Periodicities of polar mesospheric clouds inferred from a meteorological analysis and forecast system
Periodicities of polar mesospheric clouds inferred from a meteorological analysis and forecast system
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DOI：
10.1002/2016jd025349
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发表时间：
2017-04
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通讯作者：
M. Stevens;R. Lieberman;D. Siskind;J. McCormack;M. Hervig;C. Englert
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文献类型：
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作者：
M. Stevens;R. Lieberman;D. Siskind;J. McCormack;M. Hervig;C. Englert
目前，控制 83 公里高度附近极地中层云 (PMC) 周期性的因素尚不明确。这主要是因为卫星和地面数据集无法解析昼夜周期内的全球中层温度变化。为了解决这一限制，我们采用了全球气象分析和预报系统，该系统吸收了中层卫星数据，并取得了两项重大进展。第一个是我们以更快的每小时节奏使用输出，从而可以定量描述昼夜（24 小时）、半日（12 小时）和昼夜振荡。第二个是输出驱动一个简单的 PMC 参数化，该参数化仅取决于当地温度、压力和水蒸气浓度。我们的研究重点是 2009 年 7 月北半球和 2008 年 1 月南半球的结果。我们发现，24小时迁移潮汐以及12小时和24小时非迁移潮主导了北部PMC振荡，而12小时和24小时非迁移潮主导了南部振荡。每个分量的月平均振幅通常为 2-6 K，较低 PMC 纬度 (50°) 的振幅较大。 2 天和 5 天的行星波也在两个半球都有贡献，月平均振幅为 1 至 3 K，尽管这些振幅在某些日子可能高达 4-6 K。在约 1000 公里的长度尺度和约 1 周的时间尺度上，我们发现局部温度振荡足以描述中纬度 PMC 观测结果。
There is currently an ambiguity in what controls polar mesospheric cloud (PMC) periodicities near 83 km altitude. This is primarily because satellite and ground‐based data sets cannot resolve global mesospheric temperature variability over the diurnal cycle. To address this limitation, we employ a global meteorological analysis and forecast system that assimilates mesospheric satellite data with two significant advances. The first is that we use output at a more rapid one hourly cadence, allowing for a quantitative description of diurnal (24 h), semidiurnal (12 h), and terdiurnal oscillations. The second is that the output drives a simple PMC parameterization which depends only on the local temperature, pressure, and water vapor concentrations. Our study focuses on results from July 2009 in the Northern Hemisphere and January 2008 in the Southern Hemisphere. We find that the 24 h migrating temperature tide as well as the 12 h and 24 h nonmigrating tides dominate northern PMC oscillations whereas the 12 h and 24 h nonmigrating tides dominate southern oscillations. Monthly averaged amplitudes for each of these components are generally 2–6 K with the larger amplitudes at lower PMC latitudes (50°). The 2 day and 5 day planetary waves also contribute in both hemispheres, with monthly averaged amplitudes from 1 to 3 K although these amplitudes can be as high as 4–6 K on some days. Over length scales of ~1000 km and timescales of ~1 week, we find that local temperature oscillations adequately describe midlatitude PMC observations.