50 MHz radar observations of mid-latitude E-region irregularities at Camp Santiago, Puerto Rico

A 50 MHz radar interferometer was used near Salinas, Puerto Rico, to probe the meter-scale E-region plasma density irregularities during two campaigns conducted in 1998. During the February-April period E-region echoing layers were primarily observed between 90 and 100 km heights. The layers were typically thin (~1 km) and unstructured, although in several cases short period (~90 s) layer oscillations were observed. During the June-July period E-region echoes showed more varied characteristics. In addition to low altitude layers, quasi-periodic structures with descending echoing layers were observed at altitudes above 100 km. Zonal motions detected during descending layer events were at times variable and oscillated between westward and eastward directions while the layer descent rates remained fixed.