Disk images of neutral temperature from the Global-scale Observations of
the Limb and Disk (GOLD) mission
Abstract
Observations of far-ultraviolet (FUV) dayglow by the Global-scale
Observations of Limb and Disk (GOLD) mission provide an opportunity for
quantifying the global-scale response of the thermosphere to solar
extreme-ultraviolet (EUV) variability and geomagnetic activity. Relative
temperature changes can be measured by monitoring changes in the
rotational structure observed in molecular nitrogen Lyman-Birge-Hopfield
(LBH) band emissions. We present a new technique for deriving neutral
temperatures from GOLD FUV observations using optimal estimation fits to
spectra containing LBH band emissions. We provide an overview of the
theoretical basis for the GOLD Level 2 neutral temperature algorithm.
Effects on derived neutral temperatures from instrument artifacts and
particle background are reviewed. We also discuss GOLD Level 1C DAY and
Level 2 TDISK data products and present representative examples of each.
We show that neutral temperatures vary with local time, exhibit a strong
seasonal dependence, and correlate strongly with geomagnetic and solar
activity. Finally, we present results from a preliminary data product
validation that show good agreement with coincident GOLD exospheric
temperatures and predictions from a global reference atmospheric model.