This software package processes raw Iridium output from the CSIR / STS CO2 instrument into a readable table format. The instrument uses an equilibrator approach to measure CO2 with a LICOR-820.

Basic instructions

  1. Go to the IMPORT page and browse your computer for the raw input files.
  2. Click Process data to reformat the data. The button also calculates pCO2 and fCO2.
  3. The data can then be saved as `CSV` or an excel spreadsheet.
  4. Plot the data with the www.plot.ly interface under MAP and TIME SERIES


About WaveGliDA



Authors: Luke Gregor and Clinton Hagan
Feedback: lukegre@gmail.com
Version: 0.3.1 (16 May 2017)
This application is built in Python using the `Flask` backend framework. Calculations are done using `Pandas`.

CO2 calculations

The CSIR/STS CO2 instrument returns the mole fraction of carbon dioxide (xCO2) as given by the LICOR-820 instrument. xCO2 is used to calculate parital pressure of CO2 and fugacity CO2 with the equations shown below. The methods presented below are in the ./backend/calculations.py file. $$ p\mbox{CO}_2^{sst} = x\mbox{CO}_2 \times P_c \times \exp(0.0423 \cdot \Delta T) $$ where $\Delta T$ is the difference between the equilibrator and sea surface temperatures. This empirical exponential relationship is as defined by Takahashi et al. (1993). Note that $\Delta T$ is considered 0 K for Wave Glider installations of the instrument, i.e. the equilibrator and sea surface temperatures are exactly the same. $P_{atm}$ is measured atmospheric pressure corrected for the partial pressure of H2O. $$P_c = (P_{atm} - P_{H_2O})$$ where $P_{H_2O}$ is calculated from salinity and temperature according to Weiss and Price (1980). This is done for both marine and atmospheric measurements of CO2.

The fugacity of CO2 is a correction for the non-ideal behaviour of CO2. This is done by calculating the vireal expansion as shown below: $$ f\mbox{CO}_2^{sst} = p\mbox{CO}_2 \times \frac{P_{atm}}{k_B T} $$ where $k_B$ is the Boltzmann constant and $T$ is the absolute temperature. This expression is equivalent to the expansion $$ \rho + B_2(T)\rho^2 + B_3(T)\rho^3 + ... , $$ where $\rho$ is the density of CO2

For more information see the code below used to calculate these functions.