Abstract:
Ground-based observations of OH(6, 2) Meinel
band nightglow were carried out at Ranchi (23.3 N,
85.3 E), India, during January–March 2011, December
2011–May 2012 and December 2012–March 2013 using
an all-sky imaging system. Near the mesopause, OH temperatures
were derived from the OH(6, 2) Meinel band intensity
information. A limited comparison of OH temperatures
(TOH/ with SABER/TIMED measurements in 30 cases was
performed by defining almost coincident criterion of 1.5
latitude–longitude and 3 min of the ground-based observations.
Using SABER OH 1.6 and 2.0 μm volume emission
rate profiles as the weighing function, two sets of OHequivalent
temperature (T1:6 and T2:0 respectively) were estimated
from its kinetic temperature profile for comparison
with OH nightglow measurements. Overall, fair agreement
existed between ground-based and SABER measurements in
the majority of events within the limits of experimental errors.
Overall, the mean value of OH-derived temperatures
and SABER OH-equivalent temperatures were 197.3 4.6,
192.0 10.8 and 192.7 10.3 K, and the ground-based temperatures
were 4–5K warmer than SABER values. A difference
of 8K or more is noted between two measurements
when the peak of the OH emission layer lies in the vicinity of
large temperature inversions. A comparison of OH temperatures
derived using different sets of Einstein transition probabilities
and SABER measurements was also performed; however,
OH temperatures derived using Langhoff et al. (1986)
transition probabilities were found to compare well.
