Observed low‐salinity plume off Gulf of Khambhat, India, during post‐monsoon period

Abstract

Freshwater outflow from river systems, joining the northeastern Arabian Sea suggests that the discharge is maximum during summer monsoon and least during other seasons. However, analysis of climatological monthly salinity and ARGO data indicate, low‐saline plumes off Gulf of Khambhat during post‐monsoon, despite the fact that there is no river discharge during this period. It is puzzling to understand the existence of relatively low‐saline waters in the region that warrants further investigation. Simulations from three‐dimensional Princeton Ocean Model (POM) suggest that the opposing winds and the associated onshore coastal currents during July seem to trap the freshwater in the gulf region. As the monsoon withdraws by September, the currents change their direction that would help in releasing the low‐saline waters to open ocean. Winter cooling of the freshwater also enhances the prospects of temperature inversions.

Argo - A Decade of Progress

“…Thus Argo enables a new understanding of the upper ocean variability of the Arabian Sea, such as summer cooling during contrasting monsoons [43], temporal variability of the core-depth of Arabian Sea High Salinity Water mass (ASHSW) and the origin of this water mass [44]. Additionally, Argo data have been used to examine buoyancy flux variations and their role in air sea interaction [45], identification of the lowsalinity plume off the Gulf of Khambhat, India [46], during the post-monsoon period, mixed layer variability of western Arabian Sea [47], and seasonal variability of the barrier layer [28]. The importance of upper ocean temperature and salinity structure during a cyclone was illustrated by [13].…”

Freshwater plume-like condition near the north-eastern coastal Arabian Sea during early Miocene: Evidence from the stable isotope record in the growth bands of gastropods (Turritella sp.)

“…However, it is more similar to that of the Hooghly Estuary, located in eastern India. We consider this excess freshwater influx as a freshwater plume-like condition as documented in the modern coastal Indian Ocean (Rao et al, 2009;Joshi et al, 2021). We have estimated around 21 psu change in the apparent salinity (Supplementary section 7) due to the enhanced freshwater influx for the early Miocene Kachchh basin, comparable with the modern estimates (Seena et al, 2019).…”

Migration history of an ariid Indian catfish reconstructed by otolith Sr/Ca and <i>δ</i>¹⁸O micro-analysis

“…1b and 2b). During the monsoon season, a low-salinity water plume with a massive sediment particle load is observed in instrumental and satellite data (Rao et al, 2009;Rahaman and Singh, 2012). Seawater d 18 O (d 18 O SW ) is stable in the upper 50 m (0.6‰, Fig.…”

“…Sea surface salinity (SSS) fluctuates a little seasonally and inter-annually at the mouth of the Gulf (approximately 0.1 psu) ( Fig. 2a), whereas SSS in the Gulf varies largely due to river discharge (Rao et al, 2009;Rahaman and Singh, 2012). Most freshwater that enters the Gulf of Khambhat comes from direct rainfall and runoff from the Narmada River.…”