def kH2CO3_NBS_CW98(TempK, Sal):
    """Carbonic acid dissociation constants following CW98."""
    F1 = 200.1 / TempK + 0.322
    pK1 = (3404.71 / TempK + 0.032786 * TempK - 14.8435 - 0.071692 * F1 * 
        Sal ** 0.5 + 0.0021487 * Sal)
    K1 = 10.0 ** -pK1
    F2 = -129.24 / TempK + 1.4381
    pK2 = (2902.39 / TempK + 0.02379 * TempK - 6.498 - 0.3191 * F2 * Sal **
        0.5 + 0.0198 * Sal)
    K2 = 10.0 ** -pK2
    return K1, K2
