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The present solar cycle is particular in many aspects: it had a delayedrising phase, it is the weakest of the last 100 years, and it presents twopeaks separated by more than one year. To understand the impact of thesecharacteristics on the solar chromosphere and coronal dynamics, images from awide wavelength range are needed. In this work we use the 17~GHz radiocontinuum, formed in the upper chromosphere and the EUV lines 304 and171~{\AA}, that come from the transition region (He II) and the corona (Fe IX,X), respectively. We analyze daily images at 304 and 171~{\AA} obtained by theAtmospheric Imaging Assembly (AIA). The 17~GHz maps were obtained by theNobeyama Radioheliograph (NoRH). To construct synoptic limb charts, wecalculated the mean emission of delimited limb areas with 100" wide and angularseparation of $5^\circ$. At the equatorial region, the results show anhemispheric asymmetry of the solar activity. The northern hemisphere dominanceis coincident with the first sunspot number peak, whereas the second peakoccurs concurrently with the increase in the activity at the south. The polaremission reflects the presence of coronal holes at both EUV wavelengths,moreover, the 17~GHz polar brightenings can be associated with the coronalholes. Until 2013, both EUV coronal holes and radio polar brightenings weremore predominant at the south pole. Since then they have not been apparent inthe north, but thus appear in the beginning of 2015 in the south as observed inthe synoptic charts. This work strengthens the association between coronalholes and the 17~GHz polar brightenings as it is evident in the synoptic limbcharts, in agreement with previous case study papers. The enhancement of theradio brightness in coronal holes is explained by the presence of brightpatches closely associated with the presence of intense unipolar magneticfields.

Comparison of solar radio and EUV synoptic limb charts during the present solar maximum