[15] for the MSLP field or in Ref. [16] or [17] for the 1000 hPa or 700 hPa field, respectively. Instead of looking for local minima, some cyclone detection algorithms compute the Laplacian of the MSLP field. Therein, cyclones coincide with local maxima, as used, e.g., in Refs. [18] and [19]. Low pressure systems are also marked by high values of relative vorticity, which is a measure for the rotation in a fluid. The 850 hPa relative vorticity field is used e.g. in Ref.