The Regional Model - REMO
Max-Planck-Institut für Meteorologie, Hamburg
REMO was developed upon the request of the reviewers within the BMBF-Förderschwerpunkt Wasserkreislauf as the atmospheric component of the coupled atmosphere-hydrology model system. Development and application of this system was considered a central task within the international BALTEX (BALTIC Sea Experiment).
MPIfM (Max Planck Institute for Meteorology) was thus asked to develop the German BALTEX Model on the basis of the former numerical weather prediction model of the German Weather Service (EUROPA-MODELL, EM, Majewski 1991) in co-operation with DKRZ, DWD and GKSS. On 16 Nov 93 it was agreed between these parties to develop a regional model suitable for climate modelling and weather forecast which subsequently was named REMO. DWD and GKSS concentrated on modifications of the EM to use REMO in forecast mode (e.g. consecutive 30 hour forecasts without data assimilation) whilst DKRZ and MPIfM focussed on developments needed for the use of REMO in climate mode.
A version of the EM which allowed to carry out long term runs was modified at MPIfM to use surface pressure, horizontal wind components, temperature, water vapour and cloud water content as prognostic variables instead of surface pressure, horizontal wind components, total heat and total water content. The EM physical parameterisation scheme remained otherwise unchanged but the physical parameterisation scheme of the global climate model ECHAM4 (Roeckner et al. 1996) was implemented as an alternative option.
A major objective of BALTEX is to understand and quantify the water and energy cycles over the Baltic Sea and its drainage basin. Therefore the validation of REMO concentrated on the hydrological components of the water cycle. Simulation results of long runs up to ten years using ECMWF re-analysis data as lateral boundary conditions have been compared successfully with observations (Jacob 2001). Furthermore, REMO participated in a model inter-comparison during the PIDCAP period (Pilot study of Intense Data Collection and Analyses of Precipitation) involving eight regional models in total (Jacob et al. 2001).
REMO runs on various platforms including scalar and vector computers such as CRAY, NEC, IBM, DEC, HP, SGI and Linux workstations. A parallel version (MPI) is also in use. Horizontal resolutions between 1/10° and 1° are currently used for simulations covering time ranges from days to centuries with both parameterisations. The following regions have been investigated with REMO: Europe, Arctic, Antarctic, Siberia, Indonesia, India, Brazil, Peru, Africa, North America, Baltic Sea, North Sea, North Atlantic, Pacific.
The atmospheric model REMO is coupled to three different hydrology models and three ocean/sea-ice models. An on-line chemistry module for tropospheric chemistry is available.
REMO is used by about 15 institutes in Germany, France, Switzerland, Greece and China. Interest in its use has been expressed by a number of further institutes in Germany and beyond. Numerous other institutes analyse the output generated by REMO.
During the next four years, REMO will be used as the atmospheric component of BALTIMOS (BALTEX Integral MOdel System) which is the BMBF funded nine partner consortium Development and validation of a coupled model system for the Baltic region. BALTIMOS consists of the modules: atmosphere, sea ice, ocean, land surface and hydrology. The main activity will be the validation of the fully coupled system. Furthermore, REMO is embedded in several other national and international projects for the next years.
Jacob, D., U. Andrae, G. Elgered, C. Fortelius, L. P. Graham, S. D. Jackson, U. Karstens, Chr. Koepken, R. Lindau, R. Podzun, B. Rockel, F. Rubel, H.B. Sass, R.N.D. Smith, B.J.J.M. Van den Hurk, X. Yang, 2001: A Comprehensive Model Intercomparison Study Investigating the Water Budget during the BALTEX-PIDCAP Period. Meteorology and Atmospheric Physics, Vol.77, Issue 1-4, 19-43.
Jacob, D., 2001: A note to the simulation of the annual and inter-annual variability of the water budget over the Baltic Sea drainage basin. Meteorology and Atmospheric Physics, Vol.77, Issue 1-4, 61-73.
Majewski, D, 1991: The Europa-Modell of the Deutscher Wetterdienst. ECMWF Seminar on numerical methods in atmospheric models, Vol.2, 147-191.
Roeckner, E., K. Arpe, L. Bengtsson, M. Christoph, M. Claussen, L. Dümenil, M. Esch, M. Giorgetta, U. Schlese, U. Schulzweida, 1996: The atmospheric general circulation model ECHAM-4: Model description and simulation of the present day climate. Max-Planck-Institut für Meteorologie Report No. 218.