Signatures of high-energy particles in H-alpha emission observed before the solar flare of 16 August 2004

The current contribution investigates the chromospheric emission preceding the onset of the solar flare of 16th August 2004 using the observations with high temporal resolution from RHESSI, Large Solar Vacuum Telescope (LSVT), Nobeyama Radioheliograph (NoRH, 17 and 34 GHz) and Siberian Solar Radio Telescope (SSRT, 5.7 GHz). The observations reveal a close temporal correlation between the H-alpha intensity observed with LSVT, hard and soft X-ray emissions observed with RHESSI, and microwave fluxes observed with NoRH and SSRT that can be caused only by high-energy particles. The images of Nobeyama radioheliograph and SSRT showed two microwave sources, but only one of which is co-spatial with the HXR-source caused by electrons with power law energy spectrum while the second one has only H-alpha emission source appearing nearly simultaneously with HXR source. The observational H-alpha results are fit by the simulations of non-thermal hydrogen emission in the chromosphere caused by beam electrons or protons using the hydrodynamic and full non-LTE approaches. Possible event scenario is discussed.