CEDAR: Critical Evaluation of the Hydroxyl Radical (OH) Meinel Band Einstein A Coefficients

几十年来，来自OH分子的Meinel带夜光发射一直被用来表征中层温度。空气工程师目前依赖于排放系数(“A系数”)，PI认为需要修改这些系数。使用现有的一组A系数恢复的温度与根据第一原理计算的实际温度最多相差15K。中间层温度的较大不确定性可能对模拟中间层和低热层(MLT)的化学、输送和环流产生不利影响。这些不确定性还破坏了监测MLT长期温度的努力。这项建议通过1)使用从天文天空光谱同时收集的大光谱范围内经强度校准的夜辉数据来确定OH温度；2)将最近获得的这种OH Meinel带线强度与最新的发射系数的第一性原理计算进行比较。这项研究将有助于理解基本的物理量子过程、小尺度和大尺度的大气运动以及低热层的长期温度变化。

The Meinel band nightglow emission from the OH molecule has been used for decades to characterize mesospheric temperatures. Aeronomers currently rely on emission coefficients ("A coefficients") that the PIs argue are in need of revision. Temperatures recovered using the existing set of A coefficients differ by up to 15 K from actual temperatures computed from first principles. Large uncertainty in the mesospheric temperature can have detrimental effects on modeling chemistry, transport and circulation of the mesosphere and lower thermosphere (MLT). The uncertainties also undermine efforts to monitor the long-term temperatures in the MLT. This proposal addresses the OH temperature determination by 1) using intensity-calibrated nightglow data that has been collected simultaneously over a large spectral range from astronomical sky spectra; 2) making comparisons between such recently obtained OH Meinel band line intensities, and the most recent first principles calculations of the emission coefficients. This research will contribute to understanding fundamental physical quantum processes, atmospheric motions on small and large scales, and long-term temperature change in the lower thermosphere.