Frequency of Bay of Bengal cyclonic storms and depressions crossing different coastal zones

Alam, Md. Mahbub; Hossain, Md. Arif; Shafee, Sultana

doi:10.1002/joc.927

Cited by 123 publications

(58 citation statements)

References 2 publications

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“…Seasonal distribution of tropical cyclones is related to the seasonal variations in the location of the monsoon trough over the Bay of Bengal (Alam et al 2003). Migration of the trough above open water facilitates the formation of depressions that sometimes initiate tropical Table 1 Excess of number of days with the rainfall within given limits, during the second half of the twentieth century.…”

Section: Pre-monsoon and Post-monsoonmentioning

confidence: 99%

Variation in the orographic extreme rain events over the Meghalaya Hills in northeast India in the two halves of the twentieth century

Prokop

Walanus

2014

Theor Appl Climatol

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The daily rainfall data for the twentieth century, from three stations across the region, constitute the basis for statistical analysis. However, the low signal-to-noise ratio makes it difficult to find any significant departure from the simplest null hypothesis of the stability of the rain record at individual stations in northeast India. Only the coarsest possible view, i.e. comparing the two halves of the century, provided strongly significant results in the numbers of days with extreme rain. Using a more general approach, the number of Fourier transform extreme amplitudes also differed significantly. Increasingly heavy events during the summer monsoon season, and partly in the pre-and post-monsoon seasons, are offset by a weakening in the winter monsoon season, so that the annual mean rainfall does not show a significant trend over the Meghalaya Hills. Apart from a greater number of years with noticeable extreme rainfall events in the second half of the twentieth century, we can also observe a more pronounced quasi-periodicity of 10-20 and 30-60 days during the same period. The detection of the latter periodicity indicates that the Madden-Julian oscillation plays an important role in the formation of extreme rainfall events over the Meghalaya Hills during extreme monsoon years.

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Section: Pre-monsoon and Post-monsoonmentioning

confidence: 99%

Variation in the orographic extreme rain events over the Meghalaya Hills in northeast India in the two halves of the twentieth century

Prokop

Walanus

2014

Theor Appl Climatol

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“…The viewpoint is further supported by the fact that the cyclones rapidly intensify whenever they encounter warm-core rings in the oceans (Shay et al 2000;Ali et al 2007). In the Bay of Bengal, there are only three or four named tropical cyclones each year, which account for less than 5% of the annual total cyclone events worldwide (Alam et al 2003). These few tropical storms, though they may not be the most intense storms on the Saffir-Simpson scale, have great potential for catastrophic impacts.…”

mentioning

confidence: 99%

Ocean Preconditioning of Cyclone Nargis in the Bay of Bengal: Interaction between Rossby Waves, Surface Fresh Waters, and Sea Surface Temperatures*

McPhaden

2011

Journal of Physical Oceanography

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An in-depth data analysis was conducted to understand the occurrence of a strong sea surface temperature (SST) front in the central Bay of Bengal before the formation of Cyclone Nargis in April 2008. Nargis changed its course after encountering the front and tracked along the front until making landfall. One unique feature of this SST front was its coupling with high sea surface height anomalies (SSHAs), which is unusual for a basin where SST is normally uncorrelated with SSHA. The high SSHAs were associated with downwelling Rossby waves, and the interaction between downwelling and surface fresh waters was a key mechanism to account for the observed SST-SSHA coupling.The near-surface salinity field in the bay is characterized by strong stratification and a pronounced horizontal gradient, with low salinity in the northeast. During the passage of downwelling Rossby waves, freshening of the surface layer was observed when surface velocities were southwestward. Horizontal convergence of freshwater associated with downwelling Rossby waves increased the buoyancy of the upper layer and caused the mixed layer to shoal to within a few meters of the surface. Surface heating trapped in the thin mixed layer caused the fresh layer to warm, whereas the increase in buoyancy from low-salinity waters enhanced the high SSHA associated with Rossby waves. Thus, high SST coincided with high SSHA.The dominant role of salinity in controlling high SSHA suggests that caution should be exercised when computing hurricane heat potential in the bay from SSHA. This situation is different from most tropical oceans, where temperature has the dominant effect on SSHA.

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“…The warmer SST together with higher tropical cyclone heat potential (TCHP) makes the BoB one of the active regions for cyclogenesis (Suzana et al, 2007;Yanase et al, 2012;Vissa et al, 2013). The majority of tropical cyclones are generated during the pre-monsoon (April-May) and post-monsoon (October-November) seasons (Alam et al, 2003;Longshore, 2008). The number of cyclones and their intensity is highly variable on seasonal and interannual timescales.…”

Section: Introductionmentioning

confidence: 99%

Estimation of oceanic subsurface mixing under a severe cyclonic storm using a coupled atmosphere–ocean–wave model

2018

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Abstract. A coupled atmosphere-ocean-wave model was used to examine mixing in the upper-oceanic layers under the influence of a very severe cyclonic storm Phailin over the Bay of Bengal (BoB) during 10-14 October 2013. The coupled model was found to improve the sea surface temperature over the uncoupled model. Model simulations highlight the prominent role of cyclone-induced near-inertial oscillations in subsurface mixing up to the thermocline depth. The inertial mixing introduced by the cyclone played a central role in the deepening of the thermocline and mixed layer depth by 40 and 15 m, respectively. For the first time over the BoB, a detailed analysis of inertial oscillation kinetic energy generation, propagation, and dissipation was carried out using an atmosphere-ocean-wave coupled model during a cyclone. A quantitative estimate of kinetic energy in the oceanic water column, its propagation, and its dissipation mechanisms were explained using the coupled atmosphere-ocean-wave model. The large shear generated by the inertial oscillations was found to overcome the stratification and initiate mixing at the base of the mixed layer. Greater mixing was found at the depths where the eddy kinetic diffusivity was large. The baroclinic current, holding a larger fraction of kinetic energy than the barotropic current, weakened rapidly after the passage of the cyclone. The shear induced by inertial oscillations was found to decrease rapidly with increasing depth below the thermocline. The dampening of the mixing process below the thermocline was explained through the enhanced dissipation rate of turbulent kinetic energy upon approaching the thermocline layer. The wave-current interaction and nonlinear wave-wave interaction were found to affect the process of downward mixing and cause the dissipation of inertial oscillations.

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Frequency of Bay of Bengal cyclonic storms and depressions crossing different coastal zones

Cited by 123 publications

References 2 publications

Variation in the orographic extreme rain events over the Meghalaya Hills in northeast India in the two halves of the twentieth century

Variation in the orographic extreme rain events over the Meghalaya Hills in northeast India in the two halves of the twentieth century

Ocean Preconditioning of Cyclone Nargis in the Bay of Bengal: Interaction between Rossby Waves, Surface Fresh Waters, and Sea Surface Temperatures*

Estimation of oceanic subsurface mixing under a severe cyclonic storm using a coupled atmosphere–ocean–wave model

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