scholarly journals Tidal wind shear observed by meteor radar and comparison with sporadic E occurrence rates based on GPS radio occultation observations

2019 ◽  
Vol 17 ◽  
pp. 213-224
Author(s):  
Christoph Jacobi ◽  
Christina Arras
Keyword(s):  
Wind Shear ◽  
Radio Occultation ◽  
Signal To Noise Ratio ◽  
Lower Thermosphere ◽  
Horizontal Component ◽  
Meteor Radar ◽  
Good Correspondence ◽  
Gps Radio Occultation ◽  
Middle Latitudes ◽  
Sporadic E

Abstract. We analyze tidal (diurnal, semidiurnal, terdiurnal, quarterdiurnal) phases and related wind shear in the mesosphere/lower thermosphere as observed by meteor radar over Collm (51.3∘ N, 13.0∘ E). The wind shear phases are compared with those of sporadic E (Es) occurrence rates, which were derived from GPS radio occultation signal-to-noise ratio (SNR) profiles measured by the COSMIC/FORMOSAT-3 satellites. At middle latitudes Es are mainly produced by wind shear, which, in the presence of a horizontal component of the Earth's magnetic field, leads to ion convergence in the region where the wind shear is negative. Consequently, we find good correspondence between radar derived wind shear and Es phases for the semidiurnal, terdiurnal, and quarterdiurnal tidal components. The diurnal tidal wind shear, however, does not correspond to the Es diurnal signal.

scholarly journals Enhanced sporadic <i>E</i> occurrence rates during the Geminid meteor showers 2006–2010

2013 ◽  
Vol 11 ◽  
pp. 313-318 ◽  
Author(s):  
C. Jacobi ◽  
C. Arras ◽  
J. Wickert
Keyword(s):  
Northern Hemisphere ◽  
Strong Correlation ◽  
Wind Shear ◽  
Radio Occultation ◽  
Semidiurnal Tide ◽  
Metallic Ions ◽  
Meteor Radar ◽  
Meteor Showers ◽  
Short Delay ◽  
Sporadic E

Abstract. Northern Hemisphere midlatitude sporadic E (Es) layer occurrence rates derived from FORMOSAT-3/COSMIC GPS radio occultation (RO) measurements during the Geminid meteor showers 2006–2010 are compared with meteor rates obtained with the Collm (51.3° N, 13.0° E) VHF meteor radar. In most years, Es rates increase after the shower, with a short delay of few days. This indicates a possible link between meteor influx and the production of metallic ions that may form Es. There is an indication that the increase propagates downward, probably partly caused by tidal wind shear. However, the correlation between Es rates and meteor flux varies from year to year. A strong correlation is found especially in 2009, while in 2010 Es rates even decrease during the shower. This indicates that additional processes significantly influence Es occurrence also during meteor showers. A possible effect of the semidiurnal tide is found. During years with weaker tidal wind shear, the correlation between Es and meteor rates is even weaker.

Tidal signatures in sporadic E occurrence rates - migrating and nonmigrating components, and comparison with neutral wind shear

2021 ◽  
Author(s):  
Christoph Jacobi ◽  
Kanykei Kandieva ◽  
Christina Arras
Keyword(s):  
Wind Shear ◽  
Signal To Noise Ratio ◽  
Ion Concentration ◽  
Vertical Shear ◽  
Neutral Wind ◽  
High Electron ◽  
Phase Measurements ◽  
Middle Latitudes ◽  
E Region ◽  
Sporadic E

&lt;p&gt;In the lower ionospheric E region, shallow regions of high electron density are found, which are called sporadic E (ES) layers. ES layers consist of thin clouds of accumulated ions. They occur mainly at middle latitudes, and they are most frequently found during the summer season. ES are generally formed at heights between 90 and 120 km. At midlatitudes, their occurrence can be described through the wind shear theory. According to this theory, ES formation is due to interaction between the metallic ion concentration, the Earth&amp;#8217;s magnetic field, and the vertical shear of the neutral wind. Here, we analyze ES occurrence rates (OR) obtained from ionospheric radio occultation measurements by the FORMOSAT-3/COSMIC constellation. To derive information on ES from RO, we use the Signal-to-Noise ratio (SNR) profiles of the GPS L1 phase measurements. If large SNR standard deviation values occur that are concentrated within a layer of less than 10 km thickness, we assume that the respective SNR profile disturbance is owing to an ES layer.&lt;/p&gt;&lt;p&gt;Midlatitude ES are found to be mainly connected with a migrating diurnal and semidiurnal component. Especially at high latitudes of the southern hemisphere, nonmigrating components such as a diurnal westward wave 2 and a semidiurnal westward wave 1 are also visible. Near the equator, a strong diurnal eastward wavenumber 3 component and a semidiurnal eastward wavenumber 2 component are found in summer and autumn. Terdiurnal and quarterdiurnal components are weaker than the diurnal and semidiurnal ones. We discuss seasonal and global distributions of migrating and nonmigrating components, and their relation to neutral wind shear derived from ground-based observations and numerical modeling.&lt;/p&gt;

scholarly journals Study of sporadic E layers based on GPS radio occultation measurements and digisonde data over the Brazilian region

