the accuracy of rain intensity measuremen ts and its

EUROPEAN COMMISSION

WG F Thematic Workshop on Implementation of the Floods Directive 2007/60/EC

“FLASH FLOODS AND PLUVIAL FLOODING”

26th – 28th May 2010, Cagliari, Italy

THE ACCURACY OF RAIN

AND ITS INFLUENCE ON

L. G. Lanza(1) , E. Vuerich

(1) Department of Civil, Environmental and Territorial

Italy

(2) Italian Meteorological Service, ReSMA, km 20,100 Braccianese Claudia, 00062

Bracciano, Italy

Abstract

As an outcome of the

gauges organized by the World

been recommended that RI measurements be standardize

international level based on knowledge obtained from those

During the WMO instrument intercomparison in the field and the

associated laboratory tests, highly accurate

collected and made available for scientific investigation. The resulting high

quality data set (contemporary one

on various measuring principles)

insights into the expected behaviour of

and further useful information for National Meteorological Services and

other users. Errors in measurements from

here reported and the pr

common statistics of rainfall extremes

* Corresponding author:

Luca G. Lanza – Dep. of Civil, Environmental and Territorial Engineering

Via Montallegro 1 – 16145 Genoa, Italy

E-mail: [email protected]

COMMISSION – WFD COMMON IMPLEMENTATION STRATEGY



May 2010, Cagliari, Italy

THE ACCURACY OF RAIN INTENSITY MEASUREMEN

AND ITS INFLUENCE ON EXTREME EVENTS STATI

, E. Vuerich(2) *

Department of Civil, Environmental and Territorial Engineering, University of Genova,

Italian Meteorological Service, ReSMA, km 20,100 Braccianese Claudia, 00062

the recent intercomparison of rainfall intensity (RI)

organized by the World Meteorological Organization (WMO), it has

been recommended that RI measurements be standardize

based on knowledge obtained from those

the WMO instrument intercomparison in the field and the

ry tests, highly accurate RI measurements have been


quality data set (contemporary one-minute RI data from 26 gauges based

on various measuring principles) was an important resou

insights into the expected behaviour of RI gauges in operational conditions


rrors in measurements from operational rain gauges are

the propagation of measurement errors into the most

common statistics of rainfall extremes is recalled based on previous work.

Dep. of Civil, Environmental and Territorial Engineering

16145 Genoa, Italy

1 WG F Thematic Workshop on Implementation of the Floods Directive 2007/60/EC

INTENSITY MEASUREMENTS

EXTREME EVENTS STATISTICS

Engineering, University of Genova,

Italian Meteorological Service, ReSMA, km 20,100 Braccianese Claudia, 00062

intercomparison of rainfall intensity (RI)

Meteorological Organization (WMO), it has

been recommended that RI measurements be standardized at an

based on knowledge obtained from those initiatives.

the WMO instrument intercomparison in the field and the

measurements have been


data from 26 gauges based

an important resource to provide

gauges in operational conditions


rain gauges are

opagation of measurement errors into the most

based on previous work.

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1 Introduction

The attention paid to accuracy and reliability in rainfall intensity (RI)

measurements is currently increasing, following

of scientific and practical issues related to the assessment of possible

climatic trends, the mitigation of natural disasters (

the hindering of desertification, the design of structures (building,

construction works) and drainage infrastructure.

effects of inaccurate rainfall data on the information derived from rain

records is not much documented in the literature.

The World Meteorological Organisation (WMO) recognised these emerging

needs and promoted a first Expert Meeting on rainfall intensity in 2001 in

Bratislava (Slovakia). Further to the definition of rainfall intensity and the

related reference accuracy and r

suggested to organise an international intercomparison of

measurement instruments, to be held first in the laboratory and then in

the field. The first Intercomparison started in 2004 and was concluded in

2005. An international standardized procedure for laboratory calibration of

catching type RI gauges and the reference instruments to be used for the

Intercomparison in the Field have become recommendations of the WMO

Commission for Instruments and Methods of Observation (C

Final results are available on the WMO Web site, and

elsewhere (Lanza et al., 2005; Lanza and Stagi, 2008).

