Role of ‘Viyaru’ cyclone on the basin-scale variability of Bay of Bengal

doi:10.21203/rs.3.rs-2568457/v1

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Role of ‘Viyaru’ cyclone on the basin-scale variability of Bay of Bengal

https://doi.org/10.21203/rs.3.rs-2568457/v1

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The Bay of Bengal (BoB) is a potentially active region for the formation of the Tropical Cyclones (TCs) and accounts for about 6% of the global annual total number of tropical storms. These TCs occur during the pre-monsoon (March-May) and post-monsoon (October-November) seasons over the BoB. Among all the pre-monsoon cyclones that occurred from 1993 to 2019, we have identified that the “Viyaru” is a typical one originated in the southern BoB, propagated approximately through the middle of the bay, and made landfall over the northern BoB. The cyclonic storm Viyaru caused a basin-scale sea surface cooling of 0.35°C by increasing the mixed layer depth by 3.5 m over the Bay of Bengal. An analysis of mixed layer heat budget terms infers that reduced short wave radiation and increased latent heat fluxes as the key factors responsible for basin-wide cooling associated with the Viyaru cyclone. We have also found that the enhanced entrainment processes even after the dissipation of the Viyaru cyclone had resulted in a post-cyclone basin-wide cooling tendency over the Bay of Bengal. The present study exemplifies the role of a pre-monsoon cyclone (Viyaru) in impacting the Bay of Bengal basin-scale variability of surface Physical Oceanographic variables and associated processes.

Tropical Cyclones

Bay of Bengal

post-cyclone impact

Ocean surface variability

Mixed layer heat budget

Tropical cyclones (TCs) comprise the principal natural hazards under synoptic-scale variability over the tropics. The TCs have profound socio-economic impacts which often cause loss of life (McPhaden et al. 2009; Sreenivas et al. 2012a; Sreenivas and Gnanaseelan 2014) and intense property loss (Sreenivas et al. 2018). These cyclones are also a major concern to farmers in India, as copious rainfall and flooding associated with TCs could cause severe floods and damage to agriculture. As a result, accurate prediction of the track and intensity of TCs has been a major challenge and agreement among meteorological communities on perspectives of various socio-economic impacts. On the other hand, TCs are proven to play a vital role in influencing the hydrological cycle, the copious rainfall associated with cyclones fills rivers and dams and could increase groundwater levels (Subrahmanyam 1988). In addition, being the major forcing factor under synoptic-scale variability, the TCs show interactions with other meteorological scales of variability. For example, the occurrence of TCs over the Arabian Sea in May could delay the southwest monsoon (Attada et al. 2019; Pratik et al. 2019). Similarly, the occurrence of TCs over the South China Sea may suppress the monsoon rainfall over India (Mao and Chan 2005; Roxy and Tanimoto 2007, 2012). Tropical cyclones also impact the upwelling process and cause increased biological activities (Sreeush et al. 2018).

Girishkumar and Ravichandran (2012) reported that cyclones that form east of 90°E in the Bay of Bengal tend to strengthen into strong cyclones when they move across the ocean for extended periods. Because of the abundance of fresh water in the surface layers, the northern sections of the BoB are one of the few places in the world's oceans where the surface water is well stratified (Sengupta et al. 2016). As a result, inside the BoB, oceanic processes are important mechanisms that shape basin-scale SST distribution and impact regional convection. According to recent studies, cyclones are responsible for instantaneous cooling of 0.3 to 3.0°C in SST in the Bay of Bengal along the cyclone track, depending on the intensity and path of the storms (Gopalakrishna et al. 1993; Chinthalu et al. 2001; Subrahmanyam et al. 2005; Sengupta et al. 2007; Maneesha et al. 2012).

Several attempts have been made to understand the seasonal variability of SST in the BoB by examining the thermodynamic processes (Sengupta and Ravichandran 2001; Sengupta et al. 2001; Shenoi 2002; Parampil et al. 2010; Neetu et al. 2012; Girishkumar et al. 2013). Vertical heat transfer from the subsurface to the mixed layer is important in the evolution of SST in the BoB (Prasad 2004; de Boyer Montégut et al. 2007; Nagura et al. 2015). The oceanic mixed layer heat budget analysis infers the relative involvement of several oceanic processes in determining the mixed layer temperature across the cooling/warming regions. Ocean mixed layer heat budget study (Thangaprakash et al. 2016) with varied seasons demonstrates that horizontal advection plays a vital role in warming the upper ocean during winter, while entrainment also plays a major role in cooling the mixed layer. A recent study of mixed layer heat budget terms by Jyothi et al. (2019) revealed that horizontal advection plays a substantial role in defining the temperature tendency for the region within the western boundary current of BoB (Jyothi et al. 2019).

