A Multi-Year Conjunction Analysis of ICON/MIGHTI and TIMED/SABER Neutral Temperatures in the Mesosphere and Lower Thermosphere

We present a multi-year statistical cross-comparison of ICON/MIGHTI and TIMED/SABER neutral temperature measurements in the Mesosphere and Lower Thermosphere (MLT) between 88 and 110 km covering the Northern Hemisphere up to mid latitudes and Southern Hemisphere low latitudes. We analyzed MIGHTI Level-2.3 (v06) and SABER Level-2.08 (v02) data, identifying conjunctions using LST+/-15min, latitude+/-2 degrees, and longitude+/-4 degrees window around each SABER measurement. Due to their orbital geometries, the analysis found frequent conjunctions widely distributed in longitude but nearly locked in local time and latitude on daily basis, enabling a direct comparison of daily longitudinal temperature variability at fixed local time and latitude. Also, this provides an opportunity for a large-scale cross-calibration statistical study of their MLT region neutral temperatures. The influence of non-migrating tides is evident in measurements from both instruments when conjunctions at a fixed local time and latitude as a function of longitudes are analyzed. Daily longitudinal temperature structures from MIGHTI and SABER show excellent agreement, capturing coherent longitudinal oscillations with peak-to-trough amplitudes of ~40-60 K likely associated with upward-propagating non-migrating tides and planetary waves. Furthermore, we present a detailed statistical analysis of conjunctions as a function of latitude, longitude, seasons, and local time by leveraging the significant geospatial and temporal spread of the conjunctions over multiple years. Statistical analyses reveal that MIGHTI daytime temperatures are more correlated (~0.82) than nighttime temperatures (~0.74) with MIGHTI daytime temperatures consistently warmer than SABER and the difference increasing with altitude from ~3 K at 88-95 km to ~26 K at 105-110 km. Nighttime differences are statistically insignificant. Their differences show a clear diurnal behavior, peaking during daytime and minimizing at nighttime. Also, their differences show seasonal dependence but no particular systematic latitudinal and longitudinal dependence. This study compares MIGHTI and SABER temperatures to clarify their similarities and differences, an understanding that is important for interpreting global MLT tidal behavior from space-based observations; it does not seek to demonstrate which instrument provides more accurate absolute MLT temperatures.