MJO using Radiosonde data over a low latitude station
Khaleelur Rahiman*, Dr. H. Aleem Basha * and Dr Thyagarajan**
*Maulana Azad National Urdu University, Hyderabad. Telangana. ** JNTU college, Pulivendula, A.P. India.
The study of atmosphere cannot be ignored, it is our environment. The lowest region in contact with solid earth, Troposphere, is characterized by a lapse rate such that temperature decreases with height. One of the most important dynamical properties of the atmosphere is its ability to support wave motion. Owing to the importance of dynamics of atmosphere the study of MJO over low latitude station is essential. Many observations have been carried out across the globe to explore MJO in the tropics. In the tropical atmosphere there are several modes of low‐frequency oscillations such as interannual, annual, and intraseasonal oscillations. Of these, the MJO (30 to 90 day period) continues to be a topic of significant interest because of its complex dynamics and a wide range of atmospheric physical processes with which it interacts. It is the large scale coupling between atmospheric circulation and tropical deep convection propagating east wards at approximately 5m/s above warm parts of Indian Ocean. Wind and temperature profiles collected by India Meteorological Department over Hyderabad for about two years (Feb 2013 – Sep 2014) has been procured. The continuous data sets of two years will be subjected to FFT analysis to obtain amplitudes and phases of different oscillations. The data collected have been analysed in the present study. Both zonal and meridional components are studied. The multi-annual values of wind for each month are obtained. Meridional velocities in the troposphere between 10km and 20km appears to be predominantly southerly with a maximum speed of 5m/s near tropopause. Above 20 km the circulation turns into northerly for almost all months. Temperature for the same period has been observed sharp inversion at 16km which is tropopause. It is found that the troposphere is dominated by oscillations in two period bands namely (6-8) and (3-4) weeks in meridional wind. The wave amplitude height profiles show that the waves have maximum amplitude below the height of tropopause at about 13-14 km. The wave energy density profile indicates that the sources of these waves are in the troposphere and that a part of the energy might be leaked into the stratosphere through vertical propagation. Further observation and modelling are required to understand the intraseasonal behaviour of wind oscillation and their propagation.
Keywords: Atmosphere, Oscillation, Troposphere, stratosphere, Zonal and Meridional winds Radiosonde etc.
InternationaleJournal of Mathematical Sciences, Technology and Humanities
Volume 6, Issue 4, Pages: 81 - 87