Intra-Annual Variation of Eddy Diffusion (k (zz) ) in the MLT, From SABER and SCIAMACHY Atomic Oxygen Climatologies.
Intra-Annual Variation of Eddy Diffusion (k (zz) ) in the MLT, From SABER and SCIAMACHY Atomic Oxygen Climatologies.
复制标题
MLT涡旋扩散（k (zz)）的年际变化，来自SABER和SCIAMACHY原子氧气体学。
DOI：
10.1029/2021jd035343
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发表时间：
2021-12-16
影响因子：
4.4
通讯作者：
Mlynczak, M.
中科院分区：
文献类型：
--
作者：
Swenson, G. R.;Vargas, F.;Jones, M.;Zhu, Y.;Kaufmann, M.;Yee, J. H.;Mlynczak, M.
关键词：
中间层和热层下层(MLT)中的原子氧(O)是在热层下层通过光解产生的氧和在中间层上层通过复合产生的化学损失之间的平衡的结果。O从低热层向下到中间层的输送主要是由涡旋扩散过程驱动的，而涡旋扩散过程是由耗散重力波和不稳定引起的。这里的动机是基于该地区的气候学来探索MLT中涡旋扩散系数(KZZ)和涡流速度的年内变化，最初由Garcia和所罗门完成(1985年，https://doi.org/10.1029/JD090iD02p03850).在目前的研究中，年内周期被分为三个区域的26个两周周期：北半球(NH)、南半球(SH)和赤道(EQ)。16年的SABER(2002-2018年)和10年的SCIAMACHY(2002-2012年)O密度测量，以及NRLMSIS®2.0用于计算原子氧的涡旋扩散速度和通量。我们的显著发现包括：NH和SH区在87公里以下的年振荡占主导地位，冬夏之间的变化系数为3-4，为83公里，在EQ区的所有高度都有一种占主导地位的半年振荡。在96公里处测得的全球平均kZZ缺乏钱学森等人推导的高层大气密度数据的年内变化(2009年，https://doi.org/10.1029/2008JA013643).K、ZZ和O密度的很大的季节(和半球)变化对于在卫星分析中分离和隔离以及纳入MLT模式是很重要的。由SABER和SCIAMACHY原子氧气候学确定了MLT中kZZ的年内变化(IAV)，推断出中纬度kZZ值在87公里以下有显著的年振荡，而赤道值每半年(80-96 KM)变化一次。与目前一些GCM使用的全球平均值相反，kZZ和O密度的半球IAV(季节性)主导MLT
Atomic oxygen (O) in the mesosphere and lower thermosphere (MLT) results from a balance between production via photo‐dissociation in the lower thermosphere and chemical loss by recombination in the upper mesosphere. The transport of O downward from the lower thermosphere into the mesosphere is preferentially driven by the eddy diffusion process that results from dissipating gravity waves and instabilities. The motivation here is to probe the intra‐annual variability of the eddy diffusion coefficient (k zz ) and eddy velocity in the MLT based on the climatology of the region, initially accomplished by Garcia and Solomon (1985, https://doi.org/10.1029/JD090iD02p03850). In the current study, the intra‐annual cycle was divided into 26 two‐week periods for each of three zones: the northern hemisphere (NH), southern hemisphere (SH), and equatorial (EQ). Both 16 years of SABER (2002–2018) and 10 years of SCIAMACHY (2002–2012) O density measurements, along with NRLMSIS® 2.0 were used for calculation of atomic oxygen eddy diffusion velocities and fluxes. Our prominent findings include a dominant annual oscillation below 87 km in the NH and SH zones, with a factor of 3–4 variation between winter and summer at 83 km, and a dominant semiannual oscillation at all altitudes in the EQ zone. The measured global average k zz at 96 km lacks the intra‐annual variability of upper atmosphere density data deduced by Qian et al. (2009, https://doi.org/10.1029/2008JA013643). The very large seasonal (and hemispherical) variations in k zz and O densities are important to separate and isolate in satellite analysis and to incorporate in MLT models. Intra‐annual variations (IAVs) of k zz in the MLT, from SABER and SCIAMACHY atomic oxygen climatologies are determined Deduced k zz values at mid‐latitudes have a prominent annual oscillation below 87 km, while equatorial values vary semiannually (80–96 km) Hemispherical IAVs (seasonal) in k zz and O density dominate the MLT, contrary to the global averages used currently in some GCMs