6 research outputs found
Momentum flux associated with gravity waves in the low-latitude troposphere
The vertical fluxes of
horizontal momentum at tropospheric heights are calculated for four days, 25â28
August 1999. The mean zonal wind during these days show the presence of strong
westward wind at the upper troposphere. Both the symmetric beam radar method
and the power spectral method of evaluation of vertical flux of zonal and
meridional momentum shows nearly the same result for quiet conditions. The
temporal evolution of the momentum flux is estimated for a day with strong
zonal shear and convection. These results indicate that on 28 August 1999, the
strong downward vertical wind in the lower altitude range is associated with
upward vertical flux of zonal momentum, and strong upward vertical wind is
associated with downward vertical flux. Similarly, the strong shear in zonal
wind is associated with the increase in negative values in vertical flux in the
upper troposphere. Analysis of the role of wave periods in the transport of
momentum flux indicates that the vertical momentum flux magnitude is not evenly
distributed in all wave periods, but instead it peaks at certain wave periods
in the range 10 to 100 min.Key words. Meteorology and
atmospheric dynamics (convective process; tropical meteorology; precipitation
Cerium(IV) ammonium nitrate induced dimerization of methoxystyrenes
4-Methoxystyrene 1 underwent dimerization to 1,4-diphenylbutane derivatives 5 and 6 in presence of CAN in methanol. But in ethanol the same reaction afforded a tetralone derivative along with 5 and 6. 3,4-Dimethoxystyrene 10 underwent dimerization in presence of CAN in methanol to afford acyclic as well as cyclic products. 3,4,5-Trimethoxystyrene 12 in presence of CAN in methanol afforded only the cyclized dimers, the tetralone 21 and the tetralin derivative 22