THE 1992 JANUARY 5 FLARE AT 13.3-UT - OBSERVATIONS FROM YOHKOH

We discuss X-ray spectra and soft X-ray images of an M1.9 flare that o ccurred on 1992 January 5 near 13.3 UT. These data were obtained with instrumentation on the Japanese Yohkoh spacecraft. They cover the enti re rise phase of the flare. To supplement these data we have ground-ba sed magnetograms and Halpha spectroheliograms. We calculate the electr on temperature and emission measure of the flare as a function of time during the early rise phase using X-ray spectral line intensities and line ratios. Using spectral line widths, line profile asymmetries, an d wavelength shifts due to the Doppler effect, we calculate the dynami cal properties of the flare. The time development of the morphology of the flare, as revealed by the soft X-ray images and the Halpha spectr oheliograms, and the physical quantities inferred from the X-ray spect ra, are compared with chromospheric evaporation models. There is an en hancement of blueshifted emission that is closely correlated with the hard X-ray bursts. Heating of one loop in the flare is consistent with a conduction-evaporation model, but heating is found in several struc tures that do not appear to be physically associated with each other. No standard evaporation model can adequately explain all of the observ ations.