Seasonal characterization of the equatorial electrojet height rise over Brazil as observed by the RESCO 50Â MHz back-scatter radar

In this paper, we present the seasonal characteristics of the post-noon rise of the equatorial electrojet 3-m irregularities scattering region observed over São Luís, Brazil (2.3∘S, 44.2∘W, dip:-0.5∘). The study is based on a 1 year data set collected by the 50 MHz coherent back-scatter radar (also known by the acronym RESCO), that started operation in 1998. Using a method to estimate the moments from each individual back-scattered power profiles that constitute the standard range-time-intensity (RTI) maps we were able to determine the following representative parameters of the electrojet: the total power back-scattered by the electrojet irregularities (EJP), the thickness of the electrojet back-scattered power profile (EJT), the height of the center of the back-scatter region, that is, the power profile, (EJC), and the noise level corresponding to each power profile (EJN). The parameterization was applied to all selected daily RTI maps from 2002. The analysis was carried out by grouping the data according to the radar beam angle (tilted 30∘ westward or eastward), the magnetic disturbance indices Kp and the season, which enables us to quantify the differences in the parameters on these bases. The results are presented and discussed here focusing on the post-noon ascent of the EJC. We will also present results on the east-west asymmetry in the radar back-scattered echo power confirming our previous results, and on the appearance of a scattering region after sunset during magnetically quiet conditions around the southern summer solstice.