First observations of quasi-periodic radar echoes from Stanford, California

We present first results from a search for quasi-periodic (QP) radar echoes in the American sector. These echoes, which are produced by underdense bac kscatter from field-aligned irregularities in nighttime midlatitude sporadi c E (E-s), have been observed in the Asian sector but never before at other longitudes. Using radar data collected during the summer in 1998 from Stan ford, California, we show that QP echoes can indeed be detected in the Amer ican sector and that they resemble those found in central and southern Japa n. We then show that the invariance of a feature in the pattern of QP echoe s, which persisted for five hours on 3 August 1998, raises questions regard ing the existing models for QP echoes.