Seasonal variability of the mixed layer in the central Arabian Sea and its implication on nutrients and primary productivity

First direct measurements of N2fixation during aTrichodesmiumbloom in the eastern Arabian Sea

“…This north‐south gradient in SST and salinity is a common feature of the Arabian Sea and has also been reported earlier [e.g., Madhupratap et al , 1996; Prasanna Kumar and Narvekar , 2005; Prakash and Ramesh , 2007]. The depth where temperature decreases to 1°C is termed as mixed layer depth (MLD), following Prasanna Kumar and Narvekar [2005]. MLD varied between 20 and 35 m at all the stations.…”

Why is the Bay of Bengal experiencing a reduced rate of sea surface warming?

“…Evaporative cooling is a process which reduces the surface temperature consequent to the release of latent heat flux to the atmosphere. This could occur either due to an increase in wind speed, which is normally encountered during summer monsoon or with the prevalence of dry air blowing over the ocean as it occurs during winter monsoon (Prasanna Kumar and Narvekar, ). The wind‐driven mixing, on the other hand, can cool the surface temperature of the ocean by mixing the warm upper ocean water with cold sub‐surface water through mechanical‐mixing and deepening of mixed layer.…”

“…Besides, the basin's waters experience seasonal wind reversal associated with Asian monsoons, having south‐westerly winds during summer monsoon (June to September) and north‐easterly winds during winter monsoon (November to February). The south‐westerly winds are generally warm and moist, while the north‐easterly winds are cold and dry (Prasanna Kumar and Narvekar, ). In response to this reversal in wind direction the surface current also reverses in the basin.…”

Renewable Gas

“…Alternatively, whilst there may be a dearth of photosynthesis occurring on land in much of the country, offshore of Iran in the Persian Gulf and the Gulf of Oman, there is some potential for cultivating seagrasses and seaweeds -the satellite imagery shows light and deep greens in the close offshore waters, indicating an ideal environment. These macroalgal species, in addition to being used to manufacture Renewable Gas, could play a role in controlling microalgal species that cause Harmful Algal Blooms, or "red tides" (FAO, 2001, Section 2.1, "Seaweed") which are prevalent in the Arabian Sea and Gulf of Oman owing to pollution (Hamzehei et al, 2013) and nutrient upwelling from a "deep mixed layer" of the Monsoon ocean Honjo and Weller, 1997;Kumar and Narvekar, 2005;Wiggert et al, 2005). Macroalgal farms would compete with microalgal species for nutrients (Al-Hafedh et al, 2012), and with care, algaculture would not disturb the deposition of biological remains on the sea floor, so the sub-sea area would still retain its high productivity (Marra and Barber, 2005) and high carbon "export" to the deeper ocean via the strong "biological pump" of the Arabian Sea.…”