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[MIS13-05] Pattern classification of parent clouds of tornadoes in Tosa Bay
Keywords:Radar observation, Tornado, Parent cloud
The coast line of Tosa Bay in Kochi Prefecture is one of the area where tornadoes frequently occur. We have continuously made the radar observation with the radar network composed of six compact polarimetric radars of Kochi University. Most of parent clouds of tornadoes reported by JMA Kochi observatory were captured by our radars from 2014 to 2020. The present study aims to classify the parent clouds of tornadoes and to clarify their characteristics. Our final goal is the establishment of warning system automatically detecting the parent clouds with machine learning.
From the results of analysis, we found that the parent clouds could be classified to following 5 patterns; supercell, wavy cloud, cloud cluster, squall line and isolated cell. Fig.1 shows the example of
supercell. The mesocyclone is shown in the southwest end of the high intensity echo region. Fig. 2 shows the example of wavy clouds appeared far away from the typhoon. The vortex is shown in the southwest end of the southern system. The example of cloud cluster composed of small cumulonimbi is shown in Fig.3 The moving velocity of the system was quite slow. Fig.4 shows the example of squall line. The moving direction was east and it has large angle with respect to the direction of the system. The example the one of the isolated cells passing through the radar was the parent cloud of a tornado is shown in Fig.5. The hook echo which shows the existence of a tornado vortex is clearly observed in the east end of the isolated cell, though its horizontal scale is small about 10 km in length.
The majority was the isolated cell. 11 cases were found to be it. The length of the isolated cells was less than 10 km in most cases. The length of the other systems exceeded 20km, but the width of wavy cloud and squall line was about 5km. The moving velocity of the supercell, wavy cloud and squall line was larger than the other systems. And we also found that the vortex located in the rear side of most of the parent clouds.
In the present study, we will discuss about the temporal change of the parent clouds.
From the results of analysis, we found that the parent clouds could be classified to following 5 patterns; supercell, wavy cloud, cloud cluster, squall line and isolated cell. Fig.1 shows the example of
supercell. The mesocyclone is shown in the southwest end of the high intensity echo region. Fig. 2 shows the example of wavy clouds appeared far away from the typhoon. The vortex is shown in the southwest end of the southern system. The example of cloud cluster composed of small cumulonimbi is shown in Fig.3 The moving velocity of the system was quite slow. Fig.4 shows the example of squall line. The moving direction was east and it has large angle with respect to the direction of the system. The example the one of the isolated cells passing through the radar was the parent cloud of a tornado is shown in Fig.5. The hook echo which shows the existence of a tornado vortex is clearly observed in the east end of the isolated cell, though its horizontal scale is small about 10 km in length.
The majority was the isolated cell. 11 cases were found to be it. The length of the isolated cells was less than 10 km in most cases. The length of the other systems exceeded 20km, but the width of wavy cloud and squall line was about 5km. The moving velocity of the supercell, wavy cloud and squall line was larger than the other systems. And we also found that the vortex located in the rear side of most of the parent clouds.
In the present study, we will discuss about the temporal change of the parent clouds.