The analysis of appropriate method for Takhli radar rainfall estimation

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Ratchawatch Hanchoowong
Walairat Bunthai1


Weather radar has the ability to consistently measure rainfall promptly as it appears in a wide range of area and offer rainfall data of high resolution in both areal and time manner. Especially when used in coordinate with rainfall data from the automatic rain gauge, the accuracy is greatly increased. However, the errors in rainfall estimation of radar persist as a result of inappropriate relationship Z-R usage, that of adjustment of radar rainfall and ground rainfall, as well as that of diverse physical appearances of the rain that differ correspondingly to their distribution in each rainfall event. This study gathered 230 rainfall events, conducting between August 25, 2018 to August 31, 2020, comprising of hourly rainfall data from 174 automatic rain gauges and radar reflectivity of Takhli radar under its measuring radius of 240 km to analyze the appropriate rainfall estimation method for Takhli radar. The result indicates that rainfall estimation that incorporate relationship Z-R and daily bias adjustment for each rainfall cluster categorized by radar reflectivity value is appropriate estimation method for Takhli radar. This method reduces most of error from inappropriate relationship Z-R usage and that from adjustment of radar rainfall and ground rainfall in comparison to other methods those are taken into consideration. When comparing the proposed method to the rainfall estimation that employs relationship Z-R and daily variable in each rainfall cluster categorized by radar reflectivity value without bias adjustment, the proposed method improve accuracy in rainfall estimation to 2.85%, 5.77%, 1.88% and 32.90% considering from RMSE, MSE, MAE and BIAS, respectively.

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บทความวิจัย (Research Article)


Morin E, Gabella M. Radar-based quantitative precipitation estimation over Mediterranean and dry climate regimes. J Geophys Res. 2007; 112: D20108.

รัชเวช หาญชูวงศ์, วลัยรัตน์ บุญไทย, ศิริลักษณ์ ชุ่มชื่น. การวิเคราะห์หาค่าปรับแก้ตามเวลารายชั่วโมงโดยประยุกต์ใช้วิธี Inverse Distance Weighting เพื่อเพิ่ม

ความถูกต้องในการประเมินฝนเรดาร์อมก๋อย. 2564; 14: 61-73.

Marshall J S, and Palmer W M K. The Distribution of Raindrops with Size. Journal of Meteorology. 1984; 5(4): 165-166.

Mapiam P P, Sriwongsitanon N. Climatological Z-R relationship for radar rainfall estimation in the upper Ping river basin. ScienceAsia. 2008; 34: 215-222.

Hanchoowong R, Weesakul U, Chumchean S. Bias correction of radar rainfall estimates based on a geostatistical technique. ScienceAsia. 2012; 38: 373-385.

Chantraket P, Detyothin C, Pankaew S, Kirtsaeng S. An Operational Weather Radar-Based Calibration of Z–R Relationship over Central Region of Thailand. Int J Eng. 2016; 2: 92–100.

Ramli S, Tahir W. Radar Hydrology: New Z/R Relationships for Quantitative Precipitation Estimation in Klang River Basin, Malaysia, International Journal of Environmental Science and Development. 2011; 2(3).

Ayat H, Kaviaanpour M R, Moazami S,Hong Y, Ghaemi E. Calibration of weather radar using region probability matching method (RPMM), Theor Appl Climatol. DOI 10.1007/s00704-017-2266-7.

Richards W G, Crozier C L. Precipitation measurement with a C-band weather radar in Southern Ontario. Atmos Ocean. 1983; 21: 2505–2514.

Smith J A, Krajewski W F. A modeling study of rainfall rate reflectivity relationships. Water Resour Res. 1993; 29: 2505–2514.

Tokay A, Short D A. Evidence from tropical raindrop spectra of the origin of rain from stratiform versus convective clouds. J Appl Meteorol. 1996; 35: 355–371.

Bringi V, Chandrasekar V, Hubbert J, Gorgucci E, Randeu W, Schoenhuber M. Raindrop size distribution in different climatic regimes from disdrometer and dual-polarized radar analysis. J Atmos Sci. 2003; 60: 354–365.

Lee G W, Zawadzki I. Variability of drop size distributions: time-scale dependence of the variability and its effects on rain estimation. J Appl Meteorol. 2005; 44: 241–255.

