scholarly journals Certified accuracy of rainfall data as a standard requirement in scientific investigations

2008 ◽  
Vol 16 ◽  
pp. 43-48 ◽  
Author(s):  
L. G. Lanza ◽  
L. Stagi
Keyword(s):  
Rainfall Intensity ◽  
Rain Gauge ◽  
Standard Requirement ◽  
Accuracy Requirement ◽  
Rain Gauges ◽  
Scientific Investigations ◽  
Intensity Measurements ◽  
Meteorological Observations ◽  
Instrument Intercomparison ◽  
Rain Data

Abstract. This paper elaborates on the rationale behind the proposed standard limits for the accuracy of rainfall intensity measurements obtained from tipping-bucket and other types of rain gauges. Indeed, based on experimental results obtained in the course of international instrument Intercomparison initiatives and specific laboratory tests, it is shown here that the accuracy of operational rain gauges can be reduced to the limits of ±1% after proper calibration and correction. This figure is proposed as a standard accuracy requirement for the use of rain data in scientific investigations. This limit is also proposed as the reference accuracy for operational rain gauge networks in order to comply with quality assurance systems in meteorological observations.

scholarly journals On the Use of Dynamic Calibration to Correct Drop Counter Rain Gauge Measurements

Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6321
Author(s):  
Mattia Stagnaro ◽  
Arianna Cauteruccio ◽  
Luca G. Lanza ◽  
Pak-Wai Chan
Keyword(s):  
Rainfall Intensity ◽  
High Sensitivity ◽  
Fast Response ◽  
Rain Gauge ◽  
Dynamic Calibration ◽  
Event Scale ◽  
Rain Gauges ◽  
Intensity Measurements ◽  
The One ◽  
The Impact

Dynamic calibration was performed in the laboratory on two catching-type drop counter rain gauges manufactured as high-sensitivity and fast response instruments by Ogawa Seiki Co. Ltd. (Japan) and the Chilbolton Rutherford Appleton Laboratory (UK). Adjustment procedures were developed to meet the recommendations of the World Meteorological Organization (WMO) for rainfall intensity measurements at the one-minute time resolution. A dynamic calibration curve was derived for each instrument to provide the drop volume variation as a function of the measured drop releasing frequency. The trueness of measurements was improved using a post-processing adjustment algorithm and made compatible with the WMO recommended maximum admissible error. The impact of dynamic calibration on the rainfall amount measured in the field at the annual and the event scale was calculated for instruments operating at two experimental sites. The rainfall climatology at the site is found to be crucial in determining the magnitude of the measurement bias, with a predominant overestimation at the low to intermediate rainfall intensity range.

scholarly journals Analysis of highly accurate rain intensity measurements from a field test site

2010 ◽  
Vol 25 ◽  
pp. 37-44 ◽  
Author(s):  
L. G. Lanza ◽  
E. Vuerich ◽  
I. Gnecco
Keyword(s):  
Rainfall Intensity ◽  
Test Site ◽  
Quality Data ◽  
Rain Intensity ◽  
Data Set ◽  
High Quality Data ◽  
Operational Conditions ◽  
Rain Gauges ◽  
Intensity Measurements ◽  
Instrument Intercomparison

Abstract. In the course of the recent WMO international instrument intercomparison in the field and the associated specific laboratory tests, highly accurate rainfall intensity measurements have been collected and made available for scientific investigation. The resulting high quality data set (contemporary one-minute rainfall intensity data from 26 gauges based on various measuring principles) constitutes an important resource to provide insights into the expected behaviour of rain intensity gauges in operational conditions and further useful information for National Meteorological Services and other users. A few aspects of the analysis of one-minute resolution rain intensity measurements are discussed in this paper, focusing on the observed deviations from a calculated reference intensity based on four pit gauges. Results from both catching and non-catching type gauges are discussed in relation with suitable tolerance limits obtained as a combination of the estimated uncertainty of the reference intensity and the WMO accuracy limits for rainfall intensity measurements. It is shown that suitably post-processed weighing gauges and tipping-bucket rain gauges had acceptable performance, while none of the non-catching rain gauges agreed well with the reference.

scholarly journals Numerical and Experimental Investigation on the Function of Siphons for Tipping-Bucket Rain Gauges

2020 ◽  
Vol 37 (7) ◽  
pp. 1189-1201 ◽  
Author(s):  
Zhao Cai ◽  
Jiufu Liu ◽  
Aimin Liao ◽  
Xuegang Li ◽  
Minhan Liao
Keyword(s):  
Structural Design ◽  
Laboratory Experiments ◽  
Rainfall Intensity ◽  
Outer Part ◽  
Rain Gauge ◽  
Cfd Simulations ◽  
Rain Gauges ◽  
Computational Fluid Dynamics Cfd ◽  
Simulation Results ◽  
Two Parameters