Note that some RI gauges were properly modified by manufacturers or

NMHS (National Meteo-Hydrological Services) after

Laboratory Intercomparison and before taking part into the Field

Intercomparison, by improving their performance in terms of accuracy and

according to the above

demonstrating the immediate u






measurements is currently increasing, following the increased


climatic trends, the mitigation of natural disasters (including


and drainage infrastructure. This notwithstanding, the


records is not much documented in the literature.



Further to the definition of rainfall intensity and the

related reference accuracy and resolution, the convened experts

suggested to organise an international intercomparison of


The first Intercomparison started in 2004 and was concluded in

ional standardized procedure for laboratory calibration of

type RI gauges and the reference instruments to be used for the


Commission for Instruments and Methods of Observation (C

Final results are available on the WMO Web site, and have been

, 2005; Lanza and Stagi, 2008).


Hydrological Services) after the results of the first



according to the above-mentioned international recommendations,

demonstrating the immediate usefulness of the intercomparison results.



the increased awareness


including flash floods),


This notwithstanding, the




Further to the definition of rainfall intensity and the

esolution, the convened experts

suggested to organise an international intercomparison of RI


The first Intercomparison started in 2004 and was concluded in

ional standardized procedure for laboratory calibration of

type RI gauges and the reference instruments to be used for the


Commission for Instruments and Methods of Observation (CIMO/WMO).

have been published


the results of the first



mentioned international recommendations,

sefulness of the intercomparison results.

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The main objective of the follow

performance of rainfall intensity measurement instruments in real world

conditions and with a special focus on high rainfall rates. In terms

accuracy, both the Laboratory and Field Intercomparison efforts have

contributed to a quantitative evaluation of counting errors (systematic

“ability to sense”) and catching errors (weather related, wetting,

splashing, evaporation -

several rain gauges demonstrated the possibility to evaluate the

performance of RI gauges at one

recommended by CIMO/WMO.

2 The WMO Intercomparison of RI gauges

The WMO Field Intercomparison o

Meteorological Instruments Experimentations and historic observatory

(RESMA) of the Italian Air Force sited in Vigna di Valle

site selected to host the Intercomparison is a green grass area of 400 m

equipped with 34 evenly positioned concrete platforms for data acquisition

(see Figure 1), and a central pit with four positions, used for the

installation of the working reference

and recommended in the previous WM

The working reference gauges were inserted in a four

Gauge Pit with gauge collectors at the ground level, according to the

standard EN13798: “Specifications for a reference rain gauge pit”.

combined analysis of the reference gauges

estimation of RI in the field, based on their demonstrated performance

during the previous Laboratory Intercomparison.

WMO Laboratory Intercomparison of RI gauges, correcte

rain gauges (TBRG) and weighing gauges (WG) with

and low uncertainty were used as working reference instruments.





The main objective of the follow-up Field Intercomparison wa


conditions and with a special focus on high rainfall rates. In terms


contributed to a quantitative evaluation of counting errors (systematic


- “ability to collect”) of RI gauges.


performance of RI gauges at one-minute resolution in time, as

recommended by CIMO/WMO.

The WMO Intercomparison of RI gauges

WMO Field Intercomparison of RI gauges was held at the


(RESMA) of the Italian Air Force sited in Vigna di Valle (Rome

site selected to host the Intercomparison is a green grass area of 400 m


), and a central pit with four positions, used for the

installation of the working reference – a set of four RI gauges

the previous WMO Laboratory Intercomparison.

The working reference gauges were inserted in a four-fold Reference Rain


standard EN13798: “Specifications for a reference rain gauge pit”.

lysis of the reference gauges did provide the best possible


during the previous Laboratory Intercomparison. Based on

WMO Laboratory Intercomparison of RI gauges, corrected tipping bucket

) and weighing gauges (WG) with a short step response

uncertainty were used as working reference instruments.


ntercomparison was to test the


conditions and with a special focus on high rainfall rates. In terms of


contributed to a quantitative evaluation of counting errors (systematic -


ct”) of RI gauges. Comparison of


minute resolution in time, as

f RI gauges was held at the Centre of


Rome). The field

site selected to host the Intercomparison is a green grass area of 400 m2,


), and a central pit with four positions, used for the

a set of four RI gauges as identified

O Laboratory Intercomparison.

fold Reference Rain


standard EN13798: “Specifications for a reference rain gauge pit”. The

provide the best possible


Based on results of the

d tipping bucket

short step response

uncertainty were used as working reference instruments.

