AERSURFACE Update. Clint Tillerson, Roger Brode. U.S. EPA / OAQPS / Air Quality Modeling Group

Transcription

1 AERSURFACE Update Clint Tillerson, Roger Brode U.S. EPA / OAQPS / Air Quality Modeling Group Regional/State/Local Modeler s Workshop September 25, 2017

2 Purpose of AERSURFACE Estimate values for surface characteristics required by AERMET for NWS and site-specific met tower locations Surface characteristics include albedo, Bowen ratio, and surface roughness length Uses the National Land Cover Database (NLCD) Not part of the regulatory modeling system

3 What does revised Guideline say? Appendix W, Section 8.4.2: The EPA recommends that the surface characteristics input to AERMET should be representative of the land cover in the vicinity of the meteorological data... Therefore, the model user should apply the latest version AERSURFACE, where applicable, for determining surface characteristics when processing measured meteorological data through AERMET. In areas where it is not possible to use AERSURFACE output, surface characteristics can be determined using techniques that apply the same analysis as AERSURFACE.

4 History Version (1/9/2008) Limited to 1992 NLCD (CONUS Only) Version (1/16/2013) Included minor enhancements and bug fixes Limited to 1992 NLCD (CONUS Only) Since 2008, NLCD products have expanded to include: 2001, 2006, and 2011 data with separate Land Cover, Impervious, and Canopy data New NLCD classifications differ from 1992 NLCD Some years include Alaska and/or Puerto Rico and/or Hawaii (can view Hawaii, yet to be able to download it) Canopy and/or Impervious percentages are available for some years, for some areas

5 NLCD Inventory Contiguous 48 states only (CONUS) CONUS, Alaska, and Puerto Rico Land Cover, Impervious, and Canopy for all 3 areas Alaska: Incomplete coverage for impervious and canopy data CONUS Only: Land Cover and Impervious Only CONUS: Land Cover, Impervious, and Canopy Alaska: Land Cover Only

6 Is there ever going to be another Version of AERSURFACE?

7 YES! Yes there is! BETA version is nearly complete!

8 So, what is the hold up?

9 Development Issues Competing Priorities (Needs) and Resources (People) Unintentionally shelved as other priorities consumed resources Complications with Classification Scheme and Interpretation Particularly for surface roughness in developed areas (e.g., airports) This is due to how the developed categories are defined for the 2001, 2006, and 2011 NLCD (building, runway, or a grassy area) AERMOD is known to be sensitive to roughness, more so than albedo and Bowen ratio (Brode et al., 2008) Evaluation Method(s) Prior to AERSURFACE, determining surface characteristics was more qualitative, based on visual inspection of aerial/satellite imagery Lack of data for areas where surface characteristics are known to perform quantitative evaluation.

10 How best to quantitatively evaluate AERSURFACE?

11 Past Evaluation Efforts Qualitative Do the values make sense based on what is known about different types of land cover? Useful but subjective, not repeatable from one individual to another. Quantitative ASOS Tropical Cyclone Wind Exposure Documentation Project Roughness length estimated for eight 45-degree sectors for over 200 ASOS sites, with limited project documentation How were roughness values determined? Qualitative or quantitative? Gust Factor Method for surface roughness, based on Wieringa (BAMS, 1980) Same problem with evaluation While the method has been around a long time, the implementation using 1-minute ASOS data (Gust Factor Tool) needs to be evaluated

12 Status of Gust Factor Tool Previously developed by EPA as a supplemental tool based on the Gust Factor Method (Wieringa, 1980). Potential aid for validating AERSURFACE derived roughness Uses ASOS 1-minute wind data Is it appropriate to cross-validate AERSURFACE and Gust Factor Tool with each other? While we intend to release the Gust Factor Tool sometime in the future, as a supplemental tool, we feel it needs an independent evaluation, as does AERSURFACE.

13 Status of AERSURFACE (BETA) A beta version has been developed by EPA Will process 1992, 2001, 2006, and 2011 NLCD Incorporates impervious and canopy data to supplement developed land cover categories Still limited to GeoTIFF files Uses a path/keyword approach similar to AERMOD Currently testing with all NLCD versions Still determining appropriate evaluation methods and data

14 Future Webinar Prior to the release of the new beta AERSURFACE, we will conduct a webinar to include: Overview of changes Guidance on usage Evaluation results Data sources When the beta version is released, EPA intends to provide the code with full documentation, including a user s guide, on SCRAM.

15 Future AERSURFACE Development Paths? Rewrite current program in a different language? Goal to be more adaptable (more easily expand to multiple file formats) Develop tools/plugins for GIS systems? Allow flexibility for different formats Allow for corrections to land cover data Other suggested development paths?