Upper atmosphere neutral temperature profiles in the auroral zone 1968–1970

1971 ◽  
Vol 19 (2) ◽  
pp. 233-241 ◽  
Author(s):  
D. Rees
Keyword(s):  
Auroral Zone ◽  
Upper Atmosphere ◽  
Temperature Profiles ◽  
Neutral Temperature

scholarly journals Mesopause region temperature variability and its trend in southern Brazil

2018 ◽  
Vol 36 (2) ◽  
pp. 301-310 ◽  
Author(s):  
Mateus S. Venturini ◽  
José V. Bageston ◽  
Nattan R. Caetano ◽  
Lucas V. Peres ◽  
Hassan Bencherif ◽  
...  
Keyword(s):  
New Technologies ◽  
Geographical Area ◽  
Lower Thermosphere ◽  
Temperature Variability ◽  
Upper Atmosphere ◽  
Atmospheric Composition ◽  
Temperature Profiles ◽  
Time Duration ◽  
First Case ◽  
Santa Maria

Abstract. Nowadays, the study of the upper atmosphere is increasing, mostly because of the need to understand the patterns of Earth's atmosphere. Since studies on global warming have become very important for the development of new technologies, understanding all regions of the atmosphere becomes an unavoidable task. In this paper, we aim to analyze the temperature variability and its trend in the mesosphere and lower thermosphere (MLT) region during a period of 12 years (from 2003 to 2014). For this purpose, three different heights, i.e., 85, 90 and 95 km, were focused on in order to investigate the upper atmosphere, and a geographic region different to other studies was chosen, in the southern region of Brazil, centered in the city of Santa Maria, RS (29∘41′02′′ S; 53∘48′25′′ W). In order to reach the objectives of this work, temperature data from the SABER instrument (Sounding of the Atmosphere using Broadband Emission Radiometry), aboard NASA's Thermosphere Ionosphere Mesosphere Energetics Dynamics (TIMED) satellite, were used. Finally, two cases were studied related to distinct grids of latitude/longitude used to obtain the mean temperature profiles. The first case considered a grid of 20∘ × 20∘ lat/long, centered in Santa Maria, RS, Brazil. In the second case, the region was reduced to a size of 15∘ × 15∘ in order to compare the results and discuss the two cases in terms of differences or similarities in temperature trends. Observations show that the size of the geographical area used for the average temperature profiles can influence the results of variability and trend of the temperature. In addition, reducing the time duration of analyses from 24 to 12 h a day also influences the trend significantly. For the smaller geographical region (15∘ × 15∘) and the 12 h daily time window (09:00–21:00 UT) it was found that the main contributions for the temperature variability at the three heights were the annual and semi-annual cycles and the solar flux influence. A smaller trend (−0.02 ± 0.16 % decade−1) was found at 90 km height and small positive trends (0.58 ± 0.26 % and 0.41 ± 0.19 % decade−1) were found at altitudes of 85 and 95 km, respectively.. Keywords. Atmospheric composition and structure (middle atmosphere – composition and chemistry; pressure, density, and temperature) – meteorology and atmospheric dynamics (climatology)

scholarly journals Spiral structures and regularities in magnetic field variations and auroras

2012 ◽  
Vol 3 (1) ◽  
pp. 1-31 ◽  
Author(s):  
Y. I. Feldstein ◽  
L. I. Gromova ◽  
M. Förster ◽  
A. E. Levitin
Keyword(s):  
Magnetic Field ◽  
Geomagnetic Field ◽  
Current System ◽  
Temporal Distribution ◽  
Auroral Oval ◽  
Auroral Zone ◽  
Upper Atmosphere ◽  
Polar Coordinates ◽  
Magnetospheric Substorms ◽  
Field Lines

