3D Convective Storm Identification, Tracking, and Forecasting—An Enhanced TITAN Algorithm

Abstract

Storm identification, tracking, and forecasting make up an essential part of weather radar and severe weather surveillance operations. Existing nowcasting algorithms using radar data can be generally classified into two categories: centroid and cross-correlation tracking. Thunderstorm Identification, Tracking, and Nowcasting (TITAN) is a widely used centroid-type nowcasting algorithm based on this paradigm. The TITAN algorithm can effectively identify, track, and forecast individual convective storm cells, but TITAN tends to provide incorrect identification, tracking, and forecasting in cases where there are dense cells whose shape changes rapidly or where clusters of storm cells occur frequently. Aiming to improve the performance of TITAN in such scenarios, an enhanced TITAN (ETITAN) algorithm is presented. The ETITAN algorithm provides enhancements to the original TITAN algorithm in three aspects. First, in order to handle the false merger problem when two storm cells are adjacent, and to isolate individual storm cells from a cluster of storms, ETITAN uses a multithreshold identification method based on mathematical morphology. Second, in the tracking phase, ETITAN proposes a dynamic constraint-based combinatorial optimization method to track storms. Finally, ETITAN uses the motion vector field calculated by the cross-correlation method to forecast the position of the individual isolated storm cells. Thus, ETITAN combines aspects of the two general classes of nowcasting algorithms, that is, cross-correlation and centroid-type methods, to improve nowcasting performance. Results of experiments presented in this paper show the performance improvements of the ETITAN algorithm.

The advanced algorithm for tracking objects (AALTO)

“…Although existing algorithms designed to detect thunderstorms, mesocyclones and tornado vortex signatures, such as thunderstorm identification, tracking, analysis and nowcasting (TITAN; Dixon and Wiener, 1993); storm cell identification and tracking (SCIT; Johnson et al, 1998); the National Severe Storms Laboratory (NSSL) Tornado vortex signature detection algorithm (TDA; Mitchell et al, 1998); the NSSL mesocyclone detection algorithm (MDA; Stumpf et al, 1998); w2segmotion (Lakshmanan et al, 2007(Lakshmanan et al, , 2009; Thunderstorm observation by radar (ThOR; Barjenbruch and Houston, 2006;Barjenbruch, 2008;Lahowetz et al, 2010) and enhanced-TITAN (E-TITAN; Han et al, 2009) include a tracking component, many recommendations to improve tracking in legacy algorithms have been proposed. For example, Johnson et al (1998) propose that SCIT should incorporate different estimates of initial storm motion throughout the domain and impose limits upon the ability of tracks to change direction.…”

Radar‐based cell tracking with fuzzy logic approach

“…Previous studies defined the convective cell as a group of 3D contiguous grids that exceed the reflectivity and volume thresholds (Dixon and Wiener, 1993;Johnson et al, 1998;Han et al, 2009a). The same definition is used in this study.…”

“…However, other issues such as sensitivities to the convective area radius and spatial reflectivity gradient in the algorithm may be raised and should be tested in detail. The variable or multi-reflectivity threshold method was alternatively suggested for use to alleviate sensitivity to the fixed single reflectivity threshold (Johnson et al, 1998;Handwerker, 2002;Han et al, 2009a). This method has advantages in identifying multiple convective cores with higher reflectivity within convective regions.…”

“…Good reviews and useful references on radar-based cell tracking techniques are given by Han et al (2009a) and Li et al (2012). Area-based approaches do not identify convective cells and thus cannot provide quantitative characteristics of individual cells.…”

“…However, the centroid tracking method can identify individual convective cells and derive the motion vectors of each cell (e.g. Rosenfeld, 1987;Dixon and Wiener, 1993;Johnson et al, 1998;Handwerker, 2002;Han et al, 2009a;Dance et al, 2010). Thunderstorm Identification, Tracking, Analysis, and Nowcasting (TITAN, Dixon and Wiener, 1993) and Storm Cell Identification and Tracking (SCIT, Johnson et al, 1998) are well-known algorithms.…”