Distribution characteristics of the summertime sporadic E in East Asia

The occurrence of global sporadic E reaches its peak in East Asia, known as the East Asia Anomaly. The relevant investigations and discussions are previously limited by either observational data unavailable in China or short of detailed comparisons of results in the popular areas of China with that in Japan, both of which are central areas of global Es occurrence probabilities. Based on spatial interpolation of Es data in more than twenty years from twenty-three vertical sounding stations in China and the surrounding countries, the results are drawn in the contour lines of spatial distribution of summer Es occurrence in East Asia, following a thorough analysis on characteristics of time variations in the center of the East Asia abnormal region. It is shown that Chongqing and Guangzhou in China together with Yamagawa, Kokubunji and Akita in Japan have remarkable Es occurrence all the time in summer, some of which is the potential peak of the East Asia abnormal region. The peak's specific location varies with different statistical index. The Es intensities in the abnormal region center are characterized with annual and diurnal variations, which are more complicated in the popular areas of Japan than in that of China, while the diurnal differences of the Es strength are more profound in the latter region, which may be of great significance to understand the cause of mid-latitude Es.