EUROPEAN COMMISSION




Those catching type instruments, out of the selected rain gauges based on

various measuring principles,

reference instruments to be installed in a pit, were preliminarily calibrated

in the laboratory before their final installation at the Field Intercomparison

site. The recognized WMO laboratory at the University of Geno

involved in this task (Lanza and Stagi, 2009)

tests adopted for the previously held WMO Laboratory Intercomparison of

RI gauges. Further tests were performed to investigated the one

performance of the involved

The results reported in this section

compared to the RI composite working reference, where the trend line is

obtained from a power law fitting of the experimental data

RIref) domain. In order

compared to the reference, the lines of th

with the procedure described in

dashed lines. For easier comparison, the in

according to the measurement technique, as shown in Figure 2

Figure 1. The experimental field in Vigna di Valle (Italy)

Results (see e.g. Lanza and Vuerich, 2009)

synchronized TBRGs, corrected by internal algorithms,






various measuring principles, and the four rain gauges selected as



site. The recognized WMO laboratory at the University of Geno

(Lanza and Stagi, 2009), using the same standard


RI gauges. Further tests were performed to investigated the one

performance of the involved instruments.

reported in this section illustrate the trend of each instrument

RI composite working reference, where the trend line is

obtained from a power law fitting of the experimental data

. In order to assess the accuracy of field measurements

compared to the reference, the lines of the tolerance region, calculated

the procedure described in Vuerich et al. (2009), are represented in

dashed lines. For easier comparison, the instruments have been

the measurement technique, as shown in Figure 2

The experimental field in Vigna di Valle (Italy)

(see e.g. Lanza and Vuerich, 2009) indicate that one

s, corrected by internal algorithms, and WGs with the



and the four rain gauges selected as



site. The recognized WMO laboratory at the University of Genoa was

, using the same standard


RI gauges. Further tests were performed to investigated the one-minute

the trend of each instrument

RI composite working reference, where the trend line is

obtained from a power law fitting of the experimental data in the (RI,

to assess the accuracy of field measurements

e tolerance region, calculated

, are represented in

struments have been grouped

the measurement technique, as shown in Figure 2.

The experimental field in Vigna di Valle (Italy).

indicate that one-minute

and WGs with the

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better dynamical stability and shortest step response are the most

accurate instruments for one

highest measurement accuracy with respect to the reference chosen.

Figure 2. Performance of the various

yMcVan = 1.31x0.90

R2 = 0.68

yPAAR = 1.15x0.96

R2 = 0.85

yLASTEM = 1.06x0.96

R2 = 0.72

yDAVIS = 1.16x0.92

R2 = 0.73

yMTX = 0.96x1.0

R2 = 0.79

yEML = 1.21x0.92

R2 = 0.75

0

20

40

60

80

100

120

140

160

180

200

220

0 20 40 60 80 100 120 140

RI reference [mm/h]

RI [m

m/h

]

AP23-PAAR

DQA031-LSI LASTEM

Rain Collector II-DAVIS

y LAMBRECHT = 1.21x

y THIES= 1.01x

0

20

40

60

80

100

120

140

160

180

200

220

0 20 40 60 80 100 120 140

RI reference [mm/h]

RI [m

m/h

]

tolerance region LB-15188-LAMBRECHT

yPLUVIO-OTT = 0.98x

yEWS = 0.98x

y GEONOR= 0.96x

0

20

40

60

80

100

120

140

160

180

200

220

0 20 40 60 80 100 120 140

RI reference [mm/h]

RI

[mm

/h]

tolerance region PLUVIO-OTT

y WXT510-VAISALA= 1.72x0.91

R2 = 0.74

y PVK ATTEX= 1.43x0.82

R2 = 0.53

yPARSIVEL-OTT = 0.82x1.10

R2 = 0.77

yPWD22-VAISALA = 0.81x0.94

R2 = 0.51

yLPM-THIES = 0.93x1.07

R2 = 0.80

0

20

40

60

80

100

120

140

160

180

200

220

0 20 40 60 80 100 120 140

RI reference [mm/h]

RI [m

m/h

]

tolerance region

PARSIVEL-OTT

LPM-THIES






accurate instruments for one-minute RI measurement, since providing the


(a)

(c)

(e)

(g)

