Authors: Andrew M. Leisner (George Mason University), Jeremey A. Grajeda (New Mexico State University), C. Nick Arge (NASA/GSFC), Michael Kirk (ASTRA), Laura Boucheron (New Mexico State University), Jie Zhang (George Mason University)

Identifying coronal holes in solar disk images is very challenging, yet critical, as they serve as a key constraint for coronal models. In this poster, we discuss a process to create synchronic coronal hole maps using the Active Contours Without Edges (ACWE) method for identifying coronal holes in EUV disk images. ACWE is an image segmentation technique that defines one or more contours by minimizing an energy function, which separate an image into foreground and background. When adapted to coronal hole segmentation, it produces a binary map of coronal holes in the original EUV image that is no longer defined by an intensity threshold. ACWE was used to derive coronal hole boundaries in a set of STEREO EUVI/A, EUVI/B, and SDO/AIA disk images from June and July 2010. The ACWE results were then combined into global synchronic maps using a synchronic map generating algorithm. By using ACWE, this synchronic map could be generated while sidestepping the issue of intercalibration of the three separate instruments. Next, the ACWE synchronic maps were directly compared to two sets of WSA model coronal hole predictions, where ADAPT photospheric magnetic field maps were used as its input. One set included an added far side active region, while the other did not. This was done quantitatively by calculating both the Jaccard index and the overlap coefficient for each set of maps.