An Economical Procedure for Cartesian Interpolation and Display of Reflectivity Factor Data in Three-Dimensional Space

Mohr, Carl G.; Vaughan, Robin L.

doi:10.1175/1520-0450(1979)018<0661:aepfci>2.0.co;2

Cited by 111 publications

(71 citation statements)

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“…This matrix was then used to create constant altitude plan position indicator (CAPPI) maps. To produce CAPPI maps from PPI is equivalent to a change of basis in R 3 which transforms the original spherical coordinates of the radar measurement into Cartesian coordinates, and constitutes a common practice in work with radar data because it makes it easier to interpret and post-process the data To create the CAPPI, we follow the interpolation method described in Mohr and Vaughan (1979) and Mohr et al (1986). This method is also used by the software Reorder (developed at NCAR), which is widely used today Rowe et al, 2011).…”

Section: Radarmentioning

confidence: 99%

The properties of convective storms in central Mexico: A radar and lightning approach

Novo

Raga

2013

Atmósfera

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RESUMENSe emplean datos del radar de Cerro Catedral (una elevación cercana a la Ciudad de México) para investigar las propiedades de las tormentas convectivas que ocurren sobre el centro de México, una región de orografía compleja. La distribución espacial muestra que las tormentas tienden a formarse y moverse hacia el oeste del radar, sobre una banda estrecha de terreno elevado. No obstante, las tormentas con los mayores volúmenes y alturas en sus topes tienden a localizarse hacia el suroeste, sobre terrenos bajos. Cada elemento convectivo se enlazó con el número de descargas eléctricas a tierra producidas en su interior, según fueron detectadas por la World Wide Lightning Location Network (Red Mundial de Localización de Rayos). Las tormentas en las que se detectaron descargas y que tuvieron un promedio de más de seis rayos en su interior, fueron significativamente más grandes e intensas que las tormentas en las que no se detectaron descargas, y tendieron a localizarse sobre terrenos más bajos. La muestra de más de 98 000 celdas identificadas se dividió en cuatro grupos de acuerdo con la elevación, para investigar posibles tendencias de las propiedades medias relacionadas con la altura del terreno, como se ha informado para otras regiones en México. En tanto que el número de tormentas por unidad de área se incrementa con la elevación del terreno, los valores promedios de las propiedades relacionadas con el tamaño (área, volumen, tope del eco) y la intensidad (reflectividad máxima, número de descargas, altura de la reflectividad máxima, máxima altura del contorno de 30 dBZ), disminuyen. Estos resultados podrían vincularse con la posibilidad de que el espesor de la parte de la nube donde ocurren los procesos de lluvia caliente sea menor en terrenos más altos. Los ciclos diurnos de la convección y del número de descargas eléctricas al norte del radar muestran un régimen de precipitación típicamente continental, con máximos a las 18:00 LT en ambas variables. No obstante, al sur del radar el máximo de descargas se detectó cerca de la medianoche, lo cual se relaciona con la convección más profunda que ocurre sobre los terrenos bajos de esa zona durante altas horas de la noche y la madrugada. ABSTRACTRadar data from Cerro Catedral (a peak close to Mexico City) were used to investigate the properties of convective storms over central Mexico, a region with complex orography. The spatial distribution shows a preference for storms to form and move to the west of radar, over a narrow band of high terrain. However, the storms with the higher volumes and echo-top heights tend to be located southwestward over lower terrain. Each radar feature was matched with the number of cloud-to-ground (CG) lightning produced inside it, as retrieved from the World Wide Lightning Location Network dataset. The storms in which lightning was detected, with an average of more than six lightning bolts, clearly outperform in size and intensity the group of storms in which lightning was not detected, and tend to lie over lower terrain. The sample ...

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Section: Radarmentioning

confidence: 99%

The properties of convective storms in central Mexico: A radar and lightning approach

Novo

Raga

2013

Atmósfera

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“…The domain is centered on the Darwin radar and has a horizontal extent of 300km by 300km.3 The levels in the vertical are 1.5km to 19.5km above ground. Bilinear interpolation determines the radar reflectivity value at the grid points by means of the Sorted Position Radar Interpolation software (SPRINT; Mohr and Vaughan, 1979),4 a software package maintained by the National Center for Atmospheric Research (NCAR).…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of Monthly Three-Dimensional Radar-Echo Characteristics to Sampling Frequency

