1 Introduction

The Indian subcontinent is prone to extreme precipitation-induced floods, earthquakes in the Himalayas, landslides, drought, and tropical cyclones in coastal areas [1, 2]. In recent years (since 2000), the Bay of Bengal and the Arabian Sea have experienced a significant increase in cyclogenesis, devastatingly affecting the eastern and western coasts of the Indian subcontinent [3]. Sea Surface Temperature (SST) considerably influences cyclogenesis as warm SST contributes to the development, intensification and movement of Tropical Cyclones [4,5,6]. According to Chia and Ropelewski [7], an SST of approximately ≥ 26.5 °C is a favorable condition for cyclogenesis on the ocean surface, and 6% of the world’s tropical cyclogenesis occurs in the Bay of Bengal and the Arabian Sea [8]. The SST has significantly warmed over the twentieth century in the tropics, attributed to anthropogenic-induced climate change [9, 10]. The increase in SST in the Bay of Bengal is less than that in the Arabian Sea [11], indicating potential low-pressure area formation. Maximum warming is observed along the Equator, with the Northern Hemisphere warming more than the Southern and the Indo-Pacific regions, which experience the most warming [12,13,14]. Due to rising CO2 levels in the atmosphere, the North Indian Ocean, including the Arabian Sea basin, is expected to experience an increase in the frequency and intensity of cyclones [15, 16]. In the Arabian Sea, the average SST of 28.5 °C is warm enough for the formation of Tropical Cyclones [17, 18], providing a pre-monsoon and post-monsoon atmospheric circulation and associated strong vertical wind shear limits for cyclone development and its intensification [19], while the increasing frequency of tropical cyclones is observed during the summer monsoon [20]. Thus, the formation of intense cyclones in the North Indian Ocean will be highly dependent on the SST and vertical wind shear [21, 22].

Notably, the first pre-monsoon cyclones in the Indian Ocean typically form in the Bay of Bengal, but in May 2021, Tauktae, the first pre-monsoon cyclone, formed in the Arabian Sea. The fifth-strongest cyclone ever recorded in the Arabian Sea, Tauktae, was an Extremely Severe Cyclonic Storm. Between 1891 and 2000, 50% of tropical cyclones that formed in the Arabian Sea and were classified as severe cyclonic storms affected the west coast of India, while 33.8% of cyclones that formed in the Bay of Bengal were classified as severe cyclonic storms affected the east coast [22]. However, in the past few decades, the average frequency of storms over the Arabian Sea and the time of year they occur have shown a changing pattern [23]. In addition, cyclones over the Arabian Sea are increasing in intensity, driven by rising greenhouse gas emission and temperature. The increasing frequency and intensity of tropical cyclones around the world caused huge impacts on human life and property, socio-economy, and the environment through the combination of very high-speed winds, extreme precipitation, and large storm surges [24, 25].

An unusually powerful tropical cyclone named Tauktae struck the Indian state of Gujarat on May 17, 2021. As Tauktae approached land, the US Joint Typhoon Warning Center reported maximum sustained winds of 100 knots (185 km/125 miles/h) and gusts up to 125 knots (230 km/145 miles), equivalent to a category 3 or 4 hurricanes (https://earthobservatory.nasa.gov/images/148325/cyclone-tauktae-strikes-india). That made Tauktae the fifth-strongest storm observed in the Arabian Sea since 1998. Winds of that strength can easily snap trees, topple power lines, and damage homes. The storm also pushed a destructive storm surge of water onto the Indian coast; reports suggest it may have been as high as 3 m in some areas. Even before making landfall, Tauktae caused a trail of destruction in Kerala, Karnataka, Goa, and Maharashtra as it brushed India northwest coast over the weekend. According to news reports, the storm contributed to the deaths of at least 12 people, destroyed hundreds of homes, and caused power outages and traffic jams. More than 150,000 people evacuated Gujarat in anticipation of Tauktae’s arrival (https://appliedsciences.nasa.gov/what-we-do/disasters/disasters-activations/cyclone-tauktae-2021). Further details about the damages/loss caused by cyclone Takutae is given in Table 1.

