def asi(tb85v, tb85h):
    """The asi ice concentration algorithm
    """
    P0 = 47.0
    P1 = 7.5
    P = tb85v - tb85h
    """method coefficients:"""
    d3=1.64/100000.0
    d2=-0.0016
    d1=0.0192
    d0=0.971
    """concentrations calculation:"""
    ct = d3 * P**3.0 + d2 * P**2.0 + d1 * P + d0
    return ct