01-05 December 2025
INCOIS, Hyderabad, India.
| Abstract Submission No. | ABS-08-0152 |
| Title of Abstract | Physical Drivers of Winter Surface Chlorophyll Blooms in the Southeastern Bay of Bengal |
| Authors | Joel John*, Akhil.V. P, Jessin Joy Alex |
| Organisation | CSIR-National Institute of Oceanography |
| Address | Padavupurackal, Chingoli.P.O Alappuzha, Kerala, India Pincode: 690532 E-mail: joelpadavupurackal@gmail.com |
| Country | India |
| Presentation | Poster |
| Abstract | The southeastern Bay of Bengal (BoB) exhibits marked seasonal and interannual variability in surface chlorophyll-a (SChl) concentrations, with a pronounced peak during the winter monsoon season (December⿿February). This study investigates the drivers of interannual variability in winter SChl blooms, emphasizing their modulation by large-scale climate modes, particularly the Indian Ocean Dipole (IOD). Twenty-eight years (1997-2024) of satellite derived SChl, sea level anomaly (SLA), mixed layer depth (MLD), and surface current data are analyzed to explore the coupling between biological productivity and upper-ocean physical processes. Climatological analysis reveals a consistent winter maximum in SChl, while interannual anomalies highlight episodic bloom enhancements linked to ocean-atmosphere interactions. Among the climate indices, the SLA based Dipole Index (SDI) shows the strongest correlation with SChl anomalies, outperforming both the Dipole Mode Index (DMI) and Niño 3.4. Positive SDI phases are associated with negative SLA, intensified westward surface currents, and elevated SChl concentrations, indicating enhanced offshore nutrient transport and lateral spread of the bloom. During strong IOD years, westward-propagating SChl anomalies match the phase speed of second-mode baroclinic Rossby waves, suggesting a dynamic coupling between upper-ocean circulation and productivity. In contrast, weaker IOD or El Niño events fail to produce similar responses. These findings underscore the dominant influence of the IOD over ENSO in shaping winter biological variability in the southeastern BoB and highlight the critical role of upper-ocean dynamics in regulating surface productivity in response to climate forcing. |
| Are you part of IIOE-2 endorsed project | no |
| Keywords | Surface chlorophyll, Interannual variability, Bay of Bengal, IOD, ENSO |
| For Awards | yes |
| Date Of Birth | 24-09-1997 |
| ECSN Registration Number | IIOE2-ECSN-0126 |