First U.S.‐China joint ground‐based Fabry‐Perot interferometer observations of longitudinal variations in the thermospheric winds

Wu, Qian; Yuan, Weihua; Xu, Jiyao; Huang, Chan; Zhang, Xiaoxin; Wang, Jingsong; Li, Tao

doi:10.1002/2014ja020089

Cited by 18 publications

(34 citation statements)

References 23 publications

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“…For the zonal winds, differences were seen in the amplitude of the maximum eastward flow (with the winds typically being faster over Morocco) as well as the timing of the reversal from eastward to westward flow (with the reversal taking place 2 h earlier in local time over PARI). Fisher et al (2015) concluded that, in line with the prior hypothesis presented by Wu et al (2014), some of these differences were likely attributable to differences in the geomagnetic latitudes of the two sites. This prompts the need to compare the data from Oukaïmeden with data from a site at a similar geomagnetic latitude.…”

Section: Comparison To Prior Observationsmentioning

confidence: 60%

Climatology of thermospheric neutral winds over Oukaïmeden Observatory in Morocco

et al. 2017

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Abstract. In order to explore coupling between the thermosphere and ionosphere and to address the lack of data relating to thermospheric neutral winds and temperatures over the African sector, a new system of instruments was installed at the Oukaïmeden Observatory located in the high Atlas Mountains, 75 km south of Marrakesh, Morocco (31.206 • N, 7.866 • W, 22.84 • N magnetic). In this work we present the first multi-year results of the climatology of meridional and zonal winds obtained during the period from January 2014 to February 2016, including observations from 648 nights. The measurements are obtained using an imaging Fabry-Pérot interferometer, which measures the 630.0 nm emissions caused by dissociative recombination of O + 2 . The basic climatology of the winds is as expected, showing zonal winds that are strongly eastward in the early evening just after sunset with a speed of 50 to 100 m s −1 decreasing in magnitude, and reversing directions in the local summer months, towards sunrise. The meridional winds are slightly poleward in the early evening during the local winter, before reversing directions around 21:00 LT. In the local summer months, the meridional winds are equatorward for the entire night, reaching a maximum equatorward speed of 75 m s −1 . We compare the observed climatologies of neutral winds to that provided by the recently updated Horizontal Wind Model (HWM14) in order to validate that model's predictions of the thermospheric wind patterns over the eastern portion of Africa. The model captures much of the features in the observational climatologies. The most notable exception is for the zonal winds during local summer, when the maximum eastward wind in the observations occurs approximately 4 h later than seen in the model results.

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Section: Comparison To Prior Observationsmentioning

confidence: 60%

Climatology of thermospheric neutral winds over Oukaïmeden Observatory in Morocco

et al. 2017

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“…The Kelan FPI system (geographically 38.7°N, 111.6°E; geomagnetically 34°N; Figure ) has a similar design to the FPI deployed at XL (Wu et al, ). Three wavelengths of nightglow at 892.0, 557.7, and 630.0 nm are observed with the integration time of 3, 3, and 5 min, respectively.…”

Section: Fpi Instruments Models and Data Analysismentioning

confidence: 99%

A Comparison of Quiet Time Thermospheric Winds Between FPI Observations and Model Calculations

