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5.2 Properties of the Clusters
Cluster 1 is centered in the Arabian Sea, near Gujarat and Maharashtra coastline.
Events in cluster 2 are long duration, originating from the south-east of the
Indian coastline and mostly progresses from East to West. Cluster 3 events are
centered near the Orissa coastline and a very high proportion make landfall.
Events in cluster 4 tend to have mostly straight tracks moving North-North
East. Cluster 5 is centered near the Tamil Nadu coastline and has comparatively
shorter length trajectories.
While clustering of tracks is determined by their spatio-temporal
characteristics, there are a number of other features of the tracks of importance.
These include genesis location, intensity, life span, landfall and seasonality.
We have analyzed the behaviour of identified five clusters with regard to these
features.
5.2.1 Genesis
The mean genesis location for each of the five clusters is reported in Table 1.
Events in cluster 1 originate in the Arabian Sea but are widely dispersed. The
remaining four clusters all consist of events originating in the Bay of Bengal.
Cluster 2 events tend to originate around the Andaman Sea whereas cluster 3
events originate near the Orissa-West Bengal Coastline. Events in clusters 4
and 5 have similar origin location but differ in their subsequent movement.
Table 1:
Averages of track properties for each of the five clusters
Genesis
Life Span
Ratio
(Days)
Cluster
NE
Lat
Long
LE
PLE
(SCS/CS)
1
56
12.78
69.35
5.39
16
29
1.7
2
37
8.05
89.52
6.73
30
81
2.7
3
55
16.59
89.42
4.4
51
93
1.1
4
53
10.18
90.65
5.15
26
49
2.8
5
36
10.6
87.26
4.67
28
78
1
Total
237
151
64
NE: Number of events; LE: Landfalling events; P: Probability (%) of landfalling events;
CS: Cyclonic storm; and SCS: Severe cyclonic storm.
5.2.2 Landfall
In order to find the tropical cyclones that originate in north Indian Ocean and
make landfall in India, India boundary was overlaid on the cyclone tracks and
the intersection points are obtained. The number of cyclones that made landfall
in each of the five clusters is given in Table 1. A total of about 64% of the
tropical cyclones have made landfall in India during 1961-2010. Cluster 3
being one of the large clusters has the highest number of landfalling cyclones
followed by cluster 2. Comparatively cluster 2 is small and has longer duration
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