Default "pure water" absorption (a) and scattering (b) coefficients. Based on:
200-300 nm: R.C. Smith and K. Baker, 1981. Appl. Optics 20(2), 177-184.
300-340 nm: smooth transition from Smith & Baker at 300 to Sogandares & Fry at 340
340-380 nm: F.M. Sogandares and E.S. Fry, 1997. Appl. Optics 36(33), 8699-8709.
380-725 nm: R.M. Pope and E.S. Fry, 1997.  Appl. Optics 36(33), 8710-8723.  
725-800 nm: R.C. Smith and K. Baker, 1981. Appl. Optics 20(2), 177-184.
800-1150nm: D. Segelstein, 1981. "The Complex Refrac. Index of Water", M.S. Thesis, U. Missouri
Measured absorption data were spline fit and resampled to 5 nm resolution.
Scattering coefs were computed from A. Morel, 1974.  "Optical Aspects Oceanogr.," Chap 1 (L&WEq. 3.31)
wavelen(nm) a(1/m)        b(1/m)        
  200.0   3.0700e+000   1.5140e-001
  205.0   2.4819e+000   1.3608e-001
  210.0   1.9900e+000   1.2263e-001
  215.0   1.6075e+000   1.1077e-001
  220.0   1.3100e+000   1.0030e-001
  225.0   1.0901e+000   9.1021e-002
  230.0   9.2700e-001   8.2776e-002
  235.0   8.1200e-001   7.5432e-002
  240.0   7.2000e-001   6.8874e-002
  245.0   6.3428e-001   6.3004e-002
  250.0   5.5900e-001   5.7739e-002
  255.0   5.0262e-001   5.3005e-002
  260.0   4.5700e-001   4.8740e-002
  265.0   4.1492e-001   4.4890e-002
  270.0   3.7300e-001   4.1407e-002
  275.0   3.2966e-001   3.8252e-002
  280.0   2.8800e-001   3.5387e-002
  285.0   2.5114e-001   3.2782e-002
  290.0   2.1500e-001   3.0409e-002
  295.0   1.7622e-001   2.8245e-002
  300.0   1.4100e-001   2.6267e-002
  305.0   1.1648e-001   2.4456e-002
  310.0   9.9000e-002   2.2797e-002
  315.0   8.5249e-002   2.1275e-002
  320.0   7.3000e-002   1.9876e-002
  325.0   6.1085e-002   1.8588e-002
  330.0   5.0000e-002   1.7402e-002
  335.0   4.0600e-002   1.6307e-002
  340.0   3.2500e-002   1.5296e-002
  345.0   2.5603e-002   1.4361e-002
  350.0   2.0400e-002   1.3496e-002
  355.0   1.7589e-002   1.2694e-002
  360.0   1.5600e-002   1.1949e-002
  365.0   1.3160e-002   1.1258e-002
  370.0   1.1400e-002   1.0615e-002
  375.0   1.1496e-002   1.0017e-002
  380.0   1.1370e-002   9.4603e-003
  385.0   9.4100e-003   8.9408e-003
  390.0   8.5100e-003   8.4561e-003
  395.0   8.1300e-003   8.0033e-003
  400.0   6.6300e-003   7.5800e-003
  405.0   5.3000e-003   7.1839e-003
  410.0   4.7300e-003   6.8131e-003
  415.0   4.4400e-003   6.4655e-003
  420.0   4.5400e-003   6.1395e-003
  425.0   4.7800e-003   5.8335e-003
  430.0   4.9500e-003   5.5461e-003
  435.0   5.3000e-003   5.2759e-003
  440.0   6.3500e-003   5.0217e-003
  445.0   7.5100e-003   4.7825e-003
  450.0   9.2200e-003   4.5571e-003
  455.0   9.6200e-003   4.3447e-003
  460.0   9.7900e-003   4.1443e-003
  465.0   1.0110e-002   3.9552e-003
  470.0   1.0600e-002   3.7766e-003
  475.0   1.1400e-002   3.6079e-003
  480.0   1.2700e-002   3.4483e-003
  485.0   1.3600e-002   3.2973e-003
  490.0   1.5000e-002   3.1544e-003
  495.0   1.7300e-002   3.0191e-003
  500.0   2.0400e-002   2.8908e-003
  505.0   2.5600e-002   2.7692e-003
  510.0   3.2500e-002   2.6538e-003
  515.0   3.9600e-002   2.5443e-003
  520.0   4.0900e-002   2.4402e-003
  525.0   4.1700e-002   2.3414e-003
  530.0   4.3400e-002   2.2475e-003
  535.0   4.5200e-002   2.1581e-003
  540.0   4.7400e-002   2.0731e-003
  545.0   5.1100e-002   1.9922e-003
  550.0   5.6500e-002   1.9151e-003
  555.0   5.9600e-002   1.8417e-003
  560.0   6.1900e-002   1.7717e-003
  565.0   6.4200e-002   1.7050e-003
  570.0   6.9500e-002   1.6413e-003
  575.0   7.7200e-002   1.5805e-003
  580.0   8.9600e-002   1.5225e-003
  585.0   1.1000e-001   1.4671e-003
  590.0   1.3510e-001   1.4141e-003
  595.0   1.6720e-001   1.3635e-003
  600.0   2.2240e-001   1.3151e-003
  605.0   2.5770e-001   1.2688e-003
  610.0   2.6440e-001   1.2245e-003
  615.0   2.6780e-001   1.1820e-003
  620.0   2.7550e-001   1.1414e-003
