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# TWERSKY

Figure: Schematic of the TWERSKY problem.

The previous Pekeris problem is modified by the inclusion of surface scatter. The rough surface involves a density of 0.092 bosses per km of width and height . Note that the KRAKEN \ result differs from the KRAKENC and SCOOTER results. This reflects the error in using a perturbation theory which however is probably negligible considering the approximations of the scatter model.

```'Pekeris problem with Twersky ice scatter'
10.0
1
'NSF'
0.092  8.2  5.1
500 0.0 5000.0
0.0 1500.0 /
5000.0  1500.0 /
'A'  0.0
5000.0  2000.0    0.0  2.0  0.0  0.0
1400.0  2000.0
1000.0                    ! RMAX (km)
1  500.0 /                ! NSD  SD(1:NSD)
1 2500.0 /                ! NRD  RD(1:NRD)
```

``` KRAKEN- Pekeris problem with Twersky ice scatter
Frequency =   10.00     NMEDIA =   1

N2-LINEAR approximation to SSP
Attenuation units: dB/mkHz
Twersky SOFT BOSS scatter model

Twersky ice model parameters:
Bumden =    0.920000E-01  Eta =    8.20      Xi =    5.10

Z          ALPHAR     BETAR      RHO       ALPHAI     BETAI

( Number of pts =   500  RMS roughness =  0.000E+00 )
0.00      1500.00      0.00     1.00       0.0000    0.0000
5000.00      1500.00      0.00     1.00       0.0000    0.0000

( RMS roughness =  0.000E+00 )
ACOUSTO-ELASTIC half-space
5000.00      2000.00      0.00     2.00       0.0000    0.0000

CLOW =   1400.0      CHIGH =   2000.0
RMAX =    1000.000000000000

Number of sources   =            1
500.0000

Number of receivers =            1
2500.000

Mesh multiplier   CPU seconds
1             8.08
2             6.19

I           K                ALPHA         PHASE SPEED
1   0.4188333967E-01  -0.7143639068E-09    1500.163396
2   0.4186964892E-01  -0.2858563396E-08    1500.653927
3   0.4184681891E-01  -0.6435953313E-08    1501.472626
4   0.4181483151E-01  -0.1145206277E-07    1502.621218
5   0.4177366141E-01  -0.1791463612E-07    1504.102129
6   0.4172327607E-01  -0.2583358102E-07    1505.918494
7   0.4166363582E-01  -0.3522095285E-07    1508.074172
8   0.4159469382E-01  -0.4609093903E-07    1510.573761
9   0.4151639611E-01  -0.5845985229E-07    1513.422622
10   0.4142868154E-01  -0.7234613786E-07    1516.626905
11   0.4133148173E-01  -0.8777040005E-07    1520.193577
12   0.4122472102E-01  -0.1047554344E-06    1524.130462
13   0.4110831629E-01  -0.1233263186E-06    1528.446279
14   0.4098217683E-01  -0.1435104786E-06    1533.150699
15   0.4084620412E-01  -0.1653378169E-06    1538.254396
16   0.4070029155E-01  -0.1888408516E-06    1543.769115
17   0.4054432412E-01  -0.2140548873E-06    1549.707744
18   0.4037817804E-01  -0.2410182110E-06    1556.084403
19   0.4020172036E-01  -0.2697723168E-06    1562.914535
20   0.4001480842E-01  -0.3003621806E-06    1570.215017
21   0.3981728933E-01  -0.3328365176E-06    1578.004282
22   0.3960899938E-01  -0.3672481421E-06    1586.302458
23   0.3938976329E-01  -0.4036543176E-06    1595.131522
24   0.3915939350E-01  -0.4421171667E-06    1604.515480
25   0.3891768932E-01  -0.4827041259E-06    1614.480566
26   0.3866443598E-01  -0.5254884517E-06    1625.055467
27   0.3839940360E-01  -0.5705497741E-06    1636.271587
28   0.3812234607E-01  -0.6179747460E-06    1648.163336
29   0.3783299981E-01  -0.6678576894E-06    1660.768466
30   0.3753108238E-01  -0.7203013712E-06    1674.128458
31   0.3721629100E-01  -0.7754178193E-06    1688.288956
32   0.3688830091E-01  -0.8333291792E-06    1703.300275
33   0.3654676364E-01  -0.8941686039E-06    1719.217978
34   0.3619130513E-01  -0.9580810818E-06    1736.103543
35   0.3582152384E-01  -0.1025224135E-05    1754.025132
36   0.3543698884E-01  -0.1095768032E-05    1773.058466
37   0.3503723827E-01  -0.1169895081E-05    1793.287833
38   0.3462177842E-01  -0.1247796785E-05    1814.807209
39   0.3419008460E-01  -0.1329666243E-05    1837.721486
40   0.3374160587E-01  -0.1415679057E-05    1862.147680
41   0.3327577965E-01  -0.1505943298E-05    1888.215805
42   0.3279207350E-01  -0.1600349816E-05    1916.068317
43   0.3229012280E-01  -0.1697989094E-05    1945.853643
44   0.3177042607E-01  -0.1793021126E-05    1977.683678
```

Figure: Transmission loss for the TWERSKY problem.

Michael B. Porter
Tue Oct 28 13:27:38 PST 1997