Daytime sodium airglow emission measurements over Trivandrum using a scanning monochromator: first results

Abstract

Abstract. This paper presents measurement of daytime Sodium (Na) airglow emissions at 589.6 nm wavelength using a ground based 1-m scanning monochromator from Trivandrum (8.5 • N, 77 • E, 0.5 • N dip latitude), a nearequatorial station in India. The Na emission intensity exhibits significant temporal variability within a day and from one day to another. The Na intensity has been compared with the daytime OH airglow intensity at 731.6 nm simultaneously measured using the unique Multiwavelength Dayglow Photometer (MWDPM). The temporal variabilities of the Na and OH intensities corroborate each other in most of the occasions without any appreciable time delay, although a small time delay up to ∼10 min has been observed at times. It appears that the variability of daytime Na emissions is influenced too by the photo-chemical excitations. The observed similarities in the Na and OH intensities are believed to be due to the similar roles played by [O] and O 3 (in their photochemical excitations) and the dynamics occurring at about the same altitude region (∼90 km). It has also been found that the gravity waves play significant role in producing the short-scale oscillations in these emissions.

Monitoring Hydrogen Plasma Reduction of Oxides by Na D Lines

“…These two lines were not matching with excitation of any of the elements such as Fe, O or H which are present inside the plasma. Since sodium doublet (Na D) lines have been well identified [12][13][14][15], but never reported for hydrogen plasma, further experiments with a low pressure sodium vapour lamp (LPSVL) was carried out. In this experiment emissions from both LPSVL and plasma were simultaneously captured by two channels of multi channel Czerny Turner spectrograph.…”

Highly varying daytime sodium airglow emissions over an equatorial station: a case study based on the measurements using a grating monochromator

“…D 1 line (5,896 Å) is chosen for the present study. Near the bottom of this absorption line, Na emission feature is noticed (Hossain et al 2010). The system is then tuned to the wavelength position of this emission feature, and the temporal variation of Na airglow intensity is measured during daytime.…”

“…They also have found through the Na airglow VER estimation using the contribution from the mesospheric ozone and temperature data that the peak emission altitude does not match the altitude of the maximum correlation between the Na atoms and the Na airglow, and hence suggested that the altitude variation of the pressure-dependent collisional quenching needs to be considered, on this occasion, to account for the observed Na airglow intensity variation. In a recent paper, Hossain et al (2010) has reported that daytime Na airglow exhibits significant variability within a day and from one day to another. Also, it has been shown that the dynamics and the chemistry affect its temporal variation.…”

“…However, photochemical excitations also influence its generation and temporal evolution (Hossain et al 2010). The well-known chemical scheme responsible for excitations of neutral Na atoms is as follows (Chapman 1939):…”

“…Since daytime groundbased measurements of sodium airglow are particularly difficult to perform, there were no contemporary systematic studies so far. Only recently, a ground-based high-resolution monochromator (with maximum resolution of 0.05 Å using 2,400 g/mm grating) has been used for systematic measurement of the daytime sodium D 1 airglow (589.6 nm) (Hossain et al 2010).…”