Most of the studies on tropical cyclones are in the perspective of either socio-economical, hydrological, meteorological, or biological impacts of cyclones over BoB, bestowed on the predictive importance of TCs. The study by Sreenivas et al. (2012b) has reported that TCs over BoB (along with TCs in the southern tropical Indian Ocean) could accelerate the basin-wide equatorial currents in the Indian Ocean and enhance the transport of warm waters from west to east. Further, it is important to mention that the synoptic variability associated with TCs can feedback large-scale oceanic circulation (Sreenivas et al. 2012b). Hence, it will be interesting to study the impact of TCs on the basin-scale variability of BoB. The BoB being part of the Indo-Pacific warm pool zone, the active convection over the Bay of Bengal could supply a significant amount of moisture to boost the Indian summer monsoon (June to September) rainfall (Gnanaseelan and Chowdary 2019; Sahoo and Yadav 2021). Every year, the BoB experiences a significant number of TCs during the three preceding months (March to May) of the summer monsoon, often called the pre-monsoon season. Hence, the cyclones that could impact the basin-wide ocean features of BoB have the potential to alter the oceanic background state for the progressing summer monsoon.

In the present study, we have examined the role of the 'Viyaru' cyclone in impacting the basin-wide oceanic features over BoB. The reason for choosing the Viyaru cyclone as a typical case is explained in subsequent sections. The rest of the paper is organized as follows. Section 2 provides a brief description of various datasets used and describes the methods. Section 3 provides a detailed description of the role of the Viyaru cyclone in impacting various physical oceanographic features over different regions and the BoB as a whole; using ocean mixed layer heat budget analysis, section 4 examines the dominant processes responsible for observed Physical Oceanographic changes in response to the Viyaru cyclone; section 5 summarizes our study with a precise description of the future scope of our study.

2.1. Data sets used

The India Meteorological Department (IMD) best-tracked cyclone data (obtained from http://www.imd.gov.in) for the period 1993–2019 is utilized to identify the tracks and dates of the evolution of cyclones over the Bay of Bengal region. This data includes the maximum three-minute sustained wind speed (in knots) and minimum sea-level pressure (in mb). Classification of tropical disturbances based on wind speed is as given by IMD. The high-resolution (25 km or 0.25°) Optimum Interpolated Sea Surface Temperature (OISST, Reynolds et al. 2007) daily data is obtained from the website (http://www.esrl.noaa.gov/psd). A high resolution (0.083 x 0.083 degree, horizontal) Ocean reanalysis product from Marine Copernicus (available at https://resources.marine.copernicus.eu/, product ID: GLOBAL_MULTIYEAR_PHY_001_030) is used to compute different terms involved in mixed layer heat budget equation (Section 2.2). This product is available from January 1993 to December 2019. This Ocean reanalysis product assimilates real/near real-time ocean in-situ and satellite observations and is forced by high-resolution ERA-Interim and ERA5 atmospheric reanalysis, hence capable to represent TC associate/induced Ocean variability (eg. Avila-Alonso et al., 2021). More information and documentation of the data are available fromhttps://catalogue.marine.copernicus.eu/documents/PUM/CMEMS-GLO-PUM-001-030.pdf. These ocean data are also used to compute the ocean mixed layer depth (MLD) and depth of 26°C isotherm (D26). Ideally, the pre-monsoon season doesn’t show the formation of a barrier layer over the Bay of Bengal (Vissa et al. 2012, 2013); hence we have adopted temperature-based criteria for defining mixed layer. The MLD is defined as the extent of the ocean surface up to which the temperature decreases by 0.8°C from the surface temperature (Vissa et al. 2013; Thangaprakash et al. 2016). To study the influence of the Viyaru cyclone on basin-scale physical properties of BoB, we have examined the daily OISST; MLD and D26 obtained from Marine Copernicus, for the period 1993–2019. The TropFlux (Kumar et al. 2012, 2013; Girishkumar et al. 2013) data are used for computing different terms involved in Eq. 2 (section 2.2) of mixed layer heat budget, and the data are available from www.incois.gov.in/tropflux. All the data that are utilized in the present study is obtained for the period 1993 to 2019, and the same period is considered in computing climatological values.

