Objective Classification of Precipitating Convective Regimes Using a Weather Radar in Darwin, Australia

Caine, Simon; Jakob, Christian; Siems, Steven T.; May, Peter T.

doi:10.1175/2008mwr2532.1

Cited by 12 publications

(7 citation statements)

References 50 publications

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“…We begin by summarizing the areal distribution of storm reflectivity values with height using contoured coverage altitude diagrams (CCAD) to further understand the relative differences between overshooting convection in both regimes. The CCAD is similar to the contoured frequency altitude diagrams used by Yuter and Houze [] except that reflectivity bin counts are divided by the total radar‐observable area at each height level following Caine et al []. First, reflectivity values ranging from 5 to 75 dBZ are tallied in 5 dBZ wide bins (5–10, 10–15 dBZ, etc.).…”

Section: C‐pol Reflectivitymentioning

confidence: 99%

Ground‐based observations of overshooting convection during the Tropical Warm Pool‐International Cloud Experiment

2014

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This study uses gridded radar data to investigate the properties of deep convective storms that penetrate the tropical tropopause layer (TTL) and overshoot the cold-point tropopause during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE). Overshooting convection during the observed break period is relatively more intense and exhibits lesser diurnal variability than severe monsoonal storms in terms of mean overshooting area in the TTL (as covered by >20 dBZ echoes). However, ground-based radar has geometrical constraints and sampling gaps at high altitude that lead to biases in the final radar product. Using synthetic observations derived from model-based data, ground-based radar is shown to underestimate the mean overshooting area in the TTL across both TWP-ICE regimes. Differences range from ∼180 km 2 (∼100 km 2 ) to ∼14 km 2 (∼8 km 2 ) between 14 and 18 km for the active (break) period. This implies that the radar is underestimating the transport of water and ice mass into the TTL by convective overshoots during TWP-ICE. The synthetic data is also used to correct profiles of the mean observed overshooting area. These are shown to differ only marginally between the two sampled regimes once the influence of a large mesoscale convective system, considered as a departure from normal monsoon behavior, was removed from the statistics. The results of our study provide a useful cross-validation comparison for satellite-based detections of overshooting top areas over Darwin, Australia.

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Section: C‐pol Reflectivitymentioning

confidence: 99%

Ground‐based observations of overshooting convection during the Tropical Warm Pool‐International Cloud Experiment

2014

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“…The algorithm has been used to investigate the detailed evolution of vertical motion and reflectivity fields in different weather systems Black et al 1996) and precipitation regimes (Caine et al 2009). In this study, CFADs were computed in convective regions that were roughly defined as areas within 10-km radius of the stormcell locations (Steiner et al 1995) identified by the SCIT algorithm (Johnson et al 1998).…”

Section: Composite Vertical Structuresmentioning

confidence: 99%

Warm Season Afternoon Thunderstorm Characteristics under Weak Synoptic-Scale Forcing over Taiwan Island

Lin

Chang²,

Jou

et al. 2011

Weather and Forecasting

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The spatial and temporal characteristics and distributions of thunderstorms in Taiwan during the warm season (May-October) from 2005 to 2008 and under weak synoptic-scale forcing are documented using radar reflectivity, lightning, radiosonde, and surface data. Average hourly rainfall amounts peaked in midafternoon (1500-1600 local solar time, LST). The maximum frequency of rain was located in a narrow strip, parallel to the orientation of the mountains, along the lower slopes of the mountains. Significant diurnal variations were found in surface wind, temperature, and dewpoint temperature between days with and without afternoon thunderstorms (TS A and non-TS A days). Before thunderstorms occurred, on TS A days, the surface temperature was warmer (about 0.58-1.58C) and the surface dewpoint temperature was moister (about 0.58-28C) than on non-TS A days. Sounding observations from northern Taiwan also showed warmer and higher moisture conditions on TS A days relative to non-TS A days. The largest average difference was in the 750-550-hPa layer where the non-TS A days averaged 2.58-3.58C drier. These preconvective factors associated with the occurrences of afternoon thunderstorms could be integrated into nowcasting tools to enhance warning systems and decision-making capabilities in real-time operations.

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“…A standard approach is to compare contoured frequency with altitude diagrams (CFADs) derived from both model and observed data (Rogers et al 2007;Van Weverberg et al 2011;Caine 2009;Caine et al 2009). Similar to the creation of CFADs, another approach is to calculate the coverage of an observed quantity and compare these measurements with model data.…”

Section: Introductionmentioning

confidence: 99%

“…Other studies have analyzed convective-permitting simulations during TWP-ICE (e.g., Wapler et al 2010;Caine 2009;Varble et al 2011;Fridlind et al 2012;Wapler and Lane 2012), exploring aggregate properties of the convective processes and their sensitivity to physical parameterizations. In the spirit of providing a proof of concept of the TITAN analysis, the simulations presented herein are designed specifically with the comparison to radar in mind, and the simulations do not encompass the entire TWP-ICE period, only a 5-day period during the break regime.…”

Section: Introductionmentioning

confidence: 99%

Statistical Assessment of Tropical Convection-Permitting Model Simulations Using a Cell-Tracking Algorithm

Caine

Lane

May

et al. 2013

Monthly Weather Review

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This study presents a method for comparing convection-permitting model simulations to radar observations using an innovative object-based approach. The method uses the automated cell-tracking algorithm, Thunderstorm Identification Tracking Analysis and Nowcasting (TITAN), to identify individual convective cells and determine their properties. Cell properties are identified in the same way for model and radar data, facilitating comparison of their statistical distributions. The method is applied to simulations of tropical convection during the Tropical Warm Pool-International Cloud Experiment (TWP-ICE) using the Weather Research and Forecasting Model, and compared to data from a ground-based radar. Simulations with different microphysics and model resolution are also conducted. Among other things, the comparisons between the model and the radar elucidate model errors in the depth and size of convective cells. On average, simulated convective cells reached higher altitudes than the observations. Also, when using a low reflectivity (25 dBZ) threshold to define convective cells, the model underestimates the size of the largest cells in the observed population. Some of these differences are alleviated with a change of microphysics scheme and higher model resolution, demonstrating the utility of this method for assessing model changes.

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Objective Classification of Precipitating Convective Regimes Using a Weather Radar in Darwin, Australia

Cited by 12 publications

References 50 publications

Ground‐based observations of overshooting convection during the Tropical Warm Pool‐International Cloud Experiment

Ground‐based observations of overshooting convection during the Tropical Warm Pool‐International Cloud Experiment

Warm Season Afternoon Thunderstorm Characteristics under Weak Synoptic-Scale Forcing over Taiwan Island

Statistical Assessment of Tropical Convection-Permitting Model Simulations Using a Cell-Tracking Algorithm

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