`library`¶

seawater.library.cndr(s, t, p)¶

Calculates conductivity ratio.

Parameters:

s(p) : array_like

salinity [psu (PSS-78)]

t(p) : array_like

temperature [℃ (ITS-90)]

p : array_like

pressure [db]

Returns:

cndr : array_like

conductivity ratio. R = C(s,t,p) / C(35,15(IPTS-68),0) [no units]

References

[R36]

Fofonoff, P. and Millard, R.C. Jr UNESCO 1983. Algorithms for computation of fundamental properties of seawater. UNESCO Tech. Pap. in Mar. Sci., No. 44, 53 pp. Eqn.(31) p.39. http://unesdoc.UNESCO.org/images/0005/000598/059832eb.pdf

Examples

>>> # Data from UNESCO 1983 p9.
>>> import seawater as sw
>>> t = T90conv([0, 10, 0, 10, 10, 30])
>>> p = [0, 0, 1000, 1000, 0, 0]
>>> s = [25, 25, 25, 25, 40, 40]
>>> sw.cndr(s, t, p)
array([ 0.49800825,  0.65499015,  0.50624434,  0.66297496,  1.00007311,
        1.52996697])

seawater.library.salds(rtx, delt)¶

Calculates Salinity differential ( $\frac{dS}{d(\sqrt{Rt})}$ ) at constant temperature.

Parameters:

rtx : array_like

$\sqrt{rt}$

delt : array_like

t-15 [℃ (IPTS-68)]

Returns:

ds : array_like

$\frac{dS}{d rtx}$

References

[R37]

Fofonoff, P. and Millard, R.C. Jr UNESCO 1983. Algorithms for computation of fundamental properties of seawater. UNESCO Tech. Pap. in Mar. Sci., No. 44, 53 pp. Eqn.(31) p.39. http://unesdoc.UNESCO.org/images/0005/000598/059832eb.pdf

Examples

>>> # Data from UNESCO 1983 p9.
>>> import numpy as np
>>> import seawater as sw
>>> delt = T90conv([15, 20, 5]) - 15
>>> rtx  = np.array([ 1, 1.0568875, 0.81705885]) ** 0.5
>>> sw.salds(rtx, delt)
array([ 78.31921607,  81.5689307 ,  68.19023687])

seawater.library.salrp(r, t, p)¶

Equation for Rp used in calculating salinity. UNESCO 1983 polynomial.

$Rp(S,T,P) = \frac{C(S,T,P)}{C(S,T,0)}$

Parameters:

r : array_like

conductivity ratio $R = \frac{C(S,T,P)}{C(35,15(IPTS-68),0)}$

t : array_like

temperature [℃ (ITS-90)]

p : array_like

pressure [db]

Returns:

rp : array_like

conductivity ratio $Rp(S,T,P) = \frac{C(S,T,P)}{C(S,T,0)}$

References

[R38]

Fofonoff, P. and Millard, R.C. Jr UNESCO 1983. Algorithms for computation of fundamental properties of seawater. UNESCO Tech. Pap. in Mar. Sci., No. 44, 53 pp. Eqn.(31) p.39. http://unesdoc.unesco.org/images/0005/000598/059832eb.pdf

Examples

>>> import seawater as sw
>>> r = [1, 1.2, 0.65]
>>> t = T90conv([15, 20, 5])
>>> p = [0, 2000, 1500]
>>> sw.salrp(r, t, p)
array([ 1.        ,  1.01694294,  1.02048638])

seawater.library.salrt(t)¶

Equation for rt used in calculating salinity. UNESCO 1983 polynomial.

$rt(t) = \frac{C(35,t,0)}{C(35,15(\textrm{IPTS-68}), 0)}$

Parameters:

t : array_like

temperature [℃ (ITS-90)]

Returns:

rt : array_like

conductivity ratio [no units]

References

[R39]

Fofonoff, P. and Millard, R.C. Jr UNESCO 1983. Algorithms for computation of fundamental properties of seawater. UNESCO Tech. Pap. in Mar. Sci., No. 44, 53 pp. Eqn.(31) p.39. http://unesdoc.unesco.org/images/0005/000598/059832eb.pdf

Examples

>>> # Data from UNESCO 1983 p9.
>>> import seawater as sw
>>> t = T90conv([15, 20, 5])
>>> sw.salrt(t)
array([ 1.        ,  1.11649272,  0.77956585])

seawater.library.seck(s, t, p=0)¶

Secant Bulk Modulus (K) of Sea Water using Equation of state 1980. UNESCO polynomial implementation.

Parameters:

s(p) : array_like

salinity [psu (PSS-78)]

t(p) : array_like

temperature [℃ (ITS-90)]

p : array_like

pressure [db].

