Observations of Radiation from Airplane during Steps

The radiations produced by airplane fling in clouds were measured by using the New Mexico Tech Lightning Mapping Array (LMA) system during STEPS in 2000. The results indicated that the source powers of airplane radiations follow an approximate Pdistribution. This is a kind of radiation produced by a discharge. The maximum powers vary from minimum locatable values of about 1W typically up to 10kW or more in the 60-66MHz passband of the receivers. The powers of airplane radiation were different for different kind of cloud in which airplane flew through. The radiation sources of airplane were strongest when airplane flew through clouds where lightning flashes were occurring in some region. For one kind of cloud, the powers of airplane radiation increased with the increases of speed of airplane. INTRODUCTION There have been several studies on charging when airplanes fly through clouds. The results show that airplane generally charges up negatively because of the triboelectric or frictional charging occurring as water or ice particles collide with the material on the surface of airplane. This may give rise to interference in modern digital control systems. So, it is of an important significant to measure the radiation power of airplane. The observations of 3-dimensional Lightning Mapping Array system (LMA) developed by New Mexico Tech have revealed a lot valuable information on thunderstorm structure and intensity, characteristics of lightning, and so on, especially the finding of inverted polarity lightning discharge [Thomas et al., 1999; Krehbiel et al., 2000]. This system was operated in the STEPS(Severe Thunderstorm Electrification and Precipitation Study) project area from mid-May to mid-August, 2000. Thirteen measurement stations were deployed over a four-county area in northwestern Kansas and eastern Colorado. The system locates the sources of impulsive VHF radio signals by accurately measuring the time that the signals arrive at the different receiving stations. Each station receives the radiation signals in an unused television channel (60-66 MHz). The arrival times are measured with 50 ns accuracy using a special PCbased digitizer card coupled to a GPS receiver. The measurements enable us to obtain accurate 3dimensional pictures of the radiation resources [Rison et al., 1999]. Each of the mapping stations was connected to an operations center in Goodland, Kansas via wireless high-speed communications links. The links were used to remotely monitor and control the station operation and for real-time processing of the observations. In this experiment, the radiations produced by airplane fling in clouds were observed except lightning flashes.