2018 ◽  
Vol 36 (2) ◽  
pp. 587-593 ◽  
Author(s):  
Laysa C. A. Resende ◽  
Christina Arras ◽  
Inez S. Batista ◽  
Clezio M. Denardini ◽  
Thainá O. Bertollotto ◽  
...  
Keyword(s):  
Radio Occultation ◽  
Signal To Noise Ratio ◽  
Satellite Measurements ◽  
Low Latitude ◽  
Middle Latitudes ◽  
Sporadic E Layers ◽  
Sporadic E ◽  
Comparative Results ◽  
Layer Development ◽  
Good Agreement

Abstract. This work presents new results about sporadic E-layers (Es layers) using GPS (global positioning system) radio occultation (RO) measurements obtained from the FORMOSAT-3/COSMIC satellites and digisonde data. The RO profiles are used to study the Es layer occurrence as well as its intensity of the signal-to-noise ratio (SNR) of the 50 Hz GPS L1 signal. The methodology was applied to identify the Es layer on RO measurements over Cachoeira Paulista, a low-latitude station in the Brazilian region, in which the Es layer development is not driven tidal winds only as it is at middle latitudes. The coincident events were analyzed using the RO technique and ionosonde observations during the year 2014 to 2016. We used the electron density obtained using the blanketing frequency parameter (fbEs) and the Es layer height (h'Es) acquired from the ionograms to validate the satellite measurements. The comparative results show that the Es layer characteristics extracted from the RO measurements are in good agreement with the Es layer parameters from the digisonde. Keywords. Ionosphere (ionosphere–atmosphere interactions)

scholarly journals Terdiurnal signatures in sporadic <i>E</i> layers at midlatitudes

2013 ◽  
Vol 11 ◽  
pp. 333-339 ◽  
Author(s):  
T. Fytterer ◽  
C. Arras ◽  
C. Jacobi
Keyword(s):  
Global Positioning System ◽  
Zonal Wind ◽  
Wind Shear ◽  
Radio Occultation ◽  
Positioning System ◽  
Meteor Radar ◽  
Satellite Mission ◽  
Global Positioning ◽  
Sporadic E ◽  
Comparison Of The Results

Abstract. Global Positioning System radio occultation measurements by the FORMOsa SATellite mission-3/Constellation Observing System for Meteorology, Ionosphere and Climate satellites were used to analyse the behaviour of the signature of the terdiurnal tide in sporadic E (ES) layers at midlatitudes (43–63° N). According to theory, the occurrence of ES is expected when the vertical zonal wind shear, which is mainly owing to solar tides, is negative. 4 yr means, based on 3-monthly running mean zonal means from December 2006–November 2010, were constructed for the terdiurnal oscillation in the occurrence frequency of ES. Comparison of the results with VHF meteor radar observations of the terdiurnal tide and the 8 h oscillation in the vertical zonal wind shear at Collm, Germany (51.3° N, 13° E) shows a clear correspondence between the 8 h in ES and in wind shear signature.

scholarly journals Quarterdiurnal signature in sporadic E occurrence rates and comparison with neutral wind shear

2018 ◽  
Author(s):  
Christoph Jacobi ◽  
Christina Arras ◽  
Christoph Geißler ◽  
Friederike Lilienthal
Keyword(s):  
Zonal Wind ◽  
Wind Shear ◽  
Lower Thermosphere ◽  
Vertical Wind Shear ◽  
Global Scale ◽  
Maximum Deviation ◽  
Driving Mechanism ◽  
Earth Magnetic Field ◽  
Sporadic E ◽  
Wind Shears

Abstract. The GPS radio occultation (RO) technique is used to study sporadic E (ES) layer plasma irregularities of the Earth’s ionosphere on a global scale using GPS signal-to-noise ratio (SNR) profiles from the COSMIC/FORMOSAT-3 satellite. The maximum deviation from the mean SNR can be attributed to the height of the ES layer. ES are generally accepted to be produced by ion convergence due to vertical wind shear in the presence of a horizontal component of the Earth magnetic field, while the wind shear is provided mainly by solar tides. Here we present analyses of quarterdiurnal (QDT) signatures in ES occurrence rates. We find from a local comparison with mesosphere/lower thermosphere wind shear obtained with a meteor radar at Collm (51:3°N, 13:0°E), that the phases of the QDT in ES agree well with those of negative wind shear for all seasons except for summer, when the QDT amplitudes are small. We also compare the global QDT ES signal with numerical model results. The global distribution of ES occurrence rates qualitatively agrees with the modeled zonal wind shears. The results indicate that zonal wind shear is indeed an important driving mechanism for the QDT seen in ES.

