Annual Report 2009-2010 - Ministry Of Earth Sciences

4 th Southern Ocean Expedition
The 4 th Southern Ocean Expedition consisting
of 19 scientific and 1 technical personnel from
different national institutions was launched from
Goa on the 12 th January, 2010 on board TDV Sagar
Nidhi for continuing the time series and other
scientific investigations in the southern ocean
region. Dr. Anil Kumar, Scientist-D, NCAOR is the
Chief Scientist of the expedition. The expedition
is on its voyage back. The following scientific
investigations are being undertaken during the
current expedition include biogeochemistry,
hydrodynamics, palaeoceanography oceanatmosphere
interaction, carbon dynamics, etc.
4.5 In-House Research and Development
4.5.1 Antarctic Ice Core Research
Field studies to collect Ground Penetrating Radar
(GPR) data to study the glaciological features
and to decide the ice core drilling locations are
underway in the central Dronning Maud Land
during the current Indian Antarctic Expedition.
An integrated study using instrumental data from
the Halley station and an ice core from the Central
Dronning Maud Land in East Antarctica revealed
that switches in the Southern Annular Mode
(SAM)-temperature relationship are more likely to
reflect natural variability in the long wave patterns
over the Southern Ocean rather than the influence
of an anthropogenic forcing.
The high resolution isotopic and accumulation
studies covering a period of past two decades using
a shallow firn core were undertaken in combination
with the instrumental data of Novlazarevskaya
station in the Central Dronning Maud Land region.
Microbiological studies in fresh snow deposits in
the coastal Antarctica revealed the crucial role of
bacteria in the air-snow biogeochemical cycling in
this region.
Glaciochemical and microbiological study of snow
from coastal Larsemann Hills, East Antarctica
revealed that elevated nutrient concentrations
in ice cap snow are responsible for the observed
high bromide concentration in snow related to
the enhanced growth of microalgae in snow and
subsequent production of bromo-carbons.
4.5.2 Linkages of Indian Monsoon with Southern
Indian Ocean and Southern Ocean
Several palaeoclimatic studies have suggested
strong correlation between the Indian summer
monsoon and northern hemisphere high latitude
climate for the past several thousand years. But
the linkages of Indian monsoon with the southern
hemisphere have received little attention in spite
of the fact that the SST and the upper ocean
heat content of the southern Indian Ocean is the
key factor for the evolution of boreal monsoon
and plays a major role in moisture convergence
and its supply to the Asian summer monsoon.
The Southern Ocean plays an important role in
governing earth’s climate through formation
of major deep and intermediate water masses
(e.g., Antarctic Bottom Water, Circumpolar
Deep Water, Antarctic Intermediate Water etc.)
and through air-sea interactions (such as airsea
fluxes of heat, momentum, freshwater etc.)
processes. Present day climatological studies have
shown that the Southern Ocean exerts control
over Indian monsoon via coupled atmosphericoceanic
pathways. It has been observed that
Southern Annular Mode (SAM) in its strong
positive phase causes increased SST over the
subtropics (~20-35°S) and middle latitudes (~50-
60°S), which in turn is followed by enhanced SST
in the equatorial Indian Ocean, which weakens
the Indian monsoon. But the question remains
whether this relationship is persistent and what
was its response to past periods of climatic
changes. During the ongoing expedition to the
Southern Ocean, cores are being collected from
the strategic locations on which high resolution
isotopic and chemical studies will be carried out
that would aid in exploring this correlation. For
carrying out isotopic analysis of seawater samples,
a new Marine Stable Isotope lab is coming up
at NCAOR.
24 Ministry of Earth Sciences : Annual Report 2009-10