WRAP RMC Phase II Wind Blown Dust Project ENVIRON International Corporation and University of California, Riverside WRAP Dust Emission Joint Forum Meeting Reno, Nevada July 27, 2004

Outline Phase I Summary – Objectives – Methodology – Data Sources – Results/Limitations Phase II Overview – Objectives – Recent Literature and Models – Revised Methodology – Data Sources – Model Performance Evaluation – Schedule

Phase I Project Summary Objectives – Develop general methodology based on ‘MacDougall Method’ – Develop 1996 gridded PM inventory of WB Dust for the Western States Estimation Methodology – Categorize vacant land & soil types (disturbance, vegetative cover, soil texture) – Identify wind tunnel emission factors – Assign threshold wind velocities, wind & precipitation events, reservoir characteristics – Apply emission factors to vacant land as a function of wind speed & soil texture

Data Sources – Land Use/Land Cover (LULC) BELD3, NALCC, NLCD – Soil Characteristics STATSGO; Soil Landscape of Canada; Intl. Soil Reference and Information Centre – Meteorological Data km MM5 – Agricultural Data BELD3; RUSLE2; CTIC

Phase I Results 20mph 10-meter wind 15mph 10-meter wind

Phase I Project Summary Limitations – Threshold surface friction velocities – Emission factors – Vacant land stability – Dust reservoirs – Rain events – Vegetation density

Phase II Project Overview Objectives – Develop improved general methodology based on Phase I recommendations and recent literature review – Develop 2002 gridded PM inventory of WB Dust for the Inter-RPO regional modeling domain – Development of surface friction velocities and threshold friction velocities – Develop improved emission flux relationships – Improved characterization of disturbed lands – Characterize vacant lands using more up-to-date databases – Conduct model performance evaluation

General Formulation Dust = f(LULC,z 0,u *,u *th,SC) u * = f(u,z 0 ) u *th = f(z 0 ) z 0 = f(LULC)

Recent Literature and Models Draxler, et al., 2001 – Regional model application – Dust emissions a function of u *, u *th, z 0 – z 0 correlated with soil properties of Persian Gulf region – Assumed all soils disturbed Zender, et al., 2003 – Global model application – Dust emissions a function of u *, u *th, z 0 – Global z 0 = 0.01 cm – Uniform soil texture Shao, 2001 – Dust emissions a function of u *, u *th, z 0 – Emphasis on particle size distribution and micro forces

Revised Methodology Threshold velocities Emission factors LULC characteristics Soil characteristics Reservoir characteristics Agricultural adjustments

Threshold Friction Velocities u *th determined from relations developed by Marticorena, et al, (1997)

Surface Roughness Lengths Land Use Typez 0 (cm) Urban50 USGS cropland/pasture5 Grassland0.1 Shrubland0.05 Forest50 Barren/Desert0.002 Bare Agricultural0.031

Emission Rates Determined from results of Alfaro and Gomes (2001) Dependent on soil type

Soil Characteristics Soil texture mapped to 4 soil groups

Soil Characteristics

Soil disturbance – Disturbed soils have a greater potential for erosion – Results in reduced threshold surface friction velocities – Soils are assumed to be undisturbed – Assumed percentage of disturbance by land use type – Threshold velocities reduced from ~20% – 90%

Reservoir Characteristics Amount and condition of soils impact dust emissions Climatological effects (rain, snow, etc.) Sandy soils dry fastest, loams medium range, clays dry slowest. Evapotranspiration rates ~ twice as high in summer than winter; ~ 1.4 times higher than spring/fall

Reservoir Characteristics Soil TypeSpring/FallSummerWinter Sand Sandy Loam Fine Sand Loam Loam Silt Loam Sandy Clay Loam Clay Loam Silty Clay Loam Clay7510 # days after precip to re-initiate wind erosion (> 2inches of rain)

Reservoir Characteristics Soil TypeSpring/FallSummerWinter Sand Sandy Loam Fine Sand Loam Loam Silt Loam Sandy Clay Loam Clay Loam324 Silty Clay Loam Clay # days after precip to re-initiate wind erosion (< 2inches of rain)

Agricultural Adjustments Non-climatic factors significantly decrease soil loss from agricultural lands Similar approach to CARB, 1997 (as in Phase I) Five “adjustment” factors simulate these effects: – Bare soil within fields – Bare borders surrounding fields – Long-term irrigation – Crop canopy cover – Post-harvest vegetative cover (residue)

Data Sources Land Use/Land Cover – National Land Cover Database (NLCD) – Biogenic Emissions Landcover Database (BELD3) Soils – State Soil Geographic Database (STATSGO) – Soil Landscape of Canada (SLC) – International Soil Reference and Information Centre Meteorology – km Gridded MM5

NLCD Summary

Model Performance Evaluation Evaluate model results for reasonableness and accuracy Compare predicted WB dust emissions near IMPROVE monitors with measured IMPROVE dust extinction (B dust ) – Identify occurrences of: 1) Zero WB dust and near-zero B dust 2) Enhanced WB dust and near-zero B dust 3) No WB dust and elevated B dust 4) Enhanced WB dust and elevated B dust Enhancements to CMAQ to track WB and other dust Evaluate model CMAQ model performance with and with out WB dust emissions

Model Performance Evaluation Refined model performance evaluation using results of Etyemezian, et al. For events characterized as wind blown dust events, determine whether dust model predicts impacts Model and measurements agree … – Analyze for trends – Systematic over- or under-prediction ? Model and measurements disagree … – Wind speed errors ? – Landuse type mischaracterization ? – Other ?

Project Schedule Draft 2002 Dust Emission Inventory: July 30, 2004 Final 2002 Dust Inventory & Project Report: August 20, 2004 Initial Model Performance Evaluation Report: August 31, 2004 Refined Model Performance Evaluation Report: October 31, 2004