Jiang

Wang

et al. 2018

JGR Space Physics

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We investigate local time, seasonal, and longitudinal variations of thermospheric horizontal winds at midlatitudes during geomagnetically quiet times by comparing winds from observations, an empirical wind model, and a numerical model. The observations are from three Fabry‐Perot interferometers (FPIs), the empirical model is the most recent version of the Horizontal Wind Model 14 (HWM14), and the numerical model is the Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model of the National Center for Atmospheric Research. The three FPI stations are located at Xinglong (geographically 40.2°N, 117.4°E; geomagnetically 35°N) and Kelan (geographically 38.7°N, 111.6°E; geomagnetically 34°N) in China and at Millstone Hill (geographically 42.6°N, 71.5°W; geomagnetically 52°N) in United States. The results show that the winds at Millstone Hill are more southward and more westward than those at Xinglong and Kelan in all seasons; the directional reversal time of zonal winds is also earlier at Millstone Hill than at the other two stations. Thermosphere‐Ionosphere‐Electrodynamics General Circulation Model shows better agreement with FPI observations in the winter months compared to summer, and in general best replicates those measurements taken at Millstone Hill. HWM14 generally produces agreement with quiet time midlatitude neutral wind measurements, with HWM14 meridional winds comparing very well throughout most of a year. HWM14 model‐data discrepancies occur mainly in the zonal winds during the winter season. Overall, HWM14 predicts MH FPI observations slightly better than it does for the data from the two Asian stations.

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“…Recently, Wu et al (2014) compared simultaneous TW observations made in China and the United States (US) for two cases in October, and pointed out that Vn during low geomagnetic activities (Kp ~ 2) shows different characteristics before midnight (LT), although they show similar characteristics for Ve during low geomagnetic activities and for Vn and Ve during quiet geomagnetic condition (Kp ~ 1). The diurnal cycle of TWs over Asia-Oceania may differ from that in the Western Hemisphere, and the relationship should depend on the geomagnetic conditions.…”

Section: Climatology Of Shigarakimentioning

confidence: 99%

“…The climatological TWs are dependent on the geographical latitude, season, and solar activity (e.g., Emmert et al 2006a). In addition, the TWs may not be longitudinally symmetric; i.e., magnetic discrepancy between geomagnetic and geographic coordinates and nonmigrating tide can cause change in the TWs (Wu et al 2014). One example of geographical-longitudinal dependency of TWs is the wave-4 structure observed in the equatorial ionosphere and thermosphere (e.g., Immel et al 2006).…”

Section: Introductionmentioning

confidence: 99%

Thermospheric Nocturnal Wind Climatology Observed by Fabry-Perot Interferometers over the Asia-Oceania Region

Yatagai

Oyama

2016

Journal of the Meteorological Society of Japan

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This study shows the horizontal structure of climatology of thermospheric nocturnal winds at a height of approximately 250 km in the Asia-Oceania region for the first time using observations made with Fabry-Perot interferometers (FPIs; optical wavelength of 630.0 nm). The FPIs used in this study were located at Shigaraki (Japan, 34.8°N, 136.1°E), Chiang Mai (Thailand, 18.8°N, 98.9°E), Kototabang (Indonesia, 0.2°S, 100.3°E), and Darwin (Australia, 12.4°S, 131.0°E). The observation data underwent quality control that involved consideration of cloud information, wind speed value, and standard deviation of results obtained from synchronous fringe images; approximately 30 % of the observation data from all the four stations were deemed suitable for use. The nocturnal diurnal changes at Shigaraki according to the local solar time were generally consistent with changes in China at similar latitudes, although the amplitudes were slightly different. All four stations showed the continuous flow pattern of the nocturnal diurnal wind in each season. The Chiang Mai and Darwin stations observed seasonal/diurnal changes similar to those observed by stations at similar latitudes on the North and the South American continents. Although there were fewer samples for Chiang Mai, Kototabang, and Darwin in the rainy season compared to that for Shigaraki, the seasonal climatology reported here can be used to provide a background long-term average status for describing anomalous events and extremes having different causes.

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First U.S.‐China joint ground‐based Fabry‐Perot interferometer observations of longitudinal variations in the thermospheric winds

Cited by 18 publications

References 23 publications

Climatology of thermospheric neutral winds over Oukaïmeden Observatory in Morocco

Climatology of thermospheric neutral winds over Oukaïmeden Observatory in Morocco

A Comparison of Quiet Time Thermospheric Winds Between FPI Observations and Model Calculations

Thermospheric Nocturnal Wind Climatology Observed by Fabry-Perot Interferometers over the Asia-Oceania Region

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