**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# CENRAP **Modeling: Need for 36**  **km versus 12 km Grid Resolution**  Ralph Morris, Gerard Mansell, Bonyoung Koo and Abby Hoats, ENVIRON International Corporation Gail Tonnesen, Mohammed Omary, Chao
- Jung Chien

and Yingqun Wang UC Riverside CENRAP Modeling Work Group Meeting Baton Rouge, Louisiana February 7, 2006**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006** 



# Background

• 2002 annual runs using CMAQ and/or CAMx are quite resource intensive

– CMAQ 36 km grid 5 days on 36 CPUs & 1,000 Gb output

– CAMx 36 km grid 9 days on 8 CPUs & 200 Gb output

– CMAQ 12 km grid ~2 weeks on 36 CPU & 2,000 Gb

– CAMx 12km grid ~3 weeks on 8 CPUs & 500 Gb output


## • SMOKE emissions modeling of 12 km grid also adds another 1
- 3 weeks of processing and 4 Tb of disk storage needed
• Preliminary Model Performance Evaluation (MPE) did not indicate improvements in model performance using 12 km grid**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006** 



# Purpose

• To determine whether 12 km grid improves the CENRAP regional haze modeling sufficiently well to justify added expense/time

– If 12 km grid does seem justified, can just 12 km meteorological be used and interpolate 36 km emissions to achieve the benefits of the 12 km grid

– flexi
- nested emissions (FE)**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006** 



# Approach

• Model three 2002 episodes at 36 km and 12 km resolution

– Spring: March 7 th 

## to April 23 th



## – Summer: August 27 th 

## to September 13 th



## – Winter: November 26 th 

## to December 15 th


# • CMAQ and CAMx 36km vs. 12km model performance comparisons

– Also perform CAMx 12km runs with emissions flexi
- nested (FE) from 36km emissions**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Spring **Episode: CMAQ Modeling 36 km**  **versus 12 km**  **Model Performance** Sulfate (SO4) Nitrate (NO3)**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Spring **Episode: CMAQ Modeling 36 km**  **versus 12 km**  **Model Performance** Organic Matter Carbon (OMC) Elemental Carbon (EC)**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Spring **Episode: CMAQ Modeling 36 km**  **versus 12 km**  **Model Performance** Soil (Other PM 2.5 

### ) Coarse Mass (CM)**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Summer Episode: SO4 Performance **CENRAP IMPROVE Monitoring**  **Sites** CMAQ 36km vs. 12km CAMx 36km vs. 12km**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Summer Episode: SO4 Performance **CENRAP C**  **ASTNet Monitoring**  **Sites** CMAQ 36km vs. 12km CAMx 36km vs. 12km**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Summer Episode: NO3 Performance **CENRAP IMPROVE Monitoring**  **Sites** CMAQ 36km vs. 12km CAMx 36km vs. 12km**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Summer Episode: OMC Performance **CENRAP IMPROVE Monitoring**  **Sites** CMAQ 36km vs. 12km CAMx 36km vs. 12km**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Summer Episode: EC Performance **CENRAP IMPROVE Monitoring**  **Sites** CMAQ 36km vs. 12km CAMx 36km vs. 12km**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Winter Episode: SO4 Performance **CENRAP IMPROVE Monitoring**  **Sites** CMAQ 36km vs. 12km CAMx 36km vs. 12km**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Winter Episode: NO3 Performance **CENRAP IMPROVE Monitoring**  **Sites** CMAQ 36km vs. 12km CAMx 36km vs. 12km**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Winter Episode: OMC Performance **CENRAP IMPROVE Monitoring**  **Sites** CMAQ 36km vs. 12km CAMx 36km vs. 12km**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Winter Episode: EC Performance **CENRAP IMPROVE Monitoring**  **Sites** CMAQ 36km vs. 12km CAMx 36km vs. 12km**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Conclusions: **36km vs.**  **12 km**

• CMAQ model performance fairly insensitive to use of 36km or 12km grid resolution
• CAMx exhibits more sensitivity to 12km grid

– Summer SO4 underprediction bias greatly reduced using 12 km grid

• Different treatment of clouds?
• Different horizontal diffusion sensitivity?

– CMAQ inversely , whereas CAMx proportional to grid cell size
• High resolution emissions?
• Other?



