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Simulations of MAP IOPs 14-15 with Lokal Modell: impact of nudging on forecast precipitation

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. 6 th CARPEDIEM Project Meeting Helsinki, June 24, 2004. Lokal Modell (LM).

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Simulations of MAP IOPs 14-15 with Lokal Modell: impact of nudging on forecast precipitation

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  1. 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 6th CARPEDIEM Project Meeting Helsinki, June 24, 2004

  2. 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

  3. 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

  4. IOP14: performed runs 03/11 00 UTC 04/11 00 UTC assimilation forecast

  5. 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)

  6. 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

  7. IOP15: performed runs

  8. 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)

  9. 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)

  10. 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

  11. 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 • Multi-analysis experiments (Hirlam-Lokal Modell)

  12. 24h precipitation cumulated from 04/11 12 UTC to 05/11 12 UTC Cntl_12 Nud_12

  13. IOP14: performed runs

  14. 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)

  15. 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)

  16. 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)

  17. 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)

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