Proceedings - C-SRNWP Project

smallest institutes contribute a so-called core group member to the programme, a researcher
who is full-time available for high-priority tasks and under the direct supervision of the
management group. This core group concept has proven to be essential for the achievement
of critical tasks at the desired time.
The cooperation with ALADIN, which had already been taking shape in earlier years, has
continued to intensify. In May, the HIRLAM All Staff Meeting was held in Sofia jointly with
the ALADIN workshop, and coincidentally also with the SRNWP Mesoscale Verification
workshop. This proved to be a very good opportunity for HIRLAM and ALADIN staff to
discuss progress and make plans in direct contact. The meeting in Sofia also was an
opportunity for the ALADIN Committee for Scientific and Strategic Issues and the HIRLAM
management group to re-align, update and refine their common plans. Several other planning
meetings have been held in 2006 on specific issues such as probabilistic forecasting and
mesoscale data assimilation. The challenge now will be to manage a transition from the
presently largely parallel activities to more truly jointly operating mixed HIRLAM-ALADIN
research and development teams.
Mesoscale modelling activities:
In the field of mesoscale modelling, a growing number of HIRLAM institutes is now gaining
experience in running 2-4 km-scale models on a (semi-)operational basis. Denmark is using
the non-hydrostatic ALADIN model with partly HIRLAM physics, while AROME has been
installed at SMHI and FMI, and will presumably be installed in 2007 at INM and KNMI.
Met.no has been running the UM at 4km for years now, and is now also implementing
(hydrostatic) HIRLAM at this resolution.
This spring, HIRLAM staff have had their first experience with phasing code into the
IFS system. It is expected that at the end of June, a recoded sub-package of the HIRLAM
physics will be phased into IFS. This HIRLAM physics will serve as a baseline, against which
to test mesoscale physics developments. The ALADIN non-hydrostatic dynamics and 3D-
VAR/FGAT assimilation system, together with the AROME physics and SURFEX surface
scheme will form the base for future mesoscale developments within the IFS framework.
Useful concepts from the present HIRLAM system, from e.g. 4D-VAR, the physics and
surface modelling, will be ported to this code.
A mesoscale code repository, including a standard system setup and common
visualization and verification tools, will be installed in the HIRLAM repository at ECMWF
later this year. Henceforth, this mesoscale system, containing HIRLAM, ALADIN and
AROME components, will be designated the HARMONIE model.
The main initial contribution from HIRLAM to the mesoscale physics package will be
the development of a coupled eddy diffusivity – mass flux convection scheme. In addition,
several parametrizations have been developed on synoptic scales which presumably will also
be useful in the mesoscale model, such as the mean and sub-grid scale orography (MSO/SSO)
scheme and the surface slope additions to the radiation scheme. The present AROME system
contains some highly sophisticated but also computationally expensive physics
parametrizations, most notably the microphysics and the radiation scheme. The impact of
replacing these complex schemes by simpler and cheaper variations will be investigated.
In the field of dynamics, HIRLAM will contribute to the ALADIN dynamics in a
number of ways: the implementation of a Mercator map factor, the development of a vertical
finite element (VFE) method, and an improved treatment of pmsl near steep orography. In
44