Predictability and Dynamics of Weather Systems in the Atlantic-European Sector (PANDOWAE)
Description:
This special collection comprises the results of the Research Group “Predictability and Dynamics of Weather Systems in the Atlantic-European Sector” (PANDOWAE), which was funded by the Deutsche Forschungsgemeinschaft (German Research Council), and which constitutes a major European contribution to the WMO World Weather Research Programme THORPEX. The research interests of PANDOWAE are the predictability and dynamics of weather systems that may lead to high impact weather in the midlatitudes. PANDOWAE research is organised into the three research areas "A: Upper-level Rossby wave trains: generation, propagation and wave-breaking", "B: Moist processes and diabatic Rossby waves", and "C: Ensembles and adaptivity (numerical modeling & predictability)". It includes theoretical studies, numerical modeling, and process studies. Part of these studies were performed in collaboration with major field campaigns such as T-PARC, HyMeX, T-NAWDEX-Falcon and future NAWDEX.
Collection organizers:
Sarah C. Jones, Deutscher Wetterdienst, Offenbach, Germany, and Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology, Germany
Aurelia Müller, Institute for Meteorology and Climate Research, Karlsruhe Institute of Technology, Germany
Predictability and Dynamics of Weather Systems in the Atlantic-European Sector (PANDOWAE)
Abstract
The first collocated measurements during THORPEX (The Observing System Research and Predictability Experiment) regional campaign in Europe in 2007 were performed by a novel four-wavelength differential absorption lidar and a scanning 2-μm Doppler wind lidar on board the research aircraft Falcon of the Deutsches Zentrum für Luft- und Raumfahrt (DLR). One mission that was characterized by exceptionally high data coverage (47% for the specific humidity q and 63% for the horizontal wind speed υh ) was selected to calculate the advective transport of atmospheric moisture qυh along a 1600-km section in the warm sector of an extratropical cyclone. The observations are compared with special 1-hourly model data calculated by the ECMWF integrated forecast system. Along the cross section, the model underestimates the wind speed on average by −2.8% (−0.6 m s−1) and overestimates the moisture at dry layers and in the boundary layer, which results in a wet bias of 17.1% (0.2 g kg−1). Nevertheless, the ECMWF model reproduces quantitatively the horizontally averaged moisture transport in the warm sector. There, the superposition of high low-level humidity and the increasing wind velocities with height resulted in a deep tropospheric layer of enhanced water vapor transport qυh . The observed moisture transport is variable and possesses a maximum of qυh = 130 g kg−1 m s−1 in the lower troposphere. The pathways of the moisture transport from southwest via several branches of different geographical origin are identified by Lagrangian trajectories and by high values of the vertically averaged tropospheric moisture transport.
Abstract
The first collocated measurements during THORPEX (The Observing System Research and Predictability Experiment) regional campaign in Europe in 2007 were performed by a novel four-wavelength differential absorption lidar and a scanning 2-μm Doppler wind lidar on board the research aircraft Falcon of the Deutsches Zentrum für Luft- und Raumfahrt (DLR). One mission that was characterized by exceptionally high data coverage (47% for the specific humidity q and 63% for the horizontal wind speed υh ) was selected to calculate the advective transport of atmospheric moisture qυh along a 1600-km section in the warm sector of an extratropical cyclone. The observations are compared with special 1-hourly model data calculated by the ECMWF integrated forecast system. Along the cross section, the model underestimates the wind speed on average by −2.8% (−0.6 m s−1) and overestimates the moisture at dry layers and in the boundary layer, which results in a wet bias of 17.1% (0.2 g kg−1). Nevertheless, the ECMWF model reproduces quantitatively the horizontally averaged moisture transport in the warm sector. There, the superposition of high low-level humidity and the increasing wind velocities with height resulted in a deep tropospheric layer of enhanced water vapor transport qυh . The observed moisture transport is variable and possesses a maximum of qυh = 130 g kg−1 m s−1 in the lower troposphere. The pathways of the moisture transport from southwest via several branches of different geographical origin are identified by Lagrangian trajectories and by high values of the vertically averaged tropospheric moisture transport.
