1. Multidimensional Data and GIS
Steve Kopp
Nawajish Noman
ESRI

2. Multidimensional Data
Data cube (3D) or hypercube (4D,5D…)
Temperature varying with time
Temperature varying with time and altitude T Y X

3. Multidimensional Data
Time = 3
Time = 2
Time = 1

4. Multidimensional Data
Time = 3
Time = 2
Time = 1

5. Multidimensional Data
Time = 1
Time = 2
Data Cube
Time = 3
Time Slices

6. Multidimensional Data
Includes variation in (x,y,z,t)

7. What is NetCDF? NetCDF (network Common Data Form)
A platform independent format for representing multi-dimensional array-orientated scientific data.
Self Describing - a netCDF file includes information about the data it contains.
Direct Access - a small subset of a large dataset may be accessed efficiently, without first reading through all the preceding data.
Sharable - one writer and multiple readers may simultaneously access the same netCDF file.
NetCDF is new to the GIS community but widely used by scientific communities for around many years

8. Why NetCDF?
Most commonly used format in the oceanographic and atmospheric science for observational data and numerical modeling
The National Center for Atmospheric Research (NCAR)
University Corporation for Atmospheric Research (UCAR) NOAA's Climate Diagnostics Center (CDC)
Los Alamos National Laboratory (LANL)
The National Center for Supercomputing Applications
US Air Force and Navy
Atmospheric Research in Australia
Australia Defense
UK Hydrographic Office
NATO
...

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: ... }

10. Storing Data in a netCDF File
mynetcdf {
dimensions : X = 4 ; Y
Time
UNLIMITED
variables
float X ( )
float Y
int Time
float Temperature ,
data 10 20 30 40
110
120
130
140 31 59 90 }

11. Storing Data in a netCDF File
mynetcdf {
dimensions : X = 4 ; Y 5
Time
UNLIMITED
variables
float X ( )
float Y
int Time
float Temperature ,
data 10 20 30 40
110
120
130
140 31 59 90
Temperature
111
211
311
411 }
Time = 1
Y = 1
X = 1 to 4

12. Storing Data in a netCDF File
mynetcdf {
dimensions : X = 4 ; Y 5
Time
UNLIMITED
variables
float X ( )
float Y
int Time
float Temperature ,
data 10 20 30 40
110
120
130
140 31 59 90
Temperature
111
211
311
411
121
221
321
421
131
231
331
431
141
241
341
441 }
Time = 1
Y = 1 to 4
X = 1 to 4

13. Storing Data in a netCDF File
mynetcdf {
dimensions : X = 4 ; Y 5
Time
UNLIMITED
variables
float X ( )
float Y
int Time
float Temperature ,
data 10 20 30 40
110
120
130
140 31 59 90
Temperature
111
211
311
411
121
221
321
421
131
231
331
431
141
241
341
441
112
212
312
412
122
222
322
422
132
232
332
432
142
242
342
442
113
213
313
413
123
223
323
423
133
233
333
433
143
243
343
443 }
Time = 1 to 3
Y = 1 to 4
X = 1 to 4

14. NetCDF Data Sources
Community Climate Systems Model (CCSM) 
The CCSM is fully-coupled, global climate model that provides state-of-the-art computer simulations of the Earth's past, present, and future climate states.
100 yrs of climate change forecast data ( )
Control runs ( ) and scenario runs
Temperature, precipitation flux, surface snow thickness, snowfall flux, cloud water content, etc.
Program for Climate Model Diagnosis and Intercomparison (PCMDI)

15. NetCDF Data Sources
Vegetation and Ecosystem Modeling and Analysis Project (VEMAP)
VEMAP was a large, collaborative, multi-agency program to simulate and understand ecosystem dynamics for the continental United States.
The VEMAP Data Portal is a central collection of files maintained and serviced by the NCAR Data Group
Climate data interval: Annual, monthly, and daily.
Data type: Historical and model results
Data: Temperature, irradiance, precipitation, humidity, incident solar radiation, vapor pressure, elevation, land area, vegetation, water holding capacity of soil, etc.

16. NetCDF Data Sources
British Atmospheric Data Center (BADC)
The role of the BADC is to assist UK atmospheric researchers to locate, access and interpret atmospheric data.
Many datasets are publicly available but datasets marked with key symbol have restricted access.
Datasets are organized by projects or organizations.
Climatology Interdisciplinary Data Collection (CIDC) has monthly means of over 70 Climate Parameters.
Met Office - Historical Central England Temperature Data has the monthly series, which begins in 1659, is the longest available instrumental record of temperature in the world. The daily series begins in 1772.

17. NetCDF Data Sources
National Oceanic & Atmospheric Administration (NOAA)
National Digital Forecast Database (NDFD)
Radar Integrated Display with Geospatial Element (RIDGE)
Precipitation Analysis
Climate Diagnostics Center

18. NetCDF in ArcGIS NetCDF data is accessed as
Raster
Feature
Table
Direct read (no scratch file)
Exports GIS data to netCDF

19. Gridded Data
Raster
Point Features

20. 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

21. Unidata NetCDF Files by Cedric David
Catalog of Datasets

22. 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

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

24. Query Via URL Format documented at Example:
Example:
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

25. NDFD Data Also Available
NWS National Digital Forecast Database
Gridded forecasts of sensible weather elements
5km resolution over continental US

26. Viewing NetCDF in ArcMap