atmospheric dynamics; numerical modeling; Rossby wave dynamics; coherent airflows; climatology; forecast verification; extratropical cyclones; moist processes; warm conveyor belts; Rossby waves; potential vorticity; THORPEX
Boettcher M. and H. Wernli (2015), Diabatic Rossby waves in the Southern Hemisphere., in Quart. J. Roy. Meteorol. Soc.
, 141, 3106-3117.
Catto J. L. E. Madonna H. Joos I. Rudeva and I. Simmonds (2015), Global relationship between fronts and warm conveyor belts and the impact on extreme precipitation., in J. Climate
, 28, 8411-8429.
Madonna E. M. Boettcher C. M. Grams H. Joos O. Martius and H. Wernli (2015), Verification of North Atlantic warm conveyor belt outflows in ECMWF forecasts., in Quart. J. Roy. Meteorol. Soc.
, 141, 1333-1344.
Madonna E. S. Limbach C. Aebi H. Joos H. Wernli and O. Martius (2014), On the co-occurrence of warm conveyor belt outflows and PV-streamers., in J. Atmos. Sci.
, 71, 3668-3673.
Schäfler A. M. Boettcher C. M. Grams M. Rautenhaus H. Sodemann and H. Wernli (2014), Planning aircraft measurements within a warm conveyor belt., in Weather
, 69, 161-166.
Schemm S. and H. Wernli (2014), The linkage between the warm and cold conveyor belts in an idealized extratropical cyclone., in J. Atmos. Sci.
, 71, 1443-1459.
Madonna E. H. Wernli H. Joos and O. Martius (2014), Warm conveyor belts in the ERA-Interim data set (1979-2010). Part I: Climatology and potential vorticity evolution., in J. Climate
, 27, 3-26.
Pfahl S. E. Madonna M. Boettcher H. Joos and H. Wernli (2014), Warm conveyor belts in the ERA-Interim data set (1979-2010). Part II: Moisture origin and relevance for precipitation., in J. Climate
, 27, 27-40.
Boettcher M. and H. Wernli (2013), A 10-yr climatology of diabatic Rossby waves in the Northern Hemisphere, in Mon. Wea. Rev.
, 141, 1139-1154.
Papritz L. and S. Schemm (2013), Development of an idealized downstream cyclone: Eulerian and Lagrangian perspective on the kinetic energy, in Tellus A
, 65, 19539.
Martius O. H. Sodemann H. Joos S. Pfahl A. Winschall M. Croci-Maspoli M. Graf, E. Madonna B. Mueller S. Schemm J. Sedlacek M. Sprenger and H. Wernli (2013), The role of upper-level dynamics and surface processes for the Pakistan flood of July 2010., in Quart. J. Roy. Meteorol. Soc.
, 139, 1780-1797.
Schemm S. H. Wernli and L. Papritz (2013), Warm conveyor belts in idealized moist baroclinic wave simulations., in J. Atmos. Sci.
, 70, 627-652.
Warm conveyor belts (WCBs) are coherent airstreams that typically develop along cold fronts associated with extratropical cyclones. These airstreams originate in the moist subtropical marine boundary layer and ascend within 1-2 days to the upper troposphere whilst moving more than 2000 km towards the pole. They occur most frequently during winter in the western North Pacific and North Atlantic where they are responsible for the major part of precipitation. WCBs are characterized by a complex interaction of physical and dynamical processes, which have not yet been investigated in full detail. The key role of WCBs for the dynamics of the synoptic and large-scale atmospheric flow stems from their profound impact upon the tropospheric distribution of potential vorticity (PV). The coherent ascent of WCBs leads to the diabatic production of a positive PV anomaly in the lower troposphere and of a negative PV anomaly in upper-level ridges just below the tropopause. When interacting with the extratropical waveguide, these negative PV anomalies can exert a profound impact upon the downstream flow evolution. Hence a WCB can be the trigger for the amplification and breaking of an upper-level Rossby wave, which is particularly relevant in situations where Rossby wave breaking events act as precursors of high-impact weather systems (e.g., heavy precipitation in the western Mediterranean, Saharan dust storms, cold air outbreaks). Recent studies indicate that errors in medium-range numerical weather predictions might be related to the inaccurate representation of WCBs and their effect on upper-level PV. In order to advance the basic understanding of these complex, non-linear and highly important dynamical processes, this project will (i) investigate the parameters and processes that determine the intensity of a WCB, its associated PV evolution and downstream effects, (ii) assess the errors in global models’ analyses and forecasts associated with the different stages of a WCB life cycle, (iii) quantify the climatological frequency of the triggering and intensification of upper-level Rossby waves by WCBs, and (iv) provide clear guidance for investigating the dynamics of WCBs during T-NAWDEX - a major international field experiment planned for autumn 2012 within the framework of THORPEX. Within three subprojects, complementary techniques will be applied in order to reach these objectives, including idealized simulations of moist baroclinic waves, real case sensitivity experiments, diagnostic investigations based upon (re-) analysis and forecast data sets, and a feature-based verification of WCBs in global models using independent observational datasets. In this way this ambitious project will contribute on the one hand to an improved basic understanding of the dynamical effects of WCBs on the downstream evolution of upper-level Rossby waves and (high-impact) surface weather events. On the other hand it will directly influence the planning and conduct of the field experiment T-NAWDEX and provide information of practical relevance for operational medium-range weather prediction.