2.2. Method - the Mixed Layer Heat Budget analysis

The Ocean mixed layer heat budget analysis is carried out to identify the dominant processes responsible for the surface ocean changes (up to the MLD) associated with the Viyaru cyclone. To understand the mechanisms and dominant processes associated with changes in the ocean mixed layer (i.e. during the active cyclone period, pre and post of the cyclone period) the mixed layer heat budget analysis is utilized. The MLD heat budget is computed using the method described in prior research (Thangaprakash et al. 2016; KBRR et al. 2020; Vijith et al. 2020). The temperature of the mixed layer is susceptible to surface heat fluxes, horizontal and vertical heat transport, and heat diffusion. However, heat diffusion via molecular processes is relatively minor in comparison to the other components, so it is ignored for ease of analysis. The mixed layer budget equation (Thangaprakash et al. 2016; KBRR et al. 2020; Vijith et al. 2020) is provided hereunder.

$$\frac{\partial T}{\partial t}=\frac{{Q}_{net}}{{\rho c}_{p}h}-\left[\left(u\frac{\partial T}{\partial x}+v\frac{\partial T}{\partial y}\right)+ H\left(Wh + \frac{dh}{dt}\right)\frac{(T-Th)}{h}\right] +\text{R}\text{e}\text{s}\text{i}\text{d}\text{u}\text{a}\text{l}$$

The temperature tendency term is given in the LHS of Eq. (1). The net surface heat flux, horizontal advection, heat flux due to vertical processes, and the residual are the separate components in the R.H.S of the equation. The net surface heat flux is indicated by Qnet.

Q_net = Q_shortwave − (Q_pen+ Q_longwave+ Q_latent+ Q_sensible) (2)

Q_shortwave= Net shortwave radiation,

Q_pen= Shortwave radiation that penetrates below the ML,

Q_longwave= Net longwave radiation,

Q_latent= Latent heat flux,

Q_sensible= Sensible heat flux.

where ρ (1,024 kg m^–3) is the density of seawater, Cp (3,993 J kg^–1K^–1) is the specific heat capacity of seawater, h (m) is the mixed layer depth (MLD), u is the zonal current velocity (ms^–1) and v is the meridional current velocity (m s^–1), T (°C) is then mixed layer temperature, ∂T/∂x and ∂T/∂y is the horizontal gradient of temperature, t is time (in days), W_h is the vertical advection (m day^–1). T_h is the temperature just below the MLD (Girishkumar et al. 2013).

Section 2.1 describes the various data sets utilised in the mixed-layer heat budget study. Except for the climatological values, all of the variables in the mixed layer budget equation are given that are presented in this study are de-trended and removed for the seasonal cycle, to quantify the changes occurring due to the Viyaru cyclone.

3.1. The typical track of the Viyaru cyclone

Figure 1 shows the study region, the Bay of Bengal (BoB), confined between latitudes 5°N to 25°N and longitudes 78°E to 100°E. The figure also shows the tracks of tropical cyclones that evolved over the Bay of Bengal during the pre-monsoon season (March to April) of the years 1993 to 2019. This period is signified by the wealth of different satellite-based oceanographic observations over BoB, hence considered as the study period. Most of these systems are originating over southern or central BoB, with varying tracks and landfall. There are five cyclonic systems that are originating in the southern Bay of Bengal (south of 5°N, Fig. 1) during the study period. Out of these, four of the systems are propagating either through the western or eastern side of the Bay of Bengal. It is interesting to mention that the track shown in red colour (i.e. of the Viyaru cyclone) is the only cyclone that travels approximately through the middle of the BoB basin. The Viyaru system is originated in the southern BoB (south of 5°N) and travelled through the BoB and reached the head of the BoB. Furthermore, the Viyaru system travels approximately through the middle of the BoB basin. Hence, we have considered the Viyaru cyclone as the typical case to study its probable impact on the oceanic factors of BoB on a basin scale.”

Cyclonic Storm Viyaru, formerly known as Cyclonic Storm ‘Mahasen’. The Viyaru cyclone caused loss of life across six countries in southern and southeastern Asia. Earlier studies were confined to the formation, propagation, and dissipation of cyclones and their socio-economic impact. The present study deals with the basin-scale variability of the Bay of Bengal and associated processes. Cyclones over the Bay of Bengal have varied socio-economic impacts. However, very few studies are dedicated to studying the impact of cyclones on the basin-scale variability of BoB. The impact of Viyaru cyclone is studied by examining the ocean surface and subsurface physical variables.

