The spread F data obtained over Lanzhou(36.1°N,103.9°E),Chongqing(29.5°N,106.4°E)and Haikou(20.0°N,110.3°E)of China during the period from 1978 to 1997 are used to analyze the occurrence ...The spread F data obtained over Lanzhou(36.1°N,103.9°E),Chongqing(29.5°N,106.4°E)and Haikou(20.0°N,110.3°E)of China during the period from 1978 to 1997 are used to analyze the occurrence characteristics.The statistical results show that the post midnight spread F occurrence is maximum during the summer solstice months of the lower solar activity period,while post sunset spread F is dominant in equinoxes of higher solar activity period over Haikou station.Over Chongqing and Lanzhou stations,spread F mostly occurs at post midnight and relates negatively with solar activity.Using regression method and Fourier expansion,the preliminary single-station model of spread F occurrence is established and the accuracy of the model is evaluated.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.40831062)the National Defense Foundation of China(Grant No.H0901008)the National Key Technology R&P Program(Grant No.2006BAB18B06)
文摘The spread F data obtained over Lanzhou(36.1°N,103.9°E),Chongqing(29.5°N,106.4°E)and Haikou(20.0°N,110.3°E)of China during the period from 1978 to 1997 are used to analyze the occurrence characteristics.The statistical results show that the post midnight spread F occurrence is maximum during the summer solstice months of the lower solar activity period,while post sunset spread F is dominant in equinoxes of higher solar activity period over Haikou station.Over Chongqing and Lanzhou stations,spread F mostly occurs at post midnight and relates negatively with solar activity.Using regression method and Fourier expansion,the preliminary single-station model of spread F occurrence is established and the accuracy of the model is evaluated.
