Nocturnal means of OH(3-1) airglow rotational temperatures from the mesopause region obtained with GRIPS 10 located at Tel Aviv University, Israel

The temperatures are derived from the rotational vibrational transition of the OH molecule originating from a thin layer in approximately 87 km centroid height. The spectra have been obtained with the Ground-based Infrared P-branch Spectrometer (GRIPS 10) located at Tel Aviv University (TAV: 32.11°E, 34.80°N) - a measurement station of the international Network for the Detection of Mesospheric Change (NDMC). It is jointly operated by the German Remote Sensing Data Center (DFD) of the German Aerospace Center (DLR) and the Department of Geophysical, Atmospheric and Planetary Sciences of Tel Aviv University (TAU). During routine operation one spectrum is obtained every 15 s, originating from a field of view of approximately 4.5° x 4.5° which corresponds to ca. 520 km2 in 87 km height, as the instruments points northwards with a zenith angle of ca. 40°. The covered wavelength range allows the observation of the OH(3-1) Q- and P-branches as well as of the OH(4-2) R- and Q-branches. Rotational temperatures are calculated using OH(3-1) P-branch emissions between 1520 nm and 1550 nm. For the estimation of a nocturnal mean value all samples of the nightly temperature time series are weighted according to their individual precision. Thus, mean temperatures between 1 and 2 K are lower compared to the unweighted arithmetic mean. A mean is only calculated, when at least two hours of observation time are available.