Night Airglow Observations Research Articles

Occurrence climatology of equatorial plasma bubbles (EPBs) using optical observations over Kolhapur, India during solar cycle-24

In this paper, the occurrence characteristics of the equatorial plasma bubbles (EPBs) using OI 630.0 nm all sky imager (ASI) night airglow observations over Kolhapur (16.8o N, 74.2o E, 10.6o dip. Lat.) during the solar cycle-24 are presented. These results are discussed in terms of season, solar and magnetic activity during years 2011 to 2018. The ASI observations were only carried out during January to May and October to December months due to unfavorable weather conditions. The results suggest that while January, February and December are the only months where EPBs were found to occur over Kolhapur in any year, but the percentage of occurrence of EPBs during these months suggests their low occurrence rate during solar minimum. A total of 683 nights of observations were carried, out of which, 93 nights are found to be magnetically disturbed nights having Ap>18. In addition, the ASI observations are also correlated with Pre-Reversal Enhancement of the vertical drift of the evening sector at Tirunelveli on few storm events for comparison. The important findings of this study are: 1) increase in the occurrence of EPBs with respect to the solar activity; 2) suppression of EPBs on 71 disturbed nights, while enhancement of EPBs on 22 nights under magnetic disturbance; 3) EPBs occurrence during equinox months is found to be higher than winter months during ascending phase of solar cycle-24.; and, 4) EPBs are mostly observed in the pre-midnight sector in the high solar activity (HSA) period, while they are seen in the post-midnight to dawn sector during the low solar activity (LSA) period. We also noticed non-occurrence of EPBs during equinox month in the year 2018 which seems to be peculiar and needs further investigations.

Night airglow in RGB mode

To study dynamics of the upper atmosphere, we consider results of the night sky photometry, using a color CCD camera and taking into account the night airglow and features of its spectral composition. We use night airglow observations for 2010–2015, which have been obtained at the ISTP SB RAS Geophysical Observatory (52° N, 103° E) by the camera with KODAK KAI-11002 CCD sensor. We estimate average brightness of the night sky in R, G, B channels of the color camera for eastern Siberia with typical values ranging from ~0.008 to 0.01 erg·cm–2·s–1. Besides, we determine seasonal variations in the night sky luminosities in R, G, B channels of the color camera. In these channels, luminosities decrease in spring, increase in autumn, and have a pronounced summer maximum, which can be explained by scattered light and is associated with the location of the Geophysical Observatory. We consider geophysical phenomena with their optical effects in R, G, B channels of the color camera. For some geophysical phenomena (geomagnetic storms, sudden stratospheric warmings), we demonstrate the possibility of quantitative relationship between enhanced signals in R and G channels and increases in intensities of discrete 557.7 and 630 nm emissions, which are predominant in the airglow spectrum.

Свечение ночной атмосферы в RGB цветовом представлении

TTo study dynamics of the upper atmosphere, we consider results of the night sky photometry, using a color CCD camera and taking into account the night airglow and features of its spectral composition. We use night airglow observations for 2010–2015, which have been obtained at the ISTP SB RAS Geophysical Observatory (52° N, 103° E) by the camera with KODAK KAI-11002 CCD sensor. We estimate average brightness of the night sky in R, G, B channels of the color camera for eastern Siberia with typical values ranging from ~0.008 to 0.01 erg·cm–2·s–1. Besides, we determine seasonal variations in the night sky luminosities in R, G, B channels of the color camera. In these channels, luminosities decrease in spring, increase in autumn, and have a pronounced summer maximum, which can be explained by scattered light and is associated with the location of the Geophysical Observatory. We consider geophysical phenomena with their optical effects in R, G, B channels of the color camera. For some geophysical phenomena (geomagnetic storms, sudden stratospheric warmings), we demonstrate the possibility of quantitative relationship between enhanced signals in R and G channels and increases in intensities of discrete 557.7 and 630 nm emissions, which are predominant in the airglow spectrum.

Mesospheric gravity wave characteristics and identification of their sources around spring equinox over Indian low latitudes

Abstract. We report OI557.7 nm night airglow observations with the help of a charged-couple device (CCD)-based all-sky camera from a low-latitude station, Gadanki (13.5° N; 79.2° E). Based on the data collected during March and April over 3 years, from 2012 to 2014 (except March 2013), we characterize the small-scale gravity wave properties. During this period, 50 gravity wave events were detected. The horizontal wavelengths of the gravity waves are found to ranging from 12 to 42 km with the phase velocity 20–90 m s−1. In most cases, these waves were propagating northward with only a few occurrences of southward propagation. In the present novel investigation from the Indian sector, each of the wave events was reverse-ray-traced to its source. The outgoing longwave radiation (OLR) suggested that tropospheric convection was a possible source for generation of the observed waves. It was found that approximately 66 % of the events were triggered directly by the convection.