(a) TBRGs with no correction

(b) TBRGs with software correction

(c) TBRGs with pulse based correction

(d) Level measurement instruments

(e) WGs with a good dynamic stability

(f) WGs with low dynamic stability

(g) Non catching gauges

Performance of the various instruments against the reference RI

160 180 200 220

PP040-MTX

AP23-PAAR

DQA031-LSI LASTEM

ARG100-EML

RIM7499020-McVan

Rain Collector II-DAVIS

tolerance region

0

20

40

60

80

100

120

140

160

180

200

220

0 20 40 60 80 100 120 140

RI reference [mm/h]

RI [m

m/h

]

tolerance region

UMB7525/I/SIAP-MICROS

PMB2-CAE

R102-ETG

y LAMBRECHT = 1.21x0.96

R2 = 0.81

y THIES= 1.01x0.99

R2 = 0.85

160 180 200 220

PT 5.4032.35.008-THIES

LB-15188-LAMBRECHT

y Precis Mecanique= 1.08x

y KNMI= 1.05x

0

20

40

60

80

100

120

140

160

180

200

220

0 20 40 60 80 100 120 140

RI reference [mm/h]

RI [m

m/h

]

tolerance region

Electrical raingauge-KNMI

yPLUVIO-OTT = 0.98x1.00

R2 = 0.90

yEWS = 0.98x1.00

R2 = 0.81

y GEONOR= 0.96x1.00

R2 = 0.89

160 180 200 220

PLUVIO-OTT

PG200-EWS

T200B-GEONOR

yMETEOSERVIS= 1.01x0.98

R2 = 0.74

y MPS= 1.09x0.95

R2 = 0.59

y VRG101-VAISALA= 1.12x0.75

R2 = 0.12

yEIGENBRODT = 1.09x0.96

R2 = 0.67

0

20

40

60

80

100

120

140

160

180

200

220

0 20 40 60 80 100 120

RI reference [mm/h]

RI [m

m/h

]

tolerance regionMRW500 -METEOSERVIS

160 180 200 220

PWD22-VAISALA

LCR-PVK ATTEX

WXT510-VAISALA



minute RI measurement, since providing the


(b)

(d)

(f)

s with no correction

s with software correction

s with pulse based correction

Level measurement instruments

WGs with a good dynamic stability

dynamic stability

instruments against the reference RI.

y ETG= 1.01x0.99

R2 = 0.88

yCAE = 0.78x1.05

R2 = 0.87

ySIAP-MICROS = 0.92x1.02

R2 = 0.73

140 160 180 200 220

UMB7525/I/SIAP-MICROS

PMB2-CAE

R102-ETG

y Precis Mecanique= 1.08x0.95

R2 = 0.77

y KNMI= 1.05x0.97

R2 = 0.82

140 160 180 200 220

RI reference [mm/h]

R013070-PRECIS MECANIQUE

140 160 180 200 220

RI reference [mm/h]

VRG101-VAISALA

TRwS-MPS

ANS 410/H-EIGENBRODT

MRW500 -METEOSERVIS

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Pulse-corrected TBRGs show similar, but less accurate results. The non

corrected TBRGs, can apply corrections via a post processing software or

provide a correction curve/table to be almost as accurate as the corrected

ones. WGs with lower dynamical

step response at the one minute time scale are less accurate.

non-catching rain gauges agreed well with the reference. Disdrometers

tended to overestimate the rainfall i

optical / capacitive sensor tended to underestimate the rainfall intensity.

3 Error propagation and its impact on statistics

The impact of inaccurate rainfall measurements on the results of scientific

investigation in rainfall related fields is not yet fully clear nor quantified.

With the exception of very few dedicated papers and/or various papers

dealing with the analysis of measurement errors themselves, the issue of

how deeply affected are the obtained results by the

data sources is rarely addressed.

of data often poses serious doubts about the significance of

experimental and theoretical

The effects are not always

negligible as well, depending on the application. Nonetheless scientific

soundness requires that all possible uncertainties are properly taken into

account, and the quality of basic data sources

measurements – should not be an exception. Also, certified accuracy is

needed for operational meteo

framework of a quality assurance system.

