Thermospheric Dynamics in Quiet and Disturbed Conditions

2017 ◽  
Vol 13 (S335) ◽  
pp. 151-158
Author(s):  
Aziza Bounhir ◽  
Zouhair Benkhaldoun ◽  
Jonathan J. Makela ◽  
Mohamed Kaab ◽  
Brian Harding ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Seasonal Effect ◽  
Quiet Time ◽  
Seasonal Behavior ◽  
Wind Pattern ◽  
Fabry Perot ◽  
Thermospheric Winds ◽  
Thermospheric Dynamics ◽  
Diurnal Tides

AbstractThis paper presents the thermospheric winds and temperature properties measured with a Fabry-Pérot interferometer (FPI) over Oukaimeden observatory (31.2°N, 7.8°W, 22.8°N magnetic) in Morocco. After Three years of successful functioning from 2014 to 2017, we can address the seasonal behavior of the temperature and the winds (vertical, zonal and meridional). The dependence of the thermospheric winds and temperature on the solar cycle is also presented. The day-to-day variations of the quiet time wind pattern exhibits the importance of other type of waves superposed to the main diurnal tides. The storm time wind and temperature exhibits also a variety of ways to react to the storm. However, there is seasonal effect to the storm that will be illustrated in this paper. The signature of the MTM phenomenon is also present in the winds and temperature in geomagnetically quiet and disturbed nights. The occurrence of this phenomenon over the studied area is also addressed.

The seasonal behavior of high-latitude thermospheric winds and ion velocities observed over one solar cycle

1996 ◽  
Vol 101 (A7) ◽  
pp. 15701-15711 ◽  
Author(s):  
A. L. Aruliah ◽  
A. D. Farmer ◽  
D. Rees ◽  
U. Brändström
Keyword(s):  
Solar Cycle ◽  
High Latitude ◽  
Seasonal Behavior ◽  
Thermospheric Winds

scholarly journals Thermospheric vertical winds in the auroral oval/polar cap region

2002 ◽  
Vol 20 (12) ◽  
pp. 1987-2001 ◽  
Author(s):  
P. A. Greet ◽  
J. L. Innis ◽  
P. L. Dyson
Keyword(s):  
Auroral Oval ◽  
Atmospheric Dynamics ◽  
Polar Cap ◽  
Frequency Distributions ◽  
Meteorology And Atmospheric Dynamics ◽  
Fabry Perot ◽  
Thermospheric Winds ◽  
Thermospheric Dynamics ◽  
Vertical Winds ◽  
Range Of Variation

Abstract. Thermospheric mean vertical winds from high-resolution Fabry-Perot Spectrometer observations of the l630 nm emission (from ~ 240 km altitude), over a four year interval 1997–2000, from Mawson (67.6° S, 62.9° E, Inv 70.5° S) and Davis (68.6° S, 78.0° E, Inv 74.6° S) are presented. Combining the four years of data shows Mawson mean hourly vertical winds vary between -10 ms-1 and +4 ms-1, while Davis mean hourly vertical winds vary between - 0 ms-1 and +10 ms-1. Mean hourly vertical winds from Mawson show little change with Kp, while at Davis the range of variation increases with increasing geomagnetic activity. Histograms of frequency distributions of such winds, and their variations with Kp and l630 nm emission intensity, are presented and discussed. Variations in mean hourly thermospheric winds and l630 nm emission intensities show at least three significant associations between mean vertical winds and the auroral oval. Mean vertical winds within the auroral oval are smaller than those outside the oval, particularly those in the polar cap. A downward wind associated with entry of the observing region into the auroral oval can be seen in both Mawson and Davis hourly mean vertical winds. Large vertical winds are seen poleward of the auroral oval/polar cap boundary, most significantly upward winds occur within ± 2 hr of magnetic midnight. Under moderately quiet geomagnetic conditions Davis passes through the auroral oval into the polar cap in the evening, but at higher Kp it passes into the polar cap earlier and larger, and more sustained mean vertical winds are observed.Key words. Meteorology and atmospheric dynamics (thermospheric dynamics)

scholarly journals Equatorial and low latitude thermospheric winds: Measured quiet time variations with season and solar flux from 1980 to 1990

1999 ◽  
Vol 104 (A8) ◽  
pp. 17091-17106 ◽  
Author(s):  
M. A. Biondi ◽  
S. Y. Sazykin ◽  
B. G. Fejer ◽  
J. W. Meriwether ◽  
C. G. Fesen
Keyword(s):  
Solar Flux ◽  
Quiet Time ◽  
Low Latitude ◽  
Time Variations ◽  
Thermospheric Winds

Seasonal behavior of H component during solar cycle 24

2021 ◽  
Author(s):  
Yasmina Bouderba ◽  
Ener Aganou ◽  
Abdenaceur Lemgharbi
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Horizontal Component ◽  
Low Latitude ◽  
Seasonal Behavior ◽  
The Earth ◽  
Earth Magnetic Field ◽  
Solar Cycle 24 ◽  
Minimum Solar Activity ◽  
Cycle 24

