# Presentation: 172662

## Use of Prognostic Meteorological Model Output in Dispersion Models

- Eighth Modeling ConferenceResearch Triangle Park, NC

## Current Approach for Meteorological Data Input

- NWS observation data
- NWS upper air soundings
- On-site data
- Parameters calculated from profiles

## Proposed Approach for Meteorological Data Input

- Utilize met model data currently available
- Regional applications and National rules
- Data must be processed for dispersion modeling
- Model-ready input pre-processed
- Default settings

## Long-Term Goal for Meteorological Data Input

- Sub-regional dispersion model applications using inputs from regional grid model applications
- Real-time or forecasted dispersion modeling – may be in conjunction with similar regional grid modeling

## Advantages to Modeled Meteorology Data

- Better geographical representation in many cases
- More consistent upper-air representation
- More scientifically sound
- Accepted for other modeling (MM5) or by NWS
- NWS updates and improvements

## Advantages to Modeled Meteorology Data

- Consistent with regional modeling applications
- Less costly to develop for modeling
- Easier transition to real-time and forecasting applications
- Should be easier to use

## General Steps

- MM5 data into dispersion model
- NCEP product data into dispersion model
- Build upon NCEP’s Eta input into CMAQ for forecasting
- Start with initialized fields, then move to forecast fields
- Evaluate every step of the way

## Test Project – Philadelphia Benzene 2001

- Goal:  To conduct an air quality model simulation using meteorological input exclusively from a prognostic grid model (MM5) as a simple replacement for NWS observation data at the same location.
- Well-characterized emissions
- Reasonable results from ISC and AERMOD
- Corresponding MM5 output available

## Philadelphia Domain from 36 km MM5

## Tasks

- Run MPRM/ISC using NWS observations and compare to original
- Run AERMET/AERMOD using NWS observations and compare to 1
- Extract met data from MM5 for corresponding grid
- Translate parameters from MM5 to AERMET output
- Calculate any values not explicitly output my MM5 but output by AERMET

## Tasks

- Replace AERMOD calculated meteorological data with MM5 output only if available from MM5
- Run AERMOD using reformatted MM5 data hybrid as meteorological input
- Examine met processor and dispersion model output

## Slide 12

**Notes:**
Close agreement in wind speeds.  Note that MM5 wind speed is at height of 38 m. 
To calculate the hourly averages, only non-missing values are used in the calculations.  The averages are based the number of non-missing hours.

To see the number of observations for each hourly average, double click on graph and view the columns marked n_nws and n_mm5

## Slide 13

## Climatology

## NWS

**Notes:**
Wind rose based on non-missing values of wind speed and direction only

Winds are from southwest for 2001 NWS with secondary max from northwest

## MM5

**Notes:**
Winds are from northwest for 2001 MM5 with secondary max from southwest and west

## Climatology

## Slide 18

## Slide 19

**Notes:**
To calculate the hourly averages, only non-missing values are used in the calculations.  The averages are based the number of non-missing hours.

To see the number of observations for each hourly average, double click on graph and view the columns marked n_nws and n_mm5

Temperatures peak around same time, NWS higher by a degree or less.

## Slide 20

**Notes:**
MM5 pressures lower in part because the pressure calculated for MM5 is actually the atmospheric pressure at 38 m, the first model level.  The pressure can be approximated to surface level by about 4 mb because pressure decreases by 1 mb for every 10 m.

Low values appear to be due to low pressure systems moving over the area.  Used weather maps to determine this.  The systems may not be particularly strong, but have low enough pressures to bring down averages

To calculate the hourly averages, only non-missing values are used in the calculations.  The averages are based the number of non-missing hours.

To see the number of observations for each hourly average, double click on graph and view the columns marked n_nws and n_mm5

## Slide 21

**Notes:**
To calculate the hourly averages, only non-missing values are used in the calculations.  The averages are based the number of non-missing hours.

To see the number of observations for each hourly average, double click on graph and view the columns marked n_nws and n_mm5

## Slide 22

**Notes:**
Peak at 20 hours for MM5 is because this time is actually 0100 UTC, the first hour retained for each 5 day simulation.  No correction of rainfall for these times.

To calculate the hourly averages, only non-missing values are used in the calculations.  The averages are based the number of non-missing hours.

To see the number of observations for each hourly average, double click on graph and view the columns marked n_nws and n_mm5

## Slide 23

**Notes:**
To calculate the hourly averages, only non-missing values are used in the calculations.  The averages are based the number of non-missing hours.

To see the number of observations for each hourly average, double click on graph and view the columns marked n_nws and n_mm5

## Slide 24

**Notes:**
Cloud cover calculated in MM5 by using the RH at closest level to 850 mb.  The cloud cover in MM5 is one level while cloud cover in the NWS is most likely from several levels.

