Models, Modeling Steps, and Output Levels

Definitions

SEMIP distinguishes between models, modeling steps, and output levels.  For SEMIP's purposes:

• A model is a specific representation of some phenomenon that takes some set of input and generates some set of (value-added) output (e.g., the Briggs plume rise model);
• A modeling step is the class of a models that perfoms a specific function, typically defined by starting with some set of specified input and creating some other set of specified output (e.g. the plume rise modeling step that takes fire emissions information and generates vertically distributed emissions); and
  
• An output level is a class of data typically organized by both being of the same conceptual content and being produced by the same modeling step.

Included Modeling Steps

 SEMIP is defined to include the following modeling steps:

• Fire Information Systems
• Fuel Loading Maps
• Total Consumption
• Time Rate of Consumption
• Emissions
• Plume Rise
• Dispersion

Within each, SEMIP includes several different actual models.  These are listed on the Models tab. 

Note that we distinguish between Total Consumption and Time Rate of Consumption steps for 2 reasons:  (1) because different information is available for each;  and (2) because the Time Rate of Consumption step adds a new dimension to the model output data.  Models that perform the Time Rate of Consumption direction implicitly also perform the Total Consumption step (Total Consumption = sum(Time Rate of Consumption)), so the worst that happens in making this distinction is that the model is run twice instead of once.

Included Output Levels

From these modeling steps, we have defined several Output Levels.  These output levels do not describe the complete set of data that can be produced by the models utilized by SEMIP.  Instead they define a crossover subset of information that most of the models are capable of producting.  Where possible, we have defined these output levels with both standard (non-optional) variables and optional variables to enable comparison across a broader range of output data.  For example, not all models can produce total consumption by fire phase (flamming, smouldering, residual).  Therefore SEMIP defines the standard Total Consumption output level variables only in terms of overall total fire consumption, but it also defines the optional Total Consumption output level variables of total consumption by phase where available.

The SEMIP output levels are:

• Basic Fire Information
  
• Fuel Loadings
• Total Consumption
• Time Rate of Consumption
• Speciated Emissions
• Vertical Plume Profile
• Total Column Smoke
• Ground Concentrations