Proceedings - C-SRNWP Project

Another important event happened, in parallel to these reorganisation steps. The annual
‘HIRLAM All Staff Meeting’ and ‘ALADIN Workshop’ were held jointly in Sofia in May,
thanks to the kind dedication of our Bulgarian colleagues. There was even a SRNWP
workshop happening in parallel in order to take advantage of the wide attendance. The
twinning of the two major events was so successful that it was decided to continue in an
alternating way for the ensuing years (Oslo in 2007, Brussels in 2008).
The scientific and technical content of the ALADIN Programme
• The scientific and technical content of ALADIN Programme can best be defined by the
three main contributing sub-projects:
i. The ‘classical’ ALADIN project, with its 15-countries operational applications, still
running in a manner hardly different from the one under the old governance, but for
the above-mentioned attention paid to transversal support to operations.
ii. The AROME project, aiming at the 2.5 km mesh-size applications and thus at an
explicit description of moist physics (relying for this on the Meso-NH physical
package), with parallel emphasis on the fine scale transcription and extension of the
lager scale data assimilation algorithms. The use of the ALADIN-NH dynamical core
with its high stability properties allows to rely on long time-steps (≥60s at 2.5 km of
mesh) in order to make the above-mentioned ambitions affordable.
iii. The ALARO intermediate endeavour, aiming at scales where deep convection is half
resolved and half parameterised. This is currently embodied by the SLHD
development at the frontier between dynamics and physics (see below) and by the
ALARO-0 physical package which, besides the above-mentioned horizontal scale
target, aims at algorithmic efficiency and tries to build a bridge with the AROME
determining parameterisation specificities.
• All the above components are more or less tightly connected to the IFS/ARPEGE global
common code, especially for the maintenance that remains a heavily centralised activity,
under the leadership of the French LTM, Claude Fischer.
• This diversity within the Programme under a single code effort offers a unique opportunity
to go for interdisciplinary thrusts on the modelling side and hence to be in a better situation
to accommodate the new links with HIRLAM while respecting the diversity of ideas and
methods that can help to better build future applications.
• For some other parts (data assimilation for instance) the transversal character is implicit,
given the very complex nature of the environment for R&D and the even tighter links with
the global applications IFS and ARPEGE. In such cases all new developments are
automatically leading to general purpose tools.
An example of interdisciplinarity
This example is not important from the scientific point of view (it requires very specific
ingredients to be meaningful) but it is quite telling from the point of view of cross-team work
and of surprises happening when merging various research streams within a NWP application.
As such it can best be described by separating the ‘contributing items’ and the ‘problems’.
Contributing items:
• The ALADIN-NH dynamical core, conceived as a switch on top of the Hydrostatic
Primitive Equations ALADIN basic code.
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