessment of the model representation of these processes, which can be interpreted with the aid of sensitivity tests using simulations where cloud and radiative parameters are varied.
|Moisture and Cloud Structure in Tropopause Region|
|Planned Observations||Moisture, temperature profiles and radiation|
|Schematic flight plan:|