Table 1 Damages caused due to cyclone Takutae.
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Due to climate change and global warming, the Northern Indian Ocean and Arabian Sea are prone to more frequent and severe tropical cyclones. Cyclone Tauktea is one of the most powerful cyclones observed in the Arabian Sea in recent decades. In addition, this cyclone was observed from May 14 to May 19, 2021, when the second COVID-19 pandemic was at its peak in India. At the same time, severe cyclone Tauktea causes an additional burden on human lives. Although this cyclone has a slightly different silent feature than the other cyclones (Table 2). Therefore, it is imperative to understand the genesis and its intensification over a period of time. Henceforth, this study aims to achieve the following objectives: (i) analyze the genesis parameters, such as SST, water vapor, surface latent heat flux, and winds, along with genesis potential parameter during the period of cyclone May 14 to May 19, 2021; (ii) determine the distribution and variability of precipitation over the areas influenced by cyclone; and (iii) qualitatively discuss the impact of cyclone Tauktea on livelihood.

Table 2 Silent feature of Takutae and its comparison with cyclone Kandla, 1998 and Amphan, 2020.
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2 Data and methodology

2.1 Data

This study used simulated data, satellite datasets, and meteorological department reports to analyze atmospheric, oceanic, and meteorological parameters. The cyclone trajectory is mapped using IMD Bulletin reports (BULLETIN NO. 36: ARB/01/2021).

The group for High-Resolution Sea Surface Temperature (GHRSST) data are used to analyze the variations in the SST before cyclogenesis. GHRSST data is also used to estimate the decadal SST anomaly in the North Indian Ocean for four different years (2000, 2010, 2020, and 2021) to measure the anomaly in SST [26]. The genesis and progression of cyclones depend on the SST in the Indian Ocean; therefore, from 1st to 14th May, 2021, the SST is monitored. The GHRSST is founded in 2002 to promote worldwide collaboration and coordination in creating advanced, real-time datasets for global, high-resolution SST using many sensors.

The spatiotemporal movement of winds, water vapor, and surface latent heat flux (SLHF) in the ocean and land surface is analysed using ERA5 hourly wind. ERA5 is the latest iteration of the European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis, providing comprehensive data on global climate and weather spanning the last 80 years. Data are accessible starting from the year 1940 and continuing thereafter. ERA5 supersedes the ERA-Interim reanalysis. ERA5 offers hourly estimations for various atmospheric, ocean-wave, and land-surface variables. The uncertainty estimate is obtained by sampling a 10-member ensemble at three-hour intervals. ERA 5 is the latest ECMWF reanalysis, providing hourly, daily, and monthly data for various atmospheric, sea state, and land surface parameters starting from 1950 until now [27]. The IFS Cycle 41r2 4D Var data assimilation method was utilized to develop ERA5. The data is accessible at a consistent spatial resolution of 0.25° by 0.25° throughout 37 pressure levels. The low to middle-level tropospheric humidity is taken from ERA5.

The Global Precipitation Measurement (GPM) is a collaborative satellite effort to deliver advanced observations of rainfall and snowfall around the globe at three-hour intervals. The IMERG algorithm is a comprehensive method that combines data from all passive-microwave devices in the GPM Constellation to generate accurate rainfall estimates. This study uses satellite-based precipitation data derived from GPM [28].

2.2 Methodology

Cyclone Tauktea formed on May 14, 2021, and was made landfall near to the Gujarat coast on May 19, 2021. Therefore, we analyze the cyclone genesis parameters such as SST, atmospheric instability, and wind shear during the abovementioned period, and its anomaly is computed concerning the last two decades. To understand the impact of the cyclone, we also analyze the precipitation during the cyclone period. The wind direction and speed are computed using both eastward and northward winds. Furthermore, we have also analyzed the wind shear during the genesis of cyclone Tauktea.

