Using two-dimensional (2D) thermal structure models and pseudo-2D chemical kinetics models, we explore how atmospheric temperatures and composition change as a function of altitude and longitude within the equatorial regions of close-in transiting Neptune-class exoplanets at different distances from their host stars. Our models predict that the day-night stratospheric temperature contrasts increase with increasing planetary effective temperatures T_eff and that the atmospheric composition changes significantly with T_eff. We find that horizontal transport-induced quenching is very effective in our simulated exo-Neptune atmospheres, acting to homogenize the vertical profiles of species abundances with longitude at stratospheric pressures where infrared observations are sensitive. Our models have important implications for planetary emission observations as a function of orbital phase with the Ariel mission. Cooler solar-composition exo-Neptunes with T_eff = 500–700 K are strongly affected by photochemistry and other disequilibrium chemical processes, but their predicted variations in infrared emission spectra with orbital phase are relatively small, making them less robust phase-curve targets for Ariel observations. Hot solar-composition exo-Neptunes with T_eff ≥ 1300 K exhibit strong variations in infrared emission with orbital phase, making them great targets for constraining global temperatures, energy-balance details, atmospheric dynamics, and the presence of certain high-temperature atmospheric constituents. However, such high-temperature exo-Neptunes are arguably less interesting from an atmospheric chemistry standpoint, with spectral signatures being dominated by a small number of species whose abundances are expected to be constant with longitude and consistent with thermochemical equilibrium. Solar-composition exo-Neptunes with T_eff = 900–1100 K reside in an interesting intermediate regime, with infrared phase curve variations being affected by both temperature and composition variations, albeit at smaller predicted phase-curve amplitudes than for the hotter planets. This interesting intermediate regime shifts to smaller temperatures as atmospheric metallicity is increased, making cool higher-metallicity Neptune-class planets appropriate targets for Ariel phase-curve observations.

我们使用二维（2D）热结构模型和伪2D化学动力学模型，研究了距近距离海王星级系外行星赤道区域在不同距离处的大气温度和组成如何随高度和经度的变化而变化他们的主人。我们的模型预测，随着行星有效温度T _eff的增加，平日夜间的温度反差增加，并且大气成分随T _eff的变化而显着变化。。我们发现，在我们模拟的外海王星大气中，水平运输诱发的猝灭非常有效，可以使红外观测敏感的平流层压力下经度均匀的物种丰度的垂直分布均匀化。我们的模型对于与Ariel任务的轨道相位有关的行星发射观测具有重要意义。T _eff = 500–700 K的较凉的太阳组成外星海王星受光化学和其他不平衡化学过程的强烈影响，但是它们预测的红外发射光谱随轨道相的变化相对较小，因此它们对于光谱的鲁棒性较弱Ariel的观察。太阳系热构成海王星与T _eff≥1300 K在红外发射随轨道相位的变化很大，使其成为约束全球温度，能量平衡细节，大气动力学以及某些高温大气成分的理想目标。然而，从大气化学的角度来看，这样的高温外海王星可能不那么令人感兴趣，光谱特征主要由少数物种组成，这些物种的丰度在经度上是恒定的，并且与热化学平衡相一致。T _eff的太阳成分外海王星= 900–1100 K处于一个有趣的中间状态，红外相曲线的变化受温度和成分变化的影响，尽管与较热的行星相比，预测的相曲线幅值较小。随着大气金属含量的增加，这种有趣的中间状态转变为较小的温度，这使冷金属含量更高的海王星级行星成为Ariel相曲线观测的合适目标。