NO2 air afterglow and O and NO densities from Odin‐OSIRIS night and ACE‐FTS sunset observations in the Antarctic MLT region

The continuum spectrum produced by the NO + O(+M) → NO2(+M) + hv chemiluminescent reaction has been detected in the upper mesospheric dark polar regions by Optical Spectrograph and Infra‐Red Imager System (OSIRIS) on the Odin spacecraft. For the sample period of 8–9 May 2005, Southern Hemisphere, limb radiance profiles of continuum spectra, resolved from OH airglow and auroral contamination, are inverted to obtain volume emission rate altitude profiles. The maximum observed differential brightness referred to zenith viewing is 1.2 × 107 photons cm−2 s−1 nm−1 at 580 nm with a measurement uncertainty 5 × 105 photons cm−2 s−1 nm−1, for an analysis range 80–101 km. Atomic oxygen densities [O] required by the analysis to derive NO densities [NO] are determined from OSIRIS O2(b1Σg+ − X3Σg−) 0‐0 band night airglow observations and from Atmospheric Chemistry Experiment‐Fourier Transform Spectrometer (ACE‐FTS) sunset ozone observations. The derived Southern Hemisphere [O] map that shows pronounced longitudinal variation, maximum of 7 × 1011 cm−3, considerably exceeding MSIS model values, and suggests significant dynamical influence. Combining the continuum observations and the derived [O], a hemispheric map of derived [NO] is assembled that also shows considerable spatial variation, maximum of 1.1 × 109 cm−3, measurement uncertainty of 3 × 107 cm−3. Comparing the two maps, the geographical distribution of [NO] differs considerably from that of [O]. From a qualitative comparison, the distribution of derived [NO] is similar to that in coordinated GUVI LBH1 auroral precipitation images. The OSIRIS‐derived [NO] agrees with the measured ACE‐FTS [NO] to within 1 × 108 cm−3. The estimated systematic uncertainty of the NO densities derived from OSIRIS observations is approximately 30%.

The signature of short-period gravity waves imaged in the OI [formula omitted] and near infrared OH nightglow emissions over Panhala

With the development of cooled CCD detector, it has become possible to detect the spatial and temporal variation of the small-scale structure in airglow emission more accurately. Using tilting filter photometers ( 630 nm and OH) and a CCD-based multi-channel all-sky imager, the night airglow observations were carried out from Kolhapur (16.8°N,74.2°E) and Panhala (17.0°N,74.2°E; height above mean sea level 3200 ft ), India, during the clear and moonless nights of January–February, 2001. The multi-wavelength airglow imaging enables us to study the horizontal structures of the small-scale gravity waves at various heights in the region of emissions and to investigate propagation of those waves in detail. Hydroxyl (OH) and OI 557.7 nm images on the night of February 18, 2001 showed row-like structures moving from north to south direction spanning over 500 km in the sky. The observed horizontal phase speed (∼50 m/ s) , wavelength (∼25 km) , wave period (∼8 min) of the atmospheric gravity waves have been determined from a set of sequential images of OI 557.7 nm (at 97 km ) and OH (at 86 km ) observed at Panhala. These are the first observation of the signature of atmospheric gravity waves using an all-sky imager in Indian region indicating perturbation in density in the mesospheric region (80– 100 km ). The possible sources of the waves to the extended region have been discussed.

A new method of deducing the atomic oxygen density profiles in the lower thermosphere using ground-based night airglow observations

A semi-empirical method has been developed to deduce the atomic oxygen density profile in the altitude range of 90 to 120 km at any instant at night, making use of the ground-based night airglow observations of (OI) 5577Å, (OI) 6300Å and OH band emission zenith intensities. Following Reed and Chandra (1975) the shape of the atomic oxygen profile is assumed to be of the Chapman type, of the form: [ O] z = [ O] m exp 1 2 [1− Z−Z m S · H ] The scale height ( H) is determined from the rotational temperature obtained from observed OH emissions. The value of the mixing factor ( S) is assumed from theory. An empirical linear relationship between the modified scale height SH and Z m , the height of maximum of density has been established, using which Z m is determined. E-region component of 5577Å line intensity is obtained from the observed total 5577Å intensity by subtracting the F-region component determined by using the 6300Å line intensity. From this, [ O] m , the maximum of [O] density, is determined using the expression of Reed and Chandra (1975). Thus knowing all the unknowns in the above expression, the [O] profile is deduced. From the night airglow observations made at Kodaikanal during the spring equinox of 1978, the mean [O] profiles between 90 and 120 km for each hour of the night have been computed using the above method.

