Hurricane Danielle

The main objective of the Aeolus mission is to address the lack of global wind profiles in the Global Observing System (GOS).

Established under the auspices of the World Meteorological Organization, GOS is a coordinated system of methods and facilities for making meteorological and environmental observations on a global scale. Atmospheric measurements are used for weather forecast models worldwide.

However, direct global measurements of 3D wind fields are lacking, representing one of the largest deficiencies in GOS and limiting improvements to numerical weather predictions and climate models.

Currently, most direct observations of the wind come from radiosondes that are launched every day from stations, most of which are in the Northern Hemisphere. Wind-field information in remote regions, over the oceans, in the tropics and Southern Hemisphere is largely indirect.

Different types of observations currently come from:

Surface data: from land stations, ships and buoys, and also from scatterometers on satellites. They are all single level data, and cannot provide any information on atmospheric profiles.

Single-level air data: mainly from aircraft at cruise altitude and cloud-motion winds derived from geostationary satellite imagery. Aircraft observations of wind and temperature are also made during ascent and descent, and are therefore ‘multi-level’ around airports.

Multi-level air data: mainly from radiosondes, wind profilers and polar-orbiting sounder data. Satellite sounders provide global coverage of radiance measurements, which can only be used indirectly.

Reliable and timely wind profiles are needed to improve our understanding of atmospheric dynamics, transport and cycling of energy, water, aerosols, chemicals and other airborne materials.

The Aeolus mission will meet the following set of measurement requirements:

The Aeolus mission will:

• Measure global wind profiles up to an altitude of 30 km
• Measure wind to an accuracy of 1 m/s in the planetary boundary layer (up to an altitude of 2 km)
• Measure wind to an accuracy of 2 m/s in the free troposphere (up to an altitude of 16 km)
• Determine the average wind velocity over 100 km tracks
• Measure 100 wind profiles per hour