def define_zone(x,y):
    """
    define the utm zone and the up/down parameters
    :param x: x coordinates
    :param y: y coordinates
    :return: new up/down & utm-zone fields
    """
    updown, zone = [], []
    for i in range(len(x)):
        updown.append('U') if y[i]>0 else updown.append('D')
        zone.append(31+int(x[i]//6))
    return updown,zone