Ionospheric and thermospheric response over Millstone Hill to the May 30, 1984, annular solar eclipse
Ionospheric and thermospheric response over Millstone Hill to the May 30, 1984, annular solar eclipse
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DOI：
10.1029/ja091ia02p01661
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发表时间：
1986-02
影响因子：
--
通讯作者：
R. Roble;B. Emery;E. Ridley
中科院分区：
文献类型：
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作者：
R. Roble;B. Emery;E. Ridley
利用美国国家大气研究中心（NCAR）的热层大气环流模式（TGCM）计算了1984年5月30日环食时热层大气的时变响应。在太平洋2°N和135°W附近，最大暗度的路径开始于日出。系统向东北方向移动，经过墨西哥中部、美国东部，然后进入大西洋，最后在北纬28度、东经4度附近的阿尔及利亚结束。偏影的面积比较大，日食期间入射到地球阳面的太阳总通量减少约6%。TGCM计算风、温度和整个热层主要成分的质量混合比的随时间变化的响应。扰动遵循日环食的路径，最大偏差发生在1700 UT附近约300公里处的温度和更高海拔的风和成分。扰动风从各个方向向阴影汇聚，在热层上层的速度达到75 m s−1。最高温度距平（−55 K）和垂直风距平（−7 m s−1）出现在阴影中心附近。在300 km的恒定高度下，N2浓度和O浓度分别降低约10%和6%。在马萨诸塞州的Millstone Hill（北纬42.6°，西经71.5°），最大遮蔽的路径在非相干散射雷达的纬度3°范围内通过。该站在1700 UT（1200 LT）时的最大太阳遮蔽率为86%。一个与时间相关的电离层一维数值模型，使用了在Millstone Hill的TGCM计算的风，温度和成分，用于计算日食期间的电子和离子密度和温度以及奇数氮物质NO，N（4S）和N（²D）的密度。与没有日食的类似控制运行相比，计算出的电子密度在F区减少了2倍，在F1区减少了4倍，在E区减少了3倍。F1区域在日食期间出现，NO+/O+比率增加。计算的电子温度下降460 K在日食期间，但然后增加200 K以下的日食，因为强烈的太阳加热的区域中的电子密度降低。计算出的离子温度一般跟随中性温度的变化。计算的热层和电离层响应与Millstone Hill非相干散射雷达的测量结果吻合得很好。
The National Center for Atmospheric Research (NCAR) thermospheric general circulation model (TGCM) is used to calculate the time-dependent thermospheric response to the May 30, 1984, annular solar eclipse. The path of maximum obscurity begins at sunrise in the Pacific Ocean near 2°N and 135°W. It moves northeastward, passing across central Mexico, the eastern United States, and then the Atlantic before ending near 28°N and 4°E in Algeria. The area of the partial shadow is relatively large, and the total solar flux incident on the dayside of the earth is decreased by about 6% during the eclipse. The TGCM calculates the time-dependent response of the winds, temperature, and the mass mixing ratios of the major constituents throughout the thermosphere. Perturbations follow the path of the annular eclipse, with maximum deviations occurring near 1700 UT at about 300 km for the temperature and at higher altitudes for the winds and composition. The perturbation winds converge from all directions toward the shadow at speeds reaching 75 m s−1 in the upper thermosphere. The maximum temperature anomaly (−55 K) and vertical wind anomaly (−7 m s−1) occur near the center of the shadow. At a constant altitude of 300 km, both the N2 density and the O density decrease by about 10% and 6%, respectively. The path of maximum obscuration passes within 3° of latitude of the incoherent scatter radar at Millstone Hill, Massachusetts (42.6°N, 71.5°W). The station experiences a maximum solar obscuration of 86% at 1700 UT (1200 LT). A time-dependent one-dimensional numerical model of the ionosphere that uses the TGCM-calculated winds, temperature, and composition at Millstone Hill is used to calculate the electron and ion densities and temperatures and the densities of the odd-nitrogen species NO, N(4S), and N(²D) during the eclipse. The calculated electron density decreases by about factors of 2 in the F region, 4 in the F1 region, and 3 in the E region compared to a similar control run without an eclipse. The F1 region emerges during the eclipse with an increase in the NO+/O+ ratio. The calculated electron temperature decreases by 460 K during the eclipse but then increases 200 K following the eclipse because of the intense solar heating in a region of reduced electron densities. The calculated ion temperature generally follows the changes in neutral temperature. The calculated thermospheric and ionospheric responses agree well with measurements made by the Millstone Hill incoherent scatter radar.