VHF profiler observations of the troposphere obtained over a flat desert in northern Per¿ show the presence of strong, quasi-sinusoidal oscillations in the vertical wind velocity with periods of around 8--18 min. These oscillations are a very typical feature of the vertical velocities over Piura. This paper presents an overview of the wave characteristics obtained at Piura until this point, including results obtained using two additional antennas built a few hundred meters to the west and south of the main antenna to measure horizontal wavelengths and phase velocities. Briefly, the Piura waves appear to have horizontal wavelengths of 1--3 km, with either westward or eastward phase velocities (in a ground-based reference frame) of 0.5--4 m s-1. Their occurrence appears to be causally related to the magnitude of the easterly wind, which blows over the Andean Cordillera some 60 km to the east of the site. ¿ 1998 American Geophysical Union