Abstract. The conception of spiral shaped precipitation regions, where solar corpuscles penetrate the upper atmosphere, was introduced into geophysics by C. Störmer and K. Birkeland at the beginning of the last century. Later, in the course of the XX-th century, spiral distributions were disclosed and studied in various geophysical phenomena. Most attention was devoted to spiral shapes in the analysis of regularities pertaining to the geomagnetic activity and auroras. We review the historical succession of perceptions about the number and positions of spiral shapes, that characterize the spatial-temporal distribution of magnetic disturbances. We describe the processes in the upper atmosphere, which are responsible for the appearance of spiral patterns. We considered the zones of maximal aurora frequency and of maximal particle precipitation intensity, as offered in the literature, in their connection with the spirals. We discuss the current system model, that is closely related to the spirals and that appears to be the source for geomagnetic field variations during magnetospheric substorms and storms. The currents in ionosphere and magnetosphere constitute together with field-aligned (along the geomagnetic field lines) currents (FACs) a common 3-D current system. At ionospheric heights, the westward and eastward electrojets represent characteristic elements of the current system. The westward electrojet covers the longitudinal range from the morning to the evening hours, while the eastward electrojet ranges from afternoon to near-midnight hours. The polar electrojet is positioned in the dayside sector at cusp latitudes. All these electrojets map along the magnetic field lines to certain plasma structures in the near-Earth space. The first spiral distribution of auroras was found based on observations in Antarctica for the nighttime-evening sector (N-spiral), and later in the nighttime-evening (N-spiral) and morning (M-spiral) sectors both in the Northern and Southern Hemispheres. The N- and M-spirals drawn in polar coordinates form an oval, along which one observes most often auroras in the zenith together with a westward electrojet. The nature of spiral distributions in geomagnetic field variations was unabmibuously interpreted after the discovery of the spiral's existence in the auroras had been established and this caused a change from the paradigm of the auroral zone to the paradigm of the auroral oval. Zenith forms of auroras are found within the boundaries of the auroral oval. The oval is therefore the region of most frequent precipitations of corpuscular fluxes with auroral energy, where anomalous geophysical phenomena occur most often and with maximum intensity. S. Chapman and L. Harang identified the existence of a discontinuity at auroral zone latitudes (Φ ∼ 67°) around midnight between the westward and eastward electrojets, that is now known as the Harang discontinuity. After the discovery of the auroral oval and the position of the westward electrojet along the oval, it turned out, that there is no discontinuity at a fixed latitude between the opposite electrojets, but rather a gap, the latitude of which varies smoothly between Φ ∼ 67° at midnight and Φ ∼ 73° at 20:00 MLT. In this respect the term ''Harang discontinuity'' represents no intrinsic phenomenon, because the westward electrojet does not experience any disruption in the midnight sector but continues without breaks from dawn to dusk hours.

scholarly journals Impact of Energetic Electron Precipitation on the Upper Atmosphere: Nitric Monoxide

2017 ◽  
Vol 11 (1) ◽  
pp. 88-104 ◽  
Author(s):  
A. Vialatte ◽  
M. Barthélemy ◽  
J. Lilensten
Keyword(s):  
Nitric Oxide ◽  
Solar Activity ◽  
Energetic Electron ◽  
Auroral Zone ◽  
Upper Atmosphere ◽  
Electron Precipitation ◽  
No Production ◽  
Neutral Atmosphere ◽  
Heating Rates ◽  
Production Rates

Background:Nitric oxide concentration in the upper atmosphere is known to be highly dependent on the solar activity. It can be transported to the stratosphere by the atmospheric circulation. In the stratosphere it is responsible for the destruction of ozone and consequently stratospheric heating rates are affected. This is one of the mechanisms by which solar variability has been suspected to drive variability in the energetic budget of the Earth climate. Therefore, it is essential to know every physical and chemical processes leading to the production or to a destruction of nitric oxide.Aim:The aim of this work is to calculate the production rate of NO+and some of the NO electronic states created by electron impact on NO at night in the auroral zone using an electron transport code.Conclusion:We study this variability under different precipitation conditions and taking into account the variability of the neutral atmosphere with the geomagnetic and solar activity. We find that the energetic electron precipitation has a very small effect on the absolute value of the NO+and NO* production rates. In order to help further research to consider the effect of NO+and NO*, we provide a table of all the production rates in a medium solar and geomagnetic activity case.

