Middle Atmospheric Dynamics

(A)  Atmospheric Waves and Oscillations

 Under this theme of the branch, the atmospheric waves and oscillations of various temporal and spatial scales have been characterised using space and ground based observations. The role of atmospheric waves, which are broadly classified into gravity waves, tides and planetary waves, in wave-mean flow interactions, wave-wave interactions, atmospheric coupling  and in modulation of  chemical  composition have been investigated. These research efforts are aimed at quantifying the role of these waves in shaping the structure, energetics and dynamics of the Earth’s middle atmosphere, which is a pre-requisite for .representation of these processes in numerical models. Mesosphere-lower thermospheric wind observations in 80-100 km altitude from the ground based meteor radar at Thumba, sounding rocket observations of winds from RH-200 in 20-65 km and balloon borne GPS-sonde observations of wind and temperature from 0-35 km along with complementary observations from satellites are extensively used for investigation of atmospheric waves and oscillations in the troposphere, stratosphere, mesosphere and lower thermosphere.  Apart from these observations, thematic campaigns are also carried out to address the specific objectives of the branch.  The following are the main focusing areas of this activity,

  1. Atmospheric Gravity waves, Tides and Planetary waves
  2. Long-period Oscillations in the Middle Atmosphere
  3. Vertical  Coupling Processes in the Atmosphere
  4. High latitude-low latitude Coupling processes including Sudden Stratosphere Warming
  5. Polar Middle Atmospheric Dynamics
  6. Whole Atmosphere Community Coupled Model(WACCM)


(B)  Strstosphere-troposphere interactions

Under this theme of the branch, the temporal and spatial variability of tropical tropopause and its role in stratosphere-troposphere interactions have been investigated using well-co-ordinated campaigns as well as space based observations. Realizing the importance of stratosphere-troposphere exchange processes, a series of experiments have been carried out to characterize the tropical tropopause and its role in transport of ozone and water vapour from troposphere to stratosphere and vice versa. The Tropical Tropopause Layer, which acts as gateway for stratosphere-troposphere interactions, has been investigated in great details. Regular water vapour measurements up to 11 km are carried out using GPS-sonde observations.  However, measurements of accurate water vapour in the lower stratosphere have been carried out using frost-point hygrometer(FPH) based balloon experiments from several parts of the country. The ozone and water vapour measurements are also carried out using ozonesonde and  FPH observations in the 0-35 km on campaign basis and on routine basis coinciding with monthly RH 200 rocket launches from Thumba. Apart from this, Indian MST radar observations as well as satellite observations have been employed to elucidate the dynamical processes around the tropopause during extreme weather events as well as during quite period. The following are the main focusing areas of this activity,

  1. Tropical Tropopause Layer Characteristics and its Variability
  2. Water Vapour and Ozone in Troposphere and Lower Stratosphere
  3. Stratosphere-Troposphere Exchange Processes
  4. Turbulence Parameters in Troposphere and Lower Stratosphere
  5. Role of Deep Convection in  Redistribution of Water Vapour
  6. Radar Observations of Dynamical Processes around Tropical Tropopause