Characteristics of the midlatitude maximum in the O I 5577 Å airglow emission rate

1979 ◽  
Vol 57 (7) ◽  
pp. 926-932 ◽  
Author(s):  
L. L. Cogger ◽  
R. Khaneja
Keyword(s):  
Atomic Oxygen ◽  
Large Scale ◽  
Emission Rate ◽  
Lower Thermosphere ◽  
Temporal Variations ◽  
Airglow Emission ◽  
The Earth ◽  
Night Side ◽  
Summer Hemisphere ◽  
Winter Hemisphere

An analysis of O I 5577 Å airglow limbs observed on the night side of the earth by a scanning photometer on board the ISIS 2 satellite has provided sufficient data to establish the existence of a prominent midlatitude maximum in the airglow emission rate. The maximum occurs near 40° latitude in the winter and near 30° in the summer, with the winter hemisphere maximum a factor of 1.6 larger than the summer hemisphere maximum. The emission rate varies by a factor of about 4 during the year with the maximum occurring several weeks after the autumn equinox. It is suggested that these spatial and temporal variations are due to the distribution of atomic oxygen which, in turn, is influenced by large scale dynamical processes in the lower thermosphere.

scholarly journals Large-Scale Waves in the Mesosphere and Lower Thermosphere Observed by SABER

2005 ◽  
Vol 62 (12) ◽  
pp. 4384-4399 ◽  
Author(s):  
Rolando R. Garcia ◽  
Ruth Lieberman ◽  
James M. Russell ◽  
Martin G. Mlynczak
Keyword(s):  
Large Scale ◽  
Middle Atmosphere ◽  
Lower Thermosphere ◽  
Normal Modes ◽  
Zonal Winds ◽  
Broadband Emission ◽  
Summer Hemisphere ◽  
Mean Structure ◽  
Mesosphere And Lower Thermosphere ◽  
The Tropics

Abstract Observations made by the Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) instrument on board NASA’s Thermosphere–Ionosphere–Mesosphere Energetics and Dynamics (TIMED) satellite have been processed using Salby’s fast Fourier synoptic mapping (FFSM) algorithm. The mapped data provide a first synoptic look at the mean structure and traveling waves of the mesosphere and lower thermosphere (MLT) since the launch of the TIMED satellite in December 2001. The results show the presence of various wave modes in the MLT, which reach largest amplitude above the mesopause and include Kelvin and Rossby–gravity waves, eastward-propagating diurnal oscillations (“non-sun-synchronous tides”), and a set of quasi-normal modes associated with the so-called 2-day wave. The latter exhibits marked seasonal variability, attaining large amplitudes during the solstices and all but disappearing at the equinoxes. SABER data also show a strong quasi-stationary Rossby wave signal throughout the middle atmosphere of the winter hemisphere; the signal extends into the Tropics and even into the summer hemisphere in the MLT, suggesting ducting by westerly background zonal winds. At certain times of the year, the 5-day Rossby normal mode and the 4-day wave associated with instability of the polar night jet are also prominent in SABER data.

Nocturnal and Semiannual Variations of the Intensity of 5577 Å Emission of Atomic Oxygen

1972 ◽  
Vol 50 (14) ◽  
pp. 1623-1629
Author(s):  
S. R. Pal ◽  
G. M. Shah
Keyword(s):  
Seasonal Variation ◽  
Atomic Oxygen ◽  
Large Scale ◽  
Lower Thermosphere ◽  
Semiannual Variation

The observed features of 5577 Å emission in night glow at Mt. Abu (India) have been presented. The midnight maximum of 5577 Å emission has been associated with the large scale circulations in the lower thermosphere. The seasonal variation of this emission is discussed in relation with the semiannual variation in the thermospheric heating.

Rocket observations of atomic oxygen density and airglow emission rate in the WAVE2000 campaign

2003 ◽  
Vol 65 (16-18) ◽  
pp. 1349-1360 ◽  
Author(s):  
N. Iwagami ◽  
T. Shibaki ◽  
T. Suzuki ◽  
H. Sekiguchi ◽  
N. Takegawa ◽  
...  
Keyword(s):  
Atomic Oxygen ◽  
Emission Rate ◽  
Airglow Emission

scholarly journals The emission of oxygen green line and density of O atom determined by using ISUAL and SABER measurements

2012 ◽  
Vol 30 (4) ◽  
pp. 695-701 ◽  
Author(s):  
H. Gao ◽  
J.-B. Nee ◽  
J. Xu
Keyword(s):  
Atomic Oxygen ◽  
Emission Rate ◽  
Temperature Structure ◽  
Emission Rates ◽  
Green Line ◽  
Atmospheric Parameters ◽  
Density Distributions ◽  
Broadband Emission ◽  
The Earth ◽  
Made In

