In-Sun Song

New method of estimating temperatures near the mesopause region using meteor radar observations

We present a novel method of estimating temperatures near the mesopause region using meteor radar observations. The method utilizes the linear relationship between the full width at half maximum (FWHM) of the meteor height distribution and the temperature at the meteor peak height. Once the proportionality constant of the linear relationship is determined from independent temperature measurements performed over a specific period of time by the Microwave Limb Sounder (MLS) instrument on board the Aura satellite, the temperature can be estimated continuously according to the measurements of the FWHM alone without additional information. The temperatures estimated from the FWHM are consistent with the MLS temperatures throughout the study period within a margin of 3.0%. Although previous methods are based on temperature gradient or pressure assumptions, the new method does not require such assumptions, which allows us to estimate the temperature at approximately 90 km with better precision.

Meteor echo height ceiling effect and the mesospheric temperature estimation from meteor radar observation

The mesospheric temperature estimation from meteor height distribution is reevaluated by using the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) and the King Sejong Station (KSS) meteor radar observations. It is found that the experimentally determined proportionality constant between the full width at half maximum (FWHM) of the meteor height distribution and temperature is in remarkable agreement with theoretical value derived from the physics-based equation and it is nearly time-invariant for the entire observation period of 2012–2016. Furthermore, for the first time we found that the FWHM provides the best estimate of temperature at slightly lower height than the meteor peak height (MPH) by about 2–3 km. This is related to the asymmetric distribution of meteor echoes around MPH, which is known to be caused by the meteor echo height ceiling effect (MHC). At higher altitude above MPH, the meteor detection rate is greatly reduced due to the MHC, and the cutoff height for this reduction follows a fixed molecular mean free path of the background atmosphere. This result indicates that the meteor height distribution can be used to estimate the mesospheric temperature, even under the asymmetric meteor echo distribution caused by the MHC at high altitude.