Field Phase Results and Data Base

The field phase was successfully run from 1st October to 30 November, 1990. With weather cooperating, 10 Intensive Observation Periods (IOPs), totalizing 15 days of observations, were conducted, covering a wide range of meteorological situations (mountain waves by northerly and southerly flows, strong events of regional winds directly influenced by the Pyrénées). The phenomenology of the various events was extensively documented during these IOPs.

In the year following the field phase, extensive work was accomplished by the participating institutes to compile a qualified observational data-set from all measurements. The data were concentrated by Meteo-France and stored into a relational database system: The PYREX data-base (Bougeault et al., 1993). Due to the unprecedented effort in enforcing the format homogeneity and the quality control of the data, and also due to the simplicity of using the relational data base system, this data base is now largely used around the world for research on orographic flows. The PYREX group indeed has decided to grant free access to these data to interested scientists from as early as January 1993. For the purpose of meso-scale modelling, data assimilation was also undertaken with operational weather prediction systems, and the supplementary radio-sounding and surface observations of PYREX. Two series of reanalyses have been produced, namely with the PERIDOT system of Meteo-France and with the ECMWF latest T213 system. Both series contain 6 hourly analyses for all IOPs. The PERIDOT reanalyses can be obtained from Meteo-France, and the ECMWF T213 reanalyses are stored under the MARS Archive at ECMWF. Both have been used by the PYREX participants to initialize successful meso-scale numerical experiments.

FIGURE 3:An example of coordinated flight plans during PYREX (IOP9).

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MAP Newsletter. October '00