3.2. Role of Viyaru cyclonic storm on physical properties of Bay of Bengal

The mixed layer depth (MLD), sea surface temperature (SST), and depth of the 26°C isotherms (D26) are the three important Oceanographic variables that influence the atmosphere above and take part in active air-sea interactions. Figure 2 shows the Hovmoller diagrams of the evolution of these physical oceanographic parameters during the period of the Viyaru cyclone over the Bay of Bengal. It is interesting to mention that the SST is cooled by a magnitude of ~ -0.35°C over the major portion of the Bay. The MLD shallows during the initial days of the cyclone (10th to 13th May 2013) and deepens during the rest of the period (14th to 16th May 2013). Furthermore, the thermocline shows shallowing in the western part of the basin and Deepening in the eastern part of the basin (i.e., east of 90°E). Hence, during the period of Viyaru cyclone propagation over the Bay of Bengal, the SST and MLD change their phases in anomalies, whereas the D26 anomaly sustains an east-west polarity throughout the evolution of the Viyaru cyclone.

Further, we have examined the nature of these physical oceanographic parameters by considering the Bay of Bengal basin as a whole (area average for 78°E to 100°E, and 5°N to 25°N). Figure 3 shows the evolution of SST, MLD, and D26 during the pre-cyclone period (i.e., 5th to 9th May 2013, 5 days), during the Viyaru cyclone period (10th to 16th May 2013), and 5 days past the decay of the cyclone (i.e., 17th to 21st May 2013). The evolution of daily climatological values of these physical oceanographic parameters is also shown in Fig. 3 (right panels). Since May is the transition period from spring to the southwest monsoon, the Bay of Bengal is subjected to gradual changes in physical oceanographic properties. The increased cloud cover reduces solar insolation (Rajeevan et al. 2001), and at the same time, the enhanced winds (Fig. 2 of Jana et al. 2018) mix the surface waters into deeper layers. Hence, the climatological SST shows a decreasing trend (Fig. 3d) and the MLD shows an increasing trend (Fig. 3e). Also, the D26 (a proxy used for the depth of the thermocline) shows deepening due to increased mixing and dominant downwelling favorable Rossby waves which propagate from the eastern rim of the Bay to the interior Bay of Bengal (Sreenivas et al. 2012a). Before the generation of the Viyaru cyclone (6th to 9th May 2013), the Bay of Bengal as a whole was characterized by increased anomalies (positive anomalies) in SST. The Viyaru cyclone had its genesis over the south-eastern Bay of Bengal on May 10th, 2013 and by May 13th it had reached the central Bay of Bengal by propagating in a north-west direction (Fig. 1). Hence, the period from 10th to 12th May is characterized by positive anomalies in SST as the Viyaru cyclone is limited to the southern parts of the Bay. By the 13th of May, the cyclone had reached the central Bay of Bengal and the basin-wide SST had shown a rapid decrease. Hence, the Bay of Bengal was subjected to basin-wide SST cooling of magnitude ~ 0.35°C in response to the Viyaru cyclone. In addition, the MLD shows rapid deepening during the Viyaru cyclone period (Fig. 3b), whereas the D26 shows a gentle increase during the period of the Viyaru cyclone and a rapid increase after the dissipation of the cyclone (Fig. 3c).

The cyclonic storms forming over the Bay of Bengal have intense socio-economical importance. Being an integral part of the Indo-Pacific warm pool zone, slight changes in ocean thermal structure over the Bay of Bengal could modulate the air-sea interactions. The Bay of Bengal basin as a whole has shown drastic changes in SST and MLD as a response to the Viyaru cyclone. It is imperative to understand the underlying processes and factors that could be responsible for the basin-wide changes in Bay of Bengal physical properties. Hence, the subsequent sections present a quantitative analysis of the ocean mixed layer heat budget to understand the processes for observed changes in the Bay of Bengal in response to the Viyaru cyclone. The method of computing mixed-layer budget terms is described in section 2.

