A new opportunity to survey the global water vapour distribution: the 2.3-micron channel of SCIAMACHY
Hans Schrijver(1), Annemieke Gloudemans(1), Christian Frankenberg(1) and Ilse Aben(1)
(1) SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, Netherlands
Good quality water vapour total columns can be obtained using SCIAMACHY's shortwave infrared channel around 2.3 micron for cloud free land scenes. This is an interesting and promising alternative to the use of the shorter wavelength (visible and near-infrared) water bands.
In order to correct for scattering effects introduced by the ice layer on the detector window a novel method has been developed.
The measured water vapour columns have been compared with spatially and temporally collocated values from European Centre for Mid-Range Weather Forecast (ECMWF) data. Agreement is very good with differences having standard deviations not higher than 0.3 g/cm2, with some regional exceptions,
for example in desert areas and the Sahel region.
The use, in the retrievals, of recently published spectroscopic data for water vapour led to a significant improvement in the agreement of the retrieved water vapour total columns and the values derived from
ECMWF data thus providing an independent verification of those data.