This function uses the airnow_downloadParseData function
to download monthly dataframes of AirNow data and restructures that data into
a format that is compatible with the PWFSLSmoke package ws_monitor
data model.
AirNow data parameters include at least the following list:
BARPR
BC
CO
NO
NO2
NO2Y
NO2X
NOX
NOOY
OC
OZONE
PM10
PM2.5
PRECIP
RHUM
SO2
SRAD
TEMP
UV-AETH
WD
WS
Setting parameters=NULL
will generate a separate dataframe for each of
the above parameters.