SCIENCE REPORTER, November 201030

Rajasekhar D, Nallathambi T, Ravi N,Shashikumar K, Pandurangan V,

Kartik T, Charles S, Sibaprasad B,Nagarajan G, & Muthukumar C

Feature Article

THE Roaring Forties, Furious Fifties and ShriekingSixties are names given by sailors to the latitudesbetween 400S–500S, 500S–600S and 600S–700Srespectively.

These terms are so called because of the clamorous,boisterous, tumultuous and turbulent weather due to theprevailing westerly winds that cause havoc owing to lesslandmass to slow the winds down. The winds are especiallyvery strong in this part of the southern hemisphere.

Sagar Nidhi, India’s pride and mostsophisticated ice class multi-disciplinaryvessel of the sub-continent, is also the firstIndian flagged research vessel that reachedthe 660 S latitude, facing 11 storms and 73nm/hr wind speed, witnessing nature’sharshest conditions and awesomebreathtaking sceneries.

It was into these turbulent winds that India’s mostsophisticated Ocean Research Vessel (ORV) Sagar Nidhiploughed its way at the beginning of this year. This was avoyage with historical significance.

The expedition was flagged off on 12th of January 2010at 0700 hrs IST from Marmagao, Goa. A team of 18 scientistssailed from the National Centre for Antarctic and OceanResearch (NCAOR), National Institute of Ocean Technology(NIOT), Cochin University of Science and Technology(CUSAT), Central Marine Fisheries Research Institute(CMFRI), and the Goa University. The voyage headed fromGoa to Mauritius and then towards Antarctica 660S (IndianSector) and again via Mauritius back to Goa.

The Antarctic Research Programme has been designedto take advantage of the unique location and environmentof the icy continent for understanding the key globalprocesses that are manifested and controlled by the southernpolar cap. The primary objective of the expedition was tounderstand the biogeochemistry and hydrodynamics of theSouth Indian Ocean. This expedition that lasted for a span ofthree months was a thumping success. Sagar Nidhi managedto collect extensive scientific data and samples.

SCIENCE REPORTER, November 2010 31

Feature Article

The scientists on board carried out high-resolutionstudies of marine sedimentary records, biogeochemistry ofthe Southern Indian Ocean, size distribution of full range ofatmospheric aerosols and different natural sources ofgeneration as well as land to ocean transport of aerosols,North-south and inter-annual variability of geostrophiccirculation & transport, thermohaline structure modulationand water masses characterization, tracing current structure

and Heat budget andcomputation of fresh waterinput.

Impact of harmful UV-B radiation on marineorganisms in Antarcticawas also studied, wherethere is a depleted ozonelayer causing a net increasein radiation. Continuousobservation foratmospheric parametersalong the entire cruise

track using AWS, Athelometer, and High Volume AirSamplers was carried out.

Current structure in the track was observedcontinuously using Acoustic Doppler Current Profiler(ADCP). Single beam depth measurements were operationalthroughout the cruise track giving the depth profile.

Ocean TechnologyScientific exploration of the oceans is necessary for effectiveutilisation of our planet earth. To view the ocean from thehuman frame of reference is always a challenging objectiveand a herculean task to execute. To succeed such ambitioustasks and carry out highly advanced research, we needstate-of-the-art equipped ocean research vessels such as SagarNidhi.

The 103-meter-long vessel, built at Fincantieri, Italy,has fully automatic diesel–electric propulsion (Azimuththrusters) equipped with Dynamic Positioning System (DPClass-II) with ample operational deck space and an A-fameto hoist 60 tonnes from a depth of 6,000 metres. The vessel isdesigned with blue-water capability with range of up to10,000 nautical miles for voyages lasting up to 45 days.

The vessel is capable of carrying out Geo-scientific,Biological, Chemical, Meteorological and Oceanographicresearch activities. Right from the design phase she wasplanned to support research in the Indian Ocean and Antarcticwaters and built accordingly. Sagar Nidhi is operated by theNational Institute of Ocean Technology, an Autonomousinstitute under the Ministry of Earth Sciences, Govt. of India.

