New instrument uses nightglow to measure winds and temperatures at three atmospheric heights

A team at Wuhan University has developed a ground-based instrument that uses faint light from the night sky to measure winds and temperatures at three heights in the upper atmosphere. Its first field campaign in Chongyang, Hubei Province, China, provided an initial assessment of the instrument under real observing conditions. The findings are published in Earth and Planetary Physics.

The new instrument, a three-wavelength Fabry-Perot interferometer, observes emissions at 892.0, 557.7, and 630.0 nanometers. These signals typically originate near 87, 97, and 250 kilometers above the ground, respectively. Selecting the three wavelengths allows one system to sample distinct atmospheric layers.

Inside the instrument, incoming light forms a pattern of concentric interference rings. Tiny shifts in the pattern reveal motion along the viewing direction, while the width of the spectral line provides information about temperature. The instrument automatically looks north, south, east, west, and overhead, switching sequentially between the three wavelengths. The resulting observations capture wind and temperature variations at multiple heights during the same night.

The team tested the system from June 12 to 15, 2024. Winds measured near 87 and 97 kilometers showed reasonable agreement with observations from a meteor radar approximately 100 kilometers away. The researchers also compared the results with the HWM14 wind model and the NRLMSIS 2.1 atmospheric model. The radar provided an independent check of horizontal winds at the lower two heights; the models supplied a broader context for interpreting the wind and temperature measurements.

The ability to observe the layer near 250 kilometers extends the coverage beyond the altitude range of the meteor-radar measurements used in this study. Combining observations from the three layers could help researchers investigate how atmospheric disturbances develop and vary with height.