Elevation-dependent turbulence-induced image degradation along a 20-km near-ground optical path from time-lapse imagery
Year: 2026
Type: article
Abstract: Although the physics of near-ground turbulence is well understood theoretically, few experimental studies examine its height-dependent structure under real-world conditions. We present a systematic observational study of elevation-dependent turbulence-induced image degradation along a 20-km near-ground horizontal path. The study is framed as an observational analysis and does not provide a rigorous connection to turbulence propagation theory; this gap is acknowledged throughout. Passive time-lapse imagery acquired at the Jornada Experimental Range (JER) in New Mexico is used—a rare long-term field dataset under natural desert conditions, from which seven summer days are analyzed. Three adjacent elevation regions spanning the upper ridge, mid-slope, and mountain base are examined using displacement variance (DV), mean squared error (MSE), and structural similarity index measure (SSIM), computed per region relative to an averaged reference frame. DV is derived from a patch-based ridge regression displacement estimator, with per-frame mean displacement subtracted to isolate turbulence-induced motion from residual refraction drift. Two primary days are examined in depth. August 6 exhibits strong turbulence with the bottom region showing the highest DV, partially consistent with boundary layer predictions. June 24 exhibits mild turbulence with the top region showing the highest DV, departing from boundary layer expectations. Intra-day ordering reversals in MSE and SSIM occur consistently around 10:30 to 11:00, whereas DV ordering remains stable throughout each day and is less correlated with solar elevation angle than MSE or SSIM. Order-of-magnitude Cn2 estimates derived from the displacement statistics fall within the expected near-ground surface-layer range, with boundary layer-consistent ordering observed on 3 of 7 days. These results demonstrate that passive imagery provides elevation-resolved observations of turbulence-induced degradation and establish an observational foundation for future passive retrieval of Cn2 as a function of height.
Source: Optical Engineering
Author: Wardeh Al-Younis
Institution: Jadara University
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W7204477936