SNSF | P3 Research Database

Jets; Atmospheric vortices; Extra-tropical cyclones; Extreme weather events; THORPEX; Weather systems; forecasting; numerical models; precursors; potential vorticity

English title	Aspects of the Dynamics of Synoptic & Menoscale Systems
Applicant	Davies Huw Cathan
Number	117639
Funding scheme	Project funding
Research institution	Institut für Atmosphäre und Klima ETH Zürich
Institution of higher education	ETH Zurich - ETHZ
Main discipline	Climatology. Atmospherical Chemistry, Aeronomy
Start/End	01.03.2008 - 31.07.2009
Approved amount	106'151.00

Lead

Lay summary
Forecasting day-to-day weather changes involves predicting the future evolution of a chaotic and complex fluid medium. Significant improvement has been achieved over the last two decades, but there remain challenges to (a) improve the skill of 3-10 day forecasts, (b) eliminate the rare (but often significant) cases of major mis-forecasts, and (c) extend the useful time-range for forecasts of extreme weather events. Advances in these three areas would be demonstrably beneficial to both society and the economy. In this project we seek to study “the origin and dynamics of the precursor(s) of cyclogenesis”. The premise is that certain identifiable flow features serve as precursors of cyclogenesis and can, in effect, provide the flow with an element of transient dynamic memory that can be exploited to enhance our predictive capability. Thus the aim is to obtain a better understanding of the origin, structure and dynamics of putative harbingers of cyclones and extreme weather events. Attention is focused on understanding the influence upon flow evolution and predictability of three specific and distinctive flow features putative precursors:- major deep convective activity in the sub-tropics; incipient synoptic vortices in the lower troposphere of the extra-tropics; and isolated vortex-like anomalies at tropopause-level in more polar regions. The overarching aim is to determine whether the early detection and better representation of these precursors would indeed enhance the predictive skill related to the fore-mentioned challenges. The approach adopted in the study is to conduct diagnostic empirically-based studies to establish the salient structural features and the dynamical and climatological characteristics of the precursors, and to undertake case study analyses and perform numerical simulations with a hierarchy of atmospheric models to identify their quintessential dynamics. To examine the origin and/or evolution of the precursors and to study their dynamics it is intended to pursue (a) climatological studies based upon the ERA-40 data set of the ECMWF, (b) dynamically-based diagnostic studies of individual events including conducting a detailed analysis of the “forecast-analysis” difference fields of realized events that resulted in “mis-forecasts”, (c) theoretical studies of simple but germane flow settings, and (d) numerical simulations performed with a range of models Forecasting day-to-day weather changes involves predicting the future evolution of a chaotic and complex fluid medium. Significant improvement has been achieved over the last two decades, but there remain challenges to (a) improve the skill of 3-10 day forecasts, (b) eliminate the rare (but often significant) cases of major mis-forecasts, and (c) extend the useful time-range for forecasts of extreme weather events. Advances in these three areas would be demonstrably beneficial to both society and the economy. In this project we seek to study “the origin and dynamics of the precursor(s) of cyclogenesis”. The premise is that certain identifiable flow features serve as precursors of cyclogenesis and can, in effect, provide the flow with an element of transient dynamic memory that can be exploited to enhance our predictive capability. Thus the aim is to obtain a better understanding of the origin, structure and dynamics of putative harbingers of cyclones and extreme weather events. In effect the study’s rationale is captured by the following causal chain : Origin & early?Dynamics of precurso(s) & ?Cyclogenesis / evolution of precursorsinteraction with wave guideEvent development Attention is focused on understanding the influence upon flow evolution and predictability of three specific and distinctive flow features putative precursors:- major deep convective activity in the sub-tropics; incipient synoptic vortices in the lower troposphere of the extra-tropics; and isolated vortex-like anomalies at tropopause-level in more polar regions. The overarching aim is to determine whether the early detection and better representation of these precursors would indeed enhance the predictive skill related to the fore-mentioned challenges. The approach adopted in the study is to conduct diagnostic empirically-based studies to establish the salient structural features and the dynamical and climatological characteristics of the precursors, and to undertake case study analyses and perform numerical simulations with a hierarchy of atmospheric models to identify their quintessential dynamics. To examine the origin and/or evolution of the precursors and to study their dynamics it is intended to pursue (a) climatological studies based upon the ERA-40 data set of the ECMWF, (b) dynamically-based diagnostic studies of individual events including conducting a detailed analysis of the “forecast-analysis” difference fields of realized events that resulted in “mis-forecasts”, (c) theoretical studies of simple but germane flow settings, and (d) numerical simulations performed with a range of models