Yuan T, Stevens M H, Englert C R, Immel T J
Center for Atmospheric and Space Sciences, Utah State University, Logan, UT, USA.
Space Science Division, Naval Research Laboratory, Washington, DC, USA.
J Geophys Res Atmos. 2021 Aug 27;126(16). doi: 10.1029/2021jd035321. Epub 2021 Aug 11.
Local full diurnal coverage of temperature variations across the turbopause (~90-115 km altitude) is achieved by combining the nocturnal observations of a Sodium (Na) Doppler lidar on the Utah State University (USU) campus (41.7°N, 248.2°E) and NASA Michelson interferometer for global high-resolution thermospheric imaging (MIGHTI)/Ionospheric connection explorer (ICON) daytime observations made in the same vicinity. In this study, utilizing this hybrid data set during summer 2020 between June 12th and July 15th, we retrieve the temperature signatures of diurnal and semidiurnal tides in this region. The tidal amplitudes of both components have similar vertical variation with increasing altitude: less than 5 K below ~98 km but increase considerably above, up to 19 K near 104 km. Both experience significant dissipation near turbopause altitudes, down to ~12 K up to 113 km for the diurnal tide and ~13 K for the semidiurnal tide near 110 km. In addition, while the semidiurnal tidal behavior is consistent with the theoretical predictions, the diurnal amplitude is considerably larger than what is expected in the turbopause region. The tidal phase profile shows a dominance of tidal components with a long vertical wavelength (longer than 40 km) for the semidiurnal tide. On the other hand, the diurnal tide demonstrates close to an evanescent wave behavior in the turbopause region, which is absent in the model results and Thermosphere ionosphere mesosphere energetics and dynamics (TIMED)/Sounding of the atmosphere using broadband radiometry (SABER) observations.
通过结合犹他州立大学校园（北纬41.7°，东经248.2°）上钠（Na）多普勒激光雷达的夜间观测数据，以及美国国家航空航天局用于全球高分辨率热层成像的迈克尔逊干涉仪（MIGHTI）/电离层连接探测器（ICON）在同一区域进行的白天观测数据，实现了对跨湍流层顶（海拔约90 - 115千米）温度变化的全天覆盖。在本研究中，利用2020年夏季6月12日至7月15日期间的这一混合数据集，我们获取了该区域日潮和半日潮的温度特征。两个分量的潮汐振幅随海拔升高具有相似的垂直变化：在约98千米以下小于5开尔文，但在该高度以上显著增加，在104千米附近高达19开尔文。两者在湍流层顶高度附近都经历了显著耗散，日潮在113千米处降至约12开尔文，半日潮在110千米附近降至约13开尔文。此外，虽然半日潮行为与理论预测一致，但日潮振幅比湍流层顶区域预期的要大得多。半日潮的潮汐相位剖面显示，具有长垂直波长（大于40千米）的潮汐分量占主导。另一方面，日潮在湍流层顶区域表现出接近倏逝波的行为，这在模型结果以及热层-电离层-中间层能量学与动力学（TIMED）/利用宽带辐射测量大气探测（SABER）观测中均未出现。
