Naslov
Frequency of rapid changes in surface pressure over Mediterranean

Autori
Tudor, Martina

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
6th HyMeX workshop 7-10 May 2012 / - Primošten : Državni hidrometeorološki zavod, 2012

Skup
6th HyMeX workshop 7-10 May 2012

Mjesto i datum
Primošten, Hrvatska, 07.05.2012. - 10.05.2012

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
mean sea level pressure; spectral filter

Sažetak
The three hourly coupling update interval is insufficient for resolving the storm in lateral boundaries as presented for the Lothar storm case. This lead to a solution where a strategy of monitoring the coupling update frequency (MCUF) has been proposed and to production of a diagnostic field in the output of the operational global model ARPEGE that indicates model points with rapid changes in surface pressure. This field is provided in the coupling files since 06 UTC run on 23rd January 2006 for the common coupling domain used in 6 countries for lateral boundary conditions (LBCs). When this field is larger than some threshold value, there is a rapid "development" in the surface pressure suggesting that a fast cyclone has moved through the area. If the point with the large value is inside the coupling zone of the ALADIN limited area model (LAM) domain, it can be expected that the ALADIN model run will miss the cyclone strength and development due to time interpolation of boundary data. When the time series of these data has been analysed for the Belgian domain, it was found that such events occurred only several times per year and they proposed to restart the model forecast from the coupling file when the storm is inside the domain using the scale selective digital filter initialization. Unfortunately, this solution would remove features present in LAM forecast and benefits of data assimilation in LAM. The analysis of the MCUF field for the common LACE coupling domain shows that this field is above the threshold far more frequently. The maximum value of the MCUF field has been extracted from each coupling file available, for 4 runs per day (starting from 00, 06, 12 and 18 UTC analyses) and extending up to 72 hour forecast with 3 hour interval (60 hours for the 18 UTC run). The spatial distribution reveals that low pressure systems move rapidly above the sea surfaces, especially the Mediterranean. The value of 0.003 has been exceeded very often until 06 UTC run on 6th February 2008, especially in the +03 hour forecast coupling files. This suggests large spin-up of the surface pressure field in the beginning of the ARPEGE forecast. The spatial distribution can be viewed as a map of the fast cyclone tracks and areas that support rapid changes in cyclone development.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

POVEZANOST RADA