Introduction The forecasting of solar eruptions and coronal mass ejections CMEs is one of the most important practical issues in solar physics. Both have crucial impacts on space weather. They occur when the magnetic field structure in the lower solar atmosphere becomes unstable. Observations suggest one of the key drivers of this instability is the emergence of complex entangled magnetic field from below the solar surface photosphere. Reliable means of predicting these eruptions in the presence of magnetic flux emergence are a key goal in the field, but have so far proved elusive. We will develop the magnetic winding flux as predictive diagnostic of eruptiveCME events. This is a measurement of distribution of entanglement in the emerging field. Highly twisted magnetic field is a strong indicator of subsequent eruptive activity, existing diagnostics at the photosphere fail to reliably detect its presence in complex observational data. The PI and Co-I have pioneered the use of magnetic winding flux in emergence simulations to overcome this problem, showing it detects when twisted magnetic field enters the solar atmosphere. They developed code to measure the magnetic winding accurately in photospheric magnetogram data the main source of observation of the solar magnetic field. To do so we must first overcome the uncertainty associated with observational data. We will perform a plethora of systematically varied magnetic flux emergence simulations, generating a data bank which will then be used to augment magnetic winding flux measurements obtained from the observational data. In particular this information will,a establish what likely structure is missing from the observed data,b assess of the level of confidence of the observational data, andc assign it to a particular class of field type to allow more consistent predictive performance.Results This pilot study demonstrated three key scientific findings regarding the magnetic winding.