  This paper discusses the time series trend and variability of the cyclone
frequencies over Bay of Bengal, particularly in order to conclude if there is
any significant difference in the pattern visible before and after the
disastrous 2004 Indian ocean tsunami based on the observed annual cyclone
frequency data obtained by India Meteorological Department over the years
1891-2015. Three different categories of cyclones- depression (<34 knots),
cyclonic storm (34-47 knots) and severe cyclonic storm (>47 knots) have been
analyzed separately using a non-homogeneous Poisson process approach. The
estimated intensity functions of the Poisson processes along with their first
two derivatives are discussed and all three categories show decreasing trend of
the intensity functions after the tsunami. Using an exact change-point
analysis, we show that the drops in mean intensity functions are significant
for all three categories. As of author's knowledge, no study so far have
discussed the relation between cyclones and tsunamis. Bay of Bengal is
surrounded by one of the most densely populated areas of the world and any kind
of significant change in tropical cyclone pattern has a large impact in various
ways, for example, disaster management planning and our study is immensely
important from that perspective.
