Evaluation of the Accuracy ofMM5/CALMET GeneratedWind Fields in SouthwesternWyomingD.N. Blewitt, CCMComments on behalf of theAmerican Petroleum InstituteImportance of AccurateMeteorological ModelingResults• For conducting regional air quality analyses forAQRVs and ozone, accurate meteorologicalmodeling results are imperative• Because Class I Areas are a concern, accurateestimates of wind direction are necessary• Because of the importance of chemical reactions,accurate estimates of wind speed are necessaryBridger Class I AreaWamsutter MetTowerJonah Met TowerLander HuntFieldSalt Mt. RangeSouthwest Wyoming GeographyMM5 Results Available forCALMET Input•MM5 was run as part of the SWWYTAF analysisusing a 36 kilometer grid for the year 1995(EarthTech, 2001The Southwest WyomingRegional CALPUFF Air Quality Modeling Study)•MM5 was run for 2002 using a 12 kilometer grid(Bureau of Land Management, 2007, Moxa ArchArea Infill Gas Development Project)•MM5 was run for for Southwest Wyoming for theyear 2006 using a 4 kilometer grid – CALMETwas not run (Environ 2008)36 and 12 Kilometer CALMETAnalysis•MM5 was used as the initial guess field forCALMET•In addition to MM5, CALMET used 22surface stations and 5 upper air stations•The modeling domain was 464 km (eastwest) by 400 km (north-south)•The grid size used in CALMET was 4kilometersJonah Meteorological Data•Data collected 1999 to 2004•10-meter tower–Wind speed–Wind direction–Temperature–Sigma theta•Data recovery in excess of 99 percent•QA/QC calibrations and audits performedaccording to EPA GuidelinesAnalysis Technique•CALMET was run and ISC met data sets for theJonah and Lander sites were extracted•Compared extracted wind rose to measured windrose•Comparison between MM5/CALMET is based onpairing in space but not time•Operational evaluation•Qualitative comparison of model output tomonitored dataJonah MM5/CALMETPredictedJonah Observed36 Kilometer Comparison**0 100 200 300 400 MM5 Wind Direction (Deg)** **0 100** **200 300** **400**

**C A**  **L M**  **E T**  **W i**  **n d**  **D i**  **r e**  **c t**  **i o**  **n (**  **D e**  **g )** **Figure 11. MM5 wind Direction vs Calmet for Wind S peeds > 1.0 m/s** **Note: Every 10 th** **point is plotted**Comparison of MM5 Wind Direction to CALMET Wind Direction36 Kilometer MM5 Run**0 1 2 3 4 5 6 7 8 9 10 11 12 13 Wind Speed Class (m/S)** **0 10** **20 30** **40**

**Frequency of Occurance (%) Measured Wind Speed** **Calmet Level 1( 10-meter) Wind Speed Comparison of Frequency of Occurance of Measured Wi** **nd Speed and Calmet Extracted Wind Speed for the Same Loc** **ation and A** **ll Stabilities NORTH** **SOUTH WEST** **EAST 5%** **10% 15%** **20% 25%** **W I** **N D** **S P** **E E** **D (** **K n** **o t** **s )** **> =** **2 2** **1 7** **- 2** **1 1** **1 -** **1 7** **7 -** **1 1** **4 -** **7 1** **- 4** **C a** **l m** **s :** **5 .** **7 7** **% NORTH** **SOUTH WEST** **EAST 5%** **10% 15%** **20% 25%** **W I** **N D** **S P** **E E** **D (** **m /** **s )** **> =** **1 1** **. 1** **8 .** **8 -** **1 1** **. 1** **5 .** **7 -** **8 .** **8 3** **. 6** **- 5** **. 7** **2 .** **1 -** **3 .** **6 0** **. 5** **- 2** **. 1** **C a** **l m** **s :** **0 .** **3 7** **%**Jonah CALMET/MM5 Predicted Jonah Measured12 Kilometer Comparison**NORTH SOUTH** **WEST EAST** **5% 10%** **15% 20%** **25% W** **I N** **D S** **P E** **E D** **( K** **n o** **t s** **) >** **= 2** **2 1** **7 -** **2 1** **1 1** **- 1** **7 7** **- 1** **1 4** **- 7** **1 -** **4 C** **a l** **m s** **: 5** **. 7** **7 %** Jonah CALMET/MM5 Predicted12 Kilometer ComparisonComparison of Measured and Modeled WindSpeeds (12 Kilometer MM5) at Jonah051015202530354045Calm 0.5-2.1 2.1-3.6 3.6-5.7 5.7-8.8 8.8-11.1 >11.1Wind Speed (m/s)

Frequency (%)Measured (2001)Modeled (2001-2003)4 Kilometer MM5 Jonah (2006) Observed Jonah (2006)Source: Environ4 Kilometer Comparison4 Kilometer MM5 4 Wamsutter (2006) Observed Wamsutter Monitor (2006)Source: Environ4 Kilometer Comparison**NORTH SOUTH** **WEST EAST** **5% 10%** **15% 20%** **25% W** **I N** **D S** **P E** **E D** **( K** **n o** **t s** **) >** **= 2** **2 1** **7 -** **2 1** **1 1** **- 1** **7 7** **- 1** **1 4** **- 7** **1 -** **4 C** **a l** **m s** **: 5** **. 7** **7 %** Comparison of 4 kilometer MM5,12 and 36 Kilometer MM5/CALMET Windroses for JonahConclusions and RecommendationsThe widespread use of meteorological model outputin air quality modeling requires:• The accuracy of MM5/CALMET model output must betested for each dispersion model application• EPA needs to coordinate a stakeholder group to developguidelines for the use of meteorological models inairquality analyses• Meteorological model accuracy is more important than thenumber of years of model results used in an air qualityanalysisConclusions andRecommendations (continued)Topics that the modeling community need toaddress:– Which meteorological model should be used?– Grid size?– How should meteorological monitoring sites beincluded in modeling?– Model performance criteria?