Research Projects

Atmospheric optical turbulence, resulting from fluctuations in air density due to thermal gradients and wind shear, is a critical factor in climate science, aviation, satellite communication, optical astronomy, and directed energy systems. A key parameter for quantifying optical turbulence is the refractive index structure parameter (Cn2), which measures the intensity of air density fluctuations. Current methods for estimating Cn2 typically rely on surface-based point measurements using devices such as sonic anemometers, Resistance Temperature Detectors (RTDs), or scintillometers. These methods often assume homogeneous turbulence over large areas, which can lead to inaccuracies when accounting for spatial variations. Time-lapse imagery could provide a comprehensive method for estimating Cn2. Although there have been isolated studies using airborne platforms to measure turbulence, these have largely focused on point measurements and have not addressed the atmospheric column. Time-lapse imagery from airborne platforms provides an opportunity to develop a novel approach for measuring optical turbulence across a larger spatial domain. The proposed research aims to bridge this gap and contribute to the development of satellite sensors for turbulence monitoring, particularly for future Indian space missions. This study will be conducted in three phases. In the first phase, in-situ surface measurements of Cn2 will be obtained using RTDs and other meteorological sensors, which will serve as baseline data for understanding surface layer Cn2. These surface measurements will be critical for validating the airborne data obtained in subsequent phases. In the second phase, time-lapse imagery will be employed to estimate Cn2 from the surface. The time-lapse images will be processed to capture variations in optical intensity and displacement. The results will help refine the methodology for estimating turbulence from time-lapse imagery and provide insights into the relationship between turbulence and meteorological conditions. The third phase will focus on airborne measurements of Cn2 using time-lapse imagery carried out using tethered balloons and drones. The data obtained from the first two phases will serve to validate and refine the airborne measurement techniques. In addition, error analysis will be conducted to improve the accuracy and reliability of the turbulence estimates derived from airborne imagery. This research represents a novel approach to measuring optical turbulence using time-lapse imagery from airborne platforms, a method hitherto unexplored. The findings will be of significant value in advancing understanding of atmospheric turbulence and will directly contribute to the development of satellite-based sensors for monitoring optical turbulence in future Indian space missions. The results will also be helpful in the design of satellite-to-Earth wireless optical communication links and directed energy applications.