Indian Antarctica Scientific Expedition:
India created history in 1982, when a team of 21 members landed on the frozen continent to carry out scientific experiments in Geology, Geophysics, Meteorology, Geomagnetism, Oceanography and Biology at the then Base Camp. The expedition stayed for a short period of 10 days to mark the beginning of Indian Polar Sciences. Two years later, a permanent station was established on the ice shelf, called Dakshin Gangotri. Further inroads were made into the continent and another station, called Maitri was established nearly 90 km away from Dakshin Gangotri Station on a rocky terrain, called Schirmarcher Oasis. This area is free of ice and consists of a number of fresh water lakes, recharged by melting snow during the short summer period. Since then, 29 expeditions have been sent to Antarctica to explore the continent in the quest of science and to gather more information for the betterment of mankind. The 30th expedition is set to sail towards the end of this year. The Dakshin Gangotri Station was manned throughout the year till 1989. The station had to be abandoned for safety reasons as it got buried under snow. The Maitri Station is in operation at present and manned throughout the year.
Antarctica, the worlds windiest, coldest and the stormiest continent has an area of 14 million sq. km. It is also called a pulsating continent as the size keeps on increasing and decreasing during different seasons. The sea around the continent starts freezing during winter, increasing the size to hundreds of km and the same starts breaking up as the summer approaches. It has one of the most hospitable terrains and harshest climates in the world. The world’s lowest temperature of –89.60 C was recorded here at the location of Geomagnetic Pole. Wind speeds can attain over 250 km/hr, and blizzards can rage for days together, rendering visibility to a few meters. 98% of the continent is covered with a thick layer of ice --- its thickness varies from 800 meters to 4.5 km. The remaining 2% of the continent is visible in the form of small hillocks and mountain ranges. This ice cap contains more than 70% of the worlds fresh water resources in frozen form. The ice flows out from the center of the continent into sea and spreads in the form of ice-shelf. Icebergs carve out of this ice shelf, which are basically huge chunks of ice broken from the ice shelf. Investigations by western countries have indicated that it should be possible to tow some of these huge icebergs to areas of water scarcity and use them as sources of fresh water. It has not been attempted so far for cost effectiveness. Antarctica is rich in mineral resources and thus attracted the Global powers and various other countries. Exploration of Antarctica and southern Oceans started in early 18th century for mostly fish, seal furs and whales. By 19th century, the continent was claimed and divided by seven countries. These countries along with five others signed a treaty in 1959, called Antarctic Treaty. The treaty decided to freeze all territorial claims and lays down that Antarctica is to be used for peaceful scientific purpose only. It provides for cooperation and exchange of scientific information and protection of vulnerable natural environment. Indian became a member of the Consultative Committee of the Antarctic Treaty on September 12, 1983 and a member of Scientific Committee on Antarctic Research (SCAR) in September 1984. Antarctica is the world’s greatest natural laboratory and attracted scientist for following reasons:
- It is an important location for studying the interaction of magnetic field with the charged particles emitted from the Sun.
- It is a stable platform for carrying out scientific investigations. Being far away from all industrial areas remains an unpolluted region. The changes due to pollution all over the Globe can be monitored from here.
- Three Oceans, namely Indian Ocean, Pacific Ocean and Atlantic Ocean meet around the continent in a distinct water body, unbroken by any land mass.
- The heat budget of the world is maintained and kept in balance by the two poles. The heat generated at the equator is transported by atmosphere and Oceans and dissipated in Space in the form of long wave Radiation.
- The glaciers from Antarctica comprise of 90% of the total ice on earth. The continent holds about 70% of the fresh water resources of the earth.
- The continent being unexploited, rich deposits of coal, iron, uranium, copper, lead, oil, gas etc. are available in Antarctica.
IIG in the Indian Antarctica Scientific Expedition
IIG has been participating in the Indian Antarctic Expeditions right from its inception. A semi permanent magnetic observatory was set up at Dakshin Gangotri (DG, 70o S, 12o E). A Fluxgate Magnetometer was set up to record magnetic variations in the three orthogonal components H, D and Z. A Proton Precession Magnetometer was operated to record the Total Magnetic Field “F” and a 30MHz analogue Riometer to record the cosmic radio noise absorption. With the shifting of DG to Maitri (70o.77S, 11o.75E geographic; 67o.29S, 57o.97E geomagnetic) to Schirmarchar Oasis, central Dronning Maud Land in 1990 – nearly 70km south of DG, the magnetic observatory has been continuously operating there. The Fluxgate Magnetometer was replaced with Digital Fluxgate Magnetometer (DFM) with 0.1 nT sensitivity in 2002. The magnetic field of the Earth is affected by the dynamic condition in the near-Earth environment of the ionosphere and magnetosphere. The Indian Antarctic Station, Maitri is a sub-auroral station during quiet magnetic conditions and is affected by the southern limb of global Sq current system. With increasing magnetic activity, the auroral oval expands and Maitri moves inside the auroral oval and is affected by auroral current system. Thus, the measurements at this station are providing valuable inputs in monitoring solar wind-magnetosphere-ionosphere interaction and energy transfer as well as understanding the secular variation in the main magnetic field. Our observations reveal that Maitri is situated in the region where maximum decline in geomagnetic field is observed. The total field was declining at a rapid rate of ~110 nT/yr till 2006. The rate of decline has now reduced and is reported as ~70nT/yr.
Three station triangulation Fluxgate Magnetometer experiment around Maitri:
The experiment was started in 1992 and repeated six times in the subsequent years to understand and determine the presence and velocity of small-scale, mobile current systems over Maitri. The auroral currents while flowing over Maitri and surroundings, leave signatures in the ground based magnetometers. The velocities are determined from the time lags in the pulsations recorded by the ground magnetometers located at the vertices of a triangle, with sides of 100-250 km. The velocities of these mobile auroral current systems lie typically between 0.5 and 3.0 km/sec.
Maitri, an ideal location for predicting Space Weather:
Maitri is ideally suited for nowcasting geospace weather, and perhaps the interplanetary weather. The former refers to the degree of disturbance in electric and magnetic fields and particle population in various regimes of the Earth’s magnetosphere. The latter refers to the magnitude and direction of the solar magnetic field components, the velocity, density and dynamic pressure of solar wind particles in interplanetary space. The magnetic field and Riometer absorption variations recorded at Maitri show good agreement with the IMF variations and the interplanetary solar wind parameters measured by WIND satellite. Thus, Maitri can be an ideal location for prediction of space weather.