Weak Ionization of Global Ionosphere in Solar Cycle 24

Following a prolonged and extreme quiet solar activity during 2008-2009,the 24th solar cycle started slowly and 5 years have passed since then.The measurement of ionospheric critical frequency(foF2)shows that it has been significantly lower in the first half of cycle 24,compared to the average le...中国地球物理学会、全国岩石学与地球动力学研讨会组委会、中国地质学会构造地质学与地球动力学专业委员会、中国地质学会区域地质与成矿专业委员会