T-NAWDEX-Falcon Campaign, October 8 - 26, 2012

A Lagrangian Experiment to quantify diabatic processes in a WCB and their potential role for forecast errors associated with mid-latitude weather systems

The T-NAWDEX-Falcon experiment is considered as a test for a future T-NAWDEX (THORPEX-North Atlantic Waveguide and Downstream Impact Experiment) experiment with a well-defined scientific objective. Because of the limited range of the aircraft the focus is on processes at the downstream end of the Atlantic waveguide over the eastern North Atlantic, Central Europe and the western Mediterranean. The project will provide a synergy with the German research group PANDOWAE , which recently started its second phase.

T-NAWDEX-Falcon is planned as a Lagrangian Experiment to quantify diabatic processes within WCBs and their importance for forecast errors associated with mid-latitude weather systems. In-situ observations are performed to observe in-cloud diabatic processes and the transport of water vapor, i.e., processes that are associated with uncertainty and sensitive to the assimilation of additional data. Diabatic processes can strongly influence the evolution and intensity of mid-latitude weather systems and are associated with latent heat release due to phase transitions of water, surface fluxes, or radiative effects, and they strongly depend on the transport of water vapor that often occurs in coherent airstreams. Additionally, the experiment will focus on the triggering and amplification of wave-guide disturbances in the region where the moist ascending WCB reaches the tropopause and impacts on the downstream weather evolution.

In addition to the thermodynamic characterization of the WCB with in-situ observations of wind, temperature and humidity, a set of dropsondes will be deployed to gain a complete view on the complex structure of the cyclone. For the first time a tracer experiment will be conducted in the surrounding of a WCB. It is attempted to measure the net latent heating along the WCB, which is interesting to compare with the representation in NWP systems.

Project partners: