Web Coverage Service(WCS)

Web Coverage Services (WCS) for climate change anomalies

We offer a number of Web Coverage Service from the NCAR Community Climate System Model (CCSM); which were run for the 4th Assessment Report (AR4) of the Intergovernmantal Panel on Climate Change (IPCC). These services are intended to serve a community of GIS users interested in climate change. We are distributing projected temperature and precipitation anomalies for a number of time periods. Anomalies are departures from an observed reference period. Our reference period is the twenty year average from the 20th Century Run for the years 1980-1999. We are distributing annual, monthly and seasonal anomalies for the near term (2020-2039), mid term (2040-2059), end of the century (2080-2099), and the last decade ( 2090-2099).

We offer downscaled projections at 4.5 km resolution for the continental US, for the variables Surface Temperature (tas) and Total Precipitation (ppt).

Below are directions on how to access the data.

Directions on accessing climate change anomalies at UCAR

1. In a web browser navigate to our THREDDS Data Server (TDS)
http://tds.gisclimatechange.ucar.edu/thredds/catalog/catalog.html

2. Click on 'anomalies'.

3. We have 4.5 km downscaled data for the continental US. For the WCS options only the downscaled data will work. Choose 'downscaled'.

4. Now your options are to choose Seasonal, Monthly, or Annual anomalies. Seasonal anomalies will have the Northern hemispheres standard seasons of WINTER (D,J,F), SPRING (M,A,M), SUMMER (J,J,A), and AUTUMN (S,O,N).

5. Your final chooses will be the dataset you are interested in working with. Each dataset has the following name structure.
ppt_SRESA1B_mid_annual_down_anomaly.nc
<VARIABLE>_<SCENARIO>_<TIMEPERIOD>_<TIME>_anomaly.nc

VARIABLErefers to the CCSM variable of interest

  • tas is surface temperature in Kelvin
    ppt is total precipitation in mm

SCENARIOrefers to the emissions scenario. For more on scenarios see the IPCC documentation

SRES scenario B1 is a lower end emissions scenario. Scenario B1 assumes :

  • population that peaks in the mid-century and declines thereafter
  • rapid changed in economic structures
  • introduction of clean and resource-efficient technologies

SRES scenario A2 is the higher end of the SRES emissions scenarios. Scenario A2 assumes:

  • increasing global population
  • regionally oriented economic growth
  • technology development is slow

SRES scenario A1B is a middle of road scenario. Scenario A1B assumes :

  • very rapid economic growth
  • global population peaks at the mid century then declines
  • introduction of more efficient technologies
  • energy sources not relying too heavily on one particular energy source

TIMEPERIODrefers to the 20 year average time period we are using in reference to the present day.

  • Near – 2020-2039
  • Mid – 2040-2059
  • End – 2080-2099
  • lastDecade – 2090-2099

TIMErefers to the months which were averaged.

  • Annual
  • Monthly
  • Seasonal

Available WCS requests:

GETCAPABILITIES– this request returns the capability file for the data set. You will see all available layers and time.

  • Service = WCS
  • Version = 1.0.0
  • Request = GetCapabilities

EXAMPLE OF REQUEST - Sample GetCapabilities request

http://tds.gisclimatechange.ucar.edu/thredds/wcs/products/files/tas_SRESB1_near_monthly_down_anomaly.nc?service=WCS&version=1.0.0&request=GetCapabilities

DESCRIBECOVERAGE -this request returns the description for the data set. You will see all available time dimensions as well as the bounding box.

  • Service = WCS
  • Version = 1.0.0
  • Request = DescribeCoverage
  • Layer = tas or ppt (optional)

EXAMPLE OF REQUEST - Sample DescribeCoverage request

http://tds.gisclimatechange.ucar.edu/thredds/wcs/products/files/tas_SRES...

GETCOVERAGE– this request will return a dataset

  • Service = WCS
  • Version = 1.0.0
  • Request = GetCoverage
  • Coverage = layer of interest either tas (temperature) or ppt (precipitation)
  • Bbox = extract data in your area of interest - format is west, south, east, north (optional only if you want to do a spatial extraction)
  • Format – type of image returned - netCDF or GeoTiff
  • ResX and ResY - if specifying a geotiff you must specify the resolution (optional)
  • Time – your can request just 1 time period or a range of time periods (use / to specify a range) (optional only if you want to extract by time)

EXAMPLE OF REQUEST - Sample GetCoverage request - returns a netCDF for the months March (03) to June (06) for air temperature anomaly for the last decade of the 21st century

http://tds.gisclimatechange.ucar.edu/thredds/wcs/products/files/tas_SRES...

Sample request- each request may take a minute to load.

Annual Scenario B1 Temperature Anomalies - Downscaled - netCDF

Annual Scenario A1B Temperature Anomalies - Downscaled

Annual Scenario A2 Temperature Anomalies - Downscaled