Season :    2011

Voyage :     5

Cruise Name :     Southern Ocean Expedition 2011

Voyage Classification :     Ocean Science, Southern Ocean Studies

Ship Name :     ORV Sagar Nidhi

Name of Chief Scientist / Leader :     Dr. N. Anilkumar, NCPOR, Goa.

Name of Deputy Chief Scientist / Leader :     Dr. R. Jeyabaskaran, CMFRI, Kochi.

The agenda for research in the Southern Ocean realm underlines the sensitivity of the Southern Ocean region to climatic variability and its importance in understanding the climate at large. The Southern Ocean research plan mainly focuses on: “Role and response of Southern Ocean to the regional and global climate variability” Towards achieving this the following objectives have been identified:- To study the inter relationship between physical, chemical and biological elements occurring across the Antarctic Circumpolar Current (ACC) and their role in carbon sequestration, biogeochemistry and climate change. To investigate the air-sea-ice interaction and to understand the role of anthropogenic aerosols over southern ocean and its effect on climate variability. To understand the implication of thermohaline variations in the Southern Ocean and the repercussion of heat and mass exchange between tropics and Polar Regions on Indian monsoon, biogeochemistry and climate. Reconstruction of the paleo-environmental conditions for selected time slices during the last glacial-interglacial cycles to provide perspectives on future climate change. To generate relevant/critical sea truth and atmospheric data for contributing to global climate data sets for prediction of climate models to mitigate/regulate climate change. Within the frame work of the above mentioned major focal themes, studies were conducted to investigate the following objectives: 1. Investigation of marine atmospheric surface layer and its dynamics. 2. Understanding the diurnal variations of physical properties and their impact on chlorophyll concentrations in the major frontal regions. 3.Study the mechanism of maintenance of deep chlorophyll maximum in the frontal 7regions. 4.Influence of mixed layer dynamics, Ekman dynamics, euphotic zone variations and eddies on the chlorophyll distribution. 5.Monitoring the changes in the oceanic thermohaline structure along two meridional repeat hydrographic sections. 6. Understanding the heat content and heat and mass transport in the study region. 7. Identifying water masses using stable isotopes ( 18 O). 8. Identify the relationship between oceanographic parameters and deep sea mega fauna and marine mammals. 9.Investigation of the source, distribution, components and chemistry of suspended particulate matter. 10. Measuring the inherent bio-optical properties of SO waters. 11. Deriving quantitative information on the types of substances (e.g. chlorophyll concentration, suspended matter, yellow substances, and attenuation coefficient ) present in the water and their concentrations, based on spectral variations. 12. Isolation and molecular characterization of novel microalgal species from SO towards exploring their metabolic potential and biological variability. 13. Study the composition of phytoplankton communities in the region, using the photosynthetic pigments as taxonomical biomarkers. 14. To determine possible relationship between phytoplankton communities (through pigment composition) and the ACC fronts zones. 15. Diurnal variability in planktonic standing stock and diversity in the two major fronts (Polar front and subtropical front)

The Expedition was very successful and all the planned research activities were accomplished. For more details please refer Cruise report.

From	Depart	To	Arrive
Portluis, Mauritius	01/24/2011	Portluis, Mauritius	03/04/2011

Southern Ocean (SO), encircling the Antarctica starts from subtropical frontal region around 35°S. SO plays a crucial role in regulating the global ocean atmospheric climate system. The Antarctic land mass covered by glaciers is the source of fresh water to the SO. Surface winds have a significant role in the mixing and dynamics of the SO. Wind driven currents and fronts in SO aids in the formation of latitudinaly separated zones with distinct physical and biological features. As compared to other oceanic regions SO is the least investigated region. Presence of ice and challenging climatic conditions make scientific measurements difficult here. Moreover, Indian Ocean sector of SO is a data sparse region. As part of the ongoing efforts to broaden our understanding of Indian Ocean sector of SO, the fifth Indian Scientific Expedition to SO was launched in January, 2011. The scientific team set sail from Port Luis, Mauritius onboard ORV Sagar Nidhi on 24 th January, 2011. The team comprised of 15 scientists from various national institutes and universities. Two scientists from Federal University of Rio Grande (FURG, Brazil) also participated in the expedition. Major operations carried out during the expedition were (i) Profiling of water column using CTD and collection of water samples with attached rosette system up to 5300 m depth (ii) Multiple plankton net sampling of zooplankton (iii) Bongo net deployment for collecting surface zooplankton (iv) Firing of XCTDs to delineate the vertical structure of water column in high resolution (v) Grab corer for sea bottom surface sampling (vi) Continuous observations of atmospheric surface layer parameters using automatic weather station (AWS). Time series observation of physical, chemical and biological parameters from two different frontal regions was a major accomplishment of this year’s expedition. The data generated during this expedition may throw more light into several intriguing aspects of the SO system.

a.Atmospheric Sciences (i) Atmospheric and Oceanic CO2 Budget (ii)Air Sea Interaction fluxes b.Physical oceanography c.Chemistry (i)Southern Ocean biogeochemical cycling ii)Bio optical properties of Southern Ocean iii)Investigation of mass concentration of suspended particulate matter iv) 6.3.4 Southern Ocean particle chemistry of the suspended matter and the seawater d.Biology i)Primary production and associated biologicalprocess and the variation of biological and physicochemical components with time ii) ACC fronts Interactions around Crozet Plateauregulation phytotoplankton Assemblage iii)Microalgal diversity in Southern Ocean iv) Surveys for marine mammals

Please refer Voyage Report

Please refer Voyage Report