Comparison of rotational temperature derived from ground‐based OH airglow observations with TIMED/SABER to evaluate the Einstein coefficients

Abstract

Ground‐based observations of the OH(9–4, 8–3, 6–2, 5–1, and 3–0) band airglows over Xinglong, China (40°24′N, 117°35′E) from December 2011 to 2014 are used to calculate rotational temperatures. The temperatures are calculated using five commonly used Einstein coefficient data sets. The kinetic temperature from Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics/Sounding the Atmosphere by Broadband Emission of Radiation (SABER) is completely independent of the OH rotational temperature. SABER temperatures are weighted vertically by weighting functions calculated for each emitting vibrational state from two SABER OH volume emission rate profiles. By comparing the ground‐based OH rotational temperature with SABER's, five Einstein coefficient data sets are evaluated. The results show that temporal variations of the rotational temperatures are well correlated with SABER's; the linear correlation coefficients are higher than 0.72, but the slopes of the fit between the SABER and rotational temperatures are not equal to 1. The rotational temperatures calculated using each set of Einstein coefficients produce a different bias with respect to SABER; these are evaluated over each of the vibrational levels to assess the best match. It is concluded that rotational temperatures determined using any of the available Einstein coefficient data sets have systematic errors. However, of the five sets of coefficients, the rotational temperature derived with Langhoff et al.'s (1986) set is most consistent with SABER. In order to get a set of optimal Einstein coefficients for rotational temperature derivation, we derive their ratios from ground‐based OH spectra and SABER temperatures statistically using 3 years of data. The use of a standard set of Einstein coefficients will be beneficial for comparing rotational temperatures observed at different sites.

Mesospheric OH layer altitude at midlatitudes: variability over the Sierra Nevada Observatory in Granada, Spain (37° N, 3° W)

“…Temperature differences do not strongly depend on temperature, so the slope is close to unity. This indicates that the errors in the Einstein coefficients used in SATI retrievals are not significant, as Liu et al (2015) concluded using a similar approach. The relative temperature drift is −0.8 K yr −1 , with SATI measuring higher temperatures with time relative to SABER.…”

“…These studies have focused on varied topics: analysis of the impact of atmospheric waves on regional and global scales, the detection of geo-hazards, the effect of sudden stratospheric warmings (SSWs), seasonal and interannual variations, external forcing response, longterm trends, cross-validation for satellite measurements, the detection of satellite drifts and the determination of OH radiative properties (e.g., López-González et al, 2009;Cho et al, 2010;Bittner et al, 2010;French and Mulligan, 2010; M. García-Comas et al: OH layer altitude over the OSN Offermann et al, 2010;Shepherd et al, 2010a, b;French and Klekociuk, 2011;García-Comas et al, 2012;Ammosov et al, 2014;Reisin et al, 2014;Liu et al, 2015;Wüst et al, 2017, to mention just a few. ).…”

Midlatitudinal Special Airglow Structures Generated by the Interaction Between Propagating Medium‐Scale Traveling Ionospheric Disturbance and Nighttime Plasma Density Enhancement at Magnetically Quiet Time

“…The MSTID airglow event was observed by the ASAI deployed at Xinglong in 1 January 2012. Rotational temperature of hydroxyl (OH) airglow emission measured by this spectrometer was previously used to compare with TIMED/SABER temperature by Liu et al (2015). Ionograms from the digisonde deployed at Shisanling are used to investigate the MSTID.…”

A comparison of OH nightglow volume emission rates as measured by SCIAMACHY and SABER

“…Many OH Einstein coefficient datasets can be found in the OH research community (Liu et al, 2015); the two latest are HITRAN molecular spectroscopic database (Gordon et al, 2017) and the OH Einstein A values calculated by Brooke et al (2016). Figure 3 shows simulated SABER OH 1.6 µm and 2.0 µm VER profiles obtained from SCIAMACHY OH limb spectral measurements using these two Einstein datasets at 20 • N-40 • N for October 2007.…”

“…local thermodynamic equilibrium (LTE) (Offermann et al, 2010;Zhu et al, 2012;Liu et al, 2015). Gravity waves passing through the OH airglow layer can be captured to study the dynamics and energy balance in the UMLT (Xu et al, 2015).…”