To calculate the hourly averages, only non-missing values are used in the calculations.  The averages are based the number of non-missing hours.

To see the number of observations for each hourly average, double click on graph and view the columns marked n_nws and n_mm5

## Slide 25

## Slide 26

**Notes:**
Peak MM5 flux 37.3 W/m2 greater than NWS flux at 1300 hrs.

To calculate the hourly averages, only non-missing values are used in the calculations.  The averages are based the number of non-missing hours.

To see the number of observations for each hourly average, double click on graph and view the columns marked n_nws and n_mm5

## Slide 27

**Notes:**
In NWS data, values of 0 are where there were no non-missing values for all observations with the given hour.
MM5 higher until around 4:00 PM, then lower than NWS until 11:00 PM. 

In MM5, w* calculated only when sensible heat flux > 0.  If heat flux less than 0,, w*=-9 (missing value).  Equation shown below where u* is friction velocity, h is PBL height, L is Monin-Obukhov length, and k is von Karmen constant.

To calculate the hourly averages, only non-missing values are used in the calculations.  The averages are based the number of non-missing hours.

To see the number of observations for each hourly average, double click on graph and view the columns marked n_nws and n_mm5

## Slide 28

## Slide 29

**Notes:**
To calculate the hourly averages, only non-missing values are used in the calculations.  The averages are based the number of non-missing hours.

To see the number of observations for each hourly average, double click on graph and view the columns marked n_nws and n_mm5

## Slide 30

**Notes:**
In NWS data, values of 0 are where there were no non-missing values for all observations with the given hour.

Only 55 observations used to calculate average.  One extreme value can drastically affect averages

To calculate the hourly averages, only non-missing values are used in the calculations.  The averages are based the number of non-missing hours.

To see the number of observations for each hourly average, double click on graph and view the columns marked n_nws and n_mm5

## Slide 31

## Slide 32

**Notes:**
In NWS data, values of 0 are where there were no non-missing values for all observations with the given hour.

Note how calculated MM5 mixing height, MM5 CALC has a later peak than the MM5 PBL, still not as late as NWS 

Calculated convective mixing heights for MM5 using w*, sensible heat flux, and temperature, based on equation 5-15 in the AERMET User’s Guide, where Z is convective mixing height, w* is convective velocity,  is density of air (1.225 kg/m3), cp is specific heat at constant pressure (1004 J/kgK), T is temperature, g is gravity (9.81 m/s2), and H is sensible heat flux.  Z is calculated only when w* is non-missing value (not equal to -9).

## Slide 33

**Notes:**
To calculate the hourly averages, only non-missing values are used in the calculations.  The averages are based the number of non-missing hours.

To see the number of observations for each hourly average, double click on graph and view the columns marked n_nws and n_mm5

## Slide 34

**Notes:**
Calculated mechanical mixing heights for MM5 peak earlier than MM5 PBL and lower peak magnitude

Calculated mechanical mixing heights for MM5 using Equation 5-26 (page 5-17 of AERMET UG) where Z is mechanical mixing height and u* is friction velocity.

## Slide 35

## Slide 36

| Summary Statistics for AERMOD Annual Average Benzene Concentrations (μg/m3) |  |  |  |  |  |  |
| --- | --- | --- | --- | --- | --- | --- |
| for Philadelphia using 1999 Emissions and 2001 Meteorological Input Data |  |  |  |  |  |  |
|   | Min Value | 20th Pct. | 40th Pct. | 60th Pct. | 80th Pct. | Max Value |
| AERMETBenzene | 0.05239 | 0.23427 | 0.32708 | 0.40961 | 0.50605 | 1.55951 |
|  |  |  |  |  |  |  |
| MM5 Benzene | 0.25023 | 0.8288 | 1.13717 | 1.38664 | 1.6522 | 3.43579 |

## Slide 37

## Slide 38

## Slide 39

## QQ Plot

**Notes:**
MM5 AERMOD concentrations higher than AERMET AERMOD concentrations and differences increase as concentrations increase.  

## Slide 41

**Notes:**
Each point is the 25th highest concentration using AERMET vs the 25th highest concentrations using MM5 for each receptor. Differences tend to increase as concentrations increase.

## Next steps – MM5 and AERMOD

- Different meteorological station locations (surface and upper-air)
- Emissions datasets similar to permit applications (not toxics)
- Expand beyond single MM5 grid cell
- Expand evaluations

## Next Steps (Beyond MM5 & AERMOD)

- Continue to evaluate
- CALPUFF adaptations of AERMOD activities (CALMM5)
- NCEP model output replaces MM5, preferably in both regional grid and local dispersion modeling
- Transition to real-time and forecast model output.
- Collaborate with Workgroup