Cross-calibration of ground-based measurement of rotational temperature of OH(3-1) at altitude ∼87 km in Maimaga (63° N, γ = 129.5° E) and SABER/TIMED satellite data

Abstract

Maimaga (63° N, λ = 129.5° E) is a base point in the meridional station network that we create in East Siberia to monitor changes in the upper mesosphere. Therefore, the comparison of measurements obtained by ground-based instruments and satellite data are relevant. It is known that the rotational temperature of hydroxyl (OH) corresponds to the temperature of the neutral atmosphere at the height of its radiation (∼87 km). The night spectrum of OH(3-1) is measured by a new Shamrock 303i spectrograph since January 2013. The rotational temperature, estimated from the ratio of the P - branches, is compared with the kinetic temperature of the atmosphere at an altitude of 87 km measured with the SABER radiometer installed aboard the TIMED satellite. The v2.0 version of the SABER temperature profiles was used (http://saber.larc.nasa.gov). The SABER measurements obtained within the area (55°N-70°N)×(115°E-135°E) have been selected. The angle of view of the ground-based spectrograph is almost in the center of the selected area. The satellite overpasses the selected area only in September-November and January-March. The spectrograph measurement is considered if the difference in time from the satellite measurement does not exceed a half of hour. The analysis of 328 cases of coincident measurements has shown that the difference in temperatures obtained from the satellite and ground-based spectrograph lies within the errors of both instruments. The correlation coefficient between two databases is equal 0.8. Based on the performed analysis, it has been concluded that a series of hydroxyl rotational temperatures can be used to study temperature variations of different time scales including long-term trends at the OH emission altitude (∼87 km).