Investigation of tipping bucket rain gauges using digital photographic technology

2020 ◽  
Author(s):  
Minhan Liao ◽  
Jiufu Liu ◽  
Aimin Liao
Keyword(s):  
Traditional Method ◽  
Rainfall Intensity ◽  
Rain Gauge ◽  
Recording Device ◽  
Calculation Formula ◽  
Rain Intensity ◽  
Primary Interest ◽  
Rain Gauges ◽  
Variation Characteristics ◽  
New Formula

<p>When 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 (T<sub>1</sub>) and the time for a complete tip (T<sub>2</sub>) were analyzed in detail. The results showed that T<sub>1</sub> and T<sub>2</sub> were functions of rainfall intensity, and T<sub>1</sub>, T<sub>2</sub> decrease as the rain intensity increases significantly (P<0.001). Moreover, excellent evidence shows that the averages of T<sub>1</sub> and T<sub>2</sub> 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.</p>

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.

Evaluation of Measurement Errors of Tipping Bucket Rain Gauges

2020 ◽  
Author(s):  
Guangxu Jiang ◽  
Jiufu Liu ◽  
Xuegang Li ◽  
Hongwei Liu ◽  
Aimin Liao
Keyword(s):  
Measurement Error ◽  
Double Layer ◽  
Measurement Errors ◽  
Rainfall Intensity ◽  
Single Layer ◽  
Intensity Variation ◽  
Water Volume ◽  
Residual Water ◽  
Rain Intensity ◽  
Rain Gauges

&lt;p&gt;The observation accuracy of rainfall processes affects every aspects of the meteorological and hydrological affairs, which is widely monitored by various types of tipping bucket rain gauges&amp;#65288;TBRs&amp;#65289;because of the simple structure and reliable performance. The study of the measurement errors of TBRs is quite valuable and necessary for improving the rainfall data quality and evaluating the uncertainty of the research based on the dataset.&lt;/p&gt;&lt;p&gt;In this study, an artificial rainfall and monitor experiment system is designed with peristaltic pump, balances, recorder and controller for the accurate rainfall and the TBRs instrumental values record, based on which the error distribution and instrument stability were analyzed. Eight types of TBRs are chose for the error evaluation experiment, including five single-layer TBRs, three double-layer TBRs. For each TBRs, we observe its performance under 6 rain intensity (0.1-4mm/min) in turn. With regard to each rain intensity, when the simulated total rainfall reaches 10 mm, the experiment stops and records the data, then repeats the same experiment 6 times.&lt;/p&gt;&lt;p&gt;The result shows that the single-layer TBRs have a good linear relationship between the rainfall and the measurement error, and the double-layer TBRs has a significant regulating effect on the continuous heavy rain intensity, which can make the rain flow steadily down to the lower tipping bucket (metering tipping bucket) with a stable rain intensity to avoid the rain intensity variation influence on the measurement error. However, due to its high resolution of 0.1mm, it is greatly affected by the residual water volume of the tipper bucket.&lt;/p&gt;&lt;p&gt;According to the results, the single-layer TBRs can correct the actual rainfall measurement process according to the error ~ rainfall intensity curve. The double-layer TBRs can play an important role in the rainy day record, but the randomness of the residual in the tipping bucket needs to be further estimated. Because the proportion of the light rainfall intensity in most of the rainfall events are quite high according to the statistics, it is necessary to have lower measurement error under the light rainfall in the TBRs chosen and calibration process. It's a good idea to choose a combination of rain gauges(0.1mm&amp;0.5mm) to improve the accuracy of rainfall and rainy day.&lt;/p&gt;

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 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.

Calibration of tipping bucket rain gauges

1998 ◽  
Vol 37 (11) ◽  
pp. 139-145 ◽  
Author(s):  
S. Overgaard ◽  
A. H. El-Shaarawi ◽  
K. Arnbjerg-Nielsen
Keyword(s):  
Water Pollution ◽  
High Resolution ◽  
Pollution Control ◽  
Time Lag ◽  
Rain Gauge ◽  
Rain Intensity ◽  
Water Pollution Control ◽  
Rain Gauges ◽  
Rain Fall ◽  
Danish Water

