wmo - teco 2008 st, petersburg, russia, 27-29 november 2008 university of genoa preliminary...
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WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
The WMO Field Intercomparison of RI gauges was started in September 2007 in
Vigna di Valle, Rome (Italy). Installation of the instruments in the field
was preceded by the laboratory calibration of all submitted catching type rain gauges at the University of Genoa.
Periodic testing of these gauges by means of dynamic calibration is now performed
throughout the measurement campaign, using a portable calibration device.
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
Laboratoryof the University of Genoa
Preliminary tests in the laboratory(see WMO Lab
Intercomparison procedure)
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
ID Model Nation Measuring principle
1 7499020BoMV2/RIMCO AUSTRALIA Tipping bucket
2 AP23/PAAR AUSTRIA Tipping bucket
3 R01 3070/PRECIS-MECANIQUE FRANCE Tipping bucket
4 PT 5.4032.35.008/THIES GERMANY Tipping bucket
5 R 102 ETG ITALY Tipping bucket
6 DQA031/LSI LASTEM ITALY Tipping bucket
7 T-PLUV UM7525/I/SIAP-MICROS ITALY Tipping bucket
8 PM B2 CAE ITALY Tipping bucket
9 RAIN COLLECTOR II7852 DAVIS USA Tipping bucket
10 15188/LAMBRECHT GERMANY Tipping bucket
11 PP040/MTX ITALY Tipping bucket
12 ARG100/ENV. MEAS. Lmt. BRASIL / UK Tipping bucket
13 MRW500 METEOSERVIS CZECH REP. Weighing gauge
14 VRG101/VAISALA FINLAND Weighing gauge
15 PLUVIO/OTT GERMANY Weighing gauge
16 T-200B / GEONOR NORVAY Weighing gauge
17 TRwS/MPS SVOLACK REP. Weighing gauge
18 ANS 410-H/EIGENBRODT GERMANY Pressure sensor
19 Electrical rain gauge/KNMI NETHERLAND Level sensor
List of catching-type instruments involved
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
Box-plots indicate the mean (solid line), median (thin line), 25-75th percentiles (box limits), 10-90th percentiles (whisker caps) and outliers (black circles).
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
Tipping-bucket (pit gauge)Aggregation : 1 min
-10
-5
0
5
10
0 100 200 300
Ir [mm/h]
Error [%]
Weighing gaugeAggregation : 1 min
-10
-5
0
5
10
0 100 200 300
Ir [mm/h]
Error [%]
Novel approach:tests are performed atone-minute resolution.“Instantaneous” RI rather than long term averages.
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
Box-plots indicate the mean (solid line), median (thin line), 25-75th percentiles (box limits), 10-90th percentiles (whisker caps) and outliers (black circles).
Best performing tipping-bucket rain gauge
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
Box-plots indicate the mean (solid line), median (thin line), 25-75th percentiles (box limits), 10-90th percentiles (whisker caps) and outliers (black circles).
Best performing weighing gauge
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
Box-plots indicate the mean (solid line), median (thin line), 25-75th percentiles (box limits), 10-90th percentiles (whisker caps) and outliers (black circles).
Typical (left) and bad (below) tipping-bucket rain gauges
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
0
100
50
0
10050 75
75
Iref [mm h-1]
Imeas [mm h-1]
200100
300
250150
100
150
200
250
300 Iref [mm h-1]
Imeas [mm h-1]
Range: 0-100 mm·h-1 Range: 100-300 mm·h-1
Note: both axes of the graphs are distorted by a power factor of three.
All catching type rain gauges
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
Range: 0-100 mm·h-1 Range: 100-300 mm·h-1
Note: both axes of the graphs are distorted by a power factor of three.
