Total Totals Index (TT)

RESULTS AND DISCUSSION

IEi 30 IEi 30

4.4.10 Total Totals Index (TT)

The model simulated time variation of TT for six different MPs coupling with KF and BMJ schemes at Barisal are shown in Figs. 4.4.6(e-f). The TT has increased continuously and fluctuating for all MPs coupling with KF scheme. The TT is found greater than 51°C (Fig.

4.4.6e) during 0700 to 0800 UTC indicates the occurrence of isolated severe storms and then

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for short period TT is found greater than 50°C for KS-KF, WSM6-KF, SBU-KF and WDM6- KF combinations, which indicates the occurrence of likely thunderstorm at Barisal.

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Fig. 4.4.6: Time variation of (a-b) CT, (c-d) VT, (e-f) TT and (g-h) K-Index using six different MP schemes coupling with KF and BMJ schemes at Barisal on 15 May 2014.

The maximum TT 54.1, 53.5, 55.6, 53.8, 53.1 and 53.1°C are simulated at 0905, 0900, 0900, 0900, 0905 and 0845 UTC for KS-KF, Lin-KF, WSM6-KF, TH-KF, SBU-KF and WDM6- KF combinations, indicates the occurrence of widely scattered severe storms. During 0700 to

108 -1'

0745 and 0805 to 0840 UTC the TT lies between 51 to 52°C (Fig. 4.4.60 for all MPs coupling with BMJ scheme and then it also continue for SBU-BMJ combination, indicates the occurrence of isolated severe storms. The TT lies between 47 to 50°C after 0850 UTC for all MPs coupling with BMJ scheme except SBU-BMJ combination.

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Fig. 4.4.7: Time variation of (a-b) CT, (c-d) VT, (e-f) TT and (g-h) K-Index using six different MP schemes coupling with KF and BMJ schemes at Chittagong on 15 May2014.

109

WRF model simulated TT at Chittagong are presented in Figs. 4.4.7(e-f). The TT has decreased and fluctuates in an irregular pattern (Fig. 4.4.7(e-f)) up to 1200 UTC for all MPs in combination with KF and BMJ schemes. The TT lies between 44 to 49°C up to 1300 UTC for all MPs coupling with KF and BMJ schemes, indicates the occurrence of likely thunderstorms at Chittagong. The maximum TT is simulated ^52.44°C (Fig. 4.4.7e) by WSM6-KF combination at 1415 UTC, indicates the occurrence of isolated severe storms and 50°C (Fig. 4.4.70 byTH-BMJ combination at 1545UTC, indicates to the occurrence of likely thunderstorms.

4.4.11 K Index (KI)

The model simulated time variation of KI for six different MPs coupling with KF and BMJ schemes at Barisal are presented in Figs. 4.4.6(g-h). The KI has increased sharply up to 0640 UTC and then fluctuates in an irregular pattern for all MPs coupling with KF and BMJ schemes. The KI ^> 40°C up to 0745 and during 0800-0920 UTC (Fig. 4.4.6g) indicates extremely unstable and maximum possibility for the occurrence of thunderstorm for all MPs coupling with KF scheme. After 0920 UTC it has decreased for all MPs coupling with KF scheme. The maximum KI has found 48.95 and 49.110C at 0855 and 0900 UTC for Lin-KF and KS-KF combinations indicates maximum possibility for the occurrence of thunderstorm at Barisal. The KI ^> 40°C up to 0830 UTC (Fig. 4.4.6h) indicates extremely unstable atmosphere for all MPs coupling with BMJ scheme. The KI> 40°C at 0905 UTC indicates the extremely unstable atmosphere for KS-BMJ, Lin-BMJ, TH-BMJ, SBU-BMJ and WDM6- BMJ combinations and then it continue up to 0945 UTC only for SBU-BMJ .combination, indicates maximum possibility the occurrence of thunderstorm.

Figs. 4.4.7(g-h) depict model simulated KI at Chittagong. Up to 1050 UTC (Fig. 4.4.7(g-h)) the KI is almost constant and then fluctuates for all MPs coupling with KF and BMJ schemes.

The KI ^> 40°C during 0500 to 1210 UTC indicates extremely unstable atmosphere for all MPs coupling with KF and BMJ schemes. After that, it has decreased for Lin-KF and WSM6-KF combinations at 1215 and 1225 UTC when KI is 40 and 39.7°C, which is very unstable atmosphere, indicates the occurrence of very likely thunderstorms.

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using six different MP schemes coupling with KF and BMJ schemes at Barisal on 15 May 2014.

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on 15 May2014.

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