Nocturnal means of OH(3-1) airglow rotational temperatures from the mesopause region obtained with GRIPS 15 located at Neumayer III, Antarctica

• Main Authors: Schmidt, Carsten, Höppner, Kathrin, Wüst, Sabine, Bittner, Michael, Weller, Rolf, Regnery, Julia
• Format: Dataset
• Language: English
• Published: World Data Center for Remote Sensing of the Atmosphere (WDC-RSAT) 2014
• Subjects: Temperature; Neumayer; Alfred Wegener Institute; Antarc*; Antarctica
• Online Access: https://dx.doi.org/10.1594/wdcrsat.7ce53chg; https://wdc.dlr.de/wdcservices/doi.php?doi=10.1594/WDCRSAT.7CE53CHG

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 15) located at Neumayer III (NEU: 70.67°S, 8.27°S) - 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 Alfred Wegener Institute for Marine and Polar Research (AWI). 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. 660 km2 in 87 km height, as the instruments points northwards with a zenith angle of 45°. 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. : GRIPS 15 is equipped with a Czerny-Turner spectrograph, an off-axis parabolic mirror in front of the entrance slit and a thermoelectrically cooled InGaAs array. Only the P1(2), P1(3) and P1(4) rotational lines of the (3-1) vibrational transition are used for the derivation of temperatures. Intensities are only read out at the line centers of the smoothed spectra due to residual overlapping of the lines at their wings. Important physical constants applied during the processing are taken from Mies (1974) (Einstein coefficients) and Krassovsky et al. (1962) (rotational term values). During strong auroral activity contamination of the airglow spectra may occur, potentially leading to a small negative bias in rotational temperatures. A randomly occurring sensor error leads to a decrease in SNR in data of 2013. However, only a minor impact on the nocturnal mean values is observed. This error will be completely corrected in later data versions. Further details concerning the derivation of rotational temperatures are presented in Schmidt, C., Höppner, K. and Bittner, M. (2013): A ground-based spectrometer equipped with an InGaAs array for routine observations of OH(3-1) rotational temperatures in the mesopause region. Journal of Atmospheric and Solar-Terrestrial Physics 102 (2013) 125–139. http://dx.doi.org/10.1016/j.jastp.2013.05.001