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一、引 言 自从35年以前做出最早的数值预报以来,数值天气预报取得了很大的进步。这些进步的取得,不仅是由于更好、更实用的模式,而且也由于在这个时期内,气象观测站的数量大 大增加。这些进步可以从许多方面看出来:例如,更准确的短期预报产品,实用的预报方法在时效上的小量延伸,以及预报种类的显著增加。 大气的可预报性是有限的。近期,Lorenz(1982),Leith(1981),Kalnay和Dalcher (1986)对全球预报误差的增长进行了研究。这些研究指出,可预报性取决于尺度;行星尺度比短期天气尺度的可预报性大。研究还指出,由于模式的改进,可使预报时限增加几天,初始误差的每一次减半又可使预报时限增加两天,因此,有用的预报技术的进一步发展,还是存在着很大潜力的。这种发展可能是逐步的,并且取决于以下几个方面的进展:
I. Introduction Since the earliest numerical forecasts were made 35 years ago, great progress has been made in numerical weather forecasting. These advances have been made not only by a better and more practical model, but also by the dramatic increase in the number of meteorological observatories during this period. These advances can be seen in many ways: for example, more accurate short-term forecast products, a modest extension of useful forecasting methods over time, and a significant increase in the types of forecasts. The predictability of the atmosphere is limited. Recently Lorenz (1982), Leith (1981), Kalnay and Dalcher (1986) studied the growth of global forecast errors. These studies indicate that predictability depends on the scale; the planetary scale is more predictable than the short-term weather scale. The study also pointed out that due to the improvement of the model, the forecast time could be increased by a few days, the halving of the initial error and the forecasting time could be increased by two days. Therefore, there is still great potential for the further development of useful forecasting techniques . This development may be gradual and depends on progress in the following areas: