Simulation of spatiotemporal interannual variability of oceanic subsurface temperature off East Africa
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Date
2023
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Publisher
African Journals Online
Abstract
The oceanic subsurface variability off East Africa in the tropical western Indian Ocean plays a crucial role in ocean dynamics and living resources as well as weather and climate variability. A regional ocean model is applied to understand the oceanic subsurface interannual variability off East Africa. The region with the highest sea surface temperature (SST) variability in the offshore region lies adjacent to strong subsurface temperature variations located between 30 and 130 m corresponding with strong variations in the thermocline depth. The weakest SST variations in the Tanzanian shelf waters lie over the subsurface waters with the smallest temperature variations in the upper 200 m with weak variations in the thermocline depth. Such signals are associated with induced forcings from the Indian Ocean Dipole (IOD) and El Niño-Southern Oscillation (ENSO) in both regions with different intensity and peaking times. The IOD-induced forcings are weaker, evolving in October and November-December in the region with the weakest and strongest SST variations, respectively. Relatively stronger ENSO induced forcings occur in both regions. Stronger signals occur in the region with the stongest SST variations throughout the year, except in August, with a peak in January. The ENSO-induced forcings occur in January to May peaking in March and April in the region with the weakest SST. Consequently, anomalous Rossby waves as well as local Ekman downwelling and upwelling associated with both large-scale modes occur in the region leading to the subsurface temperature variations.
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Full Text Article.
Also available at https://www.ajol.info/index.php/wiojms/article/view/220816
Keywords
Thermocline, Oceanic subsurface temperature, Indian Ocean Dipole, Upwelling, Downwelling, East Africa, Oceanic subsurface variability, Sea surface temperature, SST, El Niño-Southern Oscillation, ENSO, Ocean dynamics, Living resources
Citation
Manyilizu, M. C. (2022). Simulation of spatiotemporal interannual variability of oceanic subsurface temperature off East Africa. Western Indian Ocean Journal of Marine Science, 21(2), 57-70.