Velocity characteristics of wind patterns in Tanzania

We present results of extensive analyses of speed and direction of wind patterns in Tanzania. The following key conclusions are made from the results. Firstly, the wind speed at each station along the eastern coast of Tanzania or on off-shore islands in the Indian ocean displays two clear minima in a year, one in March and the other in the September-November period. The former minimum coincides with a complete change in wind direction from north or north-east to south or south-west, while the latter minimum coincides with a complete change in wind direction from south or south-east to north or north-east. None of the eastern coastal stations has a wind direction component that continuously persists throughout the year. Secondly, each of the inland stations either displays no pronounced minimum at all in a year or displays only one pronounced minimum in a year. The latter minimum coincides with partial changes in wind direction from a dominantly preferred/common wind direction. Interestingly, each of these (inland) stations has a specific wind direction component that persists consistently throughout the year. This implies existence of a more or less permanent wind field at constant direction over the inland, but not the coastal region of Tanzania. (C) 1997 Elsevier Science Ltd.