A discussion on D and E region winds over Europe - Winds and temperatures in the auroral zone and their relations to geomagnetic activity

1972 ◽  
Vol 271 (1217) ◽  
pp. 563-575 ◽  
Keyword(s):  
Electric Fields ◽  
Geomagnetic Activity ◽  
Atmospheric Temperature ◽  
Global Scale ◽  
Auroral Zone ◽  
Neutral Wind ◽  
Wind Speeds ◽  
A Value ◽  
Neutral Temperature ◽  
E Region

Measurements of neutral wind velocity and neutral atmospheric temperature above 90 km in the auroral zone have shown distinct correlations with local and global geomagnetic activity respectively. Individual magnetic substorms have been observed to produce neutral wind speeds of over 500 m -s at 130 to 150 km. Ion-neutral particle drag is a likely accelerating mechanism with enhanced meridional electric fields and electron density. These wind disturbances can theoretically propagate to mid-latitudes in the night hemisphere and produce anomalously high neutral wind speeds on a global scale especia y during geomagnetic storm conditions. Such anomalously high wind speeds have been observed on several occasions at mid-latitude sites during disturbed conditions. Neutral temperature values in the auroral zone show a positive correlation with geomagnetic activity with a relatively slow decay following heating. The temperature dependence upon the G9 index (which is representative of jQ) is altitude dependent, increasing from a value near to the global mean (25 K per unit C9) at 140 km to an enhanced value of 50 K per unit G9 at 165 km. Auroral zone measurements are only possible during the period September to April inclusive; however, in this period, during quiet geomagnetic conditions and between 130 and 200 km, there is a decrease of neutral temperature of 150±50K between mid-latitudes (30° N) and the aurora zone (70° N) which is significantly greater than the polewards decrease of temperature predicted from satellite drag density data.

scholarly journals Sensitivity of Upper Atmosphere to Different Characteristics of Flow Bursts in the Auroral Zone

2021 ◽  
Author(s):  
Cheng Sheng ◽  
Yue Deng ◽  
Christine Gabrielse ◽  
Larry R. Lyons ◽  
Yukitoshi Nishimura ◽  
...  
Keyword(s):  
Auroral Zone ◽  
Upper Atmosphere ◽  
Different Characteristics

scholarly journals Data Analysis of Upper Atmosphere Temperature Detected by Sounding Rockets in China

2017 ◽  
Vol 34 (3) ◽  
pp. 555-565 ◽  
Author(s):  
J. W. Li ◽  
Z. Sheng ◽  
Z. Q. Fan ◽  
S. D. Zhou ◽  
W. L. Shi
Keyword(s):  
Temperature Data ◽  
Upper Atmosphere ◽  
Statistical Characteristics ◽  
Sounding Rocket ◽  
Temperature Profiles ◽  
Sounding Rockets ◽  
Temperature Changes ◽  
Broadband Emission ◽  
Atmosphere Temperature ◽  
The Mean

AbstractSounding rockets launched by China have collected data on the upper atmosphere for nearly 50 years. In this work, the data accuracy and variable characteristics of upper atmosphere temperature data, gathered at heights of 20–60 km over Jiuquan, China, during 1974–2014, were analyzed. The relative accuracy of sounding rocket temperature data was determined by comparing the data with Mass Spectrometer and Incoherent Scatter (MSIS) model data by season, and with Sounding of the Atmosphere using Broadband Emission Radiometry (SABER) from the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) satellite by year. The sounding rocket temperature data showed differences from MSIS in every season, with the minimum difference occurring in summer, the next smallest difference in winter, and the maximum difference occurring in autumn. The sounding rocket data showed smaller differences from the SABER data, although the deviation still fluctuated depending on the date and hour of the observations. In addition, the temperature distributions of the temperature profiles were examined at different times at the same heights. By linearly fitting the mean temperature profiles of each season, the statistical characteristics of the temperature changes with height were explored.

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