The top panels of Fig. 4 show the nature of climatological net shortwave radiation, net long-wave radiation, latent heat flux, and sensible heat flux for the duration of 10th to 16th May. The sign convention of ‘positive’ towards the ocean and ‘negative’ away from the ocean surface is used for all the fluxes. Being the extreme spring transition month, the month of May is subjected to increased solar radiation. The Bay of Bengal as a whole gains heat in the form of net shortwave radiation (Fig. 4a). The net short-wave radiation is maximum (> 210 Wm^− 2) in the western parts of the Bay, whereas it is relatively low in the eastern parts of the Bay. The net long-wave radiation shows negative values over major parts of the Bay. The increased ocean surface temperatures enhance the long-wave radiation, resulting in a net loss of energy from the ocean. The loss of energy as long-wave radiation is maximum over the western Bay of Bengal (> 40 W/m²) compared to the eastern parts of the Bay. The latent heat flux is characterized by a net loss from the ocean to the atmosphere (negative values, Fig. 4c). The dry atmosphere and increased surface temperatures could enhance the latent heat flux from the ocean to the atmosphere. The magnitude of sensible heat flux (Fig. 4d) is very low compared to the other fluxes presented here. The sensible heat flux in the western Bay of Bengal shows positive values, where the ocean gains thermal energy from the atmosphere and vice-versa for central and eastern parts of the Bay of Bengal basin.

The anomalies influxes during the Viyaru cyclone period (10-13th May 2013) are shown in the middle panels of Fig. 4. The anomalies during the Viyaru period presented here can be attributed to the cyclone influence, as the anomalies are computed after de-trending (and seasonal cyclone removed) the mixed layer budget terms (section. 2). The net shortwave radiation shows negative anomalies over the major portion of the Bay of Bengal, and the ambient regions along the track of the Viyaru cyclone are characterized by strong negative values (~ -50 W/m²) in net short-wave radiation (Fig. 4e). The increased cloud cover during the Viyaru cyclone reduces the incoming solar radiation. The net long-wave radiation shows positive anomalies over the major extent of the Bay of Bengal. As the climatological values of net long-wave radiation infer negative values ranging from − 38 to -50 W/m² (Fig. 4b), the positive anomalies of ~ 10 W/m² (Fig. 4f) infer reduced long-wave radiation flux from the ocean during the period of the Viyaru cyclone. The decreased SSTs during the active cyclone period (Fig. 2a) reduce thermal radiation from the ocean surface into the atmosphere. The latent heat flux (anomalies) during Viyaru (Fig. 4g) infers enhanced convection along the southern and central Bay of Bengal. The sensible heat flux shows enhanced heat transport from the ocean to the atmosphere, especially along the track of the Viyaru cyclone (Fig. 4h). The reduction in incoming shortwave radiation, enhanced longwave flux, and sensible and latent heat fluxes from the ocean to the atmosphere during the Viyaru cyclone period infer reduced heat content from the ocean surface layer, which could cool the ocean surface. The further changes in the ocean's mixed layer and thermal structure due to the Viyaru cyclone are presented by examining the processes associated with mixed layer dynamics.

Figure 5 shows the oceanic mixed layer temperature tendency and the net heat flux terms. Before the Viyaru cyclone (upper panels, Fig. 5), the oceanic mixed layer temperature over the Bay of Bengal was dominated by an increasing tendency (positive values, Fig. 5a). The heat and radiant fluxes are also favorable for heating the Bay of Bengal. In response to the Viyaru cyclone, the net heat flux terms have conducively enhanced surface ocean (up to mixed layer) cooling (Fig. 5, middle panels). It is interesting to mention that the fluxes that are altered during the period of Viyaru cyclone (Fig. 4, middle panels) are in a phase of restoration after the dissipation of cyclone as observed by opposite polarity in the fluxes (Fig. 4 lower panels) compared to the fluxes during the active period of Viyaru cyclone (Fig. 4, middle panels). The lower panels of Fig. 5 show the net fluxes term and tendency term for 5 days after the dissipation of the Viyaru cyclone. It is interesting to note that, after the dissipation of the cyclone, the ocean has gained energy through the terms involved in net heat fluxes (Eq. 2, Section 2). However, the Bay of Bengal is still dominated by a negative mixed layer temperature tendency, which infers that even after the dissipation of the cyclone; some oceanic processes are favorable to cool the Bay of Bengal.

