guess_TA {respirometry}

Estimate total alkalinity from salinity

Description

Estimate total alkalinity from salinity and temperature of surface seawater according to Lee et al. 2006. Useful when a rough guess of TA is needed because measuring TA is not possible or practical.

Usage

guess_TA(temp = 25, sal = 35, region = NULL, extend = TRUE)

Arguments

temp

temperature (°C). Default is 25 °C.

sal

salinity (psu). Default is 35 psu. 31 \le sal \le 38; may be narrower for some regions.

region

(optional) geographic region. Options are "(Sub)tropics", "Equatorial Upwelling Pacific", "North Atlantic", "North Pacific", and "Southern Ocean". Default is NULL. If undefined, the average from all these regions is used.

extend

logical. If salinity is \le 5 psu outside of the bounds defined by Lee et al. 2006 (see Details), should a guess be extrapolated? Default is TRUE.

Details

(Sub)tropics

temp \ge 20 and 31 \le sal \le 38

Equatorial Upwelling Pacific

temp \ge 18 and 31 \le sal \le 36.5

North Atlantic

0 \le temp \le 20 and 31 \le sal \le 37

North Pacific

temp \le 20 and 31 \le sal \le 35

Southern Ocean

temp \le 20 and 33 \le sal \le 36

Estimates total alkalinity using the equations provided by Lee et al. 2006 (Geophysical Research Letters). While these equations are designed for open ocean environments, they can provide a rough estimate even for coastal environments. For improved estimate accuracy, the geographic region can be provided. The North Pacific region is longitude-dependent so a longitude of 150 °W is assumed which provides a typical value within the range. Only applicable for surface waters, not very accurate for the ocean interior.

Value

An estimate of the total alkalinity (umol / kg). If NA or NaN are returned, confirm the temp and sal values are within acceptable ranges for the region of interest.

Author(s)

Matthew A. Birk, [e-mail]

References

Lee K, Tong LT, Millero FJ, Sabine CL, Dickson AG, Goyet C, Park G-H, Wanninkhof R, Feely RA, Key RM. 2006. Global relationships of total alkalinity with salinity and temperature in surface waters of the world’s oceans. Geophys Res Lett. 33:L19605.

See Also

predict_pH

Examples

guess_TA(temp = 22, sal = 33)
guess_TA(temp = 12, sal = 33, region = "North Atlantic")
guess_TA(temp = 20, sal = 31:35)

guess_TA(sal = 31) # salinity is within bounds
guess_TA(sal = 30) # salinity is outside the bounds and TA is extrapolated
guess_TA(sal = 30, extend = FALSE) # do not extrapolate TA
guess_TA(sal = 25, extend = TRUE) # will not extrapolate with sal > 5 psu out of bounds