Determination of day-time OH emission heights using simultaneous meteor radar, day-glow photometer and TIMED/SABER observations over Thumba (8.5°N, 77°E)

Abstract

Simultaneous day-glow photometer and meteor radar observations are used for determining the day-time OH emission height for the first time over Thumba (8.5° N, 77° E). The meteor radar observations are extensively used to obtain the ambipolar diffusion coefficient (D_a) profile in the 82-98 km height region and are compared with OH rotational temperature (TOH) measurements. The height profile of correlation coefficient between D_a and TOH showed a maximum at 90 km. These ground based estimates are then compared with space based OH volume emission rate (VER) observations by TIMED/SABER satellite over this latitude, which showed an excellent agreement. Further, the temporal variation of OH emission heights showed tidal modulation of OH emission heights. The significance of the present results lies in determining the day-time OH emission height for the first time using collocated radar and photometer observations, which will have implications in interpreting TOH in the MLT region.