Variability of various nightglow emissions from about 100,000 VLT/X-shooter spectra

2021 ◽  
Author(s):  
Stefan Noll ◽  
Wolfgang Kausch
Keyword(s):  
Solar Activity ◽  
Time Scales ◽  
Gravity Waves ◽  
Chemical Species ◽  
Activity Cycle ◽  
Peak Height ◽  
Lower Atmosphere ◽  
Atmospheric Conditions ◽  
Data Set ◽  
Mesopause Region

<p>Chemiluminescent emission from the mesopause region between 75 and 105 km dominates the Earth's low-to-mid-latitude nocturnal radiation in the wavelength domain from the near-UV to the near-IR. This nightglow consists of various roto-vibrational bands of molecules such as hydroxyl and molecular oxygen as well as individual lines from atoms such as oxygen and sodium. In principle, each line shows an individual vertical emission profile with a characteristic mean peak height and a typical full width at half maximum of less than 10 km. The total emission rate, peak height, and shape of the different profiles depend on the temperature, density, and the concentrations of different chemical species, especially of atomic oxygen. As the state of the mesopause region is strongly affected by the solar activity (especially via the rate of hard UV photons that produce highly reactive radicals) and different kinds of passing waves such as tides and gravity waves that mainly originate in the lower atmosphere, nightglow is also highly variable and can, thus, be used to trace the different processes. Various ground- and space-based observing strategies have already been applied. However, recording the variations of many different (and especially weak) emission lines in parallel with good temporal coverage for perturbations with time scales from minutes to years is challenging. </p><p>In this context, we have now achieved to process about 100,000 medium-resolution spectra with a wavelength coverage from 0.3 to 2.5 µm that were taken with the astronomical X-shooter spectrograph at the Very Large Telescope of the European Southern Observatory at Cerro Paranal in Chile between 2009 and 2019. This promising data set allows us to study the variability of hundreds of nightglow lines and mutual correlations on time scales from those related to gravity waves to those related to the solar activity cycle. We will show first results. The goal of the project will be a better understanding of the nightglow layering and the sensitivity of the different emissions to different kinds of changes in the atmospheric conditions. </p>

MEDIUM-TERM OSCILLATIONS OF THE SOLAR ACTIVITY

2021 ◽  
Vol 44 ◽  
pp. 85-91
Author(s):  
V.N. Obridko ◽  
◽  
D.D. Sokoloff ◽  
V.V. Pipin ◽  
A.S. Shibalova ◽  
...  
Keyword(s):  
Solar Activity ◽  
Activity Cycle ◽  
Solar Interior ◽  
Local Fields ◽  
Lower Atmosphere ◽  
High Solar Activity ◽  
Dynamo Model ◽  
Sunspot Activity ◽  
Geomagnetic Variations ◽  
Near Surface

In addition to the well-known 11-year cycle, longer and shorter characteristic periods can be isolated in variations of the parameters of helio-geophysical activity. Periods of about 36 and 60 years were revealed in variations of the geomagnetic activity and an approximately 60-year periodicity, in the evolution of correlation between the pressure in the lower atmosphere and the solar activity. Similar periods are observed in the cyclonic activity. Such periods in the parameters of the solar activity are difficult to identify because of a limited database available; however, they are clearly visible in variations of the asymmetry of the sunspot activity in the northern and southern solar hemispheres. In geomagnetic variations, one can also isolate oscillations with the characteristic periods of 5-6 years (QSO) and 2-3 years (QBO). We have considered 5-6-year periodicities (about half the main cycle) observed in variations of the sunspot numbers and the intensity of the dipole component of the solar magnetic field. A comparison with different magnetic dynamo models allowed us to determine the possible origin of these oscillations. A similar result can be reproduced in a dynamo model with nonlinear parameter variations. In this case, the activity cycle turns out to be anharmonic and contains other periodicities in addition to the main one. As a result of the study, we conclude that the 5-6-year activity variations are related to the processes of nonlinear saturation of the dynamo in the solar interior. Quasi-biennial oscillations are actually separate pulses related little to each other. Therefore, the methods of the spectral analysis do not reveal them over large time intervals. They are a direct product of local fields, are generated in the near-surface layers, and are reliably recorded only in the epochs of high solar activity.

Long-term variations of the oxygen red 630 nm line nightglow intensity

2007 ◽  
Vol 85 (2) ◽  
pp. 189-198 ◽  
Author(s):  
N B Gudadze ◽  
G G Didebulidze ◽  
G Sh. Javakhishvili ◽  
M G Shepherd ◽  
M V Vardosanidze
Keyword(s):  
Line Intensity ◽  
Peak Height ◽  
Mean Value ◽  
Lower Atmosphere ◽  
Data Set ◽  
Term Trend ◽  
Long Term Trend ◽  
Long Term Variations ◽  
Red Line

