scholarly journals Sporadic E layer at mid-latitudes: average properties and influence of atmospheric tides

2014 ◽  
Vol 32 (11) ◽  
pp. 1427-1440 ◽  
Author(s):  
A. Pignalberi ◽  
M. Pezzopane ◽  
E. Zuccheretti
Keyword(s):  
Diurnal Variation ◽  
Atmospheric Tides ◽  
Fast Fourier Transform Analysis ◽  
June July August ◽  
Solar Cycle 24 ◽  
Sporadic E Layer ◽  
Sporadic E ◽  
Cycle 24 ◽  
June July

Abstract. This paper describes a study of the daily variability shown by the main characteristics of the sporadic E (Es) layer, that is the top frequency (ftEs) and the lowest virtual height (h'Es). The study is based on ionograms recorded by the Advanced Ionospheric Sounder by the Istituto Nazionale di Geofisica e Vulcanologia (AIS-INGV) ionosondes installed in the ionospheric stations at Rome (41.8° N, 12.5° E) and Gibilmanna (37.9° N, 14.0° E), Italy, during the summer (June, July, August and September) of 2013, a year falling in the ascending phase of solar cycle 24. The ftEs presents a diurnal variation characterized by two maxima, the first around noon is very well defined and the second in the evening/night is much less defined; the amplitude of both maxima decreases from June to September accompanied by a general decrease of the ftEs values which is more pronounced in the daytime than in the nighttime. h'Es also presents a diurnal variation characterized by two maxima but, unlike ftEs, these present the same amplitude which is independent from the considered month. Assuming that both ftEs and h'Es trends are influenced by the atmospheric tides, the height–time–intensity (HTI) technique was applied to deeply investigate how these waves control the Es dynamics. The HTI study, along with a fast Fourier transform analysis, show that a well-defined semidiurnal periodicity characterizes the Es layer dynamics most accurately in June and July, while in August and September the daytime semidiurnal periodicity becomes weaker and the role of the diurnal periodicity is consequently highlighted.

scholarly journals Mid Latitude Sporadic E-layer Variability during Ascending Phase of Solar Cycle 24

2017 ◽  
Vol 9 (1) ◽  
pp. 27-41
Author(s):  
R. Atulkar ◽  
P. A. Khan ◽  
A. A. Mansoori ◽  
P. K. Purohit
Keyword(s):  
Solar Cycle ◽  
Summer Season ◽  
High Solar Activity ◽  
Night Time ◽  
Solar Cycle 24 ◽  
E Region ◽  
Sporadic E Layer ◽  
Sporadic E ◽  
Cycle 24 ◽  
Short Time

The paper presents a comparative study of the ionospheric sporadic E layer parameters (fbEs, foEs, and h’Es) retrieved from ground based ionosonde at mid latitude station Yamagawa, Japan (31.20 N, 130.370 E) during the ascending phase of 24th solar cycle i.e. during January 2012 to December 2014. The comparison between the E-region parameters has been carried out on a diurnal, seasonal, annual and day night basis. The diurnal maxima of foEs, fbEs, and h’Es are generally higher during high solar activity. From the present study it is found that the highest values of fbEs are observed during the summer while the lowest values are observed during autumn at mid latitude. Similarly, the highest values of foEs are observed during the summer season while the lowest values are recorded in autumn season. However, the highest values of h’Es are recorded during the spring and the lowest values are recorded in autumn. The variability of Es during the day and night time is also studied. The sporadic E can form and disappear in a short time during either the day or night. We have also studied the percentage occurrence of sporadic E. The occurrence of Es changes from year to year.

scholarly journals MANIFESTATION OF SOLAR ACTIVITY AND DYNAMICS OF THE ATMOSPHERE IN VARIATIONS OF 577.7 AND 630.0 nm ATMOSPHERIC EMISSIONS IN SOLAR CYCLE 24

2020 ◽  
Vol 6 (3) ◽  
pp. 81-85
Author(s):  
Aleksandr Mikhalev
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Atomic Oxygen ◽  
Correlation Coefficients ◽  
Atmospheric Emissions ◽  
Annual Average ◽  
Solar Cycle 24 ◽  
Cycle 24 ◽  
Activity Indices

In the paper, variations of the night emission intensities in the 557.7 and 630 nm atomic oxygen lines [OI] in 2011–2019 have been analyzed. The analysis is based on data from the ISTP SB RAS Geophysical Observatory. The emission intensities are compared with atmospheric, solar, and geophysical parameters. High correlation coefficients between monthly average and annual average 630.0 nm emission intensities and solar activity indices F10.7 have been obtained. This suggests a key role of solar activity in variations of this emission in the period of interest. Variations of the 557.7 nm emission demonstrate to a greater extent the correlations of the stratospheric zonal wind (QBO.U30 index) with quasi-biennial oscillations. The causes of the weak dependence of the 557.7 nm emission intensity on solar activity in solar cycle 24 are discussed.

