The Horizontal and Vertical Wind Profiles of the Subtropical and Polar Jet for January 1–7, 1956 and the Variation of the Equivalent Barotropic Level

All the available wind information over central, west and north Europe, the Atlantic Ocean, the United States and Canada has been studied for a period of seven days, January 1–7, 1956 0300 Z. The axis of the subtropical and the polar jets have been chosen as reference coordinates. Mean horizontal and vertical wind profiles have been computed at 100 km intervals from the axis of both jets and are discussed. Based on these profiles, the average wind and the equivalent barotropic level is computed. It is shown that the height of the equivalent barotropic level changes as the distance from the axis of the jet varies. The equivalent barotropic level is shown to have a maximum height of 432 mb at the axis of the subtropical jet and a minimum height of 560 at a distance of 1,000 km north of the polar jet. Finally, an average E.B.L. is computed and is shown to have a height of 505 mb.