# Presentation: 686378

## An Improved Approach To Updating Regulatory Dispersion Models

**8****th**** Modeling**
**Conference**
**RTP, NC**

**September 23, 2005**

## An Improved Approach To Updating Regulatory Dispersion Models

**Presenters**
**Desmond T. Bailey****1**
**Roger W. Brode****2**

**1 ****NOAA on assignment to EPA **
**2 ****MACTEC Federal Programs, Inc.**

## Standard Operating Procedure

**Implemented when changes are made to a regulatory dispersion model**
**Completed prior to the release of the updated model**

## Objectives

**Identify**
**Resolve**
**Document**

## The Analysis Tool

**Manages the execution of the old and new model components**
**Takes care of file management**
**Extracts results from model output files**
**Identifies differences in model estimates**
**Creates summary reports**

## Resolving Differences

**Expected (unexpected) ?**
**Model component ?**
**Compiler related ?**
**Significance ?**
**OK to release/approve update ?**

## Options for Approval of Update

**Approve all components**
**with qualifications**
**without qualifications**
**Approve selected components**
**with qualifications**
**Without qualifications**

## Transparency

**Results of the analysis will be made available with the release of the update**
**The analysis tool and all necessary files for running the tool will  be made available**

## Overview of CALPUFF Test Dataset

**Ten scenarios covering range of source types, modeling domains and meteorology**
**Base version of modeling system (April 2003) compared to Beta version (July 2004) – *****Primary Analysis***
**If differences are found, *****Secondary Analysis***** can be performed for affected scenarios**
***Secondary Analysis***** designed to attribute differences to CALMET, CALPUFF or both**

## Resolving Differences Model Component ?

## Scenario Components

**Sources**
**Modeling Domains**
**Terrain**
**Meteorology**
**Dispersion**

## Description of Scenarios

- Large-scale domain in Pacific NW - NWS data only
- Same as 1 with MM5 NOOBS option
- Medium-scale domain in Pacific NW with MM5/NWS
- Medium-scale domain near Shenandoah NP
- Small-scale complex flow with deep valley
- Idealized hill with steady-state met – similarity
- Idealized hill with steady-state met – PG
- Flat terrain with steady-state met – similarity
- Flat terrain with steady-state met – PG
- Idealized hill with simulated wind shear

## Description of Sources

**Four core sources included in all scenarios:**
- Ground-level area source (20m by 200m)
- 10m volume source
- 30m non-buoyant point source
- 65m buoyant point source
**Two sets of core sources included in Scenarios 1, 2, and 5 at different locations within domain**
**Scenario 3 also includes 99m buoyant stack near coast**
**Scenario 4 also includes buoyant area source**
**Scenarios 6 and 7 also include three PRIME downwash sources (35m buoyant, 35m capped, 50m buoyant)**

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## Scenario 5 – Columbia River Gorge

## Idealized Scenario 6

**Scenario 6 includes idealized 300m hill at center of 10km by 10km domain**
**Sources located at left edge of domain, upwind of hill**
**Simulated steady-state meteorology:**
**6 hours of stable**
**6 hours of near-neutral**
**6 hours of convective**
**Uses dispersion based on similarity theory**

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## Idealized Scenarios 7, 8 & 9

**Scenario 7 is same as Scenario 6, except for use of PG-based dispersion**
**Scenario 8 is same as Scenario 6, except for use of flat terrain**
**Scenario 9 is same as Scenario 8, except for use of PG-based dispersion**

## Idealized Scenario 10

**Uses same idealized hill as Scenario 6**
**Sources located near southwest edge of domain, “upwind” of hill**
**Simulated steady-state meteorology, with WS and WD shear; using CTDM Profile**
**6 hours of stable**
**6 hours of near-neutral**
**Uses dispersion based on similarity theory**

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## Summary of Results

**Mostly minor differences in all Scenarios, except for Scenario 10 – all differences attributable to CALMET**
**Maximum difference for ranked high value of 5.2% occurred for volume source in Scenario 4**
**Maximum differences in ranked high values were generally less than about 0.3%**
**No consistent trend in terms of bias of differences**

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## Issues/Lessons Learned

**Base versions of CALMET and CALPUFF do not support Lambert Conformal (LCC) option**
**Guidance for reference latitudes for LCC option**
**No source grouping available in CALPUFF/ CALPOST – separate runs for each source**
**Fixed array limits – recompilation issues**
**Prognostic data limits do not match CALMET grid limits**
**Limit on DEM files for TERREL in Scenarios 1 and 2**
**No slug option for PRIME sources**
**Unsupported NWS met data formats (ISHWO)**