scholarly journals Special Structures of Sodium Layer Observed in the Daytime Over Beijing, China

2020 ◽  
Vol 237 ◽  
pp. 04005
Author(s):  
Yuan Xia ◽  
Guotao Yang ◽  
Jihong Wang ◽  
Xuewu Cheng ◽  
Faquan Li
Keyword(s):  
Signal To Noise Ratio ◽  
Lower Thermosphere ◽  
Meteor Radar ◽  
Diurnal Cycles ◽  
Dual Channel ◽  
Sodium Layer ◽  
Mesosphere And Lower Thermosphere ◽  
Beijing China ◽  
Observation Results ◽  
Mlt Region

In this paper the observation of sodium (Na) layer in mesosphere and lower thermosphere (MLT) region over complete diurnal cycles based on broadband Na lidar at Yanqing Station, Beijing, China (40.5°N,116°E ) was reported. Faraday filters with dual-channel design were used in the lidar receiving unit to suppress the strong background light in the daytime, which allow observation of Na layer with an acceptable signal-to-noise ratio (SNR) under sunlit condition. Several special structures of Na layer observed in the daytime was discussed. The simultaneous continuous observation of zonal wind by meteor radar was presented for comparison. These observation results can provide direct and reliable supports for the study of mesopause dynamics and solar effect on Na layer.

Global ionosonde and GPS radio occultation sporadic-E intensity and height comparison

2020 ◽  
Vol 199 ◽  
pp. 105200
Author(s):  
Joshua Y. Gooch ◽  
Jonah J. Colman ◽  
Omar A. Nava ◽  
Daniel J. Emmons
Keyword(s):  
Radio Occultation ◽  
Gps Radio Occultation ◽  
Sporadic E

Simulated GPS radio occultation signals from sporadic-E layers

2020 ◽  
Author(s):  
Daniel Emmons
Keyword(s):  
Radio Occultation ◽  
Plasma Frequency ◽  
Signal Amplitude ◽  
Scintillation Index ◽  
Gps Radio Occultation ◽  
Multiple Phase ◽  
Maximum Variance ◽  
Sporadic E Layers ◽  
Sporadic E ◽  
Screen Model

&lt;p&gt;A multiple phase screen model is used to simulate GPS radio occultation signals through varying sporadic-E layers.&amp;#160; The length, vertical extent, and plasma frequency of the sporadic-E layers are varied to analyze the effect on the signal received by a low earth orbiting satellite.&amp;#160; A nonlinear relationship between the maximum variance in the signal amplitude and the plasma frequency is observed.&amp;#160; For certain frequency ranges, the predictions match previous studies that have used the S&lt;sub&gt;4 &lt;/sub&gt;scintillation index to predict fbEs values. Additionally, the spectra of the signals are analyzed as a function of the different parameters providing an alternative approach for extracting sporadic-E parameters from GPS radio occultation measurements.&amp;#160;&lt;/p&gt;

scholarly journals Semidiurnal tidal signature in sporadic E occurrence rates derived from GPS radio occultation measurements at higher midlatitudes

2009 ◽  
Vol 27 (6) ◽  
pp. 2555-2563 ◽  
Author(s):  
C. Arras ◽  
C. Jacobi ◽  
J. Wickert
Keyword(s):  
Global Positioning System ◽  
Zonal Wind ◽  
Radio Occultation ◽  
Positioning System ◽  
Semidiurnal Tide ◽  
Meteor Radar ◽  
Global Positioning ◽  
Sporadic E Layer ◽  
Sporadic E ◽  
Wind Shears

Abstract. GPS (Global Positioning System) Radio occultation (RO) measurements from CHAMP, GRACE and FORMOSAT-3/COSMIC satellites at Northern Hemisphere midlatitides (50°–55° N) are analysed to obtain the diurnal variation of sporadic E layer occurrence frequency in 2006 and 2007. Interconnections with zonal wind shears measured by meteor radar at Collm (51.3° N, 13° E), Germany, are investigated. According to theory, maximum Es occurrence is expected when the zonal wind shear, which is mainly produced by the semidiurnal tide in midlatitudes, is negative. This is confirmed by the present measurements and analysis.

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