openair package. Files are imported from a remote
server operated by AEA that provides air quality data
files as R data objects.importSAQN(site = "gla4", year = 2009, pollutant = "all")site = c("gla4", "ed") --- to import Glasgow
Kerbside and Edinbrugh Centre for example.year = 1990:2000.
To import several specfic years use year = c(1990,
1995, 2000) for example.pollutant = c("nox",
"no2").importSAQN function has been written to make
it easy to import data from the Scottish Air Quality
Network (SAQN) ---
openair functions.
The site codes and pollutant names can be upper or lower
case. The function will issue a warning when data less
than six months old is downloaded, which may not be
ratified.
The data are imported by stacking sites on top of one
another and will have field names site,
code (the site code) and pollutant.
Sometimes it is useful to have columns of site data. This
can be done using the reshape function --- see
examples below.
All units are expressed in mass terms for gaseous species
(ug/m3 for NO, NO2, NOx (as NO2), SO2; and mg/m3 for CO).
PM10 concentrations are provided in gravimetric units of
ug/m3 or scaled to be comparable with these units. Over
the years a variety of instruments have been used to
measure particulate matter and the technical issues of
measuring PM10 are complex. In recent years the
measurements rely on FDMS (Filter Dynamics Measurement
System), which is able to measure the volatile component
of PM. In cases where the FDMS system is in use there
will be a separate volatile component recorded as 'v10',
which is already included in the absolute PM10
measurement. Prior to the use of FDMS the measurements
used TEOM (Tapered Element Oscillating. Microbalance) and
these concentrations have been multiplied by 1.3 to
provide an estimate of the total mass including the
volatile fraction.
The few BAM (Beta-Attenuation Monitor) instruments that
have been incorporated into the network throughout its
history have been scaled by 1.3 if they have a heated
inlet (to account for loss of volatile particles) and
0.83 if they do not have a heated inlet. The few TEOM
instruments in the network after 2008 have been scaled
using VCM (Volatile Correction Model) values to account
for the loss of volatile particles. The object of all
these scaling processes is to provide a reasonable degree
of comparison between data sets and with the reference
method and to produce a consistent data record over the
operational period of the network, however there may be
some discontinuity in the time series associated with
instrument changes.
No corrections have been made to teh PM2.5 data. The
volatile component of FDMS PM2.5 (where available) is
shown in the 'v2.5' column.
While the function is being developed, the following site
codes should help with selection. importAURN for data elsewhere in the UK
and importKCL for importing comprehensive
data in and around London.## import all pollutants from Glasgow Roadside
glas <- importSAQN(site = "gla4", year = 2000:2009)
## import all pollutants from Lerwick rural site (O3)
ler <- importSAQN(site = "lerw", year = 2005:2010)
## import all pollutants from Glasgow/Dundee Centre for 2009
all <- importSAQN(site = c("gla3", "dun3"), year = 2009)Run the code above in your browser using DataLab