Volume imaging of aspect sensitivity in VHF radar backscatters: first results inferred from the Advanced Indian MST radar (AIR). Issue 12 (18th June 2022)

• Record Type: Journal Article
• Authors: Das, Siddarth Shankar; Ratnam, M.Venkat; Rao, M. Durga; Uma, K. N.
• Is Part Of: International journal of remote sensing. Volume 43:Issue 12(2022)
• Page Start: 4517
• Page End: 4540
• Publication Date: 2022-06-18
• Subjects: MST radar -- aspect sensitivity -- isotropic -- anisotropic turbulence; Remote sensing -- Periodicals; Télédétection -- Périodiques; 621.3678
• DOI: 10.1080/01431161.2022.2111667
• Languages: English
• ISSNs: 0143-1161

Abstract

ABSTRACT: Very-high frequency (VHF) radar echoes are known to be aspect sensitive in general, which could be either the manifestation of a thin stable layer providing sharp refractive index gradient or shear-driven steep layer structures. The present study for the first time shows the volume imaging of aspect sensitivity in the recently upgraded Advanced Indian Mesosphere Stratosphere Troposphere (MST) radar (AIR). The present configuration of radar can provide a better understanding of three-dimensional structures of turbulence and instabilities, which was not possible when the radar was operated in two orthogonal planes. Both isotropic and anisotropic layers/turbulence are observed at various height levels over the radar volume. Enhanced aspect sensitivity is observed between 6 and 9 km, which is attributed to the presence of dynamic instability arising due to strong wind shear and atmospheric stability. All the scatterers tend to become isotropic when both the square of wind shear and stability parameters are above 0.25 × 10 −3 s −2 . Due to the high aspect sensitivity, there may be an underestimate of 5–10% in wind velocity measurements, and it is higher for the low off-zenith beam angle.