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NetCDF in ArcGIS 9.2

NetCDF in ArcGIS 9.2. Overview. Introduction to Multidimensional Data What is netCDF? Some netCDF data sources Working with netCDF in ArcGIS. T. Y. X. Multidimensional Data. Data cube (3D) or hypercube (4D,5D…) Temperature of a location varying with time

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NetCDF in ArcGIS 9.2

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  1. NetCDF in ArcGIS 9.2 UC 2006 Tech Session

  2. Overview • Introduction to Multidimensional Data • What is netCDF? • Some netCDF data sources • Working with netCDF in ArcGIS UC 2006 Tech Session

  3. T Y X Multidimensional Data Data cube (3D) or hypercube (4D,5D…) • Temperature of a location varying with time • Temperature at a locationvarying with time and altitude • E.g. for every x, y, z… you can store multiple variables with multiple time steps UC 2006 Tech Session

  4. Multidimensional Data Time = 1 Time = 2 Data Cube Time = 3 Time Slices UC 2006 Tech Session

  5. Gridded Data Regular Grid Irregular Grid (as points) UC 2006 Tech Session

  6. Multidimensional Data Time = 3 Time = 2 Time = 1 UC 2006 Tech Session

  7. Multidimensional Data UC 2006 Tech Session

  8. T Y Z X What is netCDF? • An array based data structure for storing multidimensional data. • N-dimensional coordinates systems • X coordinate (e.g. longitude) • Y coordinate (e.g. latitude) • Z coordinate (e.g. altitude) • Time dimension • … other dimensions • Variables – support for multiple variables • Temperature, humidity, pressure, salinity, etc • Geometry – implicit or explicit • Regular grid (implicit) • Irregular grid • Points UC 2006 Tech Session

  9. What is a NetCDF file? NetCDF is a binary file A NetCDF file consists of: Global Attributes: Describe the contents of the file Dimensions: Define the structure of the data (e.g Time, Depth, Latitude, Longitude) Variables: Holds the data in arrays shaped by Dimensions Variable Attributes: Describes the contents of each variable CDL (network Common Data form Language) description takes the following form netCDF name { dimensions: ... variables: ... data: ... } UC 2006 Tech Session

  10. CF Convention There are many flavors or conventions of netCDF data, ArcGIS relies on the CF Convention. Climate and Forecast (CF) Convention http://www.unidata.ucar.edu/software/netcdf/docs/conventions.html Initially developed for • Climate and forecast data • Atmosphere, surface and ocean model-generated data • Also used for observational datasets • CF is the most widely used convention for geospatial netCDF data. It has the best coordinate system handling. UC 2006 Tech Session

  11. NetCDF Data Sources • Community Climate Systems Model (CCSM)  http://www.ccsm.ucar.edu, https://www.earthsystemgrid.org/ • Program for Climate Model Diagnosis and Intercomparison (PCMDI) http://www-pcmdi.llnl.gov/ • Vegetation and Ecosystem Modeling and Analysis Project (VEMAP) http://dataportal.ucar.edu/vemap/main.html • British Atmospheric Data Center (BADC) http://badc.nerc.ac.uk/data/ • National Digital Forecast Database (NDFD) http://www.nws.noaa.gov/ndfd/ • Radar Integrated Display with Geospatial Element (RIDGE) http://www.srh.weather.gov/ridge/ • Precipitation Analysis http://www.srh.noaa.gov/rfcshare/precip_download.php • Climate Diagnostics Center http://www.cdc.noaa.gov/ UC 2006 Tech Session

  12. NetCDF in ArcGIS • NetCDF data is accessed as • Raster • Feature • Table • Direct read • Exports GIS data to netCDF UC 2006 Tech Session

  13. NetCDF Tools Toolbox: Multidimension Tools • Make NetCDF Raster Layer • Make NetCDF Feature Layer • Make NetCDF Table View • Raster to NetCDF • Feature to NetCDF • Table to NetCDF • Select by Dimension UC 2006 Tech Session

  14. NetCDF Layer/Table Properties Raster Feature Table UC 2006 Tech Session

  15. Using NetCDF Data Behaves the same as any layer or table Display • Same display tools for raster and feature layers will work on netCDF raster and netCDF feature layers. • Graphing • Driven by the table just like any other chart. • Animation • Multidimensional data can be animated through a dimension (e.g. time, pressure, elevation) • Analysis Tools • A netCDF layer or table will work just like any other raster layer, feature layer, or table. (e.g. create buffers around netCDF points, reproject rasters, query tables, etc.) UC 2006 Tech Session

  16. NetCDF and Coordinate Systems • Geographic Coordinate Systems (GCS) • X dimension units: degrees_east • Y dimension units: degrees_north • Projected Coordinate Systems (PCS) • X dimension standard_name: projection_x_coordinate • Y dimension standard_name: projection_y_coordinate • Variable has a grid_mapping attribute. • CF conventions currently supports only eight predefined coordinate systems • Undefined • If not GCS or PCS • ArcGIS writes (and recognizes) PE String as a variable attribute. UC 2006 Tech Session

  17. Emerging Standards • CF Version 2 • The next generation of the Climate and Forecast convention of netCDF, just beginning. • GALEON • OGC testbed project to evaluate netCDF suitability as a WCS well known binary. • Common Data Model (CDM) • A new API to access netCDF, HDF, GRIB, and OpenDAP through a single API. • NcML • NetCDF Markup Language, like GML for netCDF earth science data UC 2006 Tech Session

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