Major advances foreseen in humidity profiling from the Water apour Lidar Experiment in Space (WALES)
Gérard, E. ; Tan, D.- G.- H. ; Garand, L. ; Wulfmeyer, V. ; Ehret, G. ; Di Girolamo, P.
Année de publication
2004
The need for an absolute standard for water vapor observations, in the
form of a global dataset with high accuracy and good spatial resolution,
has long been recognized. The European Space Agency's Water Vapour
Lidar Experiment in Space (WALES) mission aims to meet this need by
providing high-quality water vapor profiles, globally and with good
vertical resolution, using a differential absorption lidar (DIAL) system
in a low earth-orbit satellite. WALES will be the first active system
to measure humidity from space routinely. With launch envisaged in the
20082010 time frame and a minimum duration of two years, the primary
mission goals are to (a) contribute to scientific research and (b)
demonstrate the feasibility of longer-term operational missions. This
paper assesses the benefits of the anticipated data to NWP through
quantitative analysis of information content. Good vertical resolution
and low random errors are shown to give substantial improvements in
analysis error in one-dimensional variational data assimilation (1DVAR)
comparisons with advanced infrared sounders. In addition, the vertical
extent of the profiles is shown to reach 16.5 km or <img src="http://journals.ametsoc.org/na101/home/literatum/publisher/ams/journals/entities/223C.gif" alt="" class="entityA" align="bottom">100
hPa, well above the limit of radiance assimilation (13 km or 200 hPa).
Also highlighted are important applications in atmospheric sciences and
climate research that would benefit from the low bias promised by
spaceborne DIAL data and their complemen-tarity to other types of
humidity observations.</div>
Accès à la notice sur le site du portail documentaire de Météo-France