QPF verification of DWD-LM and LAMI model using high resolution non-GTS data in Piedmont region and Northern Italy Working Group 5: Verification and Case Studies (Co-ordinator C.Cacciamani ARPA-SMR) 4th COSMO meeting September 2002 Warsaw Massimo Milelli Elena Oberto Renata Pelosini Paolo Bertolotto

Overview: the W.P since Athens Verification of the QPF based on the Lokal DWD model using high resolution non-GTS data coming from: –Piedmont Region (from 01/2000 to 06/2002) –Italian Regions (Trentino, Veneto, Emilia Romagna, Marche, Liguria, Piemonte) from 03/2001 to 06/2002 For Piedmont region we have averaged over warning areas; for Italian region over boxes sized 0.50° *0.50° (about 50 km * 50 km) that represent the measurement of a mean basin.

Piedmont “warning areas” 11 “basins”, 3000 km 2 each –1-2 ECMWF grid points –60 Lokal Modell grid points Each “basin” is a group of neighbouring hydrological catchments

Verification over Piedmont basins average in 24h (01/ /2002) LM12 is slightly better than LM00 overestimate for low thresholds for the first 24h greater underestimate of LM00 for high thresholds The first 24h are better than the second (decline with time)

Verification over Piedmont basins average in 24h (01/ /2002) Good results (all the points are in the upper left part) LM12+24: good skills for all thresholds (%HR>>%FAR) skill decreases with time

Situation of data set for Italy:  data used  data not yet useful  data soon available

Verification over Italy, box 0.5° average in 24h (03/ /2002) Underestimate for thresholds > 10 mm Are these stations representative of high precipitation? About 45 grid point/box compare with 4/5 station point: is there any smooth of the forecasted signal ?

Verification over Italy, box 0.5° average in 24h (03/ /2002)

2 Sensitivity: we have carried out a parametric study of the averaging mesh size, in order to find the optimum area for QPF evaluation. Data from: –Piedmont Region (from 01/2000 to 06/2002) –Italian Regions (Trentino, Veneto, Emilia Romagna, Marche, Liguria, Piemonte) from 03/2001 to 06/2002

AA perform slightly better Sensitivity over Piedmont, boxes average in 24h 01/ /2002

verification sensitive to the definition of the areas Sensitivity over Piedmont, boxes average in 24h 01/ /2002

Sensitive to area size not all the boxes considered all the boxes taken into account Sensitivity over italian regions, boxes average in 24h 03/ /2002

Sensitivity over italian regions, boxes average in 24h 03/ /2002

3 Verification of LAMI model using high resolution non- GTS data from Piedmont region, warning areas averaged, over period from 06/2002 to 08/2002 Lami12 is better than Lami00 the first 24h overestimate more than the second 24h

A comparison of the two models: Lami +24 overestimates more than LM +24 Lami +48 has a different behaviour with respect to the thresholds and it is worse than LM +48

Conclusions Generally, the 12 runs (LAMI and LM-DWD) have better skills more inertia of the atmosphere at 00 UTC in the triggering of the precipitation The model performance decreases with time (known !) Lami first 24h overestimates the precipitation: probably due to the missing data assimilation cycle Sensitivity tests show a great dependency of the QPF skill on area definition; this definition has to be based on the morphology and on the climatology of severe events the QPF skill for hydrogeological risk assessment over Piedmont is good (importance of working with end-user targeted verification)

Precipitation thresholds for warning over Piedmont basins averaged in 24h 01/ /2001