Study of Interplanetary CMEs/Shocks During Solar Cycle 24 Using Drag-Based Model: The Role of Solar Wind

Solar Physics ◽  
2019 ◽  
Vol 294 (4) ◽  
Author(s):  
K. Suresh ◽  
S. Prasanna Subramanian ◽  
A. Shanmugaraju ◽  
Bojan Vršnak ◽  
S. Umapathy
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Solar Cycle 24 ◽  
Cycle 24

scholarly journals Climatology of ionosphere over Nepal based on GPS TEC data from 2008 to 2018

2020 ◽  
Author(s):  
Drabindra Pandit ◽  
Basudev Ghimire ◽  
Christine Amory-Mazaudier ◽  
Rolland Fleury ◽  
Narayan Prasad Chapagain ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Diurnal Variation ◽  
Gps Tec ◽  
Maximum Value ◽  
Spring Equinox ◽  
Solar Cycle 24 ◽  
Cycle 24 ◽  
Almost All

Abstract. In this study, we analyze the climatology of ionosphere over Nepal based on GPS derived VTEC observed from four stations: KKN4 (27.80° N, 85.27° E), GRHI (27.95° N, 82.49° E), JMSM (28.80° N, 83.74° E), DLPA (28.98° N,82.81° E) during years 2008 to 2018. The study illustrates the diurnal, monthly, annual, seasonal and solar cycle variations of VTEC during all time of solar cycle 24. The results clearly revel the presence of equinoctial asymmetry in TEC which is more pronounced in maximum phases of solar cycle in year 2014 at KKN4 station followed by descending, ascending and minimum phases. Diurnal variation of VTEC showed short-lived day minimum which occurs between 5:00 to 6:00 LT at all the stations considered with diurnal peak between around 12:00 to 15:00 LT. The maximum value of TEC is observed during spring equinox than autumn equinox with a few anomalies. Similarly, winter anomalies are noticed during increasing and maximum phases of the solar cycle2011 and 2014 from almost all stations taken in the study.

scholarly journals Occurrence of blanketing E<sub>s</sub> layer (E<sub>sb</sub>) over the equatorial region during the peculiar minimum of solar cycle 24

2014 ◽  
Vol 32 (5) ◽  
pp. 553-562 ◽  
Author(s):  
V. Yadav ◽  
B. Kakad ◽  
C. K. Nayak ◽  
G. Surve ◽  
K. Emperumel
Keyword(s):  
Solar Cycle ◽  
Close Association ◽  
Equatorial Electrojet ◽  
Equatorial Region ◽  
Ambient Conditions ◽  
Equatorial Station ◽  
Vernal Equinox ◽  
Solar Cycle 24 ◽  
Sporadic E ◽  
Cycle 24

Abstract. A thin and highly dense sporadic E layer, which can occasionally block the upper ionospheric layers, is called blanketing sporadic E (Esb). We present the statistical seasonal local time occurrence pattern of Esb at equatorial station Tirunelveli (8.7° N, 77.8° E, dip latitude 0.7° N) during the extended minimum of solar cycle 24 (2007–2009). In spite of nearly the same average solar activity during both 2007 and 2009, considerable differences are noticed in the seasonal occurrence of Esb during this period. The percentage of Esb occurrence is found to be the highest during the summer solstice (&amp;geq; 50%) for both 2007 and 2009, which is in general accordance with the earlier studies. The occurrences of Esb during the vernal equinox (~ 33%) and January–February (~ 28%) are substantial in 2009 as compared to those during the same seasons in 2007. We find that, during winter (January–February), ~ 75% of Esb occurred during or just after the period of sudden stratospheric warming (SSW). We suggest that enhanced Esb occurrence during winter (January–February) and the vernal equinox of 2009 could be associated with SSW-driven changes in the E region ambient conditions. Furthermore, the close association of Esb with counter equatorial electrojet (CEEJ) suggested by earlier studies is re-examined carefully using the scenario of Esb occurrence on non-CEEJ days. Such an exercise is crucial as we are unaware whether the physical mechanisms driving Esb and CEEJ are linked or not. We find that, of all the seasons, the association of Esb and CEEJ is strongest during winter (November–December).

scholarly journals MANIFESTATION OF SOLAR ACTIVITY AND DYNAMICS OF THE ATMOSPHERE IN VARIATIONS OF 577.7 AND 630.0 nm ATMOSPHERIC EMISSIONS IN SOLAR CYCLE 24

2020 ◽  
Vol 6 (3) ◽  
pp. 99-104
Author(s):  
Aleksandr Mikhalev
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Atomic Oxygen ◽  
Correlation Coefficients ◽  
Atmospheric Emissions ◽  
Annual Average ◽  
Solar Cycle 24 ◽  
Cycle 24 ◽  
Activity Indices