Steiner¹,

Houze²

1998

Journal of the Meteorological Society of Japan

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Estimates of any precipitation characteristics based on temporally sparse observations entail uncertainty because of the natural variability of rainfall in space and time. This study measures the sampling-related uncertainties of monthly mean reflectivity profile and surface rainfall distribution. Radar and rain gauge data collected during the 1993/94 monsoon season at Darwin, Australia, are used to show the sensitivity of monthly three-dimensional radar-echo and precipitation characteristics to the frequency of observation. The data are partitioned into convective, stratiform, and anvil components according to the horizontal and vertical structure of the echoes. The analyses of this study reveal the expected trend that the uncertainties of estimated precipitation characteristics using infrequent observations scale with rainfall amount. The results have implications for climatological studies using spaceborne observation platforms revisiting a given area intermittently.The Tropical Rainfall Measuring Mission (TRMM) satellite radar, which will revisit a given 500km by 500km region approximately twice daily, will likely encounter significant problems in estimating the vertical profile of radar reflectivity in the tropics. Monthly mean reflectivity statistics (based on observations within 150km of the Darwin radar) exhibit a sampling-related uncertainty of about 20% in both rain and snow. In addition, the radar signal of the TRMM satellite will be highly attenuated below the 00C level, and the precipitation radar will be insensitive to reflectivity less than about 20 dBZ. Therefore, the spaceborne radar will have an obscured view of the vertical precipitation structure. Reliable reflectivity statistics based on TRMM satellite radar data may be obtained primarily within an altitude range of about 5-7.5km-an altitude range though that is important for cloud electrification because of the mixed-phase precipitation processes taking place there. The sampling uncertainty, signal attenuation, and radar sensitivity vary with precipitation type. Moreover, estimation of the convective rain fraction will be compromised by uncertainties in the echo classification as well as a choice of Z -R relation. These results imply the importance of information collected by ground validation site radars to improve upon TRMM satellite estimates of precipitation characteristics and the derived vertical profile of latent heating.

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“…The reflectivity data in spherical co-ordinates (r, , ) were converted into 3D constant altitude plan position indicators (3D CAPPIs) in Cartesian co-ordinates (x, y, z) with both horizontal and vertical resolutions of 0.5 km using bilinear interpolation (Mohr and Vaughn, 1979). The horizontal range of the 3D CAPPIs was limited to 180 km to alleviate the observational loss of shallow convection or the initial stage of convective cells with top heights of <2 km (the base heights of the 1.0 ∘ radar beam at the lowest elevation angle of 0.5 ∘ is around 2 km at 180 km).…”

Section: Datamentioning

confidence: 99%

Radar‐based cell tracking with fuzzy logic approach

Jung

Lee

2015

Meteorological Applications

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This study presents a new algorithm Fuzzy logic Algorithm for Storm Tracking (FAST) for tracking convective cells in 3D Cartesian co-ordinates. A fuzzy logic approach was applied to track cells with objectively determined membership functions (MFs) and weights that were derived from a large set of convective cell tracks (2326 pairs of convective cells). Three feature parameters (cell motion speed, area change ratio and axis transformation ratio) were selected by Bayesian information criterion and combined through fuzzy logic. FAST was evaluated with three skill scores using 2561 (2456) pairs of convective cells with (without) mergers and splits. The performance was tested in comparison with Thunderstorm Identification, Tracking, Analysis, and Nowcasting (TITAN) as a baseline method. For reference tracks without merger and split, the critical success index (CSI) of FAST reaches about 0.89. FAST shows better skill scores (CSI = 0.92 and 0.89 at speed limitations of 16.1 m s −1 and 25.0 m s −1 , respectively) than those of TITAN (CSI = 0.89 and 0.82 at the same speed limitations) and is independent of the number of convective cells and the speed limitation. When mergers and splits are considered in the reference, the tracking performance of FAST (FAST MS ) with a merger and split process is always better than that of TITAN (TITAN MS ) with a merger and split process and is independent of speed limitations. When FAST (=FAST noMS ) does not include a merger and split process, its tracking performance is better than that of TITAN MS at speed limitation of > 20 m s −1 .

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An Economical Procedure for Cartesian Interpolation and Display of Reflectivity Factor Data in Three-Dimensional Space

Cited by 111 publications

References 0 publications

The properties of convective storms in central Mexico: A radar and lightning approach

The properties of convective storms in central Mexico: A radar and lightning approach

Sensitivity of Monthly Three-Dimensional Radar-Echo Characteristics to Sampling Frequency

Radar‐based cell tracking with fuzzy logic approach

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