Page 384 - Fundamentals of Air Pollution 3E

V. Model Performance, Accuracy, and Utilization 339

Because of their inclusion of the effects of building downwash, the ISC2
(Industrial Source Complex) models (16), ISCST and ISCLT (short-term
performing calculations by hourly periods and long-term using the joint
frequencies of wind direction, wind speed, and Pasquill stability, commonly
referred to as STAR, STability ARray data) are recommended. The ISC2
models differ only slightly from the earlier ISC models (several small errors
that make little difference in the resulting calculations were corrected). The
receding of the model to result in ISC2 was requested by EPA to overcome
a difficult-to-understand code that had resulted from a number of changes
that had been incorporated. The ISC models will make calculations for
three types of sources: point, area, and volume. There are recognized
deficiencies in the area source algorithm incorporated in the ISC models.
EPA is supporting work to create an improved algorithm for incorporation
in the models.

G. Availability of Models
Until 1989 models were made available from the National Technical Infor-
mation Service of the Department of Commerce on 9-track magnetic tape.
EPA's Office of Research and Development explored the use of electronic
bulletin boards in the mid-1980s and began 24-hour operation of the UNA-
MAP bulletin board in the fall of 1987. This has continued as the AMRB
(Applied Modeling Research Branch) Bulletin Board Service (BBS) furnish-
ing modeling information from the Office of Research and Development.
To use a BBS, all that is needed is a personal computer with a modem (to
connect to a telephone line) and some file-transfer protocol such as Kermit
or Ymodem. The AMRB BBS in Research Triangle Park, NC is reached on
(919) 541-1325 and the system operator on (919) 541-1376.
Seeing the success of the UNAMAP BBS, EPA's Office of Air Quality
Planning and Standards started a BBS for information on regulatory models
in June 1989. This has expanded to a BBS called TTN, Technology Transfer
Network. This BBS, in Durham, NC, is reached on (919) 541-5742 and the
system operator on (919) 541-5384. A part of this BBS called SCRAM ,
Support Center for Regulatory Air Models, contains model FORTRAN
codes, model executable codes for use on personal computers, meteorologi-
cal data, and in some cases model user's guides. Much of the information
is downloaded in "packed" form, and software to unpack the files must
also be downloaded from the bulletin board.
Private vendors are another source of models and information. Specially
designed packages are available for many of the regulatory approved mod-
els. These packages usually provide easier data entry through use of data-
entry screens and capability of output graphics. The data-entry screens
usually save professional time, especially for occasional model users. Addi-
tional advantages are technical support from the vendor and, if a mainte-