THE SOLAR INFLUENCE ON TROPICAL CYCLONES OCCURES OVER BAN OF BENGAL AND ARABIAN SEA AREA

During last few decades a prominent example of extreme weather event in Indian Ocean region is Cyclonic Storm. In this paper annual variation of different categories of tropical Cyclonic Storms like Tropical over Bay Of Bengal (BOB) and Arabian Sea (ARS) have been analyzed .The analysis revels that the total number of cyclone (TNC) has increased with high rate (gradient being +1.67 per year) and although C.S. is more over BOB than that over ARS. The rate of increase of C.S. over Arabian Sea is more than that over Bay of Bengal. Furthermore, two interesting features have been noted: (i) Monsoon tends to prohibit the formation of C.S (ii) Cyclonic Storm(C.S.) increases with the increase of Global Sea Surface Temperature (GSST) during said period. An attempt has also been made to find out the influence of solar activity on these extreme weather events. Keeping in mind that the Sun Spot Number (SSN) is an indicator of the strength of solar effects, it has been found that in most of the times the high value of SSN is associated with small number of total cyclone (C.S.). High SSN (> 90) and number of cyclones shows high Correlation coefficient (0.78) .Significance at 99.99% level while Correlation Coefficient (C.C.) of cyclones with time is 0.53 and with SSN < 60 it is0.095 . Thus it appears that although C.S. frequency is increasing with time, Sun’s Spot’s influence is such that it basically opposes the formation of cyclone provided SSN exceeds certain critical value (roughly 90).