Date: Sun, 05 Jul 2009 22:49:10 +0100
From: Martin Shough <parcellular@btinternet.com>
Subject: Re: Wanna help? Okinawa (nr), Guam sometime in 1945 - radar

Nr. Guam, Western Pacific
PRECIS: A US Navy radar officer who requested anonymity recalled several incidents of unexplained radar returns on his vessel's air search radar in the area between Guam and Saipan during the summer of 1945. Typically they appeared as "large groups" of echoes detected at about 100 miles range on courses inbound towards the ship. Plotted speeds were over 1000 mph. The targets "passed overhead at approximately two thousand feet and showed up on the radar screen as definitely solid objects." Visual lookouts on alert deckside saw nothing, and the radar officer himself on one occasion went on deck to search the sky, but he too saw nothing. He was adamant that the targets were not due to "ionized clouds, inversions, sea gulls, mechanical defects, or any of the other common explanations." The equipment was carefully checked and found to be functioning properly.

NOTES: Statistically speaking, the summer months in a tropical zone 14 degrees from the equator might favour anomalous propagation (AP) conditions, and several of the features described here are characteristic of AP. Others - such as "passing overhead at 2000 feet", which implies an incidence moving close to or through the normal - are perhaps not. But despite the officer's convictions, allowance has to be made for the fact that these incidents were apparently recalled some years after the event and details may be unreliable. Furthermore, radar theory was very much in its infancy in 1945, and it is doubtful that even an experienced operator would have been familiar with many of the vagaries of anomalous propagation which, at the time, were the subject of intense allied research under the direction of the Wave Propagation Committees of the US Joint and Combined Chiefs of Staff. Some of the fundamentals of radio ducting were coming to be understood, but mechanisms such as scattering from winddriven waves on an inversion surface, insect "angels" and the dielectric properties of clear air turbulence were not fully described until the mid 'fifties or even later. Many examples of such radar ghosts in the AP-prone atmosphere of the Far East theatre are known to have been studied by Naval Operations during and after the war, and the likelihood is that the "solid although invisible objects" reported here fall in the AP category.