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A proxy for horizontal electric currents in the solar photosphere wassuggested. For a set of evolving active regions (ARs) observed with {\it Solarand Heliospheric Observatory (SOHO)} Michelson Doppler Imager (MDI) in the highresolution mode, the dissipation spectrum, $k^2E(k)$, and the spatial structureof dissipation, i.e., the Stokes dissipation function $\epsilon(x,y)$, werecalculated from the observed $B_z$ component of the magnetic field. Thesefunctions allowed us to calculate (a part of) the horizontal electric currentdensity in the photosphere. It was shown that as an active region emerges,large-scale horizontal electric currents are gradually generated and determinea bulk of dissipation. When an active region decays, the large-scale horizontalcurrents decay faster than the small-scale ones. The density of horizontalcurrents in active regions is in the range of $<j_h > \sim (0.008 - 0.028)$A/m$^2$, that is compatible with the density of vertical currents in activeregions. We suggest two possible mechanisms for generation of such horizontalcurrents in the photosphere. One of them is the drift motions of chargedparticles in the medium of varying plasma pressure gradient in a horizontalplane at the periphery of a sunspot. Such a drift can produce quasi-circularclosed horizontal currents around sunspots. Another possibility could be anexistence of horizontal axial current inside a highly twisted horizontalmagnetic structure laying in the photosphere along the magnetic neutral line.The horizontal currents may contribute significantly to the dynamics of thephotosphere/corona coupling, as well as the estimation of non-potentiality ofARs.

Spectrum of Magnetic Dissipation and Horizontal Electric Currents in the Solar Photosphere