<p>In this work we will show the behavior of the horizontal component H of the Earth Magnetic Field (EMF) along the seasons during the period of solar cycle 24 lasting from 2009 to 2019. By means of  continuous measurements of geomagnetic components (X, Y) of the EMF, we compute the horizontal component H at the Earth’s surface. The data are recorded with a time resolution of one minute at Tamanrasset observatory in Algeria at the geographical coordinates of 22.79° North and 5.53° East. These data are available from the INTERMAGNET network. We find that the variation in amplitude of the hourly average of H component at low latitude changes from a season to another and it is greater at the maximum solar activity than at the minimum solar activity.</p><p><strong>Keywords:</strong> Solar cycle 24, Season, Horizontal component H. </p>

scholarly journals High time resolution measurements of the thermosphere from Fabry-Perot Interferometer measurements of atomic oxygen

2007 ◽  
Vol 25 (6) ◽  
pp. 1269-1278 ◽  
Author(s):  
E. A. K. Ford ◽  
A. L. Aruliah ◽  
E. M. Griffin ◽  
I. McWhirter
Keyword(s):  
Gravity Waves ◽  
Time Resolution ◽  
Lower Thermosphere ◽  
Line Emission ◽  
Auroral Oval ◽  
High Time ◽  
High Time Resolution ◽  
Short Period ◽  
Fabry Perot ◽  
Thermospheric Winds

Abstract. Recent advances in the performance of CCD detectors have enabled a high time resolution study of the high latitude upper thermosphere with Fabry-Perot Interferometers (FPIs) to be performed. 10-s integration times were used during a campaign in April 2004 on an FPI located in northern Sweden in the auroral oval. The FPI is used to study the thermosphere by measuring the oxygen red line emission at 630.0 nm, which emits at an altitude of approximately 240 km. Previous time resolutions have been 4 min at best, due to the cycle of look directions normally observed. By using 10 s rather than 40 s integration times, and by limiting the number of full cycles in a night, high resolution measurements down to 15 s were achievable. This has allowed the maximum variability of the thermospheric winds and temperatures, and 630.0 nm emission intensities, at approximately 240 km, to be determined as a few minutes. This is a significantly greater variability than the often assumed value of 1 h or more. A Lomb-Scargle analysis of this data has shown evidence of gravity wave activity with waves with short periods. Gravity waves are an important feature of mesosphere-lower thermosphere (MLT) dynamics, observed using many techniques and providing an important mechanism for energy transfer between atmospheric regions. At high latitudes gravity waves may be generated in-situ by localised auroral activity. Short period waves were detected in all four clear nights when this experiment was performed, in 630.0 nm intensities and thermospheric winds and temperatures. Waves with many periodicities were observed, from periods of several hours, down to 14 min. These waves were seen in all parameters over several nights, implying that this variability is a typical property of the thermosphere.

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

2018 ◽  
Vol 123 (9) ◽  
pp. 7789-7805 ◽  
Author(s):  
Guoying Jiang ◽  
Jiyao Xu ◽  
Wenbin Wang ◽  
Wei Yuan ◽  
Shunrong Zhang ◽  
...  
Keyword(s):  
Quiet Time ◽  
Model Calculations ◽  
Thermospheric Winds

scholarly journals COMPOSITION AND SPECTRAL PROPERTIES OF THE 1 AU QUIET-TIME SUPRATHERMAL ION POPULATION DURING SOLAR CYCLE 23

2009 ◽  
Vol 693 (2) ◽  
pp. 1588-1600 ◽  
Author(s):  
M. A. Dayeh ◽  
M. I. Desai ◽  
J. R. Dwyer ◽  
H. K. Rassoul ◽  
G. M. Mason ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Spectral Properties ◽  
Quiet Time ◽  
Solar Cycle 23

SOLAR ENERGETIC PARTICLES

2005 ◽  
Vol 20 (29) ◽  
pp. 6634-6641
Author(s):  
PÉTER KIRÁLY
Keyword(s):  
Solar Cycle ◽  
Interplanetary Space ◽  
Energetic Particles ◽  
Vital Role ◽  
Solar Energetic Particles ◽  
Interstellar Space ◽  
Interplanetary Shocks ◽  
Quiet Time ◽  
Solar Origin ◽  
Suprathermal Particles

Energetic particles recorded in the Earth environment and in interplanetary space have a multitude of origins, i.e. acceleration and propagation histories. At early days practically all sufficiently energetic particles were considered to have come either from solar flares or from interstellar space. Later on, co-rotating interplanetary shocks, the termination shock of the supersonic solar wind, planetary bow shocks and magnetospheres, and also coronal mass ejections (CME) were recognized as energetic particle sources. It was also recognized that less energetic (suprathermal) particles of solar origin and pick-up ions have also a vital role in giving rise to energetic particles in interplanetary disturbances. The meaning of the term "solar energetic particles" (SEP) is now somewhat vague, but essentially it refers to particles produced in disturbances fairly directly related to solar processes. Variation of intensity fluctuations with energy and with the phase of the solar cycle will be discussed. Particular attention will be given to extremes of time variation, i.e. to very quiet periods and to large events. While quiet-time fluxes are expected to shed light on some basic coronal processes, large events dominate the fluctuation characteristics of cumulated fluence, and the change of that fluctuation with energy and with the phase of the solar cycle may also provide important clues. Mainly ISEE-3 and long-term IMP-8 data will be invoked. Energetic and suprathermal particles that may never escape into interplanetary space may play an important part in heating the corona of the sun.

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