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    CTL and Drought - Part 3
Drought Data Inquiry

Below are three maps of the United States that use the Palmer Drought Index to show the severity of drought. According to NOAA's North American Drought: A Paleo Perspective, this index is explained as follows:

The Palmer Drought Severity Index (PDSI) has been the most commonly used drought index in the United States and was developed to measure intensity, duration, and spatial extent of drought. PDSI values are derived from measurements of precipitation, air temperature, and local soil moisture, along with prior values of these measures. Values range from -6.0 (extreme drought) to +6.0 (extreme wet conditions), and have been standardized to facilitate comparisons from region to region.

Select which time period you think best represents each map. Make a better educated guess by visiting NOAA's Climate Diagnostic Center's Monthly Mean Compositing Page and inputting PDSI as the variable and the time ranges given below. You can also access this page from CTL Data Access Page.

Palmer Drought Index Maps

Map 1

Map 2

Map 3

PDSI Legend

-4.0 or less
(Extreme Drought)

-3.0 to -3.9
(Severe Drought)

-2.0 to -2.9
(Moderate Drought)

-1.9 to +1.9
(Near Normal)

+2.0 to +2.9
(Unusual Moist spell)

+3.0 to +3.9
(Very Moist Spell)

+4.0 and above
(Extremely Moist)

Answer the questions below.

correct on first try

  1. What time period does Map 1 represent?    

  2. What time period does Map 2 represent?    

  3. What time period does Map 3 represent?    

Where to go from here

Once you have figured out which map displays the best PDSI index for a given time period, explore these date ranges in the CTL. Some follow up inquiry could include:

  • What climate observations were made during these time periods?
  • Do any climate forcing factors such as ENSO influence these droughts?
  • Check out the Data Access Page to retrieve precipitation and hydrology data for a region and time period of interest. Find other "drought signatures" using Find Your Place, the USGS Water Data site and the National Resources Conservation Service's National Water and Climate Center.
Click the Drought Button to Return to the Tutorial Page

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http://www.ncdc.noaa.gov/paleo/ctl/drought3.html
Downloaded Wednesday, 25-Nov-2009 12:12:58 EST
Last Updated Wednesday, 20-Aug-2008 11:22:39 EDT by paleo@noaa.gov
Please see the Paleoclimatology Contact Page or the NCDC Contact Page if you have questions or comments.