All tipping-bucket rain gauges
0
100
50
0
10050 75
75
Iref [mm h-1]
Imeas [mm h-1]
200100
300
250150
100
150
200
250
300
Iref [mm h-1]
Imeas [mm h-1]
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
Range: 0-100 mm·h-1 Range: 100-300 mm·h-1
Note: both axes of the graphs are distorted by a power factor of three.
Tipping-bucket rain gauges with correction
0
100
50
0
10050 75
75
Iref [mm h-1]
Imeas [mm h-1]
200100
300
250150
100
150
200
250
300 Iref [mm h-1]
Imeas [mm h-1]
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
Range: 0-100 mm·h-1 Range: 100-300 mm·h-1
Note: both axes of the graphs are distorted by a power factor of three.
Weighing rain gauges
0
100
50
0
10050 75
75
Iref [mm h-1]
Imeas [mm h-1]
200100
300
250150
100
150
200
250
300 Iref [mm h-1]
Imeas [mm h-1]
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
A portable device was developed at the University of Genoa with the aim of providing the on-site capability of performing the same kind of tests that were preliminarily used for calibration of all submitted catching type rain gauges under controlled conditions in the laboratory.
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
The principle exploited by this portable device is that of preserving a constant
hydraulic head over a given orifice area by ensuring the automatic and continuous
pressure adaptation of the air/water contained inside a closed container.
The transit time of the water level between two fixed limits is the only variable to be
measured to complete the test at any reference rainfall intensity.
In order to reduce the sampling error, with reference to e.g. a tipping-bucket rain gauge
having a resolution of 0,2 mm (bucket volume of 20 g) and a collector’s area of 0,1
m2, the container should be filled in with at least 2 litres of water, so that at least 100 tips
of the buckets will occur. Patent n° 102006A000868 dated 07/12/2006
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
Application in the field test site
WMO procedure for field verification …
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
ConclusionsThe laboratory phase of the RI Field Intercomparison proved to be very useful in providing basic information on the behaviour of the catching type instruments involved, in order to single out counting errors from the assessment of the overall accuracy of the instruments, with specific reference to their catching errors and uncertainties due to the operating conditions (dynamic performances, wind and atmospheric conditions, etc.). In this view the laboratory calibration tests were performed at the resolution of one minute, so that the spreading of the errors around their average value already investigated during the previous Laboratory Intercomparison could be also evaluated.
The development of a portable Field Calibration Device to be used for checking the instruments as installed – with no need to return them to the laboratory where standard calibration tests can be performed – was very effective in keeping the behaviour of the instruments under control throughout the measurement campaign. The operational procedure is that of comparing on a regular basis the calibration data of each instrument at a few calibration points (constant flow rates) with the full calibration curves preliminarily obtained in the laboratory, and this is currently used as a criterion to assess the correct behaviour of that particular instrument.
WMO - TECO 2008St, Petersburg, Russia, 27-29 November 2008
University of Genoa
PRELIMINARY LABORATORY CALIBRATION AND VERIFICATION OF THE GAUGES USING A FIELD CALIBRATION DEVICE LANZA, L.G., STAGI, L., VUERICH, E. and F. MALASPINA
ITALIAN AIR FORCEMETEOROLOGICAL SERVICE
Future perspectives
The calibration in the field using a portable device allows investigating the achievable uncertainty in the field – filling the gap between precise (though far from the real world) laboratory tests and the necessary metrological confirmation in the field.
The experience gained at the laboratory of the University of Genoa and at the field site in Vigna di Valle (Rome) were very fruitful and allowed to develop a consistentspecific know-how on rainfall intensity measurements and the related instruments.
It is important that after completion of this RI intercomparison the acquired know-how and the professional capacities developed are not abandoned. Specific operational structures dedicated to rainfall intensity measurements so as to ensure the quality, continuity, homogeneity and archiving/accessibility of the related information could be easily built upon such capacities.This same structures will exploit the above capacity and technical-scientific know-how as well as operational capacities in verification, calibration, metrological confirmation and performance testing on prototype and commercial instruments.