Mesoscale Spatial Variability of Lower Thermospheric Winds During the Anomalous Transport Rocket Experiment

• Published in: Journal of geophysical research. Space physics 2022-05, Vol.127 (5), p.n/a
• Main Authors: Lehmacher, Gerald A., Larsen, Miguel F., Zanetti, Jessica
• Format: Article
• Language: English
• Subjects: Aluminum; Diurnal variations; Gravity waves; Payloads; Semidiurnal tides; Spatial variability; Statistical analysis; Thermospheric winds; Tidal waves; Tracers; Wave motion; Wave propagation; Waves; Wind; Wind fluctuations; Wind profiles; Wind shear; Wind structure; Wind variations
• ISSN: 2169-9380; 2169-9402
• DOI: 10.1029/2022JA030378

We present observations and analysis of seven horizontal wind profiles obtained by the trimethyl aluminum (TMA) tracer method on 27 March 2012 over the Atlantic ocean near Wallops Island, Virginia (37.9°N, 75.4°W). Payloads were launched in order to produce quasi‐simultaneous trails separated by tens to hundreds of kilometers. Tracer positions evolving in time and space were triangulated from three locations along the Atlantic seaboard and wind profiles between 90 and 140 km calculated. The wind profiles present a coherent wind structure dominated by very strong diurnal and semidiurnal tides up to 110 km and an upward propagating inertia‐gravity wave between 110 and 140 km. Properties such as horizontal and vertical wavelength could be extracted from the simultaneous observations at separate locations. A statistical analysis of the wind differences was performed to estimate power‐law coefficients of the second structure function at mesoscales. They show scale‐independence in the region of the largest wind shears, 100–110 km, and a scaling coefficient characteristic for isotropic wind fluctuations above and below this region. Plain Language Summary We present seven upper atmospheric wind profiles (90–140 km) measured with the tracer method. The winds were observed at seven different locations spaced over 500 km along a line from the Mid‐Atlantic coast. The winds show very similar structures below 110 km, presumably due to very large atmospheric tidal waves. A very distinct, smaller wave motion is evident above 110 km, because it was sampled at different locations. In some regions the variability of the winds show signs of large‐scale turbulence. Key Points Seven simultaneous wind profiles in the lower thermosphere, horizontally separated by up to 600 km, are dominated by strong tides A large‐scale upward propagating inertia‐gravity wave is evident in the observations The region between 100 and 110 km shows the largest mesoscale variability of winds and wind shears, independent of separation scale