Kotal et al. [29] created a genesis potential parameter (GPP) by utilizing the variables of vorticity at 850 hPa, relative humidity in the middle troposphere, instability in the middle troposphere, and vertical wind shear. These data at specific pressure levels are taken from ERA5. The investigation revealed that each variable utilized in GPP uniquely contributes to the intensification of a low-pressure system. The intensification processes are influenced directly by the first three factors and inversely by the fourth. The GPP is defined as:

$$\begin{aligned} GPP & = \frac{{\xi_{850} \times M \times I}}{S}\quad {\text{if}}\;\xi_{850} > 0,\;{\text{M}} > 0\;{\text{and}}\;{\text{I}} > 0 \\ & = 0\quad {\text{if}}\;\upxi _{850} \le 0,\;{\text{M}} \le 0\;{\text{or}}\;{\text{I}} \le 0, \\ \end{aligned}$$

where ξ850 = low-level relative vorticity (at 850 hPa) in 10–5/S, S = vertical wind shear between 200 and 850 hPa (m/s), M = [RH − 40]/30 = middle troposphere relative humidity, where RH is the mean relative humidity between 700 and 500 hPa and I = (T850 − T500) °C = middle-tropospheric instability (temperature difference between 850 and 500 hPa).

3 Results and discussion

3.1 Trajectory of tropical cyclone Tauktae

The tropical cyclone Tauktae began as a depression near the Lakshadweep islands on May 14, 2021, at 03:30 (IST) with a wind speed of 40 km/h (Fig. 1). On the same day, it intensified further into a deep depression and further transformed into a cyclonic storm on May 15, 2021, with a wind speed of 60–90 km/h. On May 16, 2021, it intensified into a severe cyclone with wind velocities of 90 to 120 km/h, and on May 17, 2021, it intensified into an extremely severe cyclonic storm (wind speed of about 120–150 km/h). It made landfall near the coasts of Gujarat at around 8:30 PM (IST). On May 19, 2021, it weakened into a depression area over Rajasthan with low wind speed (40–50 km/h) and formed a well-defined area of low pressure (Fig. 1). Tauktae discharged wind speeds of up to 190 km/h, and its landfall caused devastation in coastal and inland regions of Gujarat (Fig. 1).

Fig. 1
figure 1

Trajectory of the Tauktae cyclone from May 14 to May 19, 2021. Here, D stands for depression, DD is a deep depression, SCS is a severe cyclonic storm, VSCS is a very severe cyclonic storm, and ESCS is an extremely severe cyclonic storm

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From 10th to 19th May, 2021, the spatiotemporal movement of winds in the ocean and on the land surface is traced using ERA5 hourly data (Fig. 2). During 10th–11th May, 2021, very low wind speed (1–5 m/s) is observed above Lakshdeep, where low pressure area seen, while very high winds (10–20 m/s) is observed from equatorial regions in the Arabian Sea towards the Lakshadweep area. The moisture-laden winds from the western Arabian Sea carried a lot of moisture to the cyclones. This phenomenon continued till May 12, 2021, and later led to a circular formation with a wind speed of 10–15 m/s, near the Lakshadweep region, forming the low-pressure area, which intensified into a depression area on May 14, 2021, with a wind speed around 20 m/s. On May 15, 2021, this depression became a deep depression and moved northwards with a wind speed of around 30 m/s. Later, it intensified into a severe cyclone. On May 16, 2021, the wind shifted northwards, agitating the coasts of Maharashtra and Karnataka at 30–40 m/s. On May 17, 2021, this cyclonic system reached the Gujarat coast with a maximum wind speed of 40 m/s, impacting Gujarat and Maharashtra with its extremely high wind speed. Later, on May 18, 2021, it moved northward across the land and caused severe devastation to the coastal regions of Gujarat. On May 19, 2021, the circular pattern of the cyclonic storm disappeared, and 5–10 m/s winds were observed blowing from the Arabian Sea towards the land surface (Fig. 2).

Fig. 2
figure 2

Winds movement across the sea surface during 11th–19th May 2021 based on ERA-5 reanalysis datasets. The red circle indicates a low pressure area

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3.2 Environmental characteristics linked to the process of intensification

Figure 3 depicts the spatiotemporal variation in SST in the Indian Ocean from 1st to May 14th, 2021 (before cyclone formation). On May 1, 2021, regions near the western coasts of India observed SST of about 30.5 °C-32 °C whereas the Bay of Bengal observed SST in the range of 28 °C to 31 °C. On May 2, 2021, there was a spatial increase in the SST range (30 °C to > 32 °C) in the Arabian Sea, whereas the Bay of Bengal region remained constant. SST in the Arabian Sea region gradually increased until May 5, 2021; significantly less variation in SST is observed in Bay of Bengal. From the 6th to 11th May, 2021, the SST in the western portion of Bay of Bengal increased from 31.5 to 32 °C before progressively decreasing to 31 °C. However, SST gradually increased from 30.5 to 32 °C in Arabian Sea regions around the western coast of India and Puducherry till May 14, 2021. The SST in the central portion of the Arabian Sea remained constant between 30 and 31.5 °C, although an increasing trend in SST is observed in the Western parts of the Arabian Sea during this period. The SST has been gradually increasing since May 7, which indicates the potential formation of depression in the regions.

