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Simulations of MAP IOPs 14-15 with Lokal Modell: impact of nudging on forecast precipitation. Francesco Boccanera, Andrea Montani ARPA – Servizio Idro-Meteorologico Regionale, Bologna, Italy. 5 th CARPEDIEM Project Meeting Dublin, December 15, 2003. Lokal Modell (LM).
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Simulations of MAP IOPs 14-15 with Lokal Modell: impact of nudging on forecast precipitation Francesco Boccanera, Andrea Montani ARPA – Servizio Idro-Meteorologico Regionale, Bologna, Italy 5th CARPEDIEM Project Meeting Dublin, December 15, 2003
Lokal Modell (LM) • Non-hydrostatic model operational at ARPA-SIM • Provided of nudging-based data assimilation scheme • Initial and boundary conditions from 3-hourly ECMWF analyses “Carpediem” model configuration Integration domain
The nudging-based assimilation scheme Assimilation period forecastperiod t= -Tnud t=t0 Observations (about 2*104 per day) During the assimilation period, a term is added to the model’s prognostic variables. This term (called “nudging term”) depends on the difference between observed and model state. Nudging term is the generic prognostic variable of the model
IOP14: performed runs 03/11 00 UTC 04/11 00 UTC assimilation forecast
24h precipitation cumulated from 04/11 00 UTC to 05/11 00 UTC IOP 14 Cntl_00(cum 0-24 hr) Nud_00 (cum 0-24 hr)
04/11/99 00 UTC 2m-temperature and 10m-wind Cntl_00 (analysis) Nud_00 (analysis) 04/11/99 06 UTC 2m-temperature and 10m-wind Cntl_00 (fcst +6 hr) Nud_00 (fcst +6 hr) -6 0 6 12 18
24h Precipitation cumulated from 06/11 00 UTC to 07/11 00 UTC IOP 15 Cntl_00(cum 0-24 hr) Nud_00 (cum 0-24 hr)
24h precipitation cumulated from 06/11 12 UTC to 07/11 12 UTC IOP 15 Cntl_12(cum 0-24 hr) Nud_12 (cum 0-24 hr)
07/11/99 00 UTC 2m-temperature and 10m-wind Cntl_00 (fcst +24 hr) Nud_00 (fcst +24 hr) Cntl_12 (fcst +12 hr) Nud_12 (fcst +12 hr) -18 -12 -6 0 6 12 18
Main results • IOP 14 • The run with data assimilation provides an improvement of precipitation forecast over North-Western Italy (when compared to the control run), although a maximum not observed is also predicted. • The nudging assimilation scheme has a negligible impact on the forecast of temperature and wind fields • IOP 15 • The run with data assimilation has a non-negligible impact on the forecast of precipitation, but does not bring a substantial improvement. • The use of the nudging assimilation scheme does not have an appreciable impact on the forecast of temperature fields; on the other hand, it allows the generation of different structures in terms of wind forecast. • Possible developments • Play with the nudging coefficients • Generate “synthetic” radar images from the forecasts of Lokal Modell
24h precipitation cumulated from 04/11 12 UTC to 05/11 12 UTC Cntl_12 Nud_12
6h precipitation cumulated from 06/11 18 UTC to 07/11 00 UTC IOP 15 Cntl_00(cum 0-24 hr) Nud_00 (cum 0-24 hr)
6h precipitation cumulated from 04/11 06 UTC to 04/11 12 UTC Cntl_00 (cum 0-6 hr) Nud_00 (cum 0-6 hr)
6h precipitation cumulated from 04/11 00 UTC to 04/11 06 UTC IOP 14 Cntl_00(cum 0-6 hr) Nud_00 (cum 0-6 hr)
6h precipitation cumulated from 06/11 18 UTC to 07/11 00 UTC IOP 15 Cntl_00(cum 0-24 hr) Nud_00 (cum 0-24 hr)