A technique for the analysis of two-dimensional data: application to OI 5577Å airglow

A method to determine whether a two-dimensional data set can be represented by two independent separable functions is demonstrated using both synthetic data and satellite observations of OI 5577Å airglow. For such cases when the functions are separable it is possible to identify the function in the presence of noise using an iterative procedure based on the properties of an equitable matrix. In the specific case of the airglow, the latitudinal and temporal variations are separable for the data set studied. The spatial structure shows a minimum near the equator, with maxima at 35° in the winter hemisphere and 25° in the summer hemisphere. The long-term temporal function shows maxima after the equinoxes, with minima near the solstice. A 12 month component has a maximum near day 300.     

Correlations among O2(0–1) atmospheric band,OH(8–3) band and [OI] 5577 Å line and among P1 (2), P1 (3) and P1 (4) lines of OH(8–3) band

Using a photometer equipped with a cooled photomultiplier RCA-C31034A and an optics consisting of three aspheric lenses, the O₂(0–1) Atmospheric band at 8645 Å and the OH(8-3) band at 7274 Å are observed simultaneously from the ground level along with [OI] 5577 Å line, to investigate the instantaneous intensity changes. The P and R branches of O₂(0–1) Atmospheric band and the P₁(4), P₂(4), [P₁(3) + P₂(3)] and [P₁(2) + P₂(2)] lines of the OH(8-3) band are spectrally clearly resolved. It is found that the O₂(0–1) Atmospheric band and the OH(8-3) band covary fairly well in intensity; it seems that the correlation coefficient during the night lies around 0.500. Interrsity correlations between the OH(8-3) band and [OI] 5577 Å line are also investigated. It is found that the correlation coefficient during a night lies around −0.200 and thus the correlation between the OH(8-3) band and [OI] 5577 A line is weaker than that between the O₂(0–1) Atmospheric band and the OH(8-3) band. Correlations among P₁(4), [P₁(3) + P₂(3)] and [P₁(2) + P₂(2)] lines of the OH(8–3) band are studied, to find that their correlations are complete within an error of experiment; the correlation coefficient during a night ranges from 0.980 to 0.997. A midnight maximum of intensity of the OH(8-3) band is hardly found. During night the OH intensity always fairly fluctuates.