La Barbera et al. (2002) investigated the propagation of me

errors into the most common statistics of rainfall extremes and found that

systematic mechanical errors of tipping

biases, e.g. in the assessment of the return period T (or the related non





s show similar, but less accurate results. The non

s, can apply corrections via a post processing software or


ones. WGs with lower dynamical stability or lack of synchronization

step response at the one minute time scale are less accurate.

catching rain gauges agreed well with the reference. Disdrometers

tended to overestimate the rainfall intensity. The microwave radar and the


Error propagation and its impact on statistics

accurate rainfall measurements on the results of scientific

ainfall related fields is not yet fully clear nor quantified.



how deeply affected are the obtained results by the actual accuracy of the

data sources is rarely addressed. The scarce attention paid at the quality

of data often poses serious doubts about the significance of

and theoretical results made available in the literature.

always dramatic, since the error propagation could be



account, and the quality of basic data sources – such

should not be an exception. Also, certified accuracy is

needed for operational meteo-hydrological networks operating within the

framework of a quality assurance system.

(2002) investigated the propagation of me


systematic mechanical errors of tipping-bucket rain gauges may lead to

biases, e.g. in the assessment of the return period T (or the related non


s show similar, but less accurate results. The non-

s, can apply corrections via a post processing software or


stability or lack of synchronization/large

step response at the one minute time scale are less accurate. None of the

catching rain gauges agreed well with the reference. Disdrometers

ntensity. The microwave radar and the


accurate rainfall measurements on the results of scientific

ainfall related fields is not yet fully clear nor quantified.



actual accuracy of the

The scarce attention paid at the quality

of data often poses serious doubts about the significance of both

results made available in the literature.

dramatic, since the error propagation could be



such as rainfall

should not be an exception. Also, certified accuracy is

hydrological networks operating within the

(2002) investigated the propagation of measurement


bucket rain gauges may lead to

biases, e.g. in the assessment of the return period T (or the related non-

EUROPEAN COMMISSION




exceedance probability) of

introduced by systematic mechanical errors of tipping bucket rain gauges

in the estimation of return periods and other statistics of rainfall extremes

was quantified in that work

figures obtained after laboratory tests over a wide set of operational rain

gauges from the network of the Liguria region of Italy. An

sample size was defined as a simple index that practitioner engineers

use to measure the influence of systematic mechanical errors on common

hydrological practice and the derived hydraulic engineering design.

The development of standard limits for the accuracy of rainfall

measurements obtained from tipping

was proposed for use in scientific investigations and as a reference for

operational rain gauge networks to comply with quality assurance systems

in meteorological observations

Molini et al. (2005 a,b) estimated t

errors on the assessment of design rainfall for urban scale applications

based on two rain rate data sets recorded at very different resolution in

time. A random cascade downscaling algorithm

processing of coarse resolu

suitable time scales. The resulting depth

obtained from the original and corrected data sets

quantify the impact of non corrected rain intensity measurements on

design rainfall and the related statistical parameters.

4 Conclusions

The bias induced by systematic mechanical errors of tipping

gauges is usually neglected in the hydrological practice, based on the

assumption that it has little influence on t

It has been demonstrated in





exceedance probability) of short-duration/high intensity events



in that work and in Molini et al. (2001), based on the error


gauges from the network of the Liguria region of Italy. An

defined as a simple index that practitioner engineers

easure the influence of systematic mechanical errors on common


development of standard limits for the accuracy of rainfall

measurements obtained from tipping-bucket and other types of

in scientific investigations and as a reference for


in meteorological observations (Lanza and Stagi, 2008).

(2005 a,b) estimated the effect of systematic mechanical



time. A random cascade downscaling algorithm was

solution data so that correction could

suitable time scales. The resulting depth-duration-frequency curves

obtained from the original and corrected data sets were derived


design rainfall and the related statistical parameters.

The bias induced by systematic mechanical errors of tipping


assumption that it has little influence on the total recorded rainfall depth.

demonstrated in recent works that, since the error increases


vents. The bias



(2001), based on the error


gauges from the network of the Liguria region of Italy. An equivalent

defined as a simple index that practitioner engineers can

easure the influence of systematic mechanical errors on common


development of standard limits for the accuracy of rainfall

bucket and other types of gauges

in scientific investigations and as a reference for


f systematic mechanical



was used for the

tion data so that correction could be applied at

frequency curves

were derived to


The bias induced by systematic mechanical errors of tipping-bucket rain


he total recorded rainfall depth.

that, since the error increases

EUROPEAN COMMISSION




with rainfall intensity, the assumption is not acceptable for the

assessment of design rainfall in

resolution required for the monitoring of rainfall intensities (due to the

very short response time of

influence of mechanical errors on the derived statistics of rainfall

extremes, with a bias that can be quantified as

about 60 to 100% on the assessment of the return period of design

rainfall for duration one hour and return periods from 20 to 200 years.

