Simultaneous Radar Reflectivity Measurements and Refractive Index Spectra in the Clear Atmosphere

Abstract

Simultaneous measurements of refractive index and radar reflectivity have been made in the clear atmosphere. The theoretical relationship between the refractive index spectrum and reflectivity de· scribed by Tatarski was used to compute reflectivity from the refractive index data. Excellent agree· ment is shown between the computed and measured reflectivity. These results indicate, (1) reflections from the clear atmosphere can be described quantitatively in terms of the refractivity spectrum, and (2) the -j refractivity spectrum well represents the atmosphere for these data out to limiting micro· scales smaller than 5 em.

Microscale ordered motions and atmospheric structure associated with thin echo layers in stably stratified zones

“…Instead, the relevant spectrum appears to be controlled by the thickness of the thin interfacial zone and the locally enhanced refractivity gradient across it. Thus the estimation of the 5-cm scale refractivity spectral density, and the associated reflectivity, by extrapolation from much larger scales in the manner of Kropfli et al (1968) is erroneous.…”

Observation of Clear-Air Echoes with 3.2-cm Radars

“…They concluded that there were two types of clear-air echoes: one is composed of discrete coherent echoes which seemed to be attributed to large insects (dot echoes), and another is composed of incoherent echoes which would be due to the fluctuations of refractive index in the clear-air. This conclusion has been supported by other experiments using ultrasensitive radars and aircrafts Konrad et al, 1968;Kropfli et al, 1968;Konrad and Robinson, 1972). It has been made clear by many authors that the fluctuations of refractive index detected as clear-air echoes were related to thin stable inversions, convective thermals, Benard convection cells, breaking gravity waves, high tropospheric layers which are sufficiently turbulent and sea breeze front (Hardy and Ottersten, 1969;Hardy and Katz, 1969;Ottersten, 1969;Atlas et al, 1970a;Konrad, 1970;Gossard et al, 1971;Konrad and Robinson, 1973;Noonkester, 1976;Yanagisawa et al, 1978).…”

Radar and sodar probing of waves and turbulence in statically stable clear-air layers

“…These layers usually correspond in height to regions having sharp vertical gradients in refractive index. Additional evidence for the existence of clear-air radar layers associated with large variations of refractive index has been given by Saxton et al (1964), Hardy et al (1966), and Kropfli et al (1968). Multiple stratifications have been reported recently by Ottersten (1969a), Katz (1969), Crane (1970), Kropfti (1971) and Starr and Browning (1972).…”