FASTEX is a field experiment designed for providing understanding of the structure, dynamics, formation and decay of the cloud systems constituent of the North-Atlantic storm track.
The unique feature of FASTEX is the desire to provide a bridge, for the first time, between the large-scale dynamics of cyclogenesis and the consequent mesoscale and cloud-scale processes within the storms. This holistic approach is very demanding in requiring a description of features such as the upper jet stream on synoptic scales at the same time as detailed radiative, dynamical and cloud structures. This has not been attempted before but it is crucial if the phenomenon is to be described in a complete enough way for inclusion in, and verification of predictions from, large-scale climate models. This goal will be achieved by means of a two-months field experiment. The observing system is multilocated and mobile. Among other things, it has an Upstream Component based on ships and aircraft in mid-Atlantic and a Multiscale Sampling Area of Ireland and based on instrumented aircraft flying in a coordinated way.
The present proposal is concerned with the field experiment itself, the delivery of the FASTEX data base and the first steps towards derivation of scientific understanding. The objectives of this proposal are:
to conduct a field experiment, FASTEX, concerning cloud systems within extra-tropical cyclones. The observing system is such that it will provide a unique data set:
(i) relating to the initiation of storms in the mid-Atlantic storm-track, (ii) relating to the structure of the developing cloud-cyclone system near western Europe.
to exploit and analyse the data emphasizing two areas:
- the development and validation of a set of parameterizations of cloud-related processes within mid-latitude cyclones for use in climate models. These parameterizations will result from improved understanding of the interaction between cloud and dynamical processes within the cyclone. It will be derived from measurements and from detailed modelling studies. - to specify the requirements in terms of resolution and of remotely measured data that will enable an Earth Observing System to describe the full spectrum of oceanic storm-track cyclones, their frequency and intensity through dynamic (3D and 4D variational) data assimilation experiments encompassing several scales.
Dynamics of cloud systems, cloud-radiation, dynamic data assimilation, field experiment.
Funding SchemeCSC - Cost-sharing contracts
130 Co. Clare
78140 Velizy Villacoublay
RG6 6FN Reading