### – What is chief driver in 36km/12km differences?

• Meteorology; Emissions; Model Formulation; Other?
• Use CAMx flexi
- nest feature applied to emissions to interpolate 36km emissions to 12 km; all other inputs at 12km**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# SO4 **Effects of 12km**  **versus Flexi**  **- Nest**  **Emissions at CENRAP IMPROVE Sites**  Summer Winter**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# NO3 **Effects of 12km**  **versus Flexi**  **- Nest**  **Emissions at CENRAP IMPROVE Sites**  Summer Winter**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# OMC **Effects of 12km**  **versus Flexi**  **- Nest**  **Emissions at CENRAP IMPROVE Sites**  Summer Winter**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# EC Effects of **12km versus**  **Flexi -**  **Nest Emissions at CENRAP**  **IMPROVE Sites** Summer Winter**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  **SO4**

**-40 -30**  **-20 -10**  **0 10**  **20 30**  **40**

**Spr ing**  **Su mme**  **r Wi**  **nte r** **F r** **a c** **t i** **o n** **a l** **B i** **a s** **( %** **) 36k**  **12k** 

### SO4 Fractional Bias **36km, 12km, 12kmFE**  CMAQ
– little sensitivity to 12km grid

**Spr ing**  **Su mme**  **r Wi**  **nte r** 

-40 -30 -20 -10 0 10 20 30 40 50

Sum me r Wi nter**F r** **a c** **t i** **o n** **a l** **B i** **a s** **( %** **)** 36k 12k 12kFE 

###  CAMx
– in summer 12km grid eliminates bias! Flexi - nested emissions similar to 12km**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

### NO3 Fractional Bias **36km, 12km, 12kmFE**  CMAQ
– some sensitivity to 12km grid **NO 3** 

**-1 20**  **-1 00**  **-8 0**  **-6 0**  **-4 0**  **-2 0**  **0 20**  **40 60**  **80**

**Spring Sum**  **mer Wi**  **nt er** **F r** **a c** **t i** **o n** **a l** **B i** **a s** **( %** **) 36k**  **12k**



###  CAMx
– little sensitivity to 12 km grid; flexi - nested emissions match 12 km emission performance

-150 -100 -50 0 50 100

Sum me r Wi nt er**F r** **a c** **t i** **o n** **a l** **B i** **a s** **( %** **)** 36k 12k 12kFE**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  **OC**

**0 5**  **10 15**  **20 25**  **30 35**  **40**

**Spri ng**  **Sum mer**  **Winter F** **r a** **c t** **i o** **n a** **l B** **i a** **s (** **% )**  **36k 12k**  

### OMC Fractional Bias **36km, 12km, 12kmFE**  CMAQ
– some sensitivity to 12km grid

– performance changes mixed. Winter performance worse than **Spri ng**  **Sum mer**  **Winter**

-90 -80 -70 -60 -50 -40 -30 -20 -10 0 10

Summ er Wi nter**F r** **a c** **t i** **o n** **a l** **B i** **a s** **( %** **)** 36k 12k 12kFE 

### CAMx  CAMx
– little sensitivity to 12 km grid; flexi - nested emissions match 12 km emission performance**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  **EC**

**-60 -50**  **-40 -30**  **-20 -10**  **0 10**  **20**

**Spr in**  **g Sum**  **me r**  **Win te**  **r F** **r a** **c t** **i o** **n a** **l B** **i a** **s (** **% )**  **36k 12k**  

### EC Fractional Bias **36km, 12km, 12kmFE**  CMAQ
– small sensitivity to 12km grid
– performance changes mixed. Winter performance improved **Spr in**  **g Sum**  **me r**  **Win te**  **r**

-50 -40 -30 -20 -10 0 10 20 30 40

Su mme r Wi nter**F r** **a c** **t i** **o n** **a l** **B i** **a s** **( %** **)** 36k 12k 12kFE 

###  CAMx
– small sensitivity to 12 km grid; flexi - nested emissions match 12 km emission performance**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Conclusions: 12km Emissions Need

• Using all 12 km inputs versus all 12 km inputs except emissions that are flexi
- nested from the 36 km emissions produces essentially identical CAMx model performance in the CENRAP domain

– Improved CAMx summer SO4 performance using 12 km grid appears due to meteorology and model formulation, not emissions

– Supports notion that if 12 km modeling is needed may be able to flexi
- nest emissions

• Significant savings in time and resources**ENVIRON/UCR CENRAP Modeling Workgroup February 6**  **- 8, 2006**  

# Recommendations: **12 km Grid**

• Wi th the possible exception of CAMx SO4 performance, little benefit in model performance seen with use of 12 km grid
• For Regional Haze Modeling at Class I Areas, use of 12 km meteorology and 36 km emissions (flexi
- nest) probably adequate

– If using CAMx can flexi
- nest autom atically

– If using CMAQ will need an external flexi
- nest type program

CMAQ will need an external type program

– Would require processing of 12 km meteorological data


### • If analyzing 8
- hour ozone and/or PM 2.5 

### may come to different recommendation
• Still have not evaluated effects of grid resolution on response to emission reductions

– VISTAS found similar 2018 visibility projections using 36km and 12km grids