Abstract. Emissions of the 557.7 nm green line airglow observed by the ISUAL (Imager of Sprites and Upper Atmospheric Lightning) instrument on board the FORMOSAT-2 satellite in May and November 2008 are studied here to derive the density distributions of the atomic oxygen by using atmospheric parameters from MSISE-00 model and TIMED (Thermosphere Ionosphere Mesosphere Energetics and Dynamics)/SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) measurements. The May observations were made in 10 days from a fixed orbit of longitude (100° E) with the results showing emission rate and O atom density both peaked at heights of about 90 km over 10° to 20° latitudes in the Northern Hemisphere (NH). In the Southern Hemisphere (SH), the emission rate and density of O atom are both low compared with those in NH. In November, the observations were made as the satellite traveled over all 14 orbits around the earth, covering all longitudes and latitudes of 25° S–45° N. Strong peaks of emission rates and O atoms are found at heights of about 95 km in the mid-latitudes in both hemispheres. In the equator, the airglow layer has a weaker emission rate but with higher altitude compared with those of mid-latitudes. In the lower and upper mesosphere at heights below 85 km and above 105 km, there are more O atoms in the equatorial regions than in the mid-latitudes. And there is a good correlation between the O atom and the temperature structure. A comparison with O atom distribution derived from OH airglow observed by TIMED/SABER at about the same time shows similar results.

Temporal and latitudinal 5577 Å airglow variations

1981 ◽  
Vol 59 (10) ◽  
pp. 1296-1307 ◽  
Author(s):  
L. L. Cogger ◽  
R. D. Elphinstone ◽  
J. S. Murphree
Keyword(s):  
Large Scale ◽  
Emission Rate ◽  
The Other ◽  
Local Production ◽  
Meridional Transport ◽  
Mean Intensity ◽  
Global Correlation ◽  
The Mean ◽  
Temporal And Spatial ◽  
Winter Hemisphere

From 32 000 [O1] 5577 Å airglow limb observations made between April 1971 and December 1972 from the ISIS-2 satellite, the major temporal and spatial night airglow features have been identified. Two methods of analysis were employed: harmonic fitting and global correlation. Airglow emission rate maxima occurred in mid-October and mid-April at all latitudes. The intensities peaked near 35° in the winter and near 25° in the summer and showed a symmetry with latitude centred about 5° in the winter hemisphere. The mean intensity at mid-latitudes was 175 R and near the equator was 120 R. From the global correlation analysis it was shown that there are two distinct contributions to the temporal and spatial airglow variations: one is from local production which dominates during the post-solstice period, and the other is from large scale meridional transport which dominates during the post-equinox period.

scholarly journals Connection between the length of day and wind measurements in the mesosphere and lower thermosphere at mid- and high latitudes

2019 ◽  
Vol 37 (1) ◽  
pp. 1-14
Author(s):  
Sven Wilhelm ◽  
Gunter Stober ◽  
Vivien Matthias ◽  
Christoph Jacobi ◽  
Damian J. Murphy
Keyword(s):  
Solar Radiation ◽  
Zonal Wind ◽  
Large Scale ◽  
Lower Thermosphere ◽  
Earth’S Rotation ◽  
The Sun ◽  
Earth's Rotation ◽  
The Earth ◽  
The Mean ◽  
Mesosphere And Lower Thermosphere

Abstract. This work presents a connection between the density variation within the mesosphere and lower thermosphere (MLT) and changes in the intensity of solar radiation. On a seasonal timescale, these changes take place due to the revolution of the Earth around the Sun. While the Earth, during the northern-hemispheric (NH) winter, is closer to the Sun, the upper mesosphere expands due to an increased radiation intensity, which results in changes in density at these heights. These density variations, i.e., a vertical redistribution of atmospheric mass, have an effect on the rotation rate of Earth's upper atmosphere owing to angular momentum conservation. In order to test this effect, we applied a theoretical model, which shows a decrease in the atmospheric rotation speed of about ∼4 m s−1 at a latitude of 45∘ in the case of a density change of 1 % between 70 and 100 km. To support this statement, we compare the wind variability obtained from meteor radar (MR) and Microwave Limb Sounder (MLS) satellite observations with fluctuations in the length of a day (LOD). Changes in the LOD on timescales of a year and less are primarily driven by tropospheric large-scale geophysical processes and their impact on the Earth's rotation. A global increase in lower-atmospheric eastward-directed winds leads, due to friction with the Earth's surface, to an acceleration of the Earth's rotation by up to a few milliseconds per rotation. The LOD shows an increase during northern winter and decreases during summer, which corresponds to changes in the MLT density due to the Earth–Sun movement. Within the MLT the mean zonal wind shows similar fluctuations to the LOD on annual scales as well as longer time series, which are connected to the seasonal wind regime as well as to density changes excited by variations in the solar radiation. A direct correlation between the local measured winds and the LOD on shorter timescales cannot clearly be identified, due to stronger influences of other natural oscillations on the wind. Further, we show that, even after removing the seasonal and 11-year solar cycle variations, the mean zonal wind and the LOD are connected by analyzing long-term tendencies for the years 2005–2016.

