Joule heating due to vertical ion currents in the lower thermosphere over the dip equator

The theory of equatorial electrojet predicts the presence of vertical ion c urrents (Pedersen currents) as a part of the electrojet current system. The vertical ion current density profile over the dip equator, that forms a pa rt of the meridional current system is derived from an electrojet model. Th e joule heating due to these currents flowing upward during daytime for a l ocal time for 1100 hrs has been estimated. The primary east-west current de nsity of the model is kept at the same value as that measured by means of r ocket-borne magnetometer on one occasion. The electrical power dissipated a s heat in the narrow belt in the height region of 100-180 lan is estimated and found to be significant. The height of maximum power dissipation coinci des with the altitude of maximum ion velocity i.e. 122 lan. By solving the heat conduction equation we obtain a maximum temperature increase of 8 degr ees K around 135 km. The importance of this localized heating in the lower thermosphere around +/-2 degrees of the dip equator is discussed.