• Murty V S N

Articles written in Journal of Earth System Science

• Suppressed biological production in the coastal waters off Visakhapatnam, India under the impact of the very severe cyclonic storm Hudhud

Tropical cyclones generally enhance biological production due to the increase in nutrients input due to vertical mixing. In contrast, the very severe cyclonic storm (VSCS)Hudhud decreased primary production due to the strong stratification associated with torrential rainfall and high suspended load from the major city where the cyclone made landfall. The study region received nutrients from the cold core eddy and coastal upwelling in the offshore and inshore regions, respectively, during pre-cyclone period and the same was suppressed under the influence of cyclonic winds led to convergence by shoreward Ekman transport. The land run-off brought nutrients to the coast during cyclone Hudhud; however, their concentrations were less than that during other cyclones (Orissa supercyclone, Sidr and Phailin). Such low nutrient levels resulted from the VSCS Hudhud crossing the urban region (Visakhapatnam city) whereas other cyclones crossed the coast over fertile agricultural lands which led to high nutrients input associated with phytoplankton blooms. Therefore, the biological response to a cyclone not only depends on the intensity of the cyclone but also on the region of the land it crosses.

• Two decades of current observations in the equatorial Indian Ocean

Deep-sea moorings in the equatorial Indian Ocean were first deployed by India in the year 2000, and currents were measured at three locations (77$^{\circ}$E, 83$^{\circ}$E, and 93$^{\circ}$E) on the equator. In this paper, we present two decades of current observations from these moorings and discuss how the moorings have evolved with time. The observations show that the 180-day (90-day) period dominates the surface and mid-depth (bottom) circulation. Though the Wyrtki Jets are strong, the near-surface currents do not show any clear semi-annual reversals. The reversals become evident only below 100 m.

$\bf{Highlights}$

$\bullet$ Twenty years of ocean current data collected at the equatorial Indian Ocean

$\bullet$ Bottom current data show strong intraseasonal variability

$\bullet$ Upward phase propagation associated with the semi-annual cycle more prominent for the mid-depth currents

$\bullet$ The semi-annual reversals not evident every year near the surface

• # Journal of Earth System Science

Volume 132, 2023
All articles
Continuous Article Publishing mode

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019