1. NetCDF Weather Data from Unidata By David Maidment, Tim Whiteaker and Cedric David Center for Research in Water Resources University of Texas at Austin

2. NetCDF Weather Data from Unidata Using real-time weather data in ArcGIS Sphere to Spheroid transformations OpenMI system for model interfacing

3. NetCDF Weather Data from Unidata Using real-time weather data in ArcGIS Sphere to Spheroid transformations OpenMI system for model interfacing

4. Ocean Sciences Unidata Universities Corporation for Atmospheric Research is a large NSF-supported atmospheric science organization in Boulder, CO UCAR was formed in 1957 Unidata provides real-time atmospheric science data to academic institutions Unidata opened in 1983 Weather data and forecasts for the last 7 days on Motherlode Earth Sciences Atmospheric Sciences National Science Foundation Geosciences Directorate UCAR CUAHSI Unidata HIS

5. Unidata NetCDF Files Catalog of Datasets –http://motherlode.ucar.edu:8080/thredds/catalog.htmlhttp://motherlode.ucar.edu:8080/thredds/catalog.html

6. NCEP NAM 12km Data North American Model Continuous grid over the continental US Model runs are made at 06Z, 12Z, 18Z and 00Z Forecasts every 3 hours out to 84 hours Accessed With –OPENDAP –HTTPServer –WCS –NetcdfServer

7. Netcdf Server Query for subset of data with Web Form Download netCDF file

8. Query Via URL Format documented at –http://motherlode.ucar.edu:8080/thredds/docs/Netcdf Server.htmlhttp://motherlode.ucar.edu:8080/thredds/docs/Netcdf Server.html Example: –http://motherlode.ucar.edu:8080/thredds/ncServer/mo del/NCEP/NAM/CONUS_12km/NAM_CONUS_12km _20060803_1800.grib2? grid=Total_precipitation &north=35&south=30&west=-90&east=-85 &time_start=0.0&time_end=12.0 Data Type Bounding Box Start/End Time

9. NDFD Data Also Available NWS National Digital Forecast Database Gridded forecasts of sensible weather elements 5km resolution over continental US http://motherlode.ucar.edu:8080/thredds/c atalog/model/NCEP/NDFD/CONUS_5km/c atalog.htmlhttp://motherlode.ucar.edu:8080/thredds/c atalog/model/NCEP/NDFD/CONUS_5km/c atalog.html

10. Viewing NetCDF in ArcMap

11. Unidata Weather in ArcMap Total Precipitation 7/21/06 – 7/24/06 Demo

12. NetCDF Weather Data from Unidata Using real-time weather data in ArcGIS Sphere to Spheroid transformations OpenMI system for model interfacing

13. Sphere – Spheroid Transformation We think of the earth as a sphere It is actually a spheroid, slightly larger in radius at the equator than at the poles Weather models are computed on a spherical earth Hydrologic models and data Are on a spheroidal earth

14. Latitude and Longitude on a Sphere Meridian of longitude Parallel of latitude  X Y Z N E W   =0-90°S P O R =0-180°E  =0-90°N Greenwich meridian =0° Equator =0° =0-180°W - Geographic longitude  - Geographic latitude R - Mean earth radius O - Geocenter

15. Definition of Latitude,  (1) Take a point S on the surface of the ellipsoid and define there the tangent plane, mn (2) Define the line pq through S and normal to the tangent plane (3) Angle pqr which this line makes with the equatorial plane is the latitude , of point S O  S m n q p r

16. Geographic and Geodetic Latitudes  N E W  = 0  =0-90°S P O R  =0-90°N On a spherical earth, the normal line always passes through the geocenter (O) of the earth – “geographic latitude”  g O  S n q p r On a spheroidal earth, the normal Line pq does not pass through the geocenter (O) of the earth – “geodetic latitude”, 

17. Application: hydrologic modeling using weather model data ArcGIS 9.2 is netCDF CF-1 compliant ? + = Watersheds on spheroid Weather data on sphere

18. Sphere – spheroid transformations http://www.crwr.utexas.edu/gis/gishydro06/index.htm

19. NetCDF Weather Data from Unidata Using real-time weather data in ArcGIS Sphere to Spheroid transformations OpenMI system for model interfacing

20. Project sponsored by the European Commission to promote integration of water models Software standards for model linking Uses model core as an “engine” http://www.openMI.org

21. OpenMI – Links Data and Simulation Models CUAHSI Observations Data Model as an OpenMI component Simple River Model Trigger (identifies what value should be calculated)

22. Typical model architecture Application User interface + engine Engine Simulates a process – flow in a channel Accepts input Provides output Model An engine set up to represent a particular location e.g. a reach of the Thames Engine Output data Input data Model application Run Write Read User interface

23. AcceptsProvides Rainfall (mm) Runoff (m 3 /s) Temperature (Deg C) Evaporation (mm) AcceptsProvides Upstream Inflow (m 3 /s) Outflow (m 3 /s) Lateral inflow (m 3 /s) Abstractions (m 3 /s) Discharges (m 3 /s) River Model Linking modelled quantities

24. Data transfer at run time Rainfall runoff Output data Input data User interface River Output data Input data User interface GetValues(..)

25. Models for the processes River (InfoWorks RS) Rainfall (database) Sewer (Mouse) RR (Sobek-Rainfall -Runoff)

26. Data exchange 3 Rainfall.GetValues River (InfoWorks-RS) Rainfall (database) Sewer (Mouse) 2 RR.GetValues 7 RR.GetValues RR (Sobek-Rainfall -Runoff) 1 Trigger.GetValues 6 Sewer.GetValues call data 4 5 8 9

27. Conclusions Use of NetCDF in ArcGIS permits direct access to real-time weather information from Unidata A sphere to spheroid transformation is required to bring the weather data into a regular map coordinate system OpenMI promises to be a good way to interconnect hydrologic data and models