create a TS diagram as a ggplot

David Kaiser 2018/01/16

Description

A TS diagram, Temperature-Salinity-diagram, plots the potential temperature of water over salinity. Many water masses have characteristic shapes in a TS diagram, which is used in physical oceanography to identify water masses and their mixing.

This function requires the input of vectors of potential temperature and salinity. The gws package is used to calculate potential density for plotting of isopycnals (contours of the same density). This calculation requires a reference pressure, which defaults to 0, the sea surface.

A third vector can optionally be supplied to col.par to be plotted in color, and can be named with a string supplied to col.name.

Use to cite a permanent archived version of the function.

Arguments

sal -- vector of salinity values

pot.temp -- vector of potential temperature values in degree C

reference.p = 0 -- reference pressure which was also used to calculate potential temperature

col.par = NA -- optional vector of a parameter to be displayed as color of the TS-pairs

col.name = "col.par" -- optional name of the "col.par" to be used on the color bar

Plot

example <- read.csv("example_data/example_data.csv")

head(example)

##   depth potential.temperature salinity
## 1  1.50                6.1272  13.2087
## 2  1.75                6.1245  13.2115
## 3  2.00                6.1236  13.2128
## 4  2.25                6.1227  13.2126
## 5  2.50                6.1229  13.2145
## 6  2.75                6.1224  13.2122

The data will be plotted using the ggplot2 package.

ggTS(sal = example$salinity, 
        pot.temp = example$potential.temperature, 
        reference.p = 0,
        col.par = example$depth, 
        col.name = "depth [m]")

NOTE: the special "Â" character does not show when the function is used in R, this seems to be a markdown/knitr problem

Since the result is a ggplot, it can be altered and amended:

p1 <- ggTS(sal = example$salinity, 
        pot.temp = example$potential.temperature, 
        reference.p = 0,
        col.par = example$depth, 
        col.name = "depth [m]")
p1 + scale_color_gradient(low = "grey", high = "black", name = "something\nelse") +
      annotate(geom = "text", x = 15, y = 6, color = "red", size = 14, label = "ADD\nSTUFF")

Plot a TS diagram with isopycnals running more horizontally

example1 <- read.csv("example_data/example_data1.csv")

head(example1)

##   depth potential.temperature salinity
## 1     0              24.30924 34.36559
## 2    10              24.09002 34.30511
## 3    20              23.58654 34.32923
## 4    30              23.19063 34.38134
## 5    40              22.88482 34.44991
## 6    50              22.45423 34.50933

ggTS(sal = example1$salinity, 
        pot.temp = example1$potential.temperature, 
        reference.p = 0,
        col.par = example1$depth, 
        col.name = "depth [m]")