A tipping bucket rain gauge measures rain fall volumes with high resolution, thus enabling calculation of rain intensities. To ensure that the volume of one tipping is independent of the rain intensity a syphon is introduced. However, the syphon introduces problems with respect to both a time lag and problems when reconstructing the underlying rain intensities. This problem is studied in detail. The rain gauge in question is a RIMCO tipping bucket rain gauge, used by the Danish Water Pollution Control Committee (DWPCC). The rain gauge has been tested in the laboratory and in the field. The study shows, that it is possible to reduce the syphon volume to a level where the problems of the syphon are small and yet maintain the same accuracy with respect to volume registrations.

scholarly journals Preliminary Evaluation of the HOBO Data Logging Rain Gauge at the Chuzhou Hydrological Experiment Station, China

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Zehui Zhou ◽  
Bin Yong ◽  
Jiufu Liu ◽  
Aimin Liao ◽  
Niu Wang ◽  
...  
Keyword(s):  
Rainfall Intensity ◽  
Rain Gauge ◽  
Maximum Deviation ◽  
Preliminary Evaluation ◽  
Data Logging ◽  
Rainfall Events ◽  
Rain Gauges ◽  
Experiment Station ◽  
Independent Power Supply ◽  
Hourly Rainfall

As a tipping bucket rain gauge, the HOBO Data Logging Rain Gauge RG3-M (RG3-M) has been widely used for the field precipitation observation owing to its superiority of independent power supply by a small portable battery. To quantify the measurement accuracy of the RG3-M gauge, a standard Manual Gauge (MG) and eight other models of tipping bucket rain gauges were installed at the Chuzhou hydrological experiment station of China. In this study, we first compared and investigated the accumulated mounts of 18 rainfall events of two RG3-M gauges benchmarked by the standard MG. Then, five typical rainfall events were chosen to further analyse the observed accuracy of the RG3-M gauge for different rainfall intensities at hourly temporal scale. Finally, the impacts of wind speed and rainfall intensity on the precipitation measurements of the RG3-M gauge were preliminarily explored. Results indicate that the RG3-M gauge measurement generally underestimates rainfall approximately −4% against the standard MG observation, but the maximum deviation even reaches −12.87%. In terms of the hourly rainfall process, the reliable measurement scope of the RG3-M gauge is ranging from 1.5 to 3 mm/h; however, it should be noted that the underestimation is rather significant at the higher rainfall rates (>6 mm/h). Last, it was found that rainfall intensity is a nonnegligible factor for influencing the measurement of the RG3-M gauge. But the windy effect seems to be insignificant in our experiments, which might be attributed to the similar exposure of the compared gauges.

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 Rain Gauge Inter-Comparison Quantifies Deficiencies in Precipitation Monitoring

La Granja ◽  
2020 ◽  
Vol 31 (1) ◽  
pp. 7-20
Author(s):  
Ryan Padrón ◽  
Jan Feyen ◽  
Mario Córdova ◽  
Patricio Crespo ◽  
Rolando Célleri
Keyword(s):  
Precipitation Amount ◽  
Rain Gauge ◽  
Maximum Deviation ◽  
Rain Intensity ◽  
Rain Gauges ◽  
Low Intensity ◽  
Tropical Highlands ◽  
Absolute Bias ◽  
Andean Highlands

Efforts to correct precipitation measurements have been ongoing for decades, but are scarce for tropical highlands. Four tipping-bucket (TB) rain gauges with different resolution that are commonly used in the Andean mountain region were compared—one DAVIS-RC-II, one HOBO-RG3-M, and two TE525MM TB gauges (with and without an Alter-type wind screen). The relative performance of these rain gauges, installed side-by-side in the Zhurucay Ecohydrological Observatory, south Ecuador, at 3780 m a.s.l., was assessed using the TB with the highest resolution (0.1 mm) as reference, i.e. the TE525MM. The effect of rain intensity and wind conditions on gauge performance was estimated as well, using 2 years of data. Results reveal that (i) precipitation amount for the reference TB is on average 5.6 to 7.2% higher than rain gauges having a resolution ≥0.2 mm; (ii) relative underestimation of precipitation from the gauges with coarser resolution is higher during low-intensity rainfall—a maximum deviation of 11% was observed for rain intensities ≤1 mm h-1; (iii) precipitation intensities of 2 mm h-1 or less that occur 75% of the time cannot be determined accurately for timescales shorter than 30 minutes because of the gauges’ resolution, e.g. the absolute bias is >10%; and (iv) wind has a similar effect on all sensors. This analysis contributes to increased accuracy and homogeneity of precipitation measurements throughout the Andean highlands, by quantifying the key role of rain-gauge resolution.

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