Table of Contents - The Atmospheric Studies Group at TRC

Section 9: CALPUFF
9.9 Ozone Data File (OZONE.DAT)
If the MESOPUFF II or RIVAD/ARM3 chemical mechanism is used to simulate the chemical
transformation of SO 2 → SO = 4 and NO x → HNO 3 NO − 3, estimates of background ambient ozone
concentration levels are required to compute the hourly conversion rates. CALPUFF provides two
options for the user to provide these data: (1) a single, typical background value appropriate for the
modeling region, or (2) ozone data from one or more ozone monitoring stations. The selection of Option
2 requires that a file called OZONE.DAT be created with the necessary data.
OZONE.DAT is a sequential, formatted data file containing three types of records: header records, timeinvariant
data records, and ozone data records. A sample OZONE.DAT file is shown in Table 9-35. The
header record contains information on the number of stations in the data set, the time period and time
zone of the data, the coordinate map projection and datum, and descriptive information regarding the file.
Horizontal coordinates are specified in this particular map projection and datum, and CALPUFF converts
these coordinates to the map projection and datum used in the modeling grid.
A set of time-invariant records are read after the header records. These records specify the coordinates of
each ozone station (see Table 9-37). A set of time-varying data follows, which contain the hourly ozone
concentration (in ppb) for each station (see Table 9-38).
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