Radar rainfall estimation for the post-event analysis of a Slovenian flash-flood case: application of the mountain reference technique at C-band frequency

Abstract. This article is dedicated to radar rainfall estimation for the post-event analysis of a Slovenian flash flood that occurred on 18 September 2007. The utility of the Mountain Reference Technique is demonstrated to quantify rain attenuation effects that affect C-band radar measurements in heavy rain. Maximum path-integrated attenuation between 15 and 20 dB were measured thanks to mountain returns for path-averaged rain rates between 10 and 15 mm h−1 over a 120-km path. The proposed technique allowed estimation of an effective radar calibration correction factor, assuming the reflectivity-attenuation relationship to be known. Screening effects were quantified using a geometrical calculation based on a digitized terrain model of the region. The vertical structure of the reflectivity was modelled with a normalized apparent vertical profile of reflectivity. Implementation of the radar data processing indicated that: (1) attenuation correction using the Hitschfeld Bordan algorithm allowed obtaining satisfactory radar rain estimates (Nash criterion of 0.8 at the event time scale); (2) due to the attenuation equation instability, it is however compulsory to limit the maximum path-integrated attenuation to be corrected to about 10 dB; (3) the results also proved to be sensitive on the parameterization of reflectivity-attenuation-rainrate relationships. The convective nature of the precipitation explains the rather good performance obtained. For more contrasted rainy systems with convective and stratiform regions, the combination of the vertical (VPR) and radial (attenuation, screening) sources of heterogeneity yields a still very challenging problem for radar quantitative precipitation estimation at C-band.

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Radar rainfall estimation for the post-event analysis of a Slovenian flash-flood case: application of the Mountain Reference Technique at C-band frequency

Hydrology and Earth System Sciences ◽

10.5194/hess-13-1349-2009 ◽

2009 ◽

Vol 13 (7) ◽

pp. 1349-1360 ◽

Cited By ~ 21

Author(s):

L. Bouilloud ◽

G. Delrieu ◽

B. Boudevillain ◽

M. Borga ◽

F. Zanon

Keyword(s):

Flash Flood ◽

Heavy Rain ◽

Radar Data ◽

Rain Attenuation ◽

Event Analysis ◽

Rainfall Estimation ◽

Radar Rainfall ◽

Band Frequency ◽

Event Time ◽

Radar Calibration

Abstract. This article is dedicated to radar rainfall estimation for the post-event analysis of a flash flood that occurred on 18 September 2007 in Slovenia. The utility of the Mountain Reference Technique is demonstrated to quantify rain attenuation effects that affect C-band radar measurements in heavy rain. Maximum path-integrated attenuation between 15 and 20 dB were estimated thanks to mountain returns for path-averaged rain rates between 10 and 15 mm h−1 over a 120-km path. Assuming the reflectivity-attenuation relationship to be known, the proposed technique allows for estimating an effective radar calibration correction factor to be accounted for in the parameterization of the attenuation correction. Screening effects are quantified using a geometrical calculation based on a digitized terrain model of the region. The vertical structure of the reflectivity is modeled with a normalized apparent vertical profile of reflectivity. Implementation of the radar data processing indicates that: (1) the combined correction for radar calibration and attenuation effects allows for obtaining satisfactory radar rain estimates (Nash criterion of 0.8 at the event time scale); (2) due to the attenuation equation instability, it is however compulsory to limit the maximum path-integrated attenuation to be corrected to about 10 dB; (3) the results also prove to be sensitive on the parameterization of reflectivity-attenuation-rainrate relationships.

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Radar rainfall estimation in the context of post-event analysis of flash-flood events

Journal of Hydrology ◽

10.1016/j.jhydrol.2010.02.035 ◽

2010 ◽

Vol 394 (1-2) ◽

pp. 17-27 ◽

Cited By ~ 35

Author(s):

Ludovic Bouilloud ◽

Guy Delrieu ◽

Brice Boudevillain ◽

Pierre-Emmanuel Kirstetter

Keyword(s):

Flash Flood ◽

Event Analysis ◽

Flood Events ◽

Rainfall Estimation ◽

Radar Rainfall

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Close-range radar rainfall estimation and error analysis

Atmospheric Measurement Techniques ◽

10.5194/amt-9-3837-2016 ◽

2016 ◽

Vol 9 (8) ◽

pp. 3837-3850 ◽

Cited By ~ 9

Author(s):

C. Z. van de Beek ◽

H. Leijnse ◽

P. Hazenberg ◽

R. Uijlenhoet

Keyword(s):

