Web Map Service (WMS)

Web Map Services (WMS) for climate change anomalies

We offer a number of Web Map 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 global model output at a 1.4 degree resolution as well as downscaled projections for the continental US at 4.5 km resolution, for the variables Surface Temperature (tas) and Total Precipitation (ppt).

Below are directions on how to access the data.

Directions for 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 the 'products' directory to access the sub-folders. 

5. Your final choices 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>_<TIME_FRAME>_<TEMPORAL_RESOLUTION>_down_anomaly.nc

VARIABLE  refers to the CCSM variable of interest

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

SCENARIO refers to the SRES 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

TIME_FRAME refers to the 20 year average time period we used to compute the anomaly. 

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

TEMPORAL_RESOLUTION refers to the months which were averaged.

  • Annual
  • Monthly
  • Seasonal 

Available WMS requests:

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

  • Service = WMS
  • Version = 1.3.0
  • Request = GetCapabilities

EXAMPLE OF REQUEST - Sample GetCapabilities for downscaled seasonal total precipitation anomly for the near term
http://tds.gisclimatechange.ucar.edu/thredds/wms/products/files/ppt_SRES...

GETMETADATA (min/max)- this request returns the min and max values for the requested variable  (open file in WordPad or NotePad)

  • Service = WMS
  • Version = 1.3.0
  • Item = minmax
  • Request = GETMetadata
  • Layers = tas or ppt
  • Bbox = your bounding box of interest - format is west, south, east, north
  • SRS = supported projection (get supported SRS from getCapabilities) ESPG:4326 for WGS84
  • Width and height = size of requested image
  • Time = time reference (retrieve times from GetCapabilities)

EXAMPLE OF REQUEST - Sample GetMetadata request - returns the min and max value of the winter season's total precipitation anomaly for the near term for scenario B1
http://tds.gisclimatechange.ucar.edu/thredds/wms/products/files/ppt_SRES...

GETMAP – this request will return an image

  • Layers = layer of interest either tas (temperature) or ppt (precipitation)
  • Bbox = your bounding box of interest - format is west, south, east, north
  • SRS = supported projection (get supported SRS from getCapabilities) ESPG:4326 for WGS84
  • CRS = coordinate system  crs:84 = WGS  crs:83 NAD83  crs:27 NAD27
  • ColorScaleRange – (optional) if you know want to specify the min and max value for the color ramp.  Use in conjunction with GEMETADATA request
  • Width  and Height  - of the returned image
  • Style – type of symbology on the image (get supported styles from GetCapabilities)
  • Format – type of image returned - image/jpeg or image/png
  • Time – the time period you want to view

EXAMPLE OF REQUEST - Sample GetMap request - returns a map of the winter season's total precipitation anomaly for the near term for scenario B1
http://tds.gisclimatechange.ucar.edu/thredds/wms/products/files/ppt_SRES...

GETLEGENDGRAPGIC – this request will return the legend for your map

  • Service = WMS
  • Version = 1.3.0
  • Request = GetLegendGraphic
  • Layers = layer of interest either tas (temperature) or ppt (precipitation) (this is only specific to our WMS...this is not a regular WMS parameter)
  • Layer = the layer you want the legend for
  • ColorScaleRange – (optional) if you know want to specify the min and max value for the color ramp.  Use in conjunction with GEMETADATA request
  • Format – type of image returned - image/jpeg or image/png
  • Time – the time period you want to view
  • Palette - the type of style you used in the getMap request

EXAMPLE OF REQUEST - Sample GetLegendGraphic request - returns a legend for the map above
http://tds.gisclimatechange.ucar.edu/thredds/wms/products/files/ppt_SRES...

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

Annual Scenario B1 Temperature Anomalies - Downscaled


Annual Scenario A1B Temperature Anomalies - Downscaled

 


Annual Scenario A2 Temperature Anomalies - Downscaled

 

Access WMS in ArcMap

1. In ArcMap click Add Data
2. Navigate to GIS Servers
3. Double click on Add WMS Server
4. In the URL drop down box type in the path to your dataset of interest.  
(Such as http://tds.gisclimatechange.ucar.edu/thredds/wms/products/files/tas_SRESB1_near_seasonal_down_anomaly.nc? )
5. Click Get Layers  
6. Click OK

7. In ArcMap add this WMS service
8. If you are working with the monthly or seasonal datasets, there are multiple times you can views.  By default in ArcMap the first time period is displayed.  In order to move over the time periods open the Time Slider Dialog

Unfortunately it is not easy to work with time varying WMS services in ArcMap at this time.   However, if you download the file through WCS then you can open the raw netCDF file in ArcMap and use the Time Animation to animate through all the time steps.  Otherwise follow the steps below to view the different time steps available through WMS.
 

In order to know the times available to you take a look at the response from the GetCapabilities request.   

Under the <Layer> tag for the variable (tas or ppt) you will see a <Dimension> tag with the name “time”. 


<Dimension name="time" units="ISO8601" multipleValues="true" current="true" default="2039-11-11T00:00:00.000Z">
                       2039-02-10T00:00:00.000Z,2039-05-11T12:00:00.000Z,2039-08-11T12:00:00.000Z,2039-11-11T00:00:00.000Z                 
</Dimension>

In the example above you will see there are 4 times (2039-02-10,  2039-05-11, 2039-08-11,2039-11-11).

By default you see the first time step (winter).  If you want to see the second time step (Spring)

  • In the Time Slider Dialog click the Properties button.
  • In the Time Display tab enter the Time step interval: to be 2172 Hours

 

  • Click OK. 
  • You can now move from the first time to the second time.
  • You must manually calculate the number of hours or days between the time periods and enter this number in to move to the third and fourth time period. 
  • Follow a similar method to move through the monthly anomalies.
  • Second time period = 2172 Spring
  • Third time period = 4380  Summer
  • Fourth time period = 6576  Autumn