Atmos. Chem. Phys. Discuss., 12, 20351-20382, 2012
www.atmos-chem-phys-discuss.net/12/20351/2012/
doi:10.5194/acpd-12-20351-2012
© Author(s) 2012. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Preliminary signs of the initiation of deep convection by GNSS
H. Brenot1, J. Neméghaire2, L. Delobbe2, N. Clerbaux2, and M. Van Roozendael1
1Belgian Institute for Space Aeronomy, Avenue Circulaire 3, 1180 Brussels, Belgium
2Royal Meteorological Institute of Belgium, Avenue Circulaire 3, 1180 Brussels, Belgium

Abstract. This study reports on the exploitation of GNSS for weather forecasts, especially for nowcasting. We focus on GPS observations (post-processing with a time resolution of 15 min) and try to establish typical configurations of the humidity field which characterise convective systems and particularly which supply forerunners of their initiation associated with deep convection. We show the critical role of GNSS horizontal gradients of humidity to detect small scale structures of the troposphere (i.e. convective cells), and then we present our strategy to obtain typical water vapour configurations by GNSS, called "H2O alert". These alerts are based on a dry/wet contrast taking place during a 30 min window before initiation of a convective system. GNSS observations have been assessed for the rainfall event of the 28–29 June 2005 using data from the Belgian dense network (baseline from 5 to 30 km). To validate our GNSS H2O alert, we use the detection of precipitation by C-band weather radar and thermal infrared radiance of the 10.8-μm channel [Ch09] of SEVIRI instrument on METEOSAT Second Generation. Our H2O alert obtains a score of about 80%.

Citation: Brenot, H., Neméghaire, J., Delobbe, L., Clerbaux, N., and Van Roozendael, M.: Preliminary signs of the initiation of deep convection by GNSS, Atmos. Chem. Phys. Discuss., 12, 20351-20382, doi:10.5194/acpd-12-20351-2012, 2012.
 
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