Variability of the Brunt–Väisälä frequency at the OH^∗-airglow layer height at low and midlatitudes

• Main Authors: S. Wüst, M. Bittner, J.-H. Yee, M. G. Mlynczak, J. M. Russell III
• Format: Article
• Language: English
• Published: Copernicus Publications 2020-11-01
• Series: Atmospheric Measurement Techniques
• Online Access: https://amt.copernicus.org/articles/13/6067/2020/amt-13-6067-2020.pdf
• ISSN: 1867-1381; 1867-8548

<p>Airglow spectrometers, as they are operated within the Network for the Detection of Mesospheric Change (NDMC; <span class="uri">https://ndmc.dlr.de</span>, last access: 1 November 2020), for example, allow the derivation of rotational temperatures which are equivalent to the kinetic temperature, local thermodynamic equilibrium provided. Temperature variations at the height of the airglow layer are, amongst others, caused by gravity waves. However, airglow spectrometers do not deliver vertically resolved temperature information. This is an obstacle for the calculation of the density of gravity wave potential energy from these measurements.</p> <p>As Wüst et al. (2016) showed, the density of wave potential energy can be estimated from data of <span class="inline-formula">OH^∗</span>-airglow spectrometers if co-located TIMED-SABER (Thermosphere Ionosphere Mesosphere Energetics Dynamics, Sounding of the Atmosphere using Broadband Emission Radiometry) measurements are available, since they allow the calculation of the Brunt–Väisälä frequency. If co-located measurements are not available, a climatology of the Brunt–Väisälä frequency is an alternative. Based on 17 years of TIMED-SABER temperature data (2002–2018), such a climatology is provided here for the <span class="inline-formula">OH^∗</span>-airglow layer height and for a latitudinal longitudinal grid of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><mn mathvariant="normal">10</mn><msup><mi/><mo>∘</mo></msup><mo>×</mo><mn mathvariant="normal">20</mn><msup><mi/><mo>∘</mo></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="46pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="8cc1678b0c8faba51e8678dc28d177c9"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="amt-13-6067-2020-ie00001.svg" width="46pt" height="11pt" src="amt-13-6067-2020-ie00001.png"/></svg:svg></span></span> at midlatitudes and low latitudes. Additionally, climatologies of height and thickness of the <span class="inline-formula">OH^∗</span>-airglow layer are calculated.</p>