In the paper, variations of the night emission intensities in the 557.7 and 630 nm atomic oxygen lines [OI] in 2011–2019 have been analyzed. The analysis is based on data from the ISTP SB RAS Geophysical Observatory. The emission intensities are compared with atmospheric, solar, and geophysical parameters. High correlation coefficients between monthly average and annual average 630.0 nm emission intensities and solar activity indices F10.7 have been obtained. This suggests a key role of solar activity in variations of this emission in the period of interest. Variations of the 557.7 nm emission demonstrate to a greater extent the correlations of the stratospheric zonal wind (QBO.U30 index) with quasi-biennial oscillations. The causes of the weak dependence of the 557.7 nm emission intensity on solar activity in solar cycle 24 are discussed.

scholarly journals The intensification of metallic layered phenomena above thunderstorms through the modulation of atmospheric tides

2018 ◽  
Author(s):  
Bingkun Yu ◽  
Xianghui Xue ◽  
Chengling Kuo ◽  
Gaopeng Lu ◽  
Xiankang Dou ◽  
...  
Keyword(s):  
Lower Ionosphere ◽  
Atmospheric Tides ◽  
Metallic Ions ◽  
Mesopause Region ◽  
Lidar Observation ◽  
Chemical Coupling ◽  
Sporadic E Layer ◽  
Sporadic E ◽  
Coupling Processes ◽  
Neutral Metal

Abstract. We present a multi-instrument experiment to study the effects of tropospheric thunderstorms on the mesopause region and the lower ionosphere. The sodium (Na) lidar observation and the ionospheric observation by two digital ionospheric sounders are used to study the variation of the neutral metal atoms and metallic ions above thunderstorms. The enhanced ionospheric sporadic E layer with a downward tidal phase is observed followed by a subsequent intensification of neutral Na density with an increase of 600 cm−3 in the mesosphere. In addition, the Na neutral chemistry and ion-molecule chemistry reactions are considered in the Na chemistry model to simulate the dynamical and chemical coupling processes in the mesosphere and ionosphere above thunderstorms. The enhanced Na layer in the simulation using the ionospheric observation as input is in agreement with the Na lidar observation. We find that the intensification of metallic layered phenomena above thunderstorms is associated with the atmospheric tides, as a result of the troposphere-mesosphere-ionosphere coupling.

scholarly journals The Possible Role of Turbopause on Sporadic‐E Layer Formation at Middle and Low Latitudes

Space Weather ◽  
2021 ◽  
Author(s):  
Qiong Tang ◽  
Chen Zhou ◽  
Huixin Liu ◽  
Yi Liu ◽  
Jiaqi Zhao ◽  
...  
Keyword(s):  
Layer Formation ◽  
Low Latitudes ◽  
Sporadic E Layer ◽  
Sporadic E

The role of electric fields in sporadic E layer formation over low latitudes under quiet and magnetic storm conditions

2014 ◽  
Vol 115-116 ◽  
pp. 95-105 ◽  
Author(s):  
M.A. Abdu ◽  
J.R. de Souza ◽  
I.S. Batista ◽  
A.M. Santos ◽  
J.H.A. Sobral ◽  
...  
Keyword(s):  
Magnetic Storm ◽  
Electric Fields ◽  
Layer Formation ◽  
Low Latitudes ◽  
Sporadic E Layer ◽  
Sporadic E

scholarly journals The role of total wind in the vertical dynamics of ions in the E-region at high latitudes

2005 ◽  
Vol 23 (4) ◽  
pp. 1191-1197
Author(s):  
M. Voiculescu ◽  
M. Ignat
Keyword(s):  
Electric Field ◽  
Diurnal Variation ◽  
High Latitudes ◽  
Ion Dynamics ◽  
Convergence Conditions ◽  
Sporadic E Layers ◽  
E Region ◽  
Sporadic E ◽  
Spatial Locations

Abstract. A seasonally dependent total neutral wind model obtained from experimental data is used to evaluate the diurnal variation of the vertical ion velocity in the E-region at a high-latitude location (Tromsø), for each season, in the presence of an electric field with a typical diurnal variation for quiet auroral days. The diurnal variation and spatial locations of the vertical convergence of ions are analyzed and the effect of the total wind on the occurrence of sporadic E-layers is inferred. The results show that the structure of the wind is an important factor in controlling the vertical velocities of ions, favoring or hindering the sporadic E-layer formation. The ion convergence conditions are improved when the permanent wind is removed, which suggests that sporadic E-layers occur when the mean wind has small values, thus allowing the electric field and/or the semidiurnal tide to control the ion dynamics. We conclude that for quiet days the formation of the sporadic layers is initiated by the electric field, while their evolution and dynamics is controlled by the wind. We also find that the seasonal variation of the Es layers cannot be related to the seasonally dependent wind shear. Although we focus on sporadic E-layers, our results can be used in the analysis of other processes involving the vertical dynamics of ions in the E-region at high latitudes.

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