Skolnik M.I. A radar method for the detection of submerged submarines

Washington: Naval Research Laboratory, 1975. - 25 p.A review of NIDAR.
Radar detections of submerged submarines have been reported sporadically from the Fleet ever since World War II. Under the project name of NIDAR, this was investigated by Destroyer Development Group Two from 1956 to 1959. Although the participants in NIDAR believed they successfully detected submerged submarines, their results were generally treated with skepticism by the scientific community. The reported results of NIDAR are briefly reviewed in this report and it is concluded that there was sufficient evidence to indicate that submarine detections were made under certain conditions. A sample of these observations are summarized. An explanation of the effect is offered which depends on the reported radar observations being like those due to reflections from elevated convective cells. These cells, it is speculated, might be due to the disturbance to the water-vapor gradient, just above the surface, caused by the passage of the Bernoulli hump generated by the passage of the submarine. Turbulent buoyant cells are formed which rise and are detectable by radar.NIDAR
Attempts to explain NIDAR
Clear air turbulence model
DiscussionAppendix