Fig. 3
figure 3

Variability in sea surface temperature (SST) derived from ERA5 from May 11 to May 19, 2021

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Water vapor is one of the important parameters that can affect the intensification of the cyclones, as it provides energy to the cyclone. We observed that the southern part of the Arabian Sea shows high water vapor values (Fig. 4). As the cyclone initiated, increased water vapor followed a similar path to the cyclone. For example, on May 14, 2021, water vapor was very high near the cyclone point in the Arabian Sea, which is clearly visible in Fig. 4. Similarly, water vapor shows very high values in further periods (i.e., cyclone genesis and dissipating point). As the cyclone made landfall, water vapor showed very low values. Similarly, the variability in SHLF is investigated during the cyclone Tauktae, as shown in Fig. 5. At the stage of depression (May 14, 0000 UTC), the SHLF was about − 5 × 105 J/m2 at the location where the cyclone originates. As cyclones intensify with time, the growth in SHLF is also observed. For instance, on May 15, cyclones intensified into a cyclonic storm from a deep depression, and high SHLF was recorded during the period, about − 25 × 105 J/m2 to − 35 × 105 J/m2. As cyclones further intensify to VSCS (May 16) and ESCS (May 17), the SHLF is about − 20 × 105 J/m2 to − 30 × 105 J/m2.

Fig. 4
figure 4

Water vapor (kg/m2) distribution during cyclone Tauktea (May 11 to May 19, 2021) derived from ERA5

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Fig. 5
figure 5

Variability in surface latent heat flux derived from ERA5 during cyclone Takutae from May 14 to May 19, 2021. Here, D stands for depression, DD is a deep depression, SCS is a severe cyclonic storm, VSCS is a very severe cyclonic storm, and ESCS is an extremely severe cyclonic storm

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Figure 6 represents the analyses of the GPP at 0000 UTC from May 14 to May 19, 2021. The progressive organization of the GPP zone is observed during the course of the period. As of 0000 UTC on May 14, there are areas in the Arabian Sea where the cyclone originates, and the GPP exceeds 30, which also conforms to the development of a low-pressure system. At 0000 UTC on May 15, a cluster of GPP with values exceeding 30 was found in the Arabian Sea when the cyclone intensified into a cyclonic storm from depression. This indicates the potential formation of a cyclone Takutae. The GPP cluster’s organization on the following day (0000 UTC on May 16) confirmed the intensification of cyclone Takutae to a very severe cyclonic storm in the region. The circular organization of the GPP cluster with values greater than 30 on 0000 UTC of May 15 and May 17 strongly suggested that the low-pressure system intensified in the following hours.

Fig. 6
figure 6

Variability in genesis potential parameter during cyclone Takutae from May 14 to May 19, 2021. Here, D stands for depression, DD is a deep depression, SCS is a severe cyclonic storm, VSCS is a very severe cyclonic storm, and ESCS is an extremely severe cyclonic storm

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3.3 Precipitation variability during cyclone

The GPM is used to track the spatiotemporal variation in precipitation during the Tauktae cyclone (10-19 May, 2021). From 10th to May 13, 2021, precipitation of moderate intensity (100–140 mm/day) was observed in the southern Arabian Sea near the Equator before the formation of cyclones (Fig. 7). On May 14, 2021, precipitation with very high intensity (280–300 mm/day) was observed in the ocean at 12° N–72° E, corresponding to a cloud-accumulating depression area. On 15th and 16th May 2021, the depression area intensified further and transformed into an extremely severe cyclonic storm with extremely intense precipitation (280–300 mm/day) in the Ocean regions. As the initial impact of the Tauktae cyclone, the western portion of Maharashtra, Kerala, and Karnataka experienced moderate precipitation (100–120 mm/day) and strong winds during this period. On May 17, 2021, cyclone Tauktae made landfall near Gujarat’s coastlines, bringing extremely heavy precipitation (250–300 mm/day). This low-pressure system shifted toward northern India on May 18, 2021, resulting in intense precipitation (40–60 mm/day) in the Rajasthan, Madhya Pradesh, and Uttar Pradesh districts (Fig. 7). Due to the influence of the Tauktae cyclone, western Uttar Pradesh, northern Madhya Pradesh, and western Bihar experienced low precipitation (10–20 mm/day) on May 19, 2021.

