function [a_phi] = aphi(wavelength, Sf)
%This function computes a_phi based on the data of Aurea M 2002 (as
%modified in her paper with Bricaud, 2005, L&O method
wl = 400:2:650;
a_pico = [1.7439
1.8264
1.9128
1.9992
2.0895
2.1799
2.2702
2.3684
2.4666
2.5687
2.6669
2.7612
2.8437
2.9183
2.989
3.0479
3.1029
3.15
3.1854
3.2089
3.2247
3.2325
3.2286
3.2168
3.1932
3.154
3.1029
3.0361
2.9576
2.8712
2.7848
2.6944
2.5137
2.4273
2.3488
2.2781
2.2486
2.2192
2.172
2.1328
2.1013
2.066
2.0267
1.9835
1.9285
1.8657
1.7989
1.7203
1.6339
1.5357
1.4336
1.3276
1.2176
1.1076
1.0016
0.8994
0.8013
0.7109
0.6284
0.5538
0.487
0.432
0.3782
0.3307
0.2875
0.2486
0.2137
0.1842
0.1599
0.1402
0.1233
0.108
0.0935
0.0789
0.0656
0.053
0.0424
0.0344
0.029
0.026
0.0258
0.0268
0.0304
0.032
0.0331
0.0347
0.0355
0.0363
0.0382
0.0401
0.0416
0.0428
0.0432
0.0432
0.0432
0.0424
0.0416
0.0408
0.0408
0.0424
0.0452
0.0503
0.0562
0.0628
0.0695
0.0758
0.0821
0.088
0.0939
0.1002
0.106
0.1123
0.1178
0.1229
0.1261
0.128
0.1288
0.1296
0.1308
0.1331
0.1371
0.1422
0.1493
0.1591
0.1728
0.1909];
a_micro = [1.574
1.584
1.6
1.617
1.633
1.654
1.669
1.674
1.684
1.697
1.708
1.71
1.716
1.737
1.763
1.793
1.812
1.827
1.83
1.834
1.824
1.8
1.771
1.741
1.712
1.685
1.667
1.65
1.641
1.631
1.631
1.623
1.616
1.606
1.592
1.568
1.542
1.509
1.481
1.459
1.437
1.415
1.399
1.387
1.377
1.367
1.349
1.338
1.319
1.301
1.271
1.242
1.222
1.196
1.169
1.141
1.118
1.096
1.075
1.057
1.035
1.013
0.992
0.977
0.959
0.944
0.927
0.909
0.888
0.868
0.847
0.826
0.806
0.785
0.764
0.737
0.711
0.682
0.653
0.626
0.604
0.58
0.555
0.535
0.514
0.501
0.487
0.478
0.475
0.468
0.464
0.459
0.452
0.452
0.449
0.443
0.433
0.424
0.416
0.406
0.401
0.4
0.403
0.408
0.416
0.429
0.443
0.458
0.473
0.487
0.495
0.499
0.504
0.514
0.521
0.525
0.532
0.535
0.534
0.535
0.532
0.528
0.526
0.528
0.538
0.549];
a_pico = interp1(wl,a_pico/a_pico(53),wavelength,'linear');
a_micro = interp1(wl,a_micro/a_micro(53),wavelength,'linear');
aphi = Sf*a_pico + (1-Sf)*a_micro;
a_phi = interp1(wavelength,aphi,wavelength,'linear');