Proceedings with Extended Abstracts (single PDF file) - Radio ...

most occidental area of South America and very sensible to the El Niño Southern Oscillation(ENSO) phenomenon.The Piura ST radar operates since 1989 (e.g., Gage et al., 1991). Since then, frequentlaunches of meteorological balloons have been done from this site to complement the windprofile observations. These soundings were carried out almost daily during the 1997-1998 ENSOphenomenon. The gathered data was used to obtain the refractive properties of the loweratmosphere including the boundary layer.4. MethodologyFigure1. Location and picture of the Piura ST radarThe meteorological soundings were made using a launch system provided by the NOAAAeronomy Laboratory in Boulder, CO. This system consists of a radiosonde and a receiver. Thetransmitter part uses a 403.5 Mhz Vaisala radiosonde which is lifted by a 200 gr. balloon filledwith helium gas, while the receiver part uses a 403.5 MHz receiver, an omni-directional antennaand a portable personal computer. The computer is programmed using the PC-TALK softwarefor reception and recording data. The recorded data are: time (t), Temperature (T), humidtemperature (T w ) and atmospheric pressure (p).According to Equations 1 and 2, the necessary data to evaluate the refraction index aretemperature (T), vapor pressure ( e ) and the atmospheric pressure (p). Vapor pressure is deducedbased on the data of temperature (T), relative humidity (HR) and humid temperature (T w ). Height(h) is calculated based on the hydrostatic balance equation.RT ⎛ p ⎞h = ln ⎜ 2⎟Equation 3g ⎝ p1 ⎠Figure 2 shows the relationship between the recorded data (T, T w , p) to get the vaporpressure ( e ) and to use them in the refractivity equation (Equation 2). To read the recorded dataand apply this relationship, an IDL (Interactive Dates Language) program was coded.67