sample_concentration

docs > software repositories > scs_analysis > commands > filtering and aggregating data

---

DESCRIPTION

The sample_concentration utility is used to inject a gas concentration value, based on a given density (micrograms per cubic metre), temperature and pressure (kPa). The reported value is in parts per billion.

Density and temperature must be supplied from the input JSON document. Atmospheric pressure may be supplied from the input JSON document. Alternatively, a pressure estimate may be supplied on the command line. In both cases, pressure should be indicated in kilopascals (kPa). If no pressure value is supplied, the standard pressure of 101.3 kPa is used.

Recognised gases are:

Gas	Molar mass
CO2	44.0100
NO	30.0100
NO2	46.0055
O3	48.0000
SO2	64.0660

The path for the node in the output document indicating concentration is based on the path for the node in the input document indicating density. For example, if the input path is SUB-PATH.dns, the output path is SUB-PATH.cnc. If a SUB-PATH.cnc field exists in the input document, it is overwritten.

SYNOPSIS

sample_concentration.py [-v] GAS DENSITY_PATH T_PATH [{P_PATH | -p PRESSURE}]

Options
--version	show program's version number and exit
-h, --help	show this help message and exit
-p PRESSURE, --pressure=PRESSURE	assume constant atmospheric pressure in kPA (default 101.3)
-v, --verbose	report narrative to stderr

EXAMPLES

csv_reader.py joined_2019-02.csv | sample_concentration.py -v NO2 ref.val.NO2.dns praxis.val.sht.tmp

DOCUMENT EXAMPLE - INPUT

{"rec": "2019-02-12T13:00:00Z", "praxis": {"val": {"NO2": {"weV": 0.300059, "cnc": 23.4, "aeV": 0.302339, "weC": -0.002793}, "sht": {"hmd": 67.6, "tmp": 13.1}}}, "ref": {"val": {"NO2": {"units": "ugm-3", "dns": 51}}}}

DOCUMENT EXAMPLE - OUTPUT

{"rec": "2019-02-12T13:00:00Z", "praxis": {"val": {"NO2": {"weV": 0.300059, "cnc": 23.4, "aeV": 0.302339, "weC": -0.002793}, "sht": {"hmd": 67.6, "tmp": 13.1}}}, "ref": {"val": {"NO2": {"units": "ugm-3", "dns": 51, "cnc": 26.0}}}}

RESOURCES

Data formats

scs_core/src/scs_core/gas/gas.py
http://www.apis.ac.uk/unit-conversion