scholarly journals A combined neural network- and physics-based approach for modeling the plasmasphere dynamics

2020 ◽  
Author(s):  
Irina Zhelavskaya ◽  
Nikita Aseev ◽  
Yuri Shprits ◽  
Maria Spasojevic
Keyword(s):  
Neural Network ◽  
Plasma Density ◽  
Large Scale ◽  
Geomagnetic Storms ◽  
Feedforward Neural Networks ◽  
Particle Interactions ◽  
Training Set ◽  
The Earth ◽  
Night Side ◽  
Time Periods

<p>Plasmasphere is a torus of cold plasma surrounding the Earth and is a very dynamic region. Its dynamics is driven by space weather. Having an accurate model of the plasmasphere is very important for wave-particle interactions and radiation belt modeling. In recent years, feedforward neural networks (NNs) have been successfully applied to reconstruct the global plasmasphere dynamics in the equatorial plane [<em>Bortnik et al</em>., 2016, <em>Zhelavskaya et al</em>., 2017, <em>Chu et al</em>., 2017]. These neural network-based models have been able to capture the large-scale dynamics of the plasmasphere, such as plume formation and the erosion of the plasmasphere on the night side. However, NNs have one limitation. When data is abundant, NNs perform really well. In contrast, when the coverage is limited or non-existent, as during geomagnetic storms, NNs do not perform well. The reason is that since these data are underrepresented in the training set, NNs cannot learn from the limited number of examples. This limitation can be overcome by employing physics-based modeling during such intervals. Physics-based models perform stably during high geomagnetic activity time periods if initialized and configured correctly. In this work, we show the combined approach to model the global plasmasphere dynamics that utilizes advantages of both neural network- and physics-based modeling and produces accurate global plasma density reconstruction during extreme events. We present examples of the global plasma density reconstruction for a number of extreme geomagnetic storms that occured in the past including the Halloween storm in 2003. We validate the global density reconstructions by comparing them to the IMAGE EUV images of the He+ particles distribution in the Earth’s plasmasphere for the same time periods.</p>

scholarly journals Connection between the length of day and wind measurements in the mesosphere and lower thermosphere at mid and high latitudes

2018 ◽  
Author(s):  
Sven Wilhelm ◽  
Gunter Stober ◽  
Vivien Matthias ◽  
Christoph Jacobi ◽  
Damian J. Murphy
Keyword(s):  
Large Scale ◽  
Lower Thermosphere ◽  
Momentum Conservation ◽  
Density Variation ◽  
Day Length ◽  
The Sun ◽  
The Earth ◽  
Geophysical Processes ◽  
Mesosphere And Lower Thermosphere ◽  
The Difference

Abstract. This work presents a connection between the density variation within the mesosphere and lower thermosphere (MLT) and changes in the intensity of the solar radiation. On a seasonal time scale, these changes take place due to the revolution of the Earth around the Sun. While the Earth, during the northern hemispheric winter, is closer to the Sun, the upper mesosphere expands due to an increased radiation intensity, which results in changes in density at these heights. Theses density variations, i.e. a vertical redistribution of atmospheric mass, have an effect on the rotation rate of Earth's upper atmosphere owing to angular momentum conservation. In order to test this effect we applied a theoretical model, which shows a decrease of the atmospheric rotation speed of about ~ 4 m/s in the case of a density change of 1 % between 70 and 100 km. To support this statement, we compare the wind variability obtained from meteor radar (MR) and MLS satellite observations with fluctuations in the length of a day (LOD). The LOD is defined as the difference between the astronomical determined time the Earth needs for a full turnaround and a standard day length of 86.400 seconds. Changes in the LOD on time scales of a year and less are primarily driven by tropospheric large scale geophysical processes. A global increase of eastward directed winds leads, due to friction with the Earth's surface, to an acceleration of the Earth's rotation by up to a few milliseconds per rotation. The LOD shows an increase during northern winter and decrease during summer, which corresponds to changes in the MLT density due to the Earth – Sun movement. Further, we show that, even after removing the seasonal and solar cycle variations, the wind and the LOD are connected, by analyzing trends for the years 2005–2016.

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