The long-term data set of total nightglow intensity of the oxygen red 630.0~nm line observed at Abastumani (41.8°N, 42.8°E) between 1957–1993 is investigated. The long-term trend and characteristic variations in solar radiation during an 11 year cycle of the red-line intensity are different after astronomical twilight (premidnight) and at midnight. The amplitude of deviation of the red-line intensity from its mean value at solar maximum and (or) minimum phase is greatest after astronomical twilight and decreases toward midnight. The long-term trend of these variations changes from its value about 0.74 R/year premidnight to its minimum negative value of about –1.92 R/year at and after midnight. This behavior of the long-term trend is considered as a possible result of an increase in electron density below the peak height (hmF2) of the ionospheric F2 layer and lowering of the height hmF2 after midnight predicted by the TIME-GCM model on the assumption of an increase in density of greenhouse gases in the lower atmosphere. The third-order regression equation (with different solar activity indices) is considered to be convenient for describing long-term variations in the mean annual red-line intensity.PACS Nos.: 94.10.Rk, 94.20.Ji, 92.60.Vb

Irradiance Observations of the Sun

1994 ◽  
Vol 143 ◽  
pp. 28-36 ◽  
Author(s):  
Claus Fröhlich
Keyword(s):  
Solar Activity ◽  
Time Scales ◽  
Solar Maximum ◽  
Activity Cycle ◽  
Total Solar Irradiance ◽  
The Sun ◽  
Direct Influence ◽  
Magnetic Network ◽  
Over Time

Measurements of the total solar irradiance during the last 14 years from satellites show variations over time scales from minutes to years and decades. The most important variance is in the range from days to several months and is related to the photospheric features of solar activity: decreasing the irradiance during the appearance of sunspots, and increasing it by faculae and the bright magnetic network. Long-term modulation by the 11-year activity cycle is observed conclusively with the irradiance being higher during solar maximum. The accuracy of the determined variability and its interpretation in terms of manifestations of activity related features on the photosphere is discussed. Besides the direct influence of the spots, faculae and magnetic network more profound changes in the thermal transport seem to influence the behaviour of the solar photospheric radiation on the solar cycle and longer time scales.

scholarly journals Observations of the Nickel Layer in the Mesopause Region at Mid-Latitudes

2020 ◽  
Vol 237 ◽  
pp. 04004
Author(s):  
Michael Gerding ◽  
Kathrin Baumgarten ◽  
John M. C. Plane
Keyword(s):  
Temperature Profile ◽  
Temperature Variation ◽  
Gravity Waves ◽  
Metal Layer ◽  
Nickel Layer ◽  
Data Set ◽  
Density Profiles ◽  
Mesopause Region ◽  
Waves And Tides ◽  
First Time

Observations of the mesospheric Ni layer have been performed by lidar in January-March 2018 at Kuehlungsborn/Germany (54°N, 12°E). These soundings provide only the second Ni data set after initial observations by Collins et al. at Chatanika/Alaska (65°N, 147°W)[1]. We utilized for the first time a transition from the low-lying excited Ni(3D) state at 341 nm. For all soundings, nightly mean peak densities varied between ~280 cm−3 and 450 cm3, which is a factor of ~40 less than previously reported for Chatanika [1]. The observed Ni abundance is especially important if compared with the abundance of other metals like Fe, and with their respective abundances in evaporating meteoroids, which form the source of the metal layer in the upper mesosphere. Here, we present exemplarily a sounding from January 8, 2018. Beside the Ni raw data and density profiles we show a temperature profile as measured simultaneously be the co-located RMR lidar and the temperature variation due to gravity waves and tides.

Trends in Parameters of the F2 Layer and the 24th Solar-Activity Cycle

2020 ◽  
Vol 60 (5) ◽  
pp. 586-596 ◽  
Author(s):  
A. D. Danilov ◽  
A. V. Konstantinova
Keyword(s):  
Solar Activity ◽  
Activity Cycle ◽  
Solar Activity Cycle

scholarly journals On the Prediction of Solar Cycles

Solar Physics ◽  
2021 ◽  
Vol 296 (1) ◽  
Author(s):  
V. Courtillot ◽  
F. Lopes ◽  
J. L. Le Mouël
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Transfer Function ◽  
Singular Spectrum Analysis ◽  
Activity Cycle ◽  
Solar Activity Cycle ◽  
Planetary Motion ◽  
Data Sets ◽  
Solar Cycles ◽  
Jovian Planets

AbstractThis article deals with the prediction of the upcoming solar activity cycle, Solar Cycle 25. We propose that astronomical ephemeris, specifically taken from the catalogs of aphelia of the four Jovian planets, could be drivers of variations in solar activity, represented by the series of sunspot numbers (SSN) from 1749 to 2020. We use singular spectrum analysis (SSA) to associate components with similar periods in the ephemeris and SSN. We determine the transfer function between the two data sets. We improve the match in successive steps: first with Jupiter only, then with the four Jovian planets and finally including commensurable periods of pairs and pairs of pairs of the Jovian planets (following Mörth and Schlamminger in Planetary Motion, Sunspots and Climate, Solar-Terrestrial Influences on Weather and Climate, 193, 1979). The transfer function can be applied to the ephemeris to predict future cycles. We test this with success using the “hindcast prediction” of Solar Cycles 21 to 24, using only data preceding these cycles, and by analyzing separately two 130 and 140 year-long halves of the original series. We conclude with a prediction of Solar Cycle 25 that can be compared to a dozen predictions by other authors: the maximum would occur in 2026.2 (± 1 yr) and reach an amplitude of 97.6 (± 7.8), similar to that of Solar Cycle 24, therefore sketching a new “Modern minimum”, following the Dalton and Gleissberg minima.

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