Fig. 7
figure 7

Variability in precipitation from May 10 to May 19, 2021derived from GPM measurement

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3.4 Implication and significance of cyclone Takutae

During May 12–19, amidst the severe second wave of the epidemic, India west coast was hit by the formidable cyclone Tauktae, resulting in the death of multiple individuals (Table 1). This cyclone was the most lethal in the Arabian Sea in the past ten years, as also indicated in Table 2 about the silent feature of Takutae and its comparison with other cyclones such as Kandla, 1998 and Amphan, 2020. Originating from the southwestern region of Lakshadweep, the cyclone severely impacted all states along India’s western coastline. Additionally, the leftovers of the cyclone resulted in rainfall in northern areas of India, the Sindh province of Pakistan, and Nepal. The western tropical Indian Ocean has experienced a long-term warming trend for over a century, surpassing the rate of warming in any other tropical ocean region [10, 30]. Currently, it has the title of being the primary factor influencing the global mean SST. Tropical cyclones derive energy from warm water, forming over regions with warm pools when temperatures exceed 28 °C. During the cyclogenesis process of Tauktae, the Arabian Sea saw elevated SST ranging from 30 to 31 °C, while it used to be cooler in the past.

The Economic and Social Commission for Asia and the Pacific (ESCAP) analysis of the convergence of cyclones Nisarga and Amphan last year and Tauktae presently, with the COVID-19 pandemic, reveals an intricate and interconnected risk scenario. Nisarga occurred during the initial phase of the pandemic, affecting only specific areas with a small number of illnesses. However, Tauktae happened during the subsequent phase of the epidemic, resulting in a convergence of an intense climatic occurrence with the ongoing pandemic. Effectively handling interconnected risk scenarios is consistently demanding. As an illustration, Tauktae hit India as the country is already dealing with a significant surge in COVID-19 cases and an outbreak of black and white fungus, often known as mucormycosis, in the impacted states. Consequently, authorities were compelled to relocate patients receiving medical care in hospitals, safeguard the crucial distribution channels for medical oxygen, and temporarily halt the ongoing immunization initiatives. During the week of Tauktae’s advance and landfall, the recorded COVID-19 cases remained the highest globally, totaling 2.5 million. Although no data indicates that Tauktae caused an increase in COVID-19 cases, it is worth noting that numerous rescuers who evacuated vulnerable regions during the Amphan and Nisraga storms last year later tested positive for the virus. The concurrent crises may prompt individuals to avoid preventative actions, adding to the surges.

4 Conclusions

  • This study investigates the meteorological parameters associated with the extremely severe cyclone Tauktae, which formed in the Arabian Sea in May 2021 due to anomalous warming.

  • The result shows a high increase in SST in western parts of the Arabian Sea (30.5 °C to 32 °C) during the initial days of May 2021, which triggered the formation of the first tropical cyclone, Tauktae.

  • Very high water vapor and SLHF values are observed over the low-pressure area, indicating potential causes of the intensification of cyclone Takutae.

  • Similarly, GPP also shows a cluster of high values (> 30) in the Arabian Sea areas throughout the cyclone progress.

  • Cyclone Tauktae impacted the eastern coastal states of India (Karnataka, Maharashtra, and Gujarat) with its extremely high wind speed (150 km/h) and extremely heavy precipitation (250–300 mm/day). Later, it weakened over Rajasthan, forming a low-pressure area with moderately low precipitation (40–60 mm/day).

  • The study highlights the nature of the tropical cyclone Tauktae in the Indian subcontinent and its impact in terms of severe precipitation and SST, contributing to assessing the aftermath of the Tauktae cyclone, which aids in developing effective preparedness strategies and disaster risk reduction.