The WMO Field Intercomparison of Rainfall Intensity Gauges was the first

intercomparison of qua

conditions and one of the most extensive in terms of the number of

instruments involved. The results of the intercomparison confirmed the

feasibility to measure and compare rainfall intensities on a one mi

time scale as required by users and recommended by CIMO and provided

information on the achievable measurement uncertainties.

References

La Barbera P., Lanza L.G. and Stagi L.: Influence of systematic mechanical errors of

tipping-bucket rain gauges o

45(2), 1-9, 2002.

Lanza, L.G. and Stagi, L.: Certified accuracy of rainfall data as a standard requirement in

scientific investigations. Adv. in Geosci.

Lanza, L.G., Leroy, M., Alexadropoulos, C., Stagi, L. and Wauben, W.:

Intercomparison of Rainfall Intensity Gauges

Lanza, L.G. and E. Vuerich: The WMO Field Intercomparison of Rain Intensity Gauges.

Amos. Res., 94, 534-543, 2009.

Molini, A., La Barbera, P., Lanza, L. G., and Stagi, L.: Rainfall intermittency and the

sampling error of tipping-bucket rain gauges.






assessment of design rainfall in hydrological applications. Indeed, the high

tion required for the monitoring of rainfall intensities (due to the

very short response time of small size catchment basins) amplifies the


extremes, with a bias that can be quantified as an und

% on the assessment of the return period of design


Field Intercomparison of Rainfall Intensity Gauges was the first

intercomparison of quantitative rainfall intensity measurements in field


The results of the intercomparison confirmed the

feasibility to measure and compare rainfall intensities on a one mi


information on the achievable measurement uncertainties.


bucket rain gauges on the statistics of rainfall extremes. Water Sci. Techn.


Adv. in Geosci., 16, 43-48, 2008.

Lanza, L.G., Leroy, M., Alexadropoulos, C., Stagi, L. and Wauben, W.:

Intercomparison of Rainfall Intensity Gauges. IOM Rep. No. 84, WMO/TD 1304, 2005.


543, 2009.


bucket rain gauges. Phys. Chem. Earth, 26, 737



ndeed, the high

tion required for the monitoring of rainfall intensities (due to the

catchment basins) amplifies the


an underestimation of

% on the assessment of the return period of design


Field Intercomparison of Rainfall Intensity Gauges was the first

ntitative rainfall intensity measurements in field


The results of the intercomparison confirmed the

feasibility to measure and compare rainfall intensities on a one minute



Water Sci. Techn.,


Lanza, L.G., Leroy, M., Alexadropoulos, C., Stagi, L. and Wauben, W.: WMO Laboratory

. IOM Rep. No. 84, WMO/TD 1304, 2005.



, 737-742, 2001.

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Molini, A., Lanza, L.G., and La Barbera, P.: The impact of

measurement errors on design rainfall for urban

1073-1088, 2005a.

Molini, A., Lanza, L.G. and La Barbera, P.: Improving the uncertainty of rain intensity

records by disaggregation techniques.

Vuerich, E., Monesi, C., Lanza, L.G., Stagi, L. and Lanzinger, E.:

Intercomparison of Rainfall Intensity Gauges

Rep. No. 99, WMO/TD No. 1504, pp. 286, 2009.





Molini, A., Lanza, L.G., and La Barbera, P.: The impact of tipping-

measurement errors on design rainfall for urban-scale applications. Hydrol. Proc.


records by disaggregation techniques. Atmos. Res., 77, 203-217, 2005b.

Vuerich, E., Monesi, C., Lanza, L.G., Stagi, L. and Lanzinger, E.:

Intercomparison of Rainfall Intensity Gauges. World Meteorological Organisation

Rep. No. 99, WMO/TD No. 1504, pp. 286, 2009.


-bucket raingauge

Hydrol. Proc., 19,


217, 2005b.

Vuerich, E., Monesi, C., Lanza, L.G., Stagi, L. and Lanzinger, E.: WMO Field

. World Meteorological Organisation – IOM

the accuracy of rain intensity measuremen ts and its

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