DOI: 10.5281/zenodo.18788837
title: High-resolution OH airglow temperatures above the Czech Republic during the passage of seismic surface waves of the M8.8 Kamchatka 2025 earthquake

description: The temperatures are derived from the rotational vibrational transition of the OH molecule originating from a thin layer in approximately 86-87 km centroid height. The spectra have been obtained with the Ground-based Infrared P-branch Spectrometers (GRIPS) located at Panská Ves (PAN: 50.53°N, 14.57°E, GRIPS 14), Czechia during the night of July 29 to July 30, 2025.

The instrument is jointly operated by the German Remote Sensing Data Center (DFD) of the German Aerospace Center (DLR) and the Institute of Atmospheric Physics of the Czech Academy of Sciences (CAS) who are part of the international Network for the Detection of Mesospheric Change (NDMC). The data set comprises 75 minutes (based on 290 individual spectra). The data are used in the study of Chum et al. 2026 ("Doppler observation of a co-seismic infrasound in the Central Europe at record breaking heights caused by the M8.8 Kamchatka 2025 earthquake", submitted to XYZ in 2026).

The wavelength range covered by the instrument 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. During routine operation one spectrum is obtained every 15s, originating from a field of view of approximately 3.5° x 3.5°, which corresponds to ca. 30 km² in 87 km height.

The instrument GRIPS 14 operated at PAN points in southward direction with both zenith and azimuth angles adjusted in such a way that its field of view (FoV) in the mesopause region lies below the ionospheric reflection point of the Panská Ves – Prague (50.04°N, 14.48°E) transmitter - receiver combination of a Continuous Doppler Sounding System (CDSS).

All GRIPS are equipped with a Czerny-Turner spectrograph 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). 

Details concerning the derivation of rotational temperatures from the airglow 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 (JASTP) 102 (2013) 125–139. https://dx.doi.org/10.1016/j.jastp.2013.05.001. Details concerning conversion factors if more recent physical constants are applied during the retrieval, are discussed in Schmidt, C., Küchelbacher, L., Wüst, S. and Bittner, M. (2023): OH airglow observations with two identical spectrometers: benefits of increased data homogeneity in the identification of variations induced by the 11-year solar cycle, the QBO, and other factors. Atmospheric Measurement Techniques (AMT), Vol. 16, 19, 4331-4356. https://doi.org/10.5194/amt-16-4331-2023.

The following table describes the content of the ASCII-file containing the data (separator between two columns is “                ” aka “TAB”).

 






Column



parameter



unit



Format



description





1



time stamp



UTC



F16.8



Julian date





2



time of day



UTC



string



HH:MM:SS (9 characters)





3



temperature



Kelvin



F5.1



-





4



temperature uncertainty



Kelvin



F3.1



-





5



Q(3-1)-radiance (branch)



a.u.



F7.1



Integrated (1496-1514nm)





6



Q(4-2)-radiance (branch)



a.u.



F7.1



Integrated (1579-1596nm)





7



radiance ratio



n.a.



F6.4



Ratio of columns 5 and 6





8



Q(4-2)-radiance (normalized)



a.u.



F6.4



Q(4-2)-radiance (column 6) normalized to data set mean