The medieval climate anomaly in Europe: Comparison of the summer and annual mean signals in two reconstructions and in simulations with data assimilation

► It is possible to constrain a climate model to follow proxy-based reconstructions using data assimilation. ► MCA in Europe displays a rich structure that cannot be characterized as uniformly warm in space and time. ► In winter, warm MCA conditions are associated with a circulation similar to the positive phase of the NAO.► In summer, warm MCA conditions are associated with reduced westerlies and an anomalous advection from North Africa.