Thermospheric wind observed by GOCE: Wind jets and seasonal variations
Thermospheric wind observed by GOCE: Wind jets and seasonal variations
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DOI：
10.1002/2016ja022938
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发表时间：
2016-07
期刊：
影响因子：
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通讯作者：
Huixin Liu;E. Doornbos;J. Nakashima
中科院分区：
文献类型：
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作者：
Huixin Liu;E. Doornbos;J. Nakashima
2010 年至 2013 年期间，GOCE 在大约 250 公里高度附近进行了四年的观测，为检查黎明和黄昏附近的风提供了大型数据集。分析揭示了安静时间F区风的空间和季节变化的有趣新特征。 (1) 赤道地区的风结构除六月至日外四季均与赤道倾角一致，晚间形成强东急流，早间形成弱西急流。这证明了热层风的磁控制。 （2）赤道傍晚东风12月达到120m/s以上，6月降至90m/s以下。这种微弱的风可能导致六月经常观察到的弱反转前增强。 (3) 中纬度地区风向年变化明显，但晚风区和早风区相位相反。当地冬季晚间东风最大（约 140 m/s），夏季最小（约 60 m/s），而早晨西风则相反。这种年度变化可能归因于中纬度夏夜异常。 (4) 虽然HWM14经验风模型比HWM07有显着改进，但都没有捕捉到风与倾角赤道的对齐情况。这导致低纬度地区所有季节所有经度晚间地区的纬向风被严重低估超过 50 m/s。因此，在使用 HWM 驱动物理模型时应小心，因为它们可能会产生较弱的向上等离子体漂移。
Four years of GOCE observation near ∼250 km altitude during 2010–2013 provide a large data set for examining winds near dawn and dusk. The analysis has revealed interesting new features on the spatial and seasonal variation of the quiet time F region wind. (1) The wind structure in equatorial regions is aligned with the dip equator in all seasons but June solstice, forming a strong eastward jet in the evening sector but a weak westward jet in the morning sector. This demonstrates a magnetic control of the thermospheric wind. (2) The equatorial evening eastward wind reaches over 120 m/s in December but drops below 90 m/s in June. This weak wind likely leads to the frequently observed weak prereversal enhancement in June. (3) At middle latitudes, winds experience a marked annual variation but with opposite phase between the evening and morning sectors. The evening eastward wind maximizes in local winter (∼140 m/s) and minimizes in local summer (∼60 m/s), while the morning westward wind behaves vice versa. This annual variation may be attributed to the Midlatitude Summer Night Anomaly. (4) Although HWM14 empirical wind model significantly improved over HWM07, neither captures the wind's alignment with the dip equator. This leads to large underestimation of zonal winds by over 50 m/s at low latitudes in the evening sector at all longitudes in all seasons. Care should thus be taken when using HWMs to drive physical models, as they likely produce weaker upward plasma drift.