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

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

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ATMOSPHERIC REFRACTIVITY PROFILES OVER PIURA ST RADARRodolfo Rodríguez, Freddy Sosa and Miguel CarriónUniversidad de Piura, Piura - Peru1. AbstractThe Piura 50-MHz ST radar is part of the Trans-Pacific Pro<strong>file</strong>r Network (TPPN) thatmonitors the atmospheric dynamics along the Equatorial Pacific Ocean. This system is inoperation since 1989 and it is located in the northern coast of Peru, (05˚ S, 80˚ W) one of thecontinental regions most affected by climatic anomalies due to the El Niño-Southern Oscillation(ENSO) phenomenon. In order to complement the atmospheric observations of wind pro<strong>file</strong>s<strong>with</strong> this radar, meteorological balloon launchings have been made to gather temperature,humidity and pressure pro<strong>file</strong>s. From these data we have deduced the first atmosphericrefractivity pro<strong>file</strong>s that the Piura radar system operates under. Characteristics and variability ofthese pro<strong>file</strong>s are shown in this work.2. IntroductionIt is well known that the macroscopic changes of radio refractive index (η) in space causerefraction or reflection and that microscopic changes cause scattering (Sato, 1989). Also, it iswidely accepted that major contributions to η at frequencies of HF through UHF bands in thetroposphere and stratosphere can be expressed approximately as (e.g., Balsley and Gage, 1980):−5−17.76x10p 3.75x10eη −1=+Equation 12T Twhere η is the refraction index, e is the vapor pressure (mB), T is the temperature (K) and p theatmospheric pressure (mB). Since in the atmosphere η is just little greater than 1 and itsvariations are very small, it is convenient to use the refractivity (N) defined as:56 77.6 p 3.75x10eN = ( η −1)x10= +Equation 22T TThe first term of Equations 1 and 2 is function of p and T and it corresponds to the contributionof the dry air. The second term is function of e and T which corresponds to the contribution ofthe water vapor in the low and medium atmosphere (Kingsley and Quegan, 1992).In this work we have applied these formulas to get the first refractivity pro<strong>file</strong>s over the Piura STradar site.3. Piura siteThe Piura ST radar is located in the oriental end of the Trans-Pacific Pro<strong>file</strong>r Network(TPPN). Like all the radars of this chain, this one is located near the equatorial line, (05˚S,80˚W), however, unlike the others, it is the only one situated in continental area. Piura is the66

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