### DRAFT

METEOROLOGICAL DATA PROCESSING

USING AERMET

FOR HEM3

US EPA Air Toxic Assessment Group

RTP NC 27711

September , 2014Meteorological Data Processing using AERMET December 201 3

For HEM3

1 BACKGROUND

The AERMOD meteorological processor, AERMET, and its supporting modeling system (AERSURFACE and AERMINUTE) w ere used to process one year of meteorological

data for over 800 observation stations across the continental United States, Alaska,
Hawaii, and Puerto Rico.

METEOROLOGICAL DATA

To estimate the boundary layer parameters required by AERMOD, AERMET requires hourly surface weather observations ( which may includ e hourly values calculated from 1

- minute data) and the full (i .e., meteorological variables reported at all levels) twice

- daily upper air soundings. The surface and upper air stations are paired to produce the required input data for AERMOD.

USEPA meteorologists obtained calendar year 2011 Integrated Surface Hour ly Data (ISHD) for over 800 Automated Surface Observation System (ASOS) stations spanning

the entire US

, as well as Puerto Rico and the US Virgin Islands

, from the Natio nal Climatic Data Center (NCDC). To support AERMET, ASOS 1

- m inute d ata for each

surface station w ere also obtained from NCDC in a DSI 6405 format.

Further, upper air sounding data for the same time period for over 80 observation sites

were obtained from the “ NOAA/ESRL ” online Radiosonde Database

. These datasets were produced b y ESRL in Forecast Systems Laboratory (FSL) format. Appendix 1 lists

the surface stations

, as well as the location, ground elevation, and anemometer height for

each station. Figure 1 is a map that shows the locations of all the surface stations. Appendi x 2 lists the upper air stations and their locations

.

AERMET PROCESSING

Utilizing the AERMET meteorological data preprocessor , and the ASOS surface and FSL upper air stations, surface and profile files for input in to AERMOD were generated

nationwide. The surface stations were paired with representative upper air stations by taking the upper air station closest to each surface station. The AERSURFACE tool was used to estimate the surface characteristics for input in to AERMET utilizing land cover

data s urrounding the surface station

. In addition, the AERMINUTE preprocessor was

u sed to process 1

- minute ASOS wind data for input in to AERMET. Table 1 outlines the approach/inputs each of the data preprocessors and tools used to generate the AERMOD

meteorolo gical data.Meteorological Data Processing using AERMET December 201 3

For HEM3

2 Figure 1 . Surface StationsMeteorological Data Processing using AERMET December 201 3

For HEM3

3 Table 1

. AERMET Processing Options AERMET Options Version 13350 1

ASOS Site Yes

Surface Data Format NCDC TD

- 3505 (ISHD) Upper Air Data Format FSL, all levels, tenths m/s Wind Speed Threshold 0.5 m/s Beta Option (U*) Y es AERMINUTE Options Version 1132 5

Include 1 minute ASOS

Data Yes, where available TD

- 6405

format AERSURFACE Options Version 13016

Landcover data USGS NLCD92 GeoTIFF format (except Alaska and Hawaii which

used 20 0 1 landcover data)

Radius for Surface Roughness Calculations 1 km

Site Characteristics Airport Site (where applicable) Arid Regions for all sites in AZ, NM, UT only Temporal resolution Monthly, 12 sectors

Site Surface Moisture Average

Snow Cover Late Winter/Winter without

continuous snow cover

– all states (except Alaska where we used continuous snow)

1 : generated with the pre

- public release version of AERMET 13350.

RESULTS

Beginning with version 12345, AERMET allows for a minimum wind speed of 0.5 m/s to be utilized when processing monitoring stations that are equipped with sonic

anemometers and for a n adjustment to the surface friction velocity (u*). The public version of AERMET available at the time we conducted the processing of this data did not include the surface friction velocity adjustment. Also at the time, an updated version of AERMET (and AERMOD) was under development that incorporated further surface friction velocity adjustments to AERMET version 12345. In anticipation of the update, EPA processed meteorological data using a pre

- public release version of AERMET and incorporated the updat ed surface friction velocity adjustment in the output. It was EPA’s judgement that the pre

- public release version of AERMET would generate AERMOD ready meteorological data very close to that generated with the 13350 version of

AERMET. The AERMET meteorol ogical data posted on the EPA’s FERA (Fate, Exposure, and Risk Analysis) website under the HEM model page was generated with the

pre

- public release version of AERMET 13350.Meteorological Data Processing using AERMET December 201 3

For HEM3

4 ly, USEPA meteorologists ran AERMOD using a model plant. Further, the surface file s were examined for completeness. If more than 10 percent of the data were missing, the

station was not considered suitable for the HEM

- 3 meteorological database. In all, 824 met station pairs ran successfully and will be included in the HEM

- 3 meteorologi cal library. A summary of these station pairs are presented in Appendix 3 of this document.