Abstract
Abstract. Measurements of the hydroxyl rotational temperature for the (8,3) Meinel band have been reported from the observations of the ratio of the relative intensities of P1(2) and P1(4) lines of the OH(8,3) band at Kolhapur (16.8° N, 74.2° E, dip lat. 10.6° N) in India during the period 1 November 2002-29 April 2003 using tilting-filter photometers. Mean values of rotational temperature have been computed for 60 nights. The monthly mean value of temperature lies in the range 194(±11)-208(±18)K. The mean rotational temperature obtained from all the measurements was found to be 202±15K. The results agree with other low-latitude measurements of rotational temperature using photometric airglow techniques. Quasi-periodic fluctuations with a period of about one to two hours have been prominent on many nights. Furthermore, the results show the general agreement between observations and model (MSIS-86) predictions.
Highlights
In order to understand the upper atmospheric variability it is essential to measure accurately the temperature and density profiles in the mesospheric region.The rotational-vibrational bands (550 nm–4.4 μm) of hydroxyl in the night airglow have been discovered by Meinel (1950)
It is assumed that the vibrationally excited OH molecules are in thermal equilibrium and the rotational temperature determined spectroscopically may be taken to be the neutral temperature of the emitting region
It was thought that the values of emissions of P1(2) and P1(4) lines and the rotational temperature computed can be meaningful
Summary
In order to understand the upper atmospheric variability it is essential to measure accurately the temperature and density profiles in the mesospheric region. The primary objective was to determine the diurnal and seasonal variation of the rotational temperature and validate it with other low-latitude measurements. Abreu and Yee (1989) have presented results from a study of diurnal and seasonal variations in the nighttime OH(8,3) emission at low latitudes using data from the AE-E satellite. Diurnal variations of OH emission intensity have been studied by many observers (Wiens and Weill, 1973; Takahashi et al, 1977; Abreu and Yee, 1989). There are four different types of nocturnal variations of temperature as observed by Agashe et al (1989) at a low-latitude station, Pune (18◦ N, 73◦ E) in India. An average temperature of 221±2 K was obtained from a selected data set of 104 spectra
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