Characteristics of acoustic gravity waves obtained from Dynasonde data

Negrea, Cătălin; Zabotin, N. A.; Bullett, Terrence; Fuller‐Rowell, T. J.; Fang, Tzu‐Wei; Codrescu, M.

doi:10.1002/2016ja022495

Cited by 20 publications

(17 citation statements)

References 39 publications

(67 reference statements)

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“…Using data from both channels and approximating the wave as plane wave, it is possible to identify the best fit horizontal wavelength of 1,800 km, period of 1.2 hr, phase speed of 400 m/s, and azimuth of propagation of 300°. These characteristics are broadly consistent with those reported for large‐scale TADs seen in the upper thermosphere (e.g., Bruinsma et al, ) and the larger‐scale TIDs seen in the ionosphere at middle thermosphere altitudes (e.g., Negrea et al, ). Utilizing a model of the airglow, it is possible to estimate the approximate amplitude of the atmospheric perturbation associated with this wave.…”

Section: Discussionsupporting

confidence: 90%

Observation of Thermospheric Gravity Waves in the Southern Hemisphere With GOLD

et al. 2020

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The middle thermosphere from~150 to 250 km is characterized by rapid increase in temperature with altitude and rapid ionization. The entire thermosphere is believed to be home to atmospheric waves that propagate through it, originating both in the atmospheric layers below and in the thermosphere itself. Within the middle thermosphere, direct observations of such waves are extremely sparse. The Global-scale Observations of the Limb and Disk (GOLD) far-ultraviolet imaging spectrometer is able to observe the middle thermosphere from geostationary orbit. During October 2018, a special observational campaign was performed, designed to identify atmospheric waves. Signatures in the 135.6-nm O airglow were seen that move northward with time, away from the southern polar region. These are consistent with a large-scale atmospheric gravity wave. These results are the first time 135.6-nm airglow has been used to track such a wave and highlight the ability of GOLD to observe such waves, even when at a modest amplitude, and track their motion.Plain Language Summary The upper region of the Earth's atmosphere, stretching from around 90-500 km above the surface, is known as the thermosphere. In this region, the temperature generally increases with altitude, but the strongest increase is in a region known as the middle thermosphere. The main source of heating in this region is absorption of ultraviolet light from the Sun, which also produces charged particles in this region, known as the ionosphere. Oscillations are observed in almost all the properties of the atmosphere at these altitudes, which are believed to result from waves within the atmosphere. In the middle thermosphere, there are very few direct observations of such waves. Global-scale Observations of the Limb and Disk (GOLD) is a new instrument that can observe the middle thermosphere by measuring emissions from the atmosphere call airglow. During a day in October 2018, GOLD observed what appear to be fluctuations in this airglow associated with such waves. The properties are determined, both from the GOLD observations and a theoretical model.

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Section: Discussionsupporting

confidence: 90%

Observation of Thermospheric Gravity Waves in the Southern Hemisphere With GOLD

et al. 2020

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“…A VIPIR system has been installed at Jicamarca in 2008. Similar gravity wave modulations observed with the VIPIR system in Wallops Island, Virginia, have been analyzed by Negrea et al (2016). The transmitter operates between 0.4 and 26 MHz with 4-kW peak power and 2% duty cycle.…”

Section: Vipir Ionogramsmentioning

confidence: 54%

Height Variation of Gaps in 150‐km Echoes and Whole Atmosphere Community Climate Model Electron Densities Suggest Link to Upper Hybrid Resonance

Lehmacher

Kudeki

et al. 2020

JGR Space Physics

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Radar echoes from the daytime lower F region near the magnetic equator, so-called 150-km echoes, have been puzzling researchers for decades. Neither the mechanisms that generate the enhanced backscatter at very high frequencies (typically 30-50 MHz), the sharp lower cutoff height, the intricate layering with multiple echo layers separated by narrow gaps, nor the modulation of the echoes by short-period gravity waves is well understood. Here we focus on the diurnal variation of the echo layers-specifically, certain wide gaps in the vertical structure-which apparently descend in the morning, reach their lowest altitude near local noon, and ascend in the afternoon, sometimes described as necklace structure based on the appearance of the layers in range-time-intensity diagrams. Analyzing high-resolution data obtained with the Jicamarca radar between 2005 and 2017, spanning more than one solar cycle, we find that (a) wide gaps and narrow lines occur in vertically stacked, systematically repeating pattern; (b) the gap heights vary with season and solar cycle; and (c) the gap heights can be associated with specific contours of plasma frequencies or electron densities. The last two findings are supported by simultaneous observations of VIPIR ionosonde reflection heights and by comparison of gap heights with electron density contours obtained with the WACCM-X 2.0 global model. Finally, the wide gaps appear to coincide with the double resonance condition, where the upper hybrid frequency equals integer multiples of the electron gyrofrequency. This may explain why field-aligned plasma irregularities are suppressed and enhanced radar backscatter is not observed inside the gaps.

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“…Many sources such as weather storm, earthquake, and solar storm can launch gravity waves/acoustic waves in the atmosphere. The waves propagate through the thermosphere, generating plasma density disturbances with varying periods of minutes to hours (e.g., Lay et al, ; Negrea et al, ; Negrea & Zabotin, ; Yue et al, ) and triggering plasma thin layer and/or plume‐type irregularities in the ionosphere (e.g., Abdu et al, ; Fritts et al, ; Li et al, ). With regard to the wavelength/period, ionospheric disturbances can be classified into three types: large, middle, and small scales.…”

Section: Introductionmentioning

confidence: 99%

Observation of Short‐Period Ionospheric Disturbances Using a Portable Digital Ionosonde at Sanya

Lan

Ning

et al. 2018

Radio Science

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A number of ionosondes have been operated in China to detect ionospheric disturbances for many years. These ionosondes, however, are not very suitable for the short‐period (<15 min) disturbances due to their poor time resolutions (>5 min). During recent years, the Institute of Geology and Geophysics, Chinese Academy of Sciences, together with the South Central University for Nationalities has been developing a portable digital ionosonde (PDI) equipped with the capability to detect and characterize small‐scale/short‐period ionospheric disturbances and to be quickly assembled and set up at temporary field stations for low‐latitude campaign coordinated observations. The PDI uses a set of technologies (e.g., code multiplexing and antenna/transmitter matching) that allow it to obtain quality Doppler ionograms at a good time resolution with small transmitting antennas. A preliminary analysis of observations by the PDI at Sanya (18.3°N, 109.6°E) shows the presence of ionospheric disturbances with periods ranging between several and tens of minutes. Interestingly, the disturbances (with different periods) were found to simultaneously occur at different F region altitudes, for example, with periods of ~5 and 20 min below and above ~180 km, respectively. The absence of shorter‐period disturbance at higher altitude is consistent with acoustic gravity waves through the region with intrinsic periods above the Brunt‐Väisälä period. The short‐period disturbances observed in F region bottomside are not evident in total electron content. The results demonstrate the capability of PDI to detect ionospheric disturbances with temporal scales down to a few minutes in routine ionogram mode. Future prospects of PDI are outlined.

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Characteristics of acoustic gravity waves obtained from Dynasonde data

Cited by 20 publications

References 39 publications

Observation of Thermospheric Gravity Waves in the Southern Hemisphere With GOLD

Observation of Thermospheric Gravity Waves in the Southern Hemisphere With GOLD

Height Variation of Gaps in 150‐km Echoes and Whole Atmosphere Community Climate Model Electron Densities Suggest Link to Upper Hybrid Resonance

Observation of Short‐Period Ionospheric Disturbances Using a Portable Digital Ionosonde at Sanya

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