Group items tagged

Formation of a huge underwater volcano offshore the Comoros.

Gaining insight into the interannual variability of the Indian Ocean Subtropical Mode Water (IOSTMW) is essential for understanding ocean dynamics in the Southwest Indian Ocean, since it carries the signal of winter mixing and transports it into the ocean interior. As the number of Argo profiles in the Southwest Indian Ocean increases, it has become possible to study temporal variations in IOSTMW using observation data. We used Argo products to examine the interannual variability of the IOSTMW from 2005 to 2020. We examined various definitions to determine the most suitable definition for IOSTMW in this study, choosing to define the IOSTMW as a layer with a vertical temperature gradient of less than 1°C per 100 meters (dT/dz< 1°C/100 m) and a temperature range of 16°C-18°C because this correlates strongly with winter heat loss in the same year. This method is particularly useful for investigating how mode water captures anomalous winter mixing signals and advects them to the ocean interior via subduction. Furthermore, we found that summer stratification can play a role in either facilitating or hindering the formation of thick IOSTMW layers. Our study indicates that thin IOSTMW layers are primarily caused by extremely weak winter heat loss associated with anomalously weak latent heat, whereas thick IOSTMW formation is aided by weak summer stratification.

Training centre for fishermen to open in Maldives.

Marine iodine speciation has emerged as a potential tracer of primary productivity, sedimentary inputs, and ocean oxygenation. The reaction of iodide with ozone at the sea surface has also been identified as the largest deposition sink for tropospheric ozone and the dominant source of iodine to the atmosphere. Accurate incorporation of these processes into atmospheric models requires improved understanding of iodide concentrations at the air-sea interface. Observations of sea surface iodide are relatively sparse and are particularly lacking in the Indian Ocean basin. Here we examine 127 new sea surface (≤10 m depth) iodide and iodate observations made during three cruises in the Indian Ocean and the Indian sector of the Southern Ocean. The observations span latitudes from ∼12°N to ∼70°S, and include three distinct hydrographic regimes: the South Indian subtropical gyre, the Southern Ocean and the northern Indian Ocean including the southern Bay of Bengal. Concentrations and spatial distribution of sea surface iodide follow the same general trends as in other ocean basins, with iodide concentrations tending to decrease with increasing latitude (and decreasing sea surface temperature). However, the gradient of this relationship was steeper in subtropical waters of the Indian Ocean than in the Atlantic or Pacific, suggesting that it might not be accurately represented by widely used parameterizations based on sea surface temperature. This difference in gradients between basins may arise from differences in phytoplankton community composition and/or iodide production rates. Iodide concentrations in the tropical northern Indian Ocean were higher and more variable than elsewhere. Two extremely high iodide concentrations (1241 and 949 nM) were encountered in the Bay of Bengal and are thought to be associated with sedimentary inputs under low oxygen conditions. Excluding these outliers, sea surface iodide concentrations ranged from 20 to 250 nM, with a median of 61

Tropical regions experience a diverse range of dense clouds, posing challenges for the daily reconstruction of chlorophyll-a concentration data. This underscores the pressing need for a practical method to reconstruct daily-scale chlorophyll-a concentrations in such regions. While traditional data reconstruction methods focus on single variables and rely on specific factors to infer missing data at specific locations, these single-variable methods may falter when applied to tropical oceans due to the scarcity of available data. Fortunately, all oceanographic variables undergo similar atmospheric and marine dynamic processes, creating internal relationships between them. This allows for the reconstruction of missing data through correlations between variables. Thus, this study introduces a multivariate reconstruction approach using the extended data interpolating empirical orthogonal function (ExDINEOF) method to reconstruct missing daily-scale chlorophyll-a concentration data. The ExDINEOF method considers the simultaneous relationships among multiple variables for data reconstruction in tropical oceans. To verify the method's robustness, missing data were reconstructed during the formation and passage of severe tropical cyclone Hudhud through the Bay of Bengal. The results demonstrate that ExDINEOF outperforms traditional data reconstruction methods, exhibiting favorable spatial distribution and enhanced accuracy within the dynamic tropical marine environment. Furthermore, an assessment of marine physical environmental factors associated with chlorophyll-a concentration data provides additional evidence for the ExDINEOF method's accuracy. Notably, the ExDINEOF method offers comprehensive spatial distribution aligned with underlying physical mechanisms governing phytoplankton distribution patterns, detailed phytoplankton growth, bloom, extinction variations in time series, satisfactory accuracy, and comprehensive local-level details.

The Tibetan Plateau uplift has induced the formation of the largest sediment source-sink system in the northeast Indian Ocean, which has become an ideal region for investigating land-sea interaction processes. However, many questions regarding sediment transport patterns and their controlling factors at different time scales remain unanswered. Therefore, in the present study, a gravity core named BoB-79, based on the southern Bay of Bengal (BoB) was selected to investigate sediment provenance shift and its corresponding mechanism to sedimentary environment change since the last glacial maximum (LGM). The clay mineral compositions are analyzed and the whole core sediments reveal a feature dominated by illite (~55%), followed by chlorite (~24%) and kaolinite (~17%), and the content of smectite (~4%) is the lowest. A trigonometric analysis of provenance discrimination of clay minerals showed that the Himalayas, together with the Indian Peninsula, represent the main sources of southern BoB sediments, and the last glacial period might have been controlled by the dominant Himalayan provenance, with an average contribution of approximately 90%. However, as a secondary source, the influence of the Indian Peninsula increased significantly during the Holocene, and its mean contribution was 24%, thus, indicating that it had a crucial effect on the evolution process of BoB. The sediment transportation pattern changed significantly from the LGM to the Holocene: in the last glacial period, the low sea level exposed the shelf area that caused the Ganges River connected with the largest submarine canyon in BoB named Swatch of No Ground (SoNG), and the Himalayan materials could be transported to the BoB directly under a strong turbidity current, thereby forming the deep sea deposition center with a sedimentation rate of 4.5 cm/kyr. Following Holocene, the sea level increased significantly, and the materials from multiple rivers around the BoB were directly imported into the continen

As oceans empty, Kenya fishermen must adapt or disappear.

The continued accumulation of sand within the iconic ring-shaped reefs inside Maldivian atolls could provide a foundation for future island development new research suggests. Islands like the Maldives are considered likely to be the first to feel the effects of climate change induced sea level rise, with future island growth essential to counter the threat of rising sea levels.

Ten years after the tsunami disaster of December 2004 the training program PROTECTS (Project for Training, Education and Consulting for Tsunami Early Warning Systems) successfully comes to a close today with a festive ceremony in Jakarta/Indonesia. After the successful implementation and hand over to Indonesia of the German-Indonesian Tsunami Early Warning System for the Indian Ocean (GITEWS), PROTECTS was a direct follow-up project of GITEWS for training and further education purposes with respect to disaster protection measures. Since the start of the PROTECTS-Program in June 2011 right up to March 2014 a total of 169 different training modules have been executed. The project was financed by the Federal Ministry for Education and Research with a total sum of 7.2 million euros.

Tanzania finally endorses EAC anti-piracy protocol.

Efforts to combat marine pollution in the Western Indian Ocean (WIO) region took a significant step forward during a weeklong training and capacity development workshop hosted by the Council for Scientific and Industrial Research (CSIR) in Durban from 7 to 11 April 2025.