Grazing control and iron limitation of primary production in the Arabian Sea: Implications for anticipated shifts in Southwest Monsoon intensity

2020 ◽  
Vol 179 ◽  
pp. 104687 ◽  
Author(s):  
James W. Moffett ◽  
Michael R. Landry
Keyword(s):  
Primary Production ◽  
Arabian Sea ◽  
Southwest Monsoon ◽  
Iron Limitation ◽  
Monsoon Intensity

scholarly journals The Arabian Sea as a high-nutrient, low-chlorophyll region during the late Southwest Monsoon

2010 ◽  
Vol 7 (1) ◽  
pp. 25-53 ◽  
Author(s):  
S. W. A. Naqvi ◽  
J. W. Moffett ◽  
M. U. Gauns ◽  
P. V. Narvekar ◽  
A. K. Pratihary ◽  
...  
Keyword(s):  
Arabian Sea ◽  
Southwest Monsoon ◽  
Iron Limitation ◽  
Simple Relationship ◽  
Ocean Colour ◽  
Eurasian Snow ◽  
High Nutrient ◽  
Biogeochemical Provinces ◽  
East West

Abstract. Extensive observations during the late Southwest Monsoon of 2004 over the Indian and Omani shelves, and along an east-west transect reveal a mosaic of biogeochemical provinces including an unexpected high-nutrient, low-chlorophyll condition off the southern Omani coast. This feature, coupled with other characteristics of the system, suggest a close similarity between the Omani upwelling system and the Peruvian and California upwelling systems, where primary production (PP) is limited by iron. An intensification of upwelling, reported to have been caused by the decline in the winter/spring Eurasian snow cover since 1997, is not supported by in situ hydrographic and chlorophyll measurements as well as a reanalysis of ocean colour data extending to 2009. Iron limitation of PP may complicate simple relationship between upwelling and PP assumed by previous workers, and contribute to the anomalous offshore occurrence of the most severe oxygen (O2) depletion in the region. Over the Indian shelf, affected by very shallow O2-deficient zone, high PP is restricted to a thin, oxygenated surface layer probably due to unsuitability of the O2-depleted environment for the growth of oxygenic photosynthesizers.

scholarly journals The phytoplankton bloom in the northwestern Arabian Sea during the southwest monsoon of 1979

1991 ◽  
Vol 96 (C11) ◽  
pp. 20623 ◽  
Author(s):  
John C. Brock ◽  
Charles R. McClain ◽  
Mark E. Luther ◽  
William W. Hay
Keyword(s):  
Arabian Sea ◽  
Phytoplankton Bloom ◽  
Southwest Monsoon

A southwest monsoon hydrographic climatology for the northwestern Arabian Sea

1992 ◽  
Vol 97 (C6) ◽  
pp. 9455 ◽  
Author(s):  
John C. Brock ◽  
Charles R. McClain ◽  
W. W. Hay
Keyword(s):  
Arabian Sea ◽  
Southwest Monsoon

Long-term history of sediment inputs to the eastern Arabian Sea and its implications for the evolution of the Indian summer monsoon since 3.7 Ma

2018 ◽  
Vol 157 (6) ◽  
pp. 908-919 ◽  
Author(s):  
Mingjiang Cai ◽  
Zhaokai Xu ◽  
Peter D. Clift ◽  
Boo-Keun Khim ◽  
Dhongil Lim ◽  
...  
Keyword(s):  
Clay Minerals ◽  
Summer Monsoon ◽  
Indian Summer Monsoon ◽  
Arabian Sea ◽  
Sediment Supply ◽  
Deccan Traps ◽  
Indus River ◽  
Eastern Arabian Sea ◽  
Monsoon Intensity ◽  
History Of

AbstractWe present a new set of clay mineral and grain-size data for the siliciclastic sediment fraction from International Ocean Discovery Program (IODP) Site U1456 located in the eastern Arabian Sea to reconstruct the variabilities in the continental erosion and weathering intensity in the western Himalaya, elucidate the sediment source-to-sink processes and discuss the potential controls underlying these changes since 3.7 Ma. The clay minerals mainly consist of smectite (0–90%, average 44%) and illite (3–90%, average 44%), with chlorite (1–26%, average 7%) and kaolinite (0–19%, average 5%) as minor components. The compositional variations in the clay minerals at IODP Site U1456 suggest four phases of sediment provenance: the Indus River (phase 1, 3.7–3.2 Ma), the Indus River and Deccan Traps (phase 2, 3.2–2.6 Ma), the Indus River (phase 3, 2.6–1.2 Ma) and the Indus River and Deccan Traps (phase 4, 1.2–0 Ma). These provenance changes since 3.7 Ma can be correlated with variations in the Indian summer monsoon intensity. The siliciclastic sediments in the eastern Arabian Sea were mainly derived from the Indus River when the Indian summer monsoon was generally weak. In contrast, when the Indian summer monsoon intensified, the siliciclastic sediment supply from the Deccan Traps increased. In particular, this study shows that the smectite/(illite+chlorite) ratio is a sensitive tool for reconstructing the history of the variation in the Indian summer monsoon intensity over the continents surrounding the Arabian Sea since 3.7 Ma.

scholarly journals Estimates of land and sea moisture contributions to the monsoonal rain over Kolkata, deduced based on isotopic analysis of rainwater

2017 ◽  
Vol 8 (2) ◽  
pp. 313-321 ◽  
Author(s):  
Shaakir Shabir Dar ◽  
Prosenjit Ghosh
Keyword(s):  
Isotopic Composition ◽  
Arabian Sea ◽  
Trajectory Analysis ◽  
Gordon Equation ◽  
Isotopic Analysis ◽  
Southwest Monsoon ◽  
Oceanic Water ◽  
Isotopic Data ◽  
Fractionation Model ◽  
Land Mass

Abstract. Moisture sources responsible for rains over Kolkata during the summer monsoon can be traced using backward air-mass trajectory analysis. A summary of such trajectories between June and September suggest that these moisture parcels originate from the Arabian Sea and travel over the dry continental region and over the Bay of Bengal (BoB) prior to their arrival at Kolkata. We use monthly satellite and ground-based observations of the hydrometeorological variables together with isotopic data of rainwater from Bangalore and Kakinada to quantify the contributions of advected continental and oceanic water vapour in the Kolkata rains. The vapour mass is modified during its transit from its original isotopic value due to addition of evaporated moisture from the BoB, and further modification occurs due to the process of rainout during transport. The evaporated component is estimated using the Craig–Gordon equation. The rainout process is simulated using a Rayleigh fractionation model. In this simulation we assume that the initial isotopic composition of vapour originating from the continent is similar to the rainwater composition measured at Bangalore. In order to explain the monthly isotopic composition in southwest monsoon rainwater at Kolkata, we invoke 65–75 % moisture contribution from the BoB; the remaining moisture is from the continental land mass.

Sign in / Sign up

Export Citation Format

Share Document