Sagar Nidhi is also being utilized for ocean engineeringpurposes. Two-third of the earth’s distinctive feature isoccupied by oceans that possess economically valuablemineral wealth such as oil & natural gas, gas hydrates,manganese nodules, submarine hydrothermal sulphides,manganese crust, phosphorites, placers, calcareous sandsand lime mud. To exploit these resources, technology isbeing developed at NIOT such as Deep Sea Mining systems,ROV’s, AUV’s, manned/unmanned submersibles, Auto

ORV Sagar Nidhi

Cruise track of SN 37 toAntarctica

Reaching Antarctica

SCIENCE REPORTER, November 201032

Feature ArticleCoring System and exploration of GasHydrates. These technologies aredemonstrated in deep seas on board SagarNidhi.

Future VisionDevelopment and economic progress of anycountry depend on its ability to meet theenergy requirements. India has realised thatincreasing imports and escalating oil pricesare going to be a hindrance to the nation’sdevelopment, and has therefore startedlooking for alternate energy sources burieddeep along India’s 7,500 km of coastline atdepths greater than 500 meters, which is avast fuel reserve that can meet our needs forseveral centuries.

Global reserves of gas hydrates areestimated to be “twice in abundancecompared to oil and gas reserves of theworld”. Gas hydrates are methane moleculeschemically formed in which a core ofmethane is trapped in a cage of watermolecules. The source of this methane isestimated to be biogenic in origin from theorganic detritus that descends to the oceanfloor where bacteria act on them to generatemethane.

The fascinating thing is that at greatpressures and low temperatures in the oceans,they are very stable crystals. If exploited andbrought to atmospheric conditions theyproduce 164 times their volume of methane,which is why it is attracting the energycraving nations.

The oceans are also source of somecrucial medicines for many deadly diseases.Antibiotics can be produced using deep seaspecies found at the abyssal plains of theoceans.

Oceans today are no more justnavigational zones but are banks ofinformation for understanding globalwarming, climatic variations with respect topresent and past and also ocean–terrainconvergence studies.

Apart from these ongoing operations,Sagar Nidhi is keen to extend extensivesupport to the country’s ocean scientists,by adding more facilities onboard in aneffort to make it a world class floatinglaboratory.

The authors are working as a team to maintain and operatethe research vessels. This team is headed by D.Rajasekhar at the National Institute of Ocean Technology,Chennai. Address: K. Shashikumar, Scientist, NationalInstitute of Ocean Technology, NIOT Campus, Velachery–Tambaram Main Road, Narayanapuram, Pallikaranai,Chennai–600100, Tamil Nadu; Email: shashi@niot.res.in

The Beaufort Sea State Scale

Sea Wind WaveState Speed in Height in Descr ipt ion Condi t ion

knots feet

0 < 01 00.00 Sea like a Mirror Calm

1 01 – 03 00.25 Ripples without Light Air

foam crests

2 03 – 06 00.50 Small wavelets. Light Breeze

Crests do not break

3 06 – 10 02.00 Large wavelets. Gentle Breeze

Scattered white caps

4 10 – 16 04.00 Small waves. Fairly Moderate

frequent white caps Breeze

5 16 – 21 06.00 Moderate waves. Fresh Breeze

Many white caps

6 21 – 27 10.00 Large waves. White Strong Breeze

foam crests.

Probably Spray

7 27 – 33 14.00 Sea heaps up and Near Gale

white foam blown in

streaks along the

direction of the wind

8 33 – 40 18.00 Moderately High Gale

waves, crests begin

to break into spindrift

9 40 – 47 23.00 High waves dense foam Strong Gale

along the direction of

the winds. Crests of

waves begin to roll over.

Spray may affect visibility

10 47 – 55 29.00 Very high waves with Storm

long over hanging crests.

The surface of the sea takes

a white appearance.

Tumblings becomes heavy

and shock l;ike. Visibility

affected

11 55 – 63 37.00 Exceptionally High waves. Violent Storm

Sea is completely covered

with long white patches of

foam in the direction of the

wind. Visibility Affected

12 > 63+ 45.00 Air is filled with foam and Hurricane

spray. Sea completely white

with driving spray. Visibility

very seriously affected.

P.S.: Sagar Nidhi faced wind speeds at 73 knots