Positive Impact ◽

Rain Gauge ◽

Minor Role ◽

Rainfall Estimation ◽

Radar Rainfall ◽

Sources Of Error ◽

Ground Clutter ◽

Received Power ◽

Radar Calibration ◽

Many Sources

Abstract. Quantitative precipitation estimation (QPE) using ground-based weather radar is affected by many sources of error. The most important of these are (1) radar calibration, (2) ground clutter, (3) wet-radome attenuation, (4) rain-induced attenuation, (5) vertical variability in rain drop size distribution (DSD), (6) non-uniform beam filling and (7) variations in DSD. This study presents an attempt to separate and quantify these sources of error in flat terrain very close to the radar (1–2 km), where (4), (5) and (6) only play a minor role. Other important errors exist, like beam blockage, WLAN interferences and hail contamination and are briefly mentioned, but not considered in the analysis. A 3-day rainfall event (25–27 August 2010) that produced more than 50 mm of precipitation in De Bilt, the Netherlands, is analyzed using radar, rain gauge and disdrometer data. Without any correction, it is found that the radar severely underestimates the total rain amount (by more than 50 %). The calibration of the radar receiver is operationally monitored by analyzing the received power from the sun. This turns out to cause a 1 dB underestimation. The operational clutter filter applied by KNMI is found to incorrectly identify precipitation as clutter, especially at near-zero Doppler velocities. An alternative simple clutter removal scheme using a clear sky clutter map improves the rainfall estimation slightly. To investigate the effect of wet-radome attenuation, stable returns from buildings close to the radar are analyzed. It is shown that this may have caused an underestimation of up to 4 dB. Finally, a disdrometer is used to derive event and intra-event specific Z–R relations due to variations in the observed DSDs. Such variations may result in errors when applying the operational Marshall–Palmer Z–R relation. Correcting for all of these effects has a large positive impact on the radar-derived precipitation estimates and yields a good match between radar QPE and gauge measurements, with a difference of 5–8 %. This shows the potential of radar as a tool for rainfall estimation, especially at close ranges, but also underlines the importance of applying radar correction methods as individual errors can have a large detrimental impact on the QPE performance of the radar.

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A physically-based radar calibration method for improved rainfall estimation: application to the Fort-Collins flash flood of 1997

Inverse Problems in Science and Engineering ◽

10.1080/17415970802166527 ◽

2009 ◽

Vol 17 (1) ◽

pp. 115-131 ◽

Cited By ~ 1

Author(s):

Amvrossios C. Bagtzoglou ◽

Justin M. Niedzialek ◽

Sandrine A. Baun ◽

Emmanouil N. Anagnostou ◽

Fred L. Ogden

Keyword(s):

Flash Flood ◽

Calibration Method ◽

Rainfall Estimation ◽

Physically Based ◽

Fort Collins ◽

Radar Calibration

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Close-range radar rainfall estimation and error analysis

10.5194/amt-2016-77 ◽

2016 ◽

Author(s):

Remco van de Beek ◽

Hidde Leijnse ◽

Pieter Hazenberg ◽

Remko Uijlenhoet

Keyword(s):

Positive Impact ◽

Rain Gauge ◽

Minor Role ◽

Rainfall Estimation ◽

Radar Rainfall ◽

Sources Of Error ◽

Ground Clutter ◽

Received Power ◽

Radar Calibration ◽

Many Sources

Abstract. Quantitative precipitation estimation (QPE) using ground-based weather radar is affected by many sources of error. The most important of these are 1) radar calibration, 2) ground clutter, 3) wet radome attenuation, 4) rain induced attenuation, 5) vertical profile of reflectivity, 6) non-uniform beam filling, and 7) variations in rain drop size distribution (DSD). This study presents an attempt to separate and quantify these sources of error in flat terrain very close to the radar (1–2 km), where 4), 5), and 6) only play a minor role. A 3-day rainfall event (25–27 August 2010) that produced more than 50 mm of precipitation in De Bilt, The Netherlands is analyzed using radar, rain gauge, and disdrometer data. Without any correction it is found that the radar severely underestimates the total rain amount (by more than 50 %). The calibration of the radar receiver is operationally monitored by analyzing the received power from the sun. This turns out to cause a 1 dB of underestimation. The operational clutter filter applied by KNMI is found to incorrectly identify precipitation as clutter, especially at near-zero Doppler velocities. An alternative simple clutter removal scheme using a clear sky clutter map improves the rainfall estimation slightly. To investigate the effect of wet radome attenuation, stable returns from buildings close to the radar are analyzed. It is shown that this may have caused an underestimation of up to 4 dB. Finally, a disdrometer is used to derive event and intra-event specific Z-R relations due to variations in the observed DSDs. Such variations may result in errors when applying the operational Marshall-Palmer Z-R relation. Correcting for all of these effects has a large positive impact on the radar derived precipitation estimates and yields a good match between radar QPE and gauge measurements, with a difference of 5 to 8 %. This shows the potential of radar as a tool for rainfall estimation, especially at close ranges, but also underlines the importance of applying radar correction methods as individual errors can have a large detrimental impact on the QPE performance of the radar.