  625.0   2.8340e-001   1.1025e-003
  630.0   2.9160e-001   1.0652e-003
  635.0   3.0120e-001   1.0294e-003
  640.0   3.1800e-001   9.9511e-004
  645.0   3.2500e-001   9.6221e-004
  650.0   3.4000e-001   9.3064e-004
  655.0   3.7100e-001   9.0034e-004
  660.0   4.1000e-001   8.7124e-004
  665.0   4.2900e-001   8.4329e-004
  670.0   4.3900e-001   8.1644e-004
  675.0   4.4800e-001   7.9064e-004
  680.0   4.6500e-001   7.6583e-004
  685.0   4.8600e-001   7.4197e-004
  690.0   5.1600e-001   7.1902e-004
  695.0   5.5900e-001   6.9694e-004
  700.0   6.2400e-001   6.7569e-004
  705.0   7.0400e-001   6.5523e-004
  710.0   8.2700e-001   6.3552e-004
  715.0   1.0070e+000   6.1655e-004
  720.0   1.2310e+000   5.9826e-004
  725.0   1.4890e+000   5.8064e-004
  730.0   1.7990e+000   5.6366e-004
  735.0   2.1289e+000   5.4728e-004
  740.0   2.3800e+000   5.3148e-004
  745.0   2.4590e+000   5.1624e-004
  750.0   2.4700e+000   5.0154e-004
  755.0   2.5098e+000   4.8735e-004
  760.0   2.5500e+000   4.7365e-004
  765.0   2.5472e+000   4.6042e-004
  770.0   2.5100e+000   4.4764e-004
  775.0   2.4460e+000   4.3530e-004
  780.0   2.3600e+000   4.2337e-004
  785.0   2.2549e+000   4.1184e-004
  790.0   2.1600e+000   4.0070e-004
  795.0   2.1042e+000   3.8993e-004
  800.0   2.0700e+000   3.7951e-004
  805.0   2.0494e+000   3.6943e-004
  810.0   2.0916e+000   3.5968e-004
  815.0   2.2463e+000   3.5024e-004
  820.0   2.4669e+000   3.4111e-004
  825.0   2.8190e+000   3.3227e-004
  830.0   3.0975e+000   3.2371e-004
  835.0   3.3423e+000   3.1542e-004
  840.0   3.7098e+000   3.0738e-004
  845.0   3.9835e+000   2.9960e-004
  850.0   4.3758e+000   2.9206e-004
  855.0   4.6308e+000   2.8476e-004
  860.0   4.9393e+000   2.7767e-004
  865.0   5.1535e+000   2.7081e-004
  870.0   5.3659e+000   2.6415e-004
  875.0   5.6114e+000   2.5769e-004
  880.0   5.8288e+000   2.5142e-004
  885.0   6.0074e+000   2.4534e-004
  890.0   6.2567e+000   2.3944e-004
  895.0   6.4708e+000   2.3372e-004
  900.0   6.8198e+000   2.2816e-004
  905.0   7.1028e+000   2.2276e-004
  910.0   7.8970e+000   2.1753e-004
  915.0   9.4786e+000   2.1244e-004
  920.0   1.1171e+001   2.0749e-004
  925.0   1.4658e+001   2.0269e-004
  930.0   1.9270e+001   1.9803e-004
  935.0   2.3414e+001   1.9349e-004
  940.0   2.9309e+001   1.8908e-004
  945.0   3.4684e+001   1.8480e-004
  950.0   3.8304e+001   1.8064e-004
  955.0   4.1981e+001   1.7659e-004
  960.0   4.4081e+001   1.7265e-004
  965.0   4.4890e+001   1.6881e-004
  970.0   4.5310e+001   1.6509e-004
  975.0   4.4852e+001   1.6146e-004
  980.0   4.3710e+001   1.5793e-004
  985.0   4.2409e+001   1.5450e-004
  990.0   4.1418e+001   1.5116e-004
  995.0   3.9679e+001   1.4790e-004
 1000.0   3.7697e+001   1.4473e-004
 1005.0    3.5354E+01    1.4165E-04
 1010.0    3.3172E+01    1.3865E-04
 1015.0    3.1161E+01    1.3572E-04
 1020.0    2.9280E+01    1.3287E-04
 1025.0    2.6888E+01    1.3009E-04
 1030.0    2.4575E+01    1.2739E-04
 1035.0    2.2381E+01    1.2475E-04
 1040.0    2.0383E+01    1.2218E-04
 1045.0    1.8520E+01    1.1968E-04
 1050.0    1.6910E+01    1.1723E-04
 1055.0    1.6084E+01    1.1485E-04
 1060.0    1.5364E+01    1.1253E-04
 1065.0    1.5049E+01    1.1026E-04
 1070.0    1.4859E+01    1.0806E-04
 1075.0    1.5202E+01    1.0590E-04
 1080.0    1.5666E+01    1.0380E-04
 1085.0    1.6563E+01    1.0175E-04
 1090.0    1.7526E+01    9.9748E-05
 1095.0    1.8617E+01    9.7795E-05
 1100.0    1.9859E+01    9.5889E-05
 1105.0    2.1560E+01    9.4029E-05
 1110.0    2.3544E+01    9.2213E-05
 1115.0    2.6554E+01    9.0440E-05
 1120.0    3.0159E+01    8.8708E-05
 1125.0    3.6170E+01    8.7018E-05
 1130.0    4.3384E+01    8.5367E-05
 1135.0    5.3152E+01    8.3754E-05
 1140.0    6.5060E+01    8.2178E-05
 1145.0    8.0012E+01    8.0639E-05
 1150.0    9.8335E+01    7.9136E-05
   -1.0  -1.0000e+000  -1.0000e+000