For such launch base applications, the needs are different from those of a standard meteorological use. Wind data are expected from the ground to at least 30 km and the vertical resolution for some of the measured profiles are requested to be better than 150 m. Moreover, characteristics of such wind profiles have already interrupt the final countdown several times and report the ARIANE launch for one day or more.
To get the best operational answer to these different needs and requests, several study axes have been planned by the French National Space Agency (CNES) in order to improve measurement, precision and forecast of the wind profile over the ARIANE launch base:
- measurements in Kourou are done through a DIGICORA/GPS system with RS80 radiosondes. This system was installed in 1997 and the computation software is upgraded regularly in order to get the last versions of VAISALA products. In the same time, we have a close collaboration with this company to exchange real-time information on data failures and now on, with a average ratio of less than 10 % of partial loss of winds from ground to more than 30 km, we obtain better results than main radio-sounding stations in the tropics; - for operational high resolution wind profile measurements, Jimsphere balloons are tracked by the 3 spaceport radar. The results are computed after each ARIANE 5 launch and provided to the CNES to take into account the wind characteristics in the ARIANE5 behavior. Simultaneously, others available couples (balloons and sounding equipment) have been tested and compared as an alternative to Jimsphere. Such investigations have been done in collaboration with MODEM, balloons industrials like GATEFF and also scientists of the French National Research Center (CNRS);
- Forecasting the wind profile is already something difficult in northern countries where meteorological models are well adapted and based on an homogeneous and well fed observations network. In the tropics, such models and outcomes have to be tested and improved. Several studies have been done by the French National Weather Service (METEO-FRANCE), at the request of the Europe's Spaceport, in order to define methods to improve the quality of the wind profile forecast over Kourou.
The knowledge of the wind profile over the launch base has to be continuously improved and new possibilities are foreseen:
- possibility to implement an operational wind profiler. Such an investment will be studied and corresponding founds requested from the European Space Agency, on a long term basis;
- results and improvement of wind profile forecast through a limited-area model (ALADIN) with limits conditions fed by the ARPEGE model;
- upgrade of the DIGICORA system and operational test and implementation of RS90 radiosondes.