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Utilization of estimated rainfall as an early warning system before flash flood event

Journal of Physics Theories and Applications ◽

10.20961/jphystheor-appl.v2i2.30670 ◽

2018 ◽

Vol 2 (2) ◽

pp. 73

Author(s):

Fara Diva Claudia ◽

Cecylia Putri Mawarni ◽

Kadek Krisna Yulianti ◽

Paulus Agus Winarso

Keyword(s):

Flash Flood ◽

Remote Sensing Data ◽

Heavy Rain ◽

Flash Floods ◽

Extreme Weather ◽

Atmospheric Dynamics ◽

Observation Data ◽

Rainfall Estimation ◽

Wrf Modeling ◽

The Impact

<p class="Abstract">On October 10, 2018 there has been extreme weather in the form of heavy rain accompanied by lightning in Tanah Datar District, West Sumatra. This extreme weather caused flash floods and landslides that killed many people. Therefore, by using remote sensing data in the form of radar and satellite as well as WRF modeling (Weather Research and Forecasting) the authors conducted analysis of heavy rainfall events to determine the estimated rainfall and atmospheric dynamics during the occurrence of flash floods and landslides. WRF modeling is used to determine the condition of atmospheric lability. For the calculation of rainfall estimation, the method used is the Convective Stratiform Technique (CST) method that utilizes satellite data and the Z-R relation selection method that utilizes radar data. Then the calculation results from each method are verified using observation data. Relative bias shows the CST method and the selection of Z-R relations tend to be overestimate, but has a very high correlation value with observation data. Information on rainfall estimation and atmospheric dynamics is expected to be used to provide early warnings aimed at minimizing losses from the impact of disasters.</p>

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Effect of R-Z Relationships Derived from Disdrometer Data on Radar Rainfall Estimation during the Heavy Rain Event on 5 July 2005

Journal of the Korean earth science society ◽

10.5467/jkess.2012.33.7.596 ◽

2012 ◽

Vol 33 (7) ◽

pp. 596-607

Author(s):

GyuWon Lee ◽

Byung-Huk Kwon

Keyword(s):

Heavy Rain ◽

Rain Event ◽

Rainfall Estimation ◽

Radar Rainfall ◽

Heavy Rain Event

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Improved radar data processing algorithms for quantitative rainfall estimation in real time

Water Science & Technology ◽

10.2166/wst.2009.282 ◽

2009 ◽

Vol 60 (1) ◽

pp. 175-184 ◽

Cited By ~ 17

Author(s):

S. Krämer ◽

H.-R. Verworn

Keyword(s):

Real Time ◽

Radar Data ◽

Real Time Control ◽

Rainfall Estimation ◽

Radar Rainfall ◽

Rain Gauges ◽

Microphysical Properties ◽

Time Control ◽

Reflectivity Data ◽

Radar Data Processing

This paper describes a new methodology to process C-band radar data for direct use as rainfall input to hydrologic and hydrodynamic models and in real time control of urban drainage systems. In contrast to the adjustment of radar data with the help of rain gauges, the new approach accounts for the microphysical properties of current rainfall. In a first step radar data are corrected for attenuation. This phenomenon has been identified as the main cause for the general underestimation of radar rainfall. Systematic variation of the attenuation coefficients within predefined bounds allows robust reflectivity profiling. Secondly, event specific R–Z relations are applied to the corrected radar reflectivity data in order to generate quantitative reliable radar rainfall estimates. The results of the methodology are validated by a network of 37 rain gauges located in the Emscher and Lippe river basins. Finally, the relevance of the correction methodology for radar rainfall forecasts is demonstrated. It has become clearly obvious, that the new methodology significantly improves the radar rainfall estimation and rainfall forecasts. The algorithms are applicable in real time.

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