Microflares in Low-lying Core Fields & Extended Coronal Heating J.G. Porter, E. Tandberg-Hanssen, R.L. Moore, D.H. Hathaway, D.A. Falconer, and K.P. Dere Marshall Space Flight Center The overall objective is to clarify the magnetic origins of coronal heating. The specific ofjective is to test our working hypothesis that in all solar regions, quiet and active, most coronal heating results from microflares and similar but cooler magnetic activity in low-lying core fields over polarity neutral lines in the photospheric magnetic flux. We will test this scenario against existing and new observations of the transition region and corona from SOHO/EIT, TRACE, and Yohkoh/SXT, along with vector magnetograms from SOHO/MDI and ground-based observatories. From these data, we propose to (1) examine the spatial distribvution of microflares to determine (a) whether microflares are concentrated at the feet of bright coronal loops or plumes in quiet regions as they are in active regions, and (b) the extent to which microflares occur on all neutral lines in the magnetic network; (2) investigate the dependence of microflaring on magnetic field strength, magnetic shear, and magnetic flux cancellation; (3) determine whether there are many microflares that are too cool to be seen in coronal images but can be seen in transition region images; (4) estimate whether the ensemble of network microflares, hot and cold, is powerful enough to drive the heating of the bulk of the corona. The proposed work builds on results from our recent and ongoing (FY96, FY97, and FY98) work supported by the Yohkoh and SOHO GI programs. The requested funding is mostly for the support of a talented postdoctoral scientist. Of relevance to NASA's Sun-Earth Connection program, our investigation will help acheive the major science goal of SOHO and TRACE of yielding a better understanding of coronal heating. In addition, our work will sharpen key questions about the magnetic roots of coronal heating to be addressed by high-resolution photospheric vector magnetograms and chromospheric and coronal images from future solar space missions such as Solar-B and Solar Lite.