Comparison of FY3D/GNOS Atmospheric Occultation Detection Temperature with TIMED/ SABER Temperature and NRLMSISE00 Model Temperature

The accurate detection of atmospheric temperature is of great significance for studying the structural characteristics and dynamic processes of the middle and upper atmosphere. The GNOS (Global Navigation Satellite System Occultation Sounder) mounted on the FY3D has been carrying out atmospheric sounding since 15 November 2017. The purpose of this study is to evaluate the atmospheric temperature data products of the FY3D satellite. This study was conducted to comparatively analyze the atmospheric temperature data within the range of 12～100 km based on FY3D occultation observation data for 3 years from January 2019 to December 2021, with the aid of TIMED/SABER detection data and NRLMSISE00 atmospheric model data. The SABER-FY3D temperature deviation (T_SABER–T_FY3D) and NRLMSISE00-FY3D temperature deviation (T_NRLMSISE00–T_FY3D) and their distribution with latitude, season, and the difference between the northern and southern hemispheres were analyzed. The results show that the three sets of temperature data have generally consistent trend with change in height. SABER-FY3D temperature deviation is positive (0～1.8 K) in the altitude range of 12～30 km, and as the altitude increases, the temperature deviation increases from 0 K at 30 km to $ - $11.6 K at 77 km. NRLMSISE00-FY3D temperature deviation is positive (0～4.4 K) in the stratosphere, and negative ($ - $2～0 K) in the mesosphere and low thermosphere. Both temperature deviations show significant variations with latitude and season. Below 60 km, SABER-FY3D temperature deviation is smaller in the low-latitude region ($ - $3.8～1.8 K) and larger in the high-latitude region ($ - $12～1.6 K), smaller in summer ($ - $0.5～2.2 K) and larger in winter ($ - $6.2～1 K); NRLMSISE00-FY3D temperature deviation is just the opposite, smaller in the high-latitude region ($ - $1.6～2.4 K) and larger in the low-latitude ($ - $3.9～6.1 K), smaller in winter ($ - $2～2.2 K),, and larger in summer($ - $1.3～7.1 K). The zero deviation lines of the two types of monthly average temperature deviations show characteristics of being higher in spring and summer and lower autumn and winter in both hemispheres. In the winter, in the altitude region of 40～60 km, the negative deviation of the SABER-FY3D average temperature in the northern hemisphere is more obvious than that in the southern hemisphere.