Global UltraViolet Imager

Deriving column-integrated thermospheric temperature with the N$_\textrm2$ Lyman–Birge–Hopfield (2,0) band

\textlessp\textgreater\textlessstrong class="journal-contentHeaderColor"\textgreaterAbstract.\textless/strong\textgreater This paper presents a new technique to derive thermospheric temperature from space-based disk observations of far ultraviolet airglow. The technique, guided by findings from principal component analysis of synthetic daytime Lyman–Birge–Hopfield (LBH) disk emissions, uses a ratio of the emissions in two spectral channels that together span the LBH (2,0) band to determine the change in band shape with respect to a change in the rotational temperature of \textlessspan class="inline-formula"\textgreaterN$_\textrm2$\textless/span\textgreater. The two-channel-ratio approach limits representativeness and measurement error by only requiring measurement of the relative magnitudes between two spectral channels and not radiometrically calibrated intensities, simplifying the forward model from a full radiative transfer model to a vibrational–rotational band model. It is shown that the derived temperature should be interpreted as a column-integrated property as opposed to a temperature at a specified altitude without utilization of a priori information of the thermospheric temperature profile. The two-channel-ratio approach is demonstrated using NASA GOLD Level 1C disk emission data for the period of 2–8 November 2018 during which a moderate geomagnetic storm has occurred. Due to the lack of independent thermospheric temperature observations, the efficacy of the approach is validated through comparisons of the column-integrated temperature derived from GOLD Level 1C data with the GOLD Level 2 temperature product as well as temperatures from first principle and empirical models. The storm-time thermospheric response manifested in the column-integrated temperature is also shown to corroborate well with hemispherically integrated Joule heating rates, ESA SWARM mass density at 460 km, and GOLD Level 2 column \textlessspan class="inline-formula"\textgreater\textlessmath xmlns="" id="M4" display="inline" overflow="scroll" dspmath="mathml"\textgreater\textlessmrow class="chem"\textgreater\textlessmi mathvariant="normal"\textgreaterO\textless/mi\textgreater\textlessmo\textgreater/\textless/mo\textgreater\textlessmsub\textgreater\textlessmi mathvariant="normal"\textgreaterN\textless/mi\textgreater\textlessmn mathvariant="normal"\textgreater2\textless/mn\textgreater\textless/msub\textgreater\textless/mrow\textgreater\textless/math\textgreater\textlessspan\textgreater\textlesssvg:svg xmlns:svg="" width="29pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="7003ba1ac83e7c29f962255ae440df67"\textgreater\textlesssvg:image xmlns:xlink="" xlink:href="amt-14-6917-2021-ie00001.svg" width="29pt" height="14pt" src="amt-14-6917-2021-ie00001.png"/\textgreater\textless/svg:svg\textgreater\textless/span\textgreater\textless/span\textgreater ratio.\textless/p\textgreater
Year of Publication
Atmospheric Measurement Techniques
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