Solar brightness distribution and its variability at 3 millimeter wavelength

Solar mapping at 3.4 millimeter wavelength has shown the existence of various spatial structures in brightness distribution. The most prominent structure is presented by the local sources of the slowly varying component of the solar radio emission. Usually they coincide with active regions. Some sources have no corresponding optical counterparts. Using synoptic radio maps, latitudinal belts of enhanced brightness were detected at the north and south hemispheres. These belts seem to coincide with sunspot zones, but the enhanced emission exists independently of sunspot group appearance. Comparison of our maps with XUV images shows a noticeable resemblance. Sources above active regions and latitudinal belts of enhanced brightness are seen in both ranges as well as coronal holes.