No abstract

Cyclonic storms having maximum winds of 34 knots and above that had genesis in north Indian Ocean have been studied with respect to the eastward passage of Madden-Julian Oscillation (MJO). In the three decades , there were a total of 118 cyclones reported in which 96 formed in the region chosen (0-15 o N, 60 o E-100 o E) for the study. Although the percentage of MJO days inducing cyclogenesis is small, it is found that tropical cyclone genesis preferentially occurred during the convective phase of MJO. This accounted for 44 cyclones of the total 54 cyclones (i.e., 81.5%) formed under MJO amplitude 1 and above. The study has shown that, when the enhanced convection of MJO is over the maritime continent and the adjoining eastern Indian Ocean, it creates the highest favorable environment for cyclogenesis in the Bay of Bengal. During this phase, westerlies at 850 hPa are strong in the equatorial region south of Bay of Bengal creating strong cyclonic vorticity in the lower troposphere along with the low vertical wind shear.

No abstract

No abstract

The Cochin University of Science and Technology (CUSAT), Cochin, India, hosts the world’s first 205-MHz stratosphere–troposphere (ST) wind profiler radar. This radar constitutes 619 three-element Yagi–Uda antennas with a power aperture product of 1.6 × 108 Wm2 and is capable of providing accurate three-dimensional wind profiles for an altitude range of 315 m–20 km. The system description and its first time validation and results from some of the radar’s potential applications are being presented. The radar wind profiles have been validated against collocated GPS–radiosonde measurements during the summer monsoon of 2016. The radar and radiosonde profiles show very good correlation with coefficients of 0.99 and 0.93 for zonal and meridional winds, respectively. The standard deviation of the radar measurements with respect to radiosonde measurements is found to be 1.85 m s−1 for zonal wind and 1.66 m s−1 for meridional wind. Moreover, the radar also detects echoes from the ionosphere. The ST radar at Cochin (10.04°N, 76.33°E; 40 m MSL) is an ideal observational facility, located in the tropics, for understanding the processes of the Indian summer monsoon at the region of its onset, which is expected to enhance science’s knowledge of monsoon dynamics.