Heat-induced temperature enhancement in the polar summer ionosphere

Observation data recorded by the European Incoherent Scatter Scientific Association in Tromsφ,Norway in August 2009 were analyzed to determine the heating effects in polar summer ionospheric modification experiments.There are two types of increases in electron temperature:large relative increases in a narrow range near 150 km and greater absolute increases in a wider range at 150-400 km.The percentage increase in temperature linearly increases with heating power,but the rate of increase decreases with increasing pump frequency.A clear two-dimensional distribution was found for the measurement made on August 15,and the heating effects are greater closer to the direction of the geomagnetic field.The heating effects obviously depend on the angle between the heating beam and geomagnetic field; as the angle increases,the heating effect decreases.