Comparison of Gage and Radar Methods of Convective Rain Measurement

Woodley, William L.; Olsen, A.R.; Herndon, Alan; Wiggert, Victor

doi:10.1175/1520-0450(1975)014<0909:cogarm>2.0.co;2

Cited by 86 publications

(32 citation statements)

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“…These data were also used for estimates of rain rates using the Z-R relationship in Marshall and Palmer (1948) (Z = aR b , where Z = dBZ, R = rain rate). However, coefficients of the Z-R relationship depend on the precipitation type and the observation area involved (Fujiwara, 1965;Woodley et al, 1975;Steiner et al, 1995). Especially, those coefficients were different between convective cloud and stratus.…”

Section: Data and Methods Of Analysis A Datamentioning

confidence: 99%

Thermodynamic characteristics associated with localized torrential rainfall events in the southwest region of the Korean peninsula

Jung

Kwon

Han

et al. 2015

Asia-Pacific J Atmos Sci

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This study uses observational data from radar and radiosonde to investigate the thermodynamic conditions related to localized torrential rainfall (LTR) in the southwest region of the Korean peninsula. Three criteria were defined for selecting LTR events: 1) hourly rainfall exceeding 30 mm h −1 recorded at any of the automated synoptic observing systems (ASOS) around Gwangju, 2) an area of rainfall at > 1 mm h −1 (as estimated from radar rain rate) of less than 20,000 km 2 , and 3) clearly defined stages of genesis and dissipation in a group of rain cells (> 10 mm h −1 ) with a duration lasting less than 24 hours. As a result, 10 cases were selected from the summer season (June-August) over the last decade (2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013). Results showed all cases occurred during the afternoon hours and that the duration and maximum rain area of convective cells (> 30 mm h −1 ) was less than 6 hours and smaller than 700 km 2 , respectively. The majority of cases showed the following thermodynamic characteristics: 1) strong convective available potential energy (CAPE > 1,500 J kg −1 ) related to surface heating, 2) weak (or no) convective inhibition (CIN < 50 J kg −1 ), 3) adequate moisture and total precipitable water (TPW ≈ 55 mm), and 4) values of storm relative helicity (SRH) of less than 10 m 2 s −2 . The area of rainfall (700 km 2 ) and the duration (6 h) in this experiment were relatively small and short, respectively, compared to those in a previous study in the middle-west region of Korea (1,000 km 2 , 9 h), but a higher CAPE (1,500 J kg −1 ) and lower SRH (10 m 2 s −2 ) were involved in this study than in the former (800 J kg −1 , 120 m 2 s −2 ).

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Section: Data and Methods Of Analysis A Datamentioning

confidence: 99%

Thermodynamic characteristics associated with localized torrential rainfall events in the southwest region of the Korean peninsula

Jung

Kwon

Han

et al. 2015

Asia-Pacific J Atmos Sci

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“…The leading edge and the trailing edge were defined as the front and rear sides of the convective center, respectively. The threshold value of 20 mm h -1 corresponds to a radar reflectivity of 42 dBZ when the ZR relationship that is applied for convectional rain by Woodley et al (1975) and Gagin et al (1985) is used. Tokay and Short (1996) found that all convective spectra measured by a disdrometer had a rainfall rate greater than 20 mm h were excluded from the analysis since data with very low rainfall rate sometimes cause large scatter in RDSD characteristics.…”

Section: Classification Of Precipitation Typementioning

confidence: 99%

Microphysical Properties of Maritime Squall Line Observed on June 2, 2008 in Taiwan

Jung

Lee

Jou

et al. 2012

Journal of the Meteorological Society of Japan

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The physical characteristics of rain are reflected by the shape of the raindrop size distribution (RDSD). Specifically, the RDSD is the result of different precipitation formation processes. We measured the RDSD at the surface in heavy rainfall during SoWMEX/TiMREX (2008) in Taiwan. The heavy rainfall was characterized by a squall line accompanied by trailing stratiform precipitation, and it was partitioned into three regions based on radar reflectivity patterns: convective line, stratiform, and reflectivity trough. The convective line was further partitioned into the convective center, leading edge, and trailing edge using a threshold rainfall intensity of 20 mm h -1 .The leading edge, which belongs to the convective line, had upward motion from the surface and contained many small drops. The leading edge was characterized by a small median volume diameter (D 0 ) and a linear shape of gamma RDSD. In the convective center, a strong updraught rose to the top of the cell with time, and many large drops over 4 mm were observed. The convective center, which had large D 0 and normalized intercept parameter (N W ), was characterized by an upward convex shape of gamma RDSD. The range of raindrop diameter decreased toward the trailing edge, with no updraught or only weak updraughts at high altitudes. The trailing edge had large shape and slope parameters, along with a more upward convex shape of gamma RDSD. A bright band was observed in the stratiform region with continual downward motion from the bright band to the surface, even though the intensity became weak. In the stratiform region, D 0 and N W were small and the gamma RDSD had an upward convex shape.The different RDSDs in each region of a maritime squall line suggest the existence of different cloud microphysical processes described by the change of RDSD parameters: the coalescence process induces an increase of D 0 and shape parameter and a decrease of N W , while the break-up process induces a decrease of D 0 and an increase of N W .In comparison with other maritime storms, the convective center has small log 10 N W and large D m value. And the convective edge region is positioned between convective center and stratiform region in the D m -log 10 N W scatter plot.

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“…Blanchard [14] proposed = 31 1.71 for orographic rain, and = 300 1.4 was proposed for convective rain [15]. The Korea Meteorological Administration (KMA) uses the equation proposed by Marshall and Palmer [16], = 200…”

Section: Introductionmentioning

confidence: 99%

Vertical Variation of Z-R Relationship at Hallasan Mountain during Typhoon Nakri in 2014

Yoo¹,

Ku²

2017

Advances in Meteorology

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Hallasan Mountain is located at the center of Jeju Island, Korea. Even though the height of the mountain is just 1,950 m, the orographic effect is strong enough to cause heavy rainfall. In this study, a rainfall event, due to Typhoon Nakri in 2014, observed in Jeju Island was analyzed fully using the radar and rain gauge data. First, the -relationship ( = ) was derived for every 250 m interval from the sea level to the mountain top. The resulting -relationships showed that the exponent could be assumed as constant but that the parameter showed a significant decreasing trend up to an altitude around 1,000 m before it increased again. The orographic effect was found to be most significant at this altitude of 1,000 m. Second, the derived -relationships were applied to the corresponding altitude radar reflectivity data to generate the rain rate field over Jeju Island. This rain rate field was then used to derive the areal-average rain rate data. These data were found to be very similar to the rain gauge estimates but were significantly different from those derived from the application of the Marshall-Palmer equation to the 1.5 km CAPPI data, which is the data type that is generally used by the Korea Meteorological Administration (KMA).

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Comparison of Gage and Radar Methods of Convective Rain Measurement

Cited by 86 publications

References 0 publications

Thermodynamic characteristics associated with localized torrential rainfall events in the southwest region of the Korean peninsula

Thermodynamic characteristics associated with localized torrential rainfall events in the southwest region of the Korean peninsula

Microphysical Properties of Maritime Squall Line Observed on June 2, 2008 in Taiwan

Vertical Variation of Z-R Relationship at Hallasan Mountain during Typhoon Nakri in 2014

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