The solar induced 27-day modulation on polar mesospheric cloud (PMC), based on the combined observations from SOFIE and MLS

Abstract. Temperature is considered to be the key driving factor of the polar mesospheric cloud (PMC) variations, and the external source of temperature change is mainly from the solar radiations. In this paper, we use the observations of vertical column of ice water content (IWC) and mesopause temperature collected by the Solar Occultation For Ice Experiment (SOFIE), combined with the temperature data of Microwave Limb Sounder (MLS), to determine the time lags between temperature and IWC anomalies in responding to the solar radiation index Y10, through superposed epoch analysis (SEA) and time lag correlation analysis methods. The results show that the IWC responses to the Y10 later than the mesospheric temperature does. Further investigation of the relationship between mesospheric temperature and PMC reveals that the average time lag day is 0 days in the northern hemisphere (NH), and 1 day in the southern hemisphere (SH). The differences in temperature response to the 27-day solar rotational modulation with atmospheric pressure and latitude are analyzed, based on the temperature observations from 2004 to 2020 by MLS. Twelve PMC seasons with 27-day periodicity are distinguished, with 9 of them have time lags increasing with atmospheric pressure (or decreasing with altitude).