EU Project Status: HERA, RAPHAEL

"Heavy Precipitation in the Alpine Region (HERA)" started in December 1996 as the first project under the auspices of MAP which is funded by the Commission of the European Communities (CEC). Nine partner institutions from the five Alpine countries A, CH, D, F and I make up the consortium which addresses the following overall objectives:

• to establish a multi-year systematic collection of heavy precipitation episodes by processing combined data sets from ground based radar, surface and upper air observations;
• to analyse major precipitation events by applying operational and research-type numerical weather forecast models and to quantify the underlying physical processes;
• to adapt airborne radar algorithms to measurements over mountainous terrain; and
• to develop and to implement new high-resolution numerical techniques (non-hydrostatic grid nesting).

The project structure consists of six work packages:

A1: systematic monitoring of precipitation systems from recent years;
A2: coherent evaluation of operational precipitation forecasts;
A3: detailed investigation of major cases;

B1: feasibility of airborne Doppler radar techniques over complex orography;
B2: implementation of advanced modelling techniques; and
B3: process studies of the key physical mechanisms.

The work packages A1, A2, A3 place the emphasis on observed cases and the application of established techniques, while packages B1, B2, B3 concentrate on process studies of key physical mechanisms and advanced techniques which are under development.

Regarding the applied methods the project aims at a balanced blend of observations from

• advanced ground based radars (some Dopplerized / polarimetric),
• routine surface networks (partly automatted),
• routine upper air soundings;

and simulations from

• operational weather forecasting models,
• research models concentrating on key mechanisms,
• tests of the next generation of operational models

in order to obtain an as complete as possible picture of heavy precipitation events in the Alpine region and the short range predictability for the atmospheric part of the hydrological cycle.

In January 1998 the HERA Progress Report (Dec. 96 - Nov. 97) was approved by the CEC. The main achievements were:

• north Alpine radar composites from up to ten radars for selected major cases extending from western Switzerland to eastern Austria;
• technical preparations for intercomparisons of operational precipitation forecasts from four meteorological services in C, D, F and I;
• advanced hindcast simulations of heavy precipitation events at the northern and the southern side of the Alps;
• first evaluation of airborne Doppler radar measurements over complex terrain;
• application of advanced grid-nesting and microphysical schemes within a new generation of numerical weather predicition models;
• identification of synoptic and convective scale processes which are conducive to the generation of heavy precipitation in the vicinity of a large mountain complex.

A sample of nine case study episodes was selected (12 hourly precipitation up to 186 mm) on which detailed investigations will be focussed during the second year of HERA. Altogether it was concluded that the original project structure proved to be well viable.

Meanwhile the related project RAPHAEL (see MAP newletter no. 7, pp. 9-11) has started on February 1, 1998, and had its kick-off meeting on February 9/10. RAPHAEL investigates precipitation in two watersheds, one to the north and one to the south of the Alps, and will couple atmospheric and hydrological models for improved runoff and flood forecasts and test them in the Ticino-Toce (Italy) and Ammer (Bavaria) watershed.