The mixed layer temperature tendency shows rapid basin-wide cooling during the active period of the Viyaru cyclone over the Bay of Bengal. The maximum rate of cooling of magnitude − 0.03 ºC/day was observed on 12th May 2013. It is interesting to mention that, a slight cooling tendency is retained even after the dissipation of the Viyaru cyclone. On the other hand, the net fluxes show a net heat gain (Fig. 6d), which in principle should heat the ocean surface layer and result in a positive mixed layer temperature tendency. However, the cooling tendency is retained for 5 days after the dissipation of the cyclone. The magnitude of the lateral induction term, the zonal and meridional advection terms (Fig. 6a) is very less compared to the rate of mixed layer temperature tendency. It is imperative to mention that the entrainment of subsurface waters into the surface (Fig. 6b) has a major impact on ocean mixed layer temperature tendency during the Viyaru period and after the dissipation of the cyclone. Negative values of entrainment with a magnitude of up to -0.20 ºC are observed during the period of Viyaru (Fig. 6b). The entrainment processes, combined with net flux terms, are responsible for the observed mixed layer temperature cooling during the period of the Viyaru cyclone. After the dissipation of the cyclone, the net flux terms are supportive of heating the ocean surface. However, a cooling of the mixed layer temperature tendency is observed even after the dissipation of the cyclone due to the persistent entrainment processes and the ocean mixed layer is cooled from the subsurface. Hence, the entrainment process is supporting the ocean mixed layer to cool for a longer period, even after the dissipation of the cyclone.

The Bay of Bengal is home to a significant number of tropical cyclones. Tropical cyclones have been the major attention to the meteorological communities due to their varied socio-economic impacts. Recent studies (eg. Sreenivas et al. 2012b) have shown that tropical cyclones can feedback to large-scale air-sea interactions. Since the Bay of Bengal is a part of the Indo-Pacific warm-pool region, small changes in the thermal structure of the Bay could alter the air-sea interactions. Even though studies reported the ocean surface cooling along the wake of the cyclone, the impact of cyclones on Bay of Bengal basin-wide physical oceanographic properties and the time scale of post-cyclone response are not well known. It is imperative to understand whether the cyclones over the Bay of Bengal could alter the basin-scale properties of the bay as a post-cyclone response.

To have an insight on the probable impact of pre-monsoon cyclones on the Bay of Bengal basin-scale variability, we have examined the tracks of pre-monsoon cyclones sustained over the Bay of Bengal. We found that Viyaru is the typical cyclone that has its origin in the southern Bay of Bengal, propagating with a track approximately mid-way to the Bay of Bengal and landfall over the northern Bay of Bengal. In the present study, we have presented the impact of the Viyaru cyclone on Bay of Bengal physical processes and examined the probable process responsible. We found that the Viyaru storm has significant impact on SST, MLD, and D26 as the response to the cyclone. Through the mixed layer heat budget analysis it is found that reduced short wave radiation, and increased latent heat fluxes as the key factors responsible for basin-wide cooling associated with the Viyaru cyclone. It is interesting to note that, even though the net fluxes are conducive to heat the ocean, the Bay of Bengal shows a cooling tendency in mixed layer temperature for a period of 5 days after the dissipation of the Viyaru cyclone. The sustained entrainment processes even after the dissipation of the Viyaru cyclone had resulted in post-cyclone basin-wide cooling tendency over the Bay of Bengal. The present study insights the observed role of a Viyaru cyclone on the basing-wide variability of Bay of Bengal physical properties and examined the processes responsible. As the cyclones during the pre-monsoon season have a high potential to determine the background state for summer monsoon, it is important to understand the probable impact of pre-monsoon cyclones and associated processes.

Acknowledgements:

The first author (GPK) acknowledges sincere thanks to the University Grants Commission (UGC) Sponsored Rajiv Gandhi National Fellowship (RGNF or NFSC)-Government of India for providing financial support. All the data sets that are utilized for this study are described in Section 2. We thankfully acknowledge the use of several reanalysis products (viz. Marine Copernicus, IMD-Tracks, INCOIS-Tropflux, and OISST) in this study. We would like to thank PMEL for making available the Ferret software, which was used for preparing figures.

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Role of ‘Viyaru’ cyclone on the basin-scale variability of Bay of Bengal

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Abstract

Figures

1. Introduction

2. Data And Methods

2.1. Data sets used

2.2. Method - the Mixed Layer Heat Budget analysis

3. Results

3.1. The typical track of the Viyaru cyclone

3.2. Role of Viyaru cyclonic storm on physical properties of Bay of Bengal

4. Processes Responsible For Observed Basin-wide Changes With Respect Of Viyaru Cyclone Over The Bay Of Bengal

5. Summary And Conclusions

Declarations

Acknowledgements:

References

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