Dhadly Manbharat S, Englert Christoph R, Drob Douglas P, Emmert John T, Niciejewski Rick, Zawdie Kate A
Space Science Division, U.S. Naval Research Laboratory, Washington, DC, USA.
Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, USA.
J Geophys Res Space Phys. 2021 Dec;126(12). doi: 10.1029/2021ja029904. Epub 2021 Nov 14.
This study cross-compares ICON/MIGHTI and Thermosphere, Ionosphere, Mesosphere Energetics & Dynamics (TIMED)/TIMED Doppler Interferometer (TIDI) MLT region neutral winds from middle Northern Hemisphere to low Southern Hemisphere latitudes. We utilized MIGHTI level-2.2 (v4) and TIDI level-3 (v11) neutral winds from January 2020 to November 2020 and found their conjunctions using a space-time window of LST ± 15 min, latitude ± 4°, and longitude ± 4° around each TIDI wind measurement. Due to the nature of their orbital geometry, frequent conjunctions occurred between MIGHTI and TIDI. These conjunctions are spread in longitudes and they occur at approximately fixed LSTs and latitudes, which allows us to compare their observed diurnal variability. MIGHTI and TIDI wind observations agree well (except on the TIDI coldside during forward flight) and show similar large amplitude longitudinal variations that can reach more than 100 m/s. MIGHTI and TIDI zonal and meridional winds show moderate correlations of 0.60 and 0.55, respectively. The slopes of regression fits for zonal and meridional winds are 0.92 and 0.91, respectively. The root mean square differences in zonal and meridional winds are 56 and 66 m/s, respectively. We found that TIDI coldside measurements in forward flight show a systematic bias and this behavior is repetitive as the instrument pointing direction is changed by the periodic TIMED yaw maneuver. The nature of this systematic bias suggests that the TIDI zero-wind references (at least for the coldside telescopes) need revision. This investigation can provide guidance toward improving the TIDI data analysis. In addition, the results of this study act as a validation of MIGHTI MLT winds.
本研究对ICON/MIGHTI和热层、电离层、中间层能量学与动力学（TIMED）/TIMED多普勒干涉仪（TIDI）从北半球中纬度到南半球低纬度的中层顶区域中性风进行了交叉比较。我们利用了2020年1月至2020年11月期间MIGHTI二级2.2（v4）和TIDI三级（v11）的中性风数据，并在每次TIDI风测量周围使用地方时±15分钟、纬度±4°和经度±4°的时空窗口来寻找它们的交汇点。由于其轨道几何形状的性质，MIGHTI和TIDI之间频繁出现交汇点。这些交汇点在经度上分布，并且在大致固定的地方时和纬度处出现，这使我们能够比较它们观测到的日变化。MIGHTI和TIDI的风观测结果吻合良好（向前飞行时TIDI冷边情况除外），并显示出相似的大幅经度变化，可达100米/秒以上。MIGHTI和TIDI的纬向风和经向风分别显示出0.60和0.55的中等相关性。纬向风和经向风回归拟合的斜率分别为0.92和0.91。纬向风和经向风的均方根差值分别为56米/秒和66米/秒。我们发现向前飞行时TIDI冷边测量存在系统偏差，并且随着仪器指向方向通过周期性的TIMED偏航操纵而改变，这种行为会重复出现。这种系统偏差的性质表明TIDI的零风参考（至少对于冷边望远镜）需要修正。这项研究可为改进TIDI数据分析提供指导。此外，本研究结果可作为对MIGHTI中层顶风的验证。