Returns:

k : array_like

secant bulk modulus [bars]

References

[R40]

Fofonoff, P. and Millard, R.C. Jr UNESCO 1983. Algorithms for computation of fundamental properties of seawater. UNESCO Tech. Pap. in Mar. Sci., No. 44, 53 pp. Eqn.(31) p.39. http://unesdoc.unesco.org/images/0005/000598/059832eb.pdf

[R41]

Millero, F.J. and Poisson, A. International one-atmosphere equation of state of seawater. Deep-Sea Res. 1981. Vol28A(6) pp625-629. doi:10.1016/0198-0149(81)90122-9

Examples

>>> # Data from Unesco Tech. Paper in Marine Sci. No. 44, p22.
>>> import seawater as sw
>>> s = [0, 0, 0, 0, 35, 35, 35, 35]
>>> t = T90conv([0, 0, 30, 30, 0, 0, 30, 30])
>>> p = [0, 10000, 0, 10000, 0, 10000, 0, 10000]
>>> sw.seck(s, t, p)
array([ 19652.21      ,  22977.2115    ,  22336.0044572 ,  25656.8196222 ,
        21582.27006823,  24991.99729129,  23924.21823158,  27318.32472464])

seawater.library.sals(rt, t)¶

Salinity of sea water as a function of Rt and T. UNESCO 1983 polynomial.

Parameters:

rt : array_like

$rt(s,t) = \frac{C(s,t,0)}{C(35, t(\textrm{IPTS-68}), 0)}$

t : array_like

temperature [℃ (ITS-90)]

Returns:

s : array_like

salinity [psu (PSS-78)]

References

[R42]

Fofonoff, P. and Millard, R.C. Jr UNESCO 1983. Algorithms for computation of fundamental properties of seawater. UNESCO Tech. Pap. in Mar. Sci., No. 44, 53 pp. Eqn.(31) p.39. http://unesdoc.UNESCO.org/images/0005/000598/059832eb.pdf

Examples

>>> # Data from UNESCO 1983 p9.
>>> import seawater as sw
>>> t = T90conv([15, 20, 5])
>>> rt = [1, 1.0568875, 0.81705885]
>>> sw.sals(rt, t)
array([ 35.        ,  37.24562718,  27.99534701])

seawater.library.smow(t)¶

Density of Standard Mean Ocean Water (Pure Water) using EOS 1980.

Parameters:

t : array_like

temperature [℃ (ITS-90)]

Returns:

dens(t) : array_like

density [kg m ³]

References

[R43]

Fofonoff, P. and Millard, R.C. Jr UNESCO 1983. Algorithms for computation of fundamental properties of seawater. UNESCO Tech. Pap. in Mar. Sci., No. 44, 53 pp. Eqn.(31) p.39. http://unesdoc.unesco.org/images/0005/000598/059832eb.pdf

[R44]

Millero, F.J. and Poisson, A. International one-atmosphere equation of state of seawater. Deep-Sea Res. 1981. Vol28A(6) pp625-629. doi:10.1016/0198-0149(81)90122-9

Examples

>>> # Data from UNESCO Tech. Paper in Marine Sci. No. 44, p22.
>>> import seawater as sw
>>> t = T90conv([0, 0, 30, 30, 0, 0, 30, 30])
>>> sw.smow(t)
array([ 999.842594  ,  999.842594  ,  995.65113374,  995.65113374,
        999.842594  ,  999.842594  ,  995.65113374,  995.65113374])

seawater.library.T68conv(T90)¶

Convert ITS-90 temperature to IPTS-68

$T68 = T90 * 1.00024$

Parameters:

t : array_like

temperature [℃ (ITS-90)]

Returns:

t : array_like

temperature [℃ (IPTS-68)]

Notes

The International Practical Temperature Scale of 1968 (IPTS-68) need to be correct to the ITS-90. This linear transformation is accurate within 0.5 ℃ for conversion between IPTS-68 and ITS-90 over the oceanographic temperature range.

References

[R45]

Saunders, P. M., 1991: The International Temperature Scale of 1990, ITS-90. WOCE Newsletter, No. 10, WOCE International Project Office, Southampton, United Kingdom, 10.

Examples

>>> import seawater as sw
>>> T68conv(19.995201151723585)
20.0

seawater.library.T90conv(t, t_type='T68')¶

Convert IPTS-68 or IPTS-48 to temperature to ITS-90.

T48 apply to all data collected prior to 31/12/1967. T68 apply to all data collected between 01/10/1968 and 31/12/1989.

$T90 = T68 / 1.00024 T90 = T48 - (4.4e-6) * T48 * (100-T48) ) / 1.00024$

Parameters:

t : array_like

temperature [℃ (IPTS-68) or (IPTS-48)]

t_type : string, optional

‘T68’ (default) or ‘T48’

Returns:

T90 : array_like

temperature [℃ (ITS-90)]

Notes

The International Practical Temperature Scale of 1968 (IPTS-68) need to be correct to the ITS-90. This linear transformation is accurate within 0.5 ℃ for conversion between IPTS-68 and ITS-90 over the oceanographic temperature range.

References

[R46]

Saunders, P. M., 1991: The International Temperature Scale of 1990, ITS-90. WOCE Newsletter, No. 10, WOCE International Project Office, Southampton, United Kingdom, 10.

[R47]

International Temperature Scales of 1948, 1968 and 1990, an ICES note, available from http://www.ices.dk/ocean/procedures/its.htm

Examples

>>> T90conv(20.004799999999999)
20.0
>>> T90conv(20., t_type='T48')
19.988162840918179

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`library`¶

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`library`¶