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

来自OH分子的Meinel波段夜光发射已经使用了几十年来表征中间层温度。目前，天文学家所依赖的是排放系数（“A系数”），而pi认为这些系数需要修正。使用现有A系数集恢复的温度与根据第一原理计算的实际温度相差高达15 K。中间层温度的巨大不确定性会对模拟中间层和低层热层的化学、运输和环流产生不利影响。这些不确定因素也破坏了监测MLT长期温度的努力。该方案解决了氢氧根温度的测定：1)使用强度校准的夜光数据，这些数据是在天文天空光谱的大光谱范围内同时收集的；2)比较最近获得的OH Meinel波段线强度和最新的第一性原理计算的发射系数。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层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.