The paper investigates the occurrence of polar mesosphere summer echoes (PMSEs) over a solar cycle. Besides the statistical study of the layered PMSE occurrence ratio, the authors propose a method to deal with the discontinuous EISCAT radar measurements. The method makes it easier to establish a relationship between the layered PMSEs and solar and geomagnetic activities. The paper presents a relatively large data set that brings results. It can be recommended in future research on the PMSEs.

After the Lushan earthquake, Ca2+, HCO3- and TDS of spring water increased significantly, which may be attributed to the enhanced interaction between water and carbonate rocks by the increment of dissolved CO2. Na+, Cl- and SO42- in water from Guanding, Zheduotang, Xinxing and Gonghe springs decreased, which may be related to the dilution of precipitation water. The increase in Na+ and SO42- in water from Erhaoying spring may result from a greater increase in sulfur-rich groundwater.

Variations of UHF-band scintillation occurrence with latitude, time and season over the low-latitude region of China are presented. The ratio of the mean foF2 at 20:00LT between two equinoxes, which could act as a proxy of the equinoctial asymmetry in the occurrences of scintillation, is proportional to the ratio between the maximum scintillation occurrence in the autumn equinox and in the vernal equinox. The empirical climatological model of scintillation occurrence probability was validated.