ISRO has started an intensive scientific campaign, involving
launch of 40 Rohini Sounding Rockets (RH 200) along with launches of
high-altitude balloons from Sriharikota and low altitude balloons from
Thiruvananthapuram to study gravity waves in the atmosphere. Ground-based
observations using National Mesosphere Stratosphere Troposphere Radar Facility
(NMRF) at Gadanki near Tirupati are also being made under this scientific
campaign which began on February 21, 2000 and will continue till the first week
of April 2000.
The instruments carried on board the Rohini sounding rockets and the balloons
measures the height structures of winds and waves in the atmosphere. The data
is used to determine the momentum fluxes associated with various types of waves
that are present in the equatorial atmosphere such as the Kelvin waves (having
periods of 10 to 20 days) and Rossby gravity waves (having periods of 4 to 5
days) in the troposphere (upto about 16 km height), stratosphere (16 to 50 km)
and mesosphere (50 t0 80 km). These waves are believed to be the major driving
forces for the evolution of quasi biennial oscillations in the atmosphere. The
knowledge about these quasi biennial oscillations is important for
understanding the interactions with meteorological phenomena at lower altitudes
such as El-Nino and La-Nino.
The Rohini sounding rockets which reach an altitude of about 70 km, along with
balloons that reach altitudes of 25 to 30 km, will collect data for 40
consecutive days. Extended periods of observations by NMRF and Rayleigh Lidar
that is collocated with NMRF at Gadanki near Tirupati are also being undertaken
to delineate shorter period gravity waves.
It is for the first time that such an elaborate scientific campaign is being
undertaken. Space Physics Laboratory of Vikram Sarabhai Space Centre, Kerala
University, National Mesosphere-Stratosphere-Troposphere Radar Facility (NMRF)
and Sri Venkateswara University besides several meteorologists are
participating in the campaign.