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Journal Article: ID no. (ISBN etc.):  1477-870X BibTeX citation key:  Bock2007b
Bock, O., Bouin, M.-N., Walpersdorf, A., Lafore, J.-P., Janicot, S., Guichard, F. & Agusti-Panareda, A. (2007) Comparison of ground-based GPS precipitable water vapour to independent observations and Numerical Weather Prediction model reanalyses over Africa. IN Quarterly Journal of the Royal Meteorological Society, 133. 2011–2027.
Added by: Devic 2008-07-07 09:27:49    Last Edited by: Fanny Lefebvre 2010-09-06 14:58:37
Categories: Water cycle
Keywords: LOP - EOP
Creators: Agusti-Panareda, Bock, Bouin, Guichard, Janicot, Lafore, Walpersdorf
Collection: Quarterly Journal of the Royal Meteorological Society
Bibliographies: cnrm, Prior150410

Peer reviewed
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Maturity index:  published

This study aims at assessing the consistency between different precipitable water vapour (PWV) datasets over Africa (between 35°N and 10°S). This region is characterized by large spatial and temporal variability of humidity but also by the scarcity of its operational observing network, limiting our knowledge of the hydrological cycle. We intercompare data from observing techniques such as ground-based Global Positioning System (GPS), radiosondes, AERONET sun photometers and SSM/I, as well as reanalyses from European Centre for Medium-Range Weather Forecasts (ERA-40) and National Center for Environmental Prediction (NCEP2). The GPS data, especially, are a new source of PWV observation in this region. PWV estimates from nine ground-based GPS receivers of the international GPS network data are used as a reference dataset to which the others are compared. Good agreement is found between observational techniques, though dry biases of 12-14% are evidenced in radiosonde data at three sites. Reasonable agreement is found between the observational datasets and ERA-40 (NCEP2) reanalyses with maximum bias 9% (14%) and standard deviation 17% (20%). Since GPS data were not assimilated in the ERA-40 and NCEP2 reanalyses, they allow for a fully independent validation of the reanalyses. They highlight limitations in the reanalyses, especially at time-scales from sub-daily to periods of a few days. This work also demonstrates the high potential of GPS PWV estimates over Africa for the analysis of the hydrological cycle, at time-scales ranging between sub-diurnal to seasonal. Such observations can help studying atmospheric processes targeted by the African Monsoon Multidisciplinary Analysis project. Copyright © 2007 Royal Meteorological Society
Last Edited by: Fanny Lefebvre