AbstractSiphons can effectively reduce the influence of rainfall intensity on the mechanical bias of tipping-bucket rain gauges (TBRs). To identify the function of siphons for TBRs, this study investigated three types of siphons: a Texas Electronics (TE) siphon, a RIMCO (RIM) siphon, and a Sutron siphon, with both computational fluid dynamics (CFD) simulations and laboratory experiments. To provide better structural designs, further simulations were conducted to adjust two parameters of the siphons: d, the distance from the cap to the outer part, and w, the distance from the main part to the cap part. The simulation results reveal that the most significant advantage of a siphon over a rain gauge collector is to provide stable outflow for the tipping bucket. The stable outflow rates were around 1.5 g s−1 (TE) and 1.55 g s−1 (RIM), while the Sutron siphon increased from 1.75 to 2.45 g s−1. The ratio of stable outflow time to a complete siphon event was 69% (TE), 81% (Sutron), and 83% (RIM). In experiments with rainfall intensity higher than 1 mm min−1, the RIM and TE siphons showed oscillations in the outflow during consecutive siphon events, whereas the Sutron siphon was relatively stable. Further simulations showed that the recommended d and w for the TE siphon are 2.5 and 1.1 mm, respectively, while the recommendations for the RIM siphon are d = 2.5 mm and w = 0.9 mm. The manufacturer’s specifications for d and w are best for the Sutron siphon. These results help to understand the functionality of siphons for TBRs, and benefit the structural design of common siphons.

scholarly journals Parameterization of the Collection Efficiency of a Cylindrical Catching-Type Rain Gauge Based on Rainfall Intensity

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3431
Author(s):  
Arianna Cauteruccio ◽  
Luca G. Lanza
Keyword(s):  
Field Experiments ◽  
Rainfall Intensity ◽  
Collection Efficiency ◽  
Fluid Dynamic ◽  
Rain Gauge ◽  
Representative Specimen ◽  
Measurement Instruments ◽  
Widespread Application ◽  
Rain Gauges ◽  
Tracking Model

Despite the numerous contributions available in the literature about the wind-induced bias of rainfall intensity measurements, adjustments based on collection efficiency curves are rarely applied operationally to rain records obtained from catching-type rain gauges. The many influencing variables involved and the variability of the results of field experiments do not facilitate the widespread application of adjustment algorithms. In this paper, a Lagrangian particle tracking model is applied to the results of computational fluid dynamic simulations of the airflow field surrounding a rain gauge to derive a simple formulation of the collection efficiency curves as a function of wind speed. A new parameterization of the influence of rainfall intensity is proposed. The methodology was applied to a cylindrical gauge, which has the typical outer shape of tipping-bucket rain gauges, as a representative specimen of most operational measurement instruments. The wind velocity is the only ancillary variable required to calculate the adjustment, together with the measured rainfall intensity. Since wind is commonly measured by operational weather stations, its use adds no relevant burden to the cost of meteo-hydrological networks.

scholarly journals Investigation of Tipping-Bucket Rain Gauges Using Digital Photographic Technology

2020 ◽  
Vol 37 (2) ◽  
pp. 327-339 ◽  
Author(s):  
Minhan Liao ◽  
Jiufu Liu ◽  
Aimin Liao ◽  
Zhao Cai ◽  
Yixin Huang ◽  
...  
Keyword(s):  
Traditional Method ◽  
Rainfall Intensity ◽  
Rain Gauge ◽  
Recording Device ◽  
Calculation Formula ◽  
Rain Intensity ◽  
Primary Interest ◽  
Rain Gauges ◽  
Variation Characteristics ◽  
New Formula

AbstractWhen studying the tipping-bucket rain gauge (TBR), it is rather difficult to make an objective and sophisticated measurement of the duration of bucket rotation. From the perspective of digital photographic technology, however, the problem can be easily solved. The primary interest of this research has been to use digital photographic technology to study the TBR under laboratory conditions. In this study, the interframe difference algorithm and a camera recording device were used. Based on three types of JDZ TBRs, the time variation characteristics of bucket rotation were obtained. The time from the beginning of a tip to the time that the bucket is horizontal T1 and the time for a complete tip T2 were analyzed in detail. The results showed that T1 and T2 were functions of rainfall intensity, and T1 and T2 decrease as the rain intensity increases significantly (P < 0.001). Moreover, excellent evidence shows that the averages of T1 and T2 were positively correlated with bucket mass. It took more time for the bucket to tip as the mass of the bucket increased. Furthermore, the error of each TBR was calculated by the new proposed error calculation formula, and the new method was compared with the traditional method. The results from the two methods were very close, which demonstrates the correctness and feasibility of the new formula. However, the traditional calibration cannot acquire the variation characteristics of the tipping time, but the proposed approach can achieve this.

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