Measurement of nitric oxide abundance in equatorial upper atmosphere.

Abstract

The altitude distribution of nitric oxide gamma band emissions in the day airglow was measured by the ultraviolet radiometer aboard a sounding rocket flown early in the morning from Thumba, India. The nitric oxide (NO) concentration could be determined for the first time in the equatorial upper atmosphere in the altitude range between 85 and 140km. The altitude distribution of NO below 105km is similar to those obtained by Meira in 1969 and by the present authors in 1973. The absolute concentration is, however, by a factor of 2 to 4 smaller than that measured in previous experiments. A maximum concentration of (2.7f0.6)x107cm 3 appears at the 105f2 km altitude. The concentration drops off quickly as the altitude increases from 105 to 120km, then decreases rather slowly at higher altitudes. The small abundance of NO can be interpreted by a combined effect of the diurnal variation of odd nitrogen species and reduced solar ultraviolet fluxes producing excited atomic nitrogen N(2D). It favors again a smaller abundance of N(2D) caused by the deactivation due to atomic oxygen.

A temperature-dependent model of the thermospheric odd nitrogen.

“…6. The results from rocket observations of NO at sunrise (SZA=90) by TISONE (1973) and at 07h LT (SZA-82) by TOHMATSU and IWAGAMI (1976) are compared with the theoretical profiles at 07h LT in Fig. 6.…”

“…It may be concluded that the concentration of odd nitrogen is determined basically by photochemical reactions above 90km in the daytime, whereas the dynamical process has an important effect during the night. TOHMATSU andIWAGAMI (1975) deduced from NO r(1, 0)-airglow observations. Here it must be noted that the observed values have been reduced by a factor 2.07 considering the revision of the fluorescence coefficient for the NO r(l, 0)-band.…”

“…Recently the NO concentration, which is considerably smaller than that in the midday, has been measured in the early morning by TOHMATSU and IWAGAMI (1976). In addition, it was found necessary to reduce the NO concentration already published by MEIRA (1971), TISONE (1973), andTOHMATSU andIWAGAMI (1975) due to the correction of the fluorescence coefficient for the NO r(1, 0)-band (Barth, C. A., private communication, 1975).…”

“…In addition, it was found necessary to reduce the NO concentration already published by MEIRA (1971), TISONE (1973), andTOHMATSU andIWAGAMI (1975) due to the correction of the fluorescence coefficient for the NO r(1, 0)-band (Barth, C. A., private communication, 1975). The N density in the thermosphere has been derived by FELDMAN and TAKACS (1974) and GERARD (1975) by the NO o-band twilightglow observations.…”

Rocket observation of near infrared airglow.

“…Nitric oxide airglow has been observed mainly through the r-and o-bands in the ultraviolet region (MEIRA, 1971;TISONE, 1973;TOHMATSU andIWAGAMI, 1975, 1976;RUSCH and BARTH, 1975;GERARD, 1975;GERARD and BARTH, 1977). Recently near infrared emission in the 4v=1 and 4v=2 sequences has also been observed by STAIR et al (1975) and by BAKER et al (1977).…”