Seo D J, Breidenbach J P. Real-time correction of spatially nonuniform bias in radar rainfall data using rain gauge measurements. J Hydrometeorol. 2002; 3: 93–111.

Chumchean S, Seed A. Sharma A. Correcting of real-time radar rainfall bias using a Kalman filtering approach. J Hydrol. 2006; 317: 123–137.

Chiang Y M, Chang F J, Jou B J D, Lin P F. Dynamic ANN for precipitation estimation and forecasting from radar observations. J Hydrol. 334, 250–261, 2007

Rendon S, Vieux B, Pathak C. Continuous forecasting and evaluation of derived Z-R relationships in a sparse rain gauge network using NEXRAD. J Hydrol Eng. 2013; 18: 175–182.

Collier C G, Larke P, May B. A weather radar correction procedure for real-time estimation of surface rainfall. Q J Roy Meteorol Soc. 1983; 109: 589–608.

Kitchen M, Brown R, Davies A G, (1994) Real-time correction of weather radar data for the effects of bright band, range and orographic growth in widespread precipitation. Q J Roy Meteorol Soc. 1994; 120: 1231-1254.

Seo D J. Real-time estimation of rainfall fields using radar rainfall and rain gage data. J Hydrol. 1998; 208: 37–52.

Chumchean S, Sharma A, Seed A (2006) An integrated approach to error correction for real-time radar-rainfall estimation. J Atmos Ocean Tech. 2006; 23: 67–79.

รัชเวช หาญชูวงศ์, วลัยรัตน์ บุญไทย, ศิริลักษณ์ ชุ่มชื่น. การวิเคราะห์หาค่าปรับแก้ตามเวลารายชั่วโมงโดยประยุกต์ใช้วิธี Inverse Distance Weighting เพื่อเพิ่มความถูกต้องในการประเมินฝนเรดาร์อมก๋อย. 2564; 14: 61-73.

Michelson D, Einfalt T, Holleman I, Gjertsen U, Friedrich K, Haase G, Lindskog M, Sztuc J. Weather radar data quality in Europe: Quality control and characterization, COST 717 Working Document WDF_20_200204_1. 2004.

Hydro & meteo GmbH&Co. KG. SCOUT Documentation Version 3.32. Hydro & meteo GmbH & Co. KG. Germany: 2016.

Woodley W, & Herndon A. A raingage evaluation of the Miami reflectivity-rainfall rate relation. Journal of Applied Meteorology.1970; 9(2): 258-264.

Marshall J S, and Palmer W M K. The Distribution of Raindrops with Size. Journal of Meteorology. 1984; 5(4): 165-166.

Futon RA, Breidenbach JP, Seo DJ, Miller DA, O’Brannon T. The WSD–88D rainfall algorithm. Weather Forecasting. 1998; 13: 377 -395.

Doelling I G, Joss J, Riedl J. Systematic variations of Z-R relationships from drop size distributions measured in northern Germany during seven years. Atmospheric Research. 1998; 47-48: 635- 649.

Steiner M, Smith J A. Reflectivity, rain rate, and kinetic energy flux relationships based on raindrop spectra. American Meteorological Society. 2000; 39 : 1923-1940.

Hagen M, Yuter S E. Relations between radar reflectivity, liquid water content, and rainfall rate during the MAP-SOP. Atmospheric Sciences. 2003; 128 : 477-494.

Germann U, Galli G, Boscacci M, Bolliger M. Radar precipitation measurement in a mountainous region, Quarterly Journal of the Royal Meteorological Society. 2006; 132: 1669-1692.

กรมฝนหลวงและการบินเกษตร. โครงการประเมินปริมาณน้า ฝนดว้ยเรดาร์ภาคตะวนัออก. กรมฝนหลวงและการบินเกษตร. 2557.

Mapiam P P, Methaprayum M, Bogaard T A, Schoups G, Veldhuis MC T. Citizen rain gauge improves hourly radar rainfall bias correction using a two-step Kalman filter, Hydrol Earth Syst Sci. 2022; 26: 775–794.

Seed A, Sirivarden L, Sun X, Jordan P, Elliot J. On the calibration of Australian weather radars. Technical report 02/7. 2002; 40.