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. 2023 Aug 30;13(1):14235.
doi: 10.1038/s41598-023-39884-y.

Analysis of marine heatwaves over the Bay of Bengal during 1982-2021

Sudhanshu Kumar  1   2 , Arun Chakraborty  3 , Raghvendra Chandrakar  1 , Abhishek Kumar  1 , Biplab Sadhukhan  1 , Riyanka Roy Chowdhury  1   4
Affiliations

Analysis of marine heatwaves over the Bay of Bengal during 1982-2021

Sudhanshu Kumar et al. Sci Rep. .

Erratum in

Abstract

Anomalous increase in sea surface temperature and its impact on natural ecosystems greatly interests the research community. Here we investigate the causes, impacts, and trends of marine heat wave (MHW) events in the Bay of Bengal (BoB) from 1982 to 2021. A total of 107 MHW events have been isolated (> 90th percentile threshold) in this Indian Ocean region, and their variation in intensity, duration, and frequency has been investigated. Our research unveils that an average of three MHW events/year accompanied by a linearly increasing trend of 1.11 MHW events/decade has been observed over the study region. It was also found that the most intense event was observed in 2016, which continued for 69 days, and had a maximum intensity of 5.29 °C and a mean intensity of 2.03 °C (above climatology mean). Moreover, it was observed that the net heat flux, along with anticyclonic eddies, was the primary cause of MHW events. Anticyclonic eddies associated with positive sea surface height anomaly were observed (> 0.20 m) in the vicinity of the most intense MHW event. Additionally, climate change and climate modes like El Niño and Indian Ocean Dipole show a high positive influence on the MHW events. Furthermore, we have examined the MHW event recurrence patterns in various regions of the BoB. From the monthly analysis, it was found that August and November had the most occurrences of MHWs, while April and May had the most extreme MHW events.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Monthly averaged SST variance of the last 10 years (January 2012–December 2021) for the BoB region (4° N−24° N; 76° E−96° E).
Figure 2
Figure 2
SST (black), seasonal climatology (blue), threshold (green), and MHW event shading of time-series plot for longest duration MHW.
Figure 3
Figure 3
Shows (a) duration, (b) maximum intensity, (c) cumulative intensity, and (d) mean intensity of all MHW events that occurred between 01 January 1982 and 30 December 2021. The dark red bar corresponds to the maximum intensity event, and the light red bar is for the event of maximum duration.
Figure 4
Figure 4
Time series of MHW events with maximum intensity (Red color shades), with different categories by dashed and dotted lines (refer to Table. 1).
Figure 5
Figure 5
Time series of (a) number of MHW events per year from January 1982 to December 2021 (black) and trend line (blue), (b) year-wise average MHW cumulative intensity.
Figure 6
Figure 6
The categorization of duration in the number of days heatwaves or heat spikes lasted at the selected location.
Figure 7
Figure 7
(a) Monthly bars for the number of MHW events, (b) duration, (c) maximum intensity, (d) cumulative intensity and (e) mean intensity are shown using boxplots from 1982 to 2021 for MHW events.
Figure 8
Figure 8
Temporal variation of SST (black), seasonal climatology (blue), threshold (green), and MHW event shading in time series from October 2015 to December 2016 and net heat flux (dark red) for the same period.
Figure 9
Figure 9
Spatial variation of SST (color) and SOC (vector) for the most intense MHW event.
Figure 10
Figure 10
Temporal variation of SST (black), climatology (blue), threshold (green), and MHW event shading in time series from October 2015 to December 2016 and SSH anomaly (Yellow).
Figure 11
Figure 11
Temporal variation of SST (black), seasonal climatology (blue), threshold (green), and MHW event shading in time series from October 2015 to December 2016 and the difference between evaporation and total precipitation (dark red) for the same period.
Figure 12
Figure 12
Time series for ONI (top) and DMI (bottom) with the maximum intensity of MHW events for the period 1982 to 2021.
Figure 13
Figure 13
Spatial variation for the occurrence of average duration of MHWs per year (left), the average number of MHW events per year (center), and annual mean intensity of MHW events (right) in the BoB region for the period (1982–2021).
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