Particulates: wind erosion modeling

Particulates, PM10, PM2.5 and increasingly PM1.0 become pollutants of primary concern in many cities and regions world wide. Health effect of fine particles that enter the respiratory pathways are reason for concern, effective control measure hotly disputed in particular where they involve restriction on individual passenger cars, access to inner city areas.

One of the important questions as the basis for any effective control measures is a reliable source apportionment between antropogenic, largely but not exclusively combustion related, and natural sources, that is wind erosion of soils, entrainment and re-suspension including very long range transport.

AirWare include a dynamic emisison model for wind erosion of soils, but also from activities such as demolition and construction activities, unpaved roads, surface mining, and many agricultural activities such as plowing and tilling or the use of harvest combines.

Operational forecasts, nowcasting
The particulate modeling is based on daily model/forecast runs over a 3-7 day forecast horizon, including:

• Downloading and pre-processing of NCEP/GFS global forecast data for the a large region around the primary area of interest, 5 to 10 times the horizontal extent in multiple layers of "nesting".
• Dynamic downscaling of the forecast (3 level nesting) with MM5;
• Running wind erosion model for the region (based on a two parameter Weibull function logarithmic wind speed distribution around MM5 hourly means, and a logarithmic threshold function of wind speed and (dynamic) erodibility based on vegetation cover, land surface, and soil/moisture data, see below;
• PM10/2.5 transport simulation with 3D Eulerian model CAMx, nested grid (two levels of nesting, two-way coupling, master and national/local domain); Model output (available for download from a dedicated web server)
• Daily updates of 3-7 day forecasts (hourly) of PM10/2.5 concentration and deposition data, regular model grid and derived statistical and graphical interpretation for up to 10 vertical layers.
• Continuous system logs and regular performance reports, self-check with real-time expert system RTXPS for on-line QA/QC, error detection, operator alerts (mail, SMS).

Historical (re-analysis) model runs:
To calibrate the model system, first step for any regional application is to re-run previous years with the latest re-analysis data to determine (historical) source areas and source contributions (possibly with historical landuse data derived from LANDSAT RS imagery). There are however several different versions of reanalysis (NCEP1, NCEP2, ERA40, ERA40 interim). Later versions usually have improved method or new data included. Reanalysis data from NCEP/NCAR are available for 1870 up to 2008: http://dss.ucar.edu/datasets/ds131.1/

The FNL data are still available from 1948 till present day. Probabilistic contribution analysis and dust mapping by super-ensembles use of several data sets and models (NCEP1, NCEP2, ERA40, ERA40interim, different models: MM5, WRF) data for probabilistic analysis. Alternative meteorological model configurations, using, for example:

• different pbl model, soil moisture model, numerical scheme, cloud
• parameterization, vortex following nesting (in WRF), etc. (also applicable for the real-time forecast runs).

Model input data compilation and processing
The cascade of the three simulations models (MM5, Emission model, CAMx) uses the following spatial inputs, compiled and pre-processed from 1 km resolution data sources to the nested model domain resolutions of 9, 3, and (optional) 1 km. The data are projected to the UTM zone of the center domain with progressively larger errors farther away from the domain center.

Basic land data for MM5 (topography, land use, soil, vegetation) can be taken from any national data base or global USGS datasets. More information about the default datasets can be found at http://eros.usgs.gov/#/Find_Data/Products_and_Data_Available/gtopo30/README

• 5 min ( ~9 km) global terrain and landuse for main domain (27 km)
• 2 min ( ~4 km) global terrain and landuse for 1st nested domain (9 km)
• 30 sec ( ~.9 km) global terrain and landuse for 2nd nested domain (3 km)

For dynamic forcings, AirWare can use and post-rpocesses NCEP/NCAR products:

• GFS (forecast): http://wwwt.emc.ncep.noaa.gov/gmb/moorthi/gam.html
• GEFS (ensemble): http://products.weather.gov/PDD/NCEPMAF.pdf
• FNL (reanalysis): http://dss.ucar.edu/datasets/ds083.2/.

Emission model and background maps:

• DEM: 1 km or (optional) 30 m resolution data sources http://free-gis-data.blogspot.com/2009/04/aster-global-digital-elevation-model.html
• Landcover, satellite derived
  • Historical: http://edc2.usgs.gov/glcc/glcc_version1.php#Eurasia
  • Recent: http://glovis.usgs.gov
• Soil data (optional): http://www.fao.org (1:5M vector map)
• NDVI (MODIS) https://lpdaac.usgs.gov/lpdaac/products/modis_overview

Transport model input data

CAMx input data (subset for the master domain, relevant for PM10/2.5 simulations;
please note that the boundary conditions for the nested domains are fully distributed and dynamic in a two-way coupling)