Potential vorcity from Meteosat water vapour imagery: a method to automatically adjust initial NWP fields
PANKIEWICZ, G.S. ; Swarbrick S.J. ; Watkin, S.C.
In the last few years, work has been undertaken at the Joint Centre for Mesoscale Meteorology to look at the use of upper-?tropospheric PV adjustment, guided by water vapour imagery, to correct errors in the initial fields of a forecast run of the Unified model. In modifying the PV field, the method uses subjective rules based on relationships noted between Meteosat water vapour imagery and PV. The modified PV fields are then inverted to provide adjustments to the corresponding wind and temperature fields. Model re-runs using this method have shown improved forecasts in several situations. An investigation has recently been completed within NWP (SA) to consider the automatic processing of water vapour imagery in order to update initial model fields in this way. An artificial neural network used in regression mode was trained using over 17500 250x250 km samples of Meteosat 6.3 microns water vapour (and 11.5 microns infrared) imagery, taken from 52 cases over the North Atlantic Ocean during 1997, with corresponding samples of diagnosed PV on the 315 K isentropic surface taken from analysis fields of the Limited Area version of the Unified Model. This ...
Accès à la notice sur le site du portail documentaire de Météo-France