An Analysis of the Benefit of Earth Observations from Space on Regional and Global Numerical Weather Prediction

The importance and economic value of earth observations from space (EOS) is shown, for instance, by recent experiments which indicate that, over the southern hemisphere, satellite data extends the life of high quality numerical forecasts by two and a half to three days. Benefits from assimilating these EOS, particularly from an Australian Region and southern hemisphere perspective have been documented. The benefits described are in relation to synoptic scale and severe weather forecasts. Instruments providing these benefits include the advanced sounders, those carried by the COSMIC Constellation and the GOES and MTSAT imagers. Examples of the beneficial impact of these data are provided and an adjoint based assessment of the impact of these data shown. Recent examples are Observing System Experiments, based on the application of these data to the operational forecast systems at NCEP and at the Australian Bureau of Meteorology. It is found in an era where populations are increasing in areas subjected to severe weather and while extreme weather events remain a considerable problem, that EOS significantly extend the life of numerical forecasts. For example in a study using both the NCEP and Australian operational forecast systems the life of a high quality numerical forecast is extended by a factor of four over the southern hemisphere by using EOS. The examples shown in this study underline the great importance and great benefit of EOS for those in both the southern and the northern hemisphere. Also underlined are future improvements in the exploitation of EOS which will further enhance their benefit to NWP.