Characteristics of wave packets in the upper troposphere. Part I : Northern Hemisphere winter

摘要: Abstract Gridded data produced by the ECMWF reanalysis project have been analyzed to document properties of wave packets in Northern Hemisphere winter midlatitude upper troposphere. Based on results from earlier investigations, 300-hPa meridional wind variations were chosen for analysis. Wave packet envelopes also defined performing complex demodulation data. The are mainly illustrated using time-lagged one-point correlation maps performed both υ′ and envelopes. show that, over most regions winter, with exception deep Tropics near Aleutian low, medium-scale waves (dominant wavenumber 5–8) exhibit characteristics downstream development occur within trains that propagate eastward group velocities much faster than phase speeds individual phases waves. Their velocity is highly correlated local time mean 200–400-hPa wind, while the...