By Peng Zhao | June 14, 2018
Carbon dioxide (CO~2~) is one of the key green house gases which play an important role in the global climate change. In academia, the sources and sinks of CO~2~ are estimated with the flux density, e.g. the amount of CO~2~ passing through a unit area in a unit time. Estimates of net ecosystem CO~2~ exchange have been attracting a lot of attention. The research on the advection flux takes care of the contribution of the advection term to the CO~2~ balance.
The advection measurement is very complex. A typical advection measurement consists of horizontal and vertical profiles of the CO~2~ mixing ratio, the air temperature, the air humidity, the air pressure, as well as chamber flux measurement. A datalogger and a microcontroller work together, which control many solenoid valves to switch the sample lines, save the data. Most of the data are recorded every a few seconds, continuously lasting several days, which makes it difficult to check the data quality and the status of the instruments.
Figure 1. Sketch of a typical advection measurement. I image the man with a cup of coffee should be me. But who should be the woman...
What is the project about?
advr is an open source R package for the advection measurement of trace gases. Currently, the version 0.0.0 has three components:
- a logger program for controlling the data logger CR1000
- a microcontroller program for controlling Arduino MEGA2560.
- R functions to process the raw meteorological and ecological data.
An output of advr is shown in Figure 2.
Figure 2. A demo output of advr.
steemr is developed in R language. The data logger program is written with the CRBasic language. The microcontroller program is composed of functions written in C/C++.
In the future, I am going to add much more features to advr, such as
- quality control of the raw advection flux data,
- automatic calculation of the advection flux,
- improvement of the chamber flux calculation with the state-of-art techniques,
- automatic visualization of quality control result and flux components (Figure 3) with a single click,
- building a user-friendly web UI for those who knows nothing of R language.
Figure 3. One of the future plans: Visualization of the flux components of an advection measurement with a single click.