def modelled_anomaly(ssh_m, ssh_tides):
    """
    Calculates the modelled ssh anomaly by finding the difference between a simulation with all forcing and a simulation with tides only.

    :arg ssh_m: An array of modelled ssh
    :type ssh_m: numpy array

    :arg ssh_tides: Array tides only simulation
    :type ssh_tides: numpy array

    :returns: anom: the difference between all_forcing and tidesonly
    """
    anom=ssh_m-ssh_tides
    return anom