Voor degenen die er niet bijkunnen (ik moest mijn proxy gebruiken).
Predictability of a zonal-wavenumber (WN) 1 stratospheric sudden warming (SSW) event occurring in December
1998 is examined using the operational 1-month forecast dataset based upon a numerical weather
prediction model (NWPM) of the Japan Meteorological Agency (JMA). The stratospheric warming in the polar
region of this event is predictable by NWPM from 1 month in advance. The amplification of tropospheric
planetary waves triggering the onset of the SSW is closely connected with weak vertical westerly shear near
the surface around 608N, in association with rather strong synoptic wave activity. Thus, the fair reproduction
of the interaction between zonal-mean flows and synoptic waves in the troposphere for promoting the generation
of WN 1 planetary waves is found to be essential for the successful prediction of this event.
The authors also point out prolonged predictability for the onset of a tropospheric blocking event occurring
over Alaska just after the warming peak. The blocking is formed because of the poleward propagation of planetary
waves causing the SSW event, which suggests a predictable downward control of the tropospheric circulation
by the stratosphere after the SSW.
Quote selectie