Verification of LAMI (Local Area
Model Italy) using non-GTS Data over
Mountainous Regions
Elena Oberto (*), Stefano Bande (*), Massimo Milelli (*)
(*) ARPA Piemonte, Torino, Italy
LAMI model
Non-hydrostatic Limited Area Model
(Italian version) developed in the
framework of the COSMO (Consortium for
Small-Scale Modelling) project between
Germany, Poland, Switzerland, Greece and
Italy.
Technical aspects:
•Domain: 50°/2°/32°/24° (234*272 grid
points)
•Resolution: 0.0625° (7.5 Km)
•Vertical layers: 35
•Forecast time: +48h (+72h available since
Dec ‘02: not taken into account because of
the poor statistics)
•Model runs: 00,12 UTC
•Boundary conditions: GME (DWD)
•Initial conditions: GME (nudging version
available since Dec ‘02: not taken into
account because of the poor statistics)
Objectives
• Verification of precipitation above 1000 m:
– LAMI model output compared to observations over the
western alpine chain. This is a study of high resolution
model reliability in case of complex orography in
perspective of the XX Olympic Winter Games in 2006.
– Period considered: Oct ‘02- Feb ‘03.
– Standard
schemes
of
precipitation
verification:
contingence tables for different thresholds and statistical
indices like BIAS, ETS, FAR and HRR.
– Very dense non-GTS network of rain gauges (126) in the
north-west part of the Alps (Piemonte, Liguria, Valle
d’Aosta, Ticino) above 1000 m.
– Method: comparison between station point and grid point
(the one with the closest elevation among the 4 surrounding
grid points).
• Verification of vertical profile:
– The new radiosounding of Cesana Pariol (1545 m), placed in the
Olympic area, is used to compare the observed and forecasted
vertical temperature profiles (at 00UTC every day)
– An other radiosounding in our region is placed near Cuneo Levaldigi
Airport (installed in 1999, since 1 year it is a GTS station): we
perform the same vertical temperature profile verification to have
a comparison with a station in a non-mountainous area.
– Mean error (BIAS) and Root Mean Square Error for each level
(averaged levels every 25hPa) of the temperature vertical profile
(00UTC LAMI run for +24h and +48h forecast time) from Dec ‘02
to Feb ‘03.
– Cesana Pariol (45° N 6.8° E):
station point 1545 m
grid point
1970 m
– Cuneo Levaldigi (44.5° N 7.6° E): station point 386 m
grid point
387 m
Rain gauges network
•126 station above 1000 m
•Regions interested:
Piemonte, Valle d’Aosta,
Liguria, Ticino
 Cesana sounding
 Cuneo sounding
LAMI00-LAMI12: comparison between the first and
the second 24h versus thresholds
ETS: results between 0.25-0.35  no significative differences between the two runs
and between the two days of integration.
BIAS: globally good results, always greater than 1, for high thresholds the first 24h
of both runs perform better especially for 12UTC.
ROC diagram
confirms previous
results: small
differences
between the two
runs, but less FAR
for the first
integration time
thresholds(mm)
LAM00_0024
LAM00_2448
LAM12_0024
LAM12_2448
OSS
FOR
OSS
FOR
OSS
FOR
OSS
FOR
5
1675
2136
1499
1804
1349
1930
1333
1676
10
1087
1282
1009
1172
895
1110
867
1046
20
586
677
576
700
497
585
457
540
35
303
350
305
434
261
308
218
309
50
193
200
191
290
158
180
121
206
75
95
122
93
183
86
80
61
105
LAMI00-LAMI12: comparison of the 12h-QPF performance
for 3 fixed thresholds
• For every thresholds there is a diurnal
cycle of error.
• The precipitation is generally
overestimated
• BIAS influenced by the diurnal cycle
more than forecast time
• BIAS better in the morning (00-12UTC)
The same behaviour comes out in
ETS index for low thresholds only;
for high thresholds (not shown
here) the signal is smoothed.
LAMI00-LAMI12: BIAS for the 6h-QPF
Concerning the low
thresholds, the same
diurnal cycle is evident: the
worst results are found
during the night (1800UTC)
Cuneo sounding
• bad agreement with
observation close to
the ground
• bias > 1 in the first
levels probably due
to a wrong heat flux
parameterisation
that gives a colder
model forecast
• above 700 hPa:
good bias for both
forecast times
• above 800 hPA:
+24h rmse is better
than +48h rmse,
slight worsening of
the results with
time.
Cesana sounding
• 800 hPa - 700
hPa: model T is
cooler than
observation due
to the elevation
difference and
to a systematic
underestimation
• worsening in
time: +24h bias
is closer to 0
than +48 bias,
+24h rmse is
higher than
+48h.
Conclusions
• Globally good skills for LAMI QPF verification:
general overestimation in precipitation, worsening
in time.
• Diurnal cycle present and quite evident with worst
results during the coldest hours.
• Good results for the vertical temperature profile
above 700 hPa.
• Problems close to the ground probably due to the
physical parameterisations.
• Next step: verification of the other variables of
the sounding (Rh, DwT, wind direction and velocity)