Abstract
The importance of mineral dust and aerosols in the transfer of bio-essential elements to terrestrial and marine ecosystems far removed from the source region is well known. Aerosol concentrations measured at the surface over the west coast of India during the SW monsoon period (June to September) are usually very low as pristine maritime air from the Southern Indian Ocean blows over this region. However, we find very high levels of mineral dust and dust derived nutrients in rainwater collected during the SW monsoon period. We show that the dry, warm and dusty Red Sea Wind and Shamal Wind from the Middle-East override the moist oceanic Low-Level Jet (Findlater Jet) of the SW monsoon and transport large quantities of dust at heights between 2 km and 5 km over the Indian Peninsula. A substantial portion is the desert dust is scavenged and wet-deposited over the Western Ghats of India where it neutralizes the acidity of rainwater and provides substantial amounts of nutrients that have the potential to impact sensitive ecosystems in this region. After the Red Sea and Shamal Winds subside in September, the alkaline rainwater reverts to the acidic range due to soluble ions derived from local carbonaceous aerosols.
Highlights
The summer heating over NW India and Tibet leads to convergence of winds from the surrounding high-pressure regions (Fig. 1) of the Indian Ocean, eastern Mediterranean and Central Asia
The presence of the dusty layer aloft is further confirmed by concomitant Micro-Pulse LIDAR time-series data over Goa (Fig. 3a–c) which indicates that the upper layer between 2 and 5 km are dominated by non-spherical mineral dust particles while the planetary boundary layer has very low aerosol content
This study investigated the transport of mineral dust from the Middle-East and NE Africa over the Arabian Sea during the summer monsoon and its effect on rainwater pH and composition over Goa, India
Summary
Received: 19 July 2017 Accepted: 26 September 2017 Published: xx xx xxxx composition and sensitive ecosystems over India. Aerosol concentrations measured at the surface over the west coast of India during the SW monsoon period (June to September) are usually very low as pristine maritime air from the Southern Indian Ocean blows over this region. Ship-based studies in the western and central Arabian Sea[16,17] and coastal stations along the west coast of India (Supplementary information Fig. 1) report low aerosols at the surface during June to September. During the same season we measured very high levels of mineral dust and dissolved nutrients in rainwater (Fig. 2; Table 1) at a station (Goa, 15° 27′N; 73° 48′E) on the west coast of India. HYSPLIT wind back-trajectories indicate the convergence of different wind systems over the western Arabian Sea and over-riding of the LLJ by the dry and dusty continental air masses (Supplementary information Fig. 3). Further detailed studies are required to understand these processes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
