Numerical weather prediction
Numerical Weather Prediction (NWP) is a process that creates mathematical models of the current weather in order to predict what the weather will be like in the future, usually within the short-term of a few days. Improving the models available for NWP is one of the primary aims of Aeolus. The global wind profiles that the mission will produce should bring the following benefits to NWP:
Better modelling, and a greater understanding, of tropical dynamics
The observations of energy and water flow that Aeolus will provide will be a major improvement in the modelling of tropical dynamics.
It is already well known that the interactions between wind, temperature and humidity play a key role in determining these dynamics, but without the quantity of data that a satellite-based observation system can provide, the interactions remain difficult to model. Data from Aeolus will improve our understanding of these interactions, which will not only lead to more accurate predictions, but also to better descriptions of the mean precipitation, the humidity, and the Hadley circulation, in the tropical region.
More useful tropical forecasts
By defining the initial state of the weather with more accuracy, and improving the modelling of wind movements, Aeolus will help create more useful tropical forecasts. The evaluation of parallel forecasts in the tropics performed with and without wind-profile observations will give an objective estimate of this benefit. Benefits are expected for the large-scale components of the flow as well as for smaller-scale weather features. This should lead, among other things, to better estimates of the position and intensity of tropical cyclones.
In the Southern hemisphere's extra-tropics, a dramatic improvement is expected in the short-range forecasting of synoptic events. The magnitude of the expected improvement is comparable to the current quality difference between the two hemispheres. In the Northern Hemisphere, there are still cases of dramatic forecast failures, at day 1 or 2, on synoptic events such as strong mid-latitude storms. The percentage of failures will be dramatically reduced with the introduction of Aeolus observations. Over the whole globe, small-scale details of intense wind events will improve for short-range forecasts because of the earlier detection of their development.
Medium-range forecasts will also improve thanks to Aeolus. By providing better definition of the planetary-scale waves, and more uniform coverage of the Earth, the satellite will enable forecasters to make more accurate predictions for both hemispheres. The greatest improvement, however, is expected to occur in the extra-tropical regions of the Southern hemisphere, where the lack of conventional data coverage currently makes predictions particularly dificult.
Aeolus will act as a much needed quality-control standard for other sources of remote-sensing data. By the time Aeolus is transmitting data to Earth, a new generation of vertical temperature and humidity sounders is likely to have become operational. The data sets from these sounders, with and without independent wind observations, can then be compared to the data from Aeolus. This will lead, indirectly, to improvements in forecasting skill, particularly in the Southern Hemisphere, where remote-sensing data are the primary source of information.