Experimental evidence of gravity waves at 80–90 km altitude from OH night airglow observations

Measurements of intensities at two fixed wavelengths in the OH (7-2) band were carried out at Mt Abu (24.6° N, 76.7° E) from 1973–76 to estimate neutral temperature in the region of 80–90 km altitude. It was observed that on some nights the temperature in this region shows periodic oscillations throughout the night. It was found from statistical analysis that the periods of these fluctuations are comparable to the theoretically predicted periods of internal gravity waves.

Correcting the oh contribution in emission line measurements in the night airglow filter photometry

From the night airglow observations of OH (7-2) and OH (8-3) bands made at Mt. Abu (24.6°N, 72.7°E geographic) we have noted that there is high positive correlation in their intensity variations (Rao and Kulkarni, 1971). Assuming covariation of the other OH band emissions and also their average emission ratios it is possible to estimate the contribution of one band ‘contaminating’ the measurement of line emission made by a filter of moderate width, from the measurement of another band. In the second method an attempt is made to estimate the OH contamination from the measurement through two filters centred on the emission line of airglow.

Yield of O( 1D) by dissociative recombination of O 2+ from night airglow observations

Ground-based photometer observations of the OI(6300 Å) night airglow compared with theoretical calculations of the integrated 6300 Å vertical volume emission rate indicate a yield of 0.15 ± 0.07 O( 1 D) atoms per recombination of O 2 + at 1000 K, including the 1S → 1D cascade effect. Implications of this result on the possible contribution of the dissociative recombination of NO + to the OI(6300 Å) night airglow are also discussed.

21. Light of the Night-Sky

Studies of airglow, zodiacal light, and galactic light in this triennium were almost as active as in the last. Results of observations obtained during and after the IQSY were the major contributions in this term. Night Airglow studies during the IQSY were widely reviewed in the Annals of the IQSY, vol. 4, in which the following articles are included:“Night Airglow Observations during the IQSY” (F. E. Roach, L. L. Smith and J. R. McKennan);“Airglow Research during and since the IQSY” (G. Weill);“Hydrogen and Hydroxyl Emissions in the Nightglow” (N. N. Shefov and Yu. L. Truttse).Proceedings of the NATO Advanced Study Institute, July 29-August 9,1968, entitled Atmospheric Emissions, contains some ten significant papers on airglow both in observations and interpretations. Many of them are referred to in the following sections.Many stations have been engaged in airglow observations since the beginning of the IASY in 1969, although the number of stations seems to be a little less than during the IGY. Stations near the equator and in the southern hemisphere, however, are more numerous and active than during the IGY in response to the strong wishes of many airglow researchers. These efforts are being made especially by G. Weill’s group of France, V. J. Dachs’ and Lange-Hesse’s groups of Germany.

OH contamination of night airglow observations at Haleakala, Hawaii

Journal of Geophysical Research (1896-1977)Volume 74, Issue 11 p. 3042-3045 Letters OH contamination of night airglow observations at Haleakala, Hawaii L. L. Smith, L. L. SmithSearch for more papers by this author L. L. Smith, L. L. SmithSearch for more papers by this author First published: 1 June 1969 https://doi.org/10.1029/JA074i011p03042Citations: 3AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume74, Issue11Space Physics1 June 1969Pages 3042-3045 RelatedInformation

Night Airglow Observations from Orbiting Spacecraft Compared with Measurements from Rockets

A luminous band around the night-time horizon, observed from orbiting capsules by J. H. Glenn and M. S. Carpenter, and identified as the horizon enhancement of the night airglow, is detected regularly in rocket-borne studies of night airglow. Values of luminance and dip angle of this band derived from Carpenter's observations agree remarkably well with values obtained from rocket data. The rocket results, however, do not support Carpenter's observation that the emission which he saw was largely the atomic oxygen line at 5577 A, but assign the principal luminosity to the green continuum.