DIFMAP Downloading Information

Files for DIFMAP and Documentation

Downloading information

Check the Readmedf.txt that follows:

DIFMAP Read Me file September 4, 1995

This disk accompanies "RECONSTRUCTING LARGE-SCALE CLIMATIC PATTERNS FROM TREE- RING DATA: A DIAGNOSTIC ANALYSIS", H.C. Fritts, University of Arizona Press, 1991. The disk contains (compressed) files of the reconstructed temperature and precipitation data for a network of weather observation sites in the United States, plus display software. The reconstructions along the east and Gulf coasts of the United States do not verify and are therefore unreliable. PLEASE DO NOT EXPECT TO GET VALID RECONSTRUCTIONS FOR STATIONS FROM THESE PARTICULAR REGIONS. In addition, the resonstructions for the seasons are not as reliable as the reconstructions for the whole year and the reconstructions for groups of years are more reliable than those for single years because tree rings integrate information over a number of seasons sometimes including several years. (See the reference for more detailed descriptions of the strengths and weaknesses of these reconstructions.) The best use of these programs is to compare reconstructions for groups of years associated with a hypothesized condition to groups of years without the hypothesized condition using the base and differemce maps.

The files on the disk are in a compressed format and must be expanded before use. Five megabytes of hard disk storage are required. To expand the data files, create a directory for the reconstructions and copy the contents of this disk into that directory. When you unzipped the DIFMAP.ZIP you expanded the programs and help files. Type TEMPDAT to expand the temperature reconstructions, and PRECPDAT to expand the precipitation reconstruction files.

You may then delete DIFMAP.ZIP, TEMPDAT.EXE, and PRECPDAT.EXE from the hard disk to save space. Two versions of the display program DIFMAP are on the disk; if your PC lacks a math coprocessor, type NOCOPRO to make the non-coprocessor version active. About 450 Kbytes of memory are required; you may need to remove memory resident software to allow the programs to run on your system.

To begin the map program, type DIFMAP or MAPCL. (MAPCL removes previously created output files). The reconstructions were made for a grid of instrumental weather stations across the US (listed in file station.lst). The program DIFMAP extracts the reconstructed data from the data files and displays the information in map form. Output can be sent to a file and printed, or displayed on an EGA or VGA color screen. Screen output requires 2 to 3 minutes to generate, while creating the printer file takes only a few seconds.

The program SERIES displays reconstructed values for a single location, as a graph or a numerical table. Documentation for the programs is in the files MANUAL.DOC and SERIES.DOC. Caution is advised when intrepting these plots. The reconstructions are derived from large-scale climatic variations so the station reconstructions will approximate the regional averages including adjoining stations more closely than the data for the particular station. Please refer to the text for discussion of the methodology of climate reconstructions, and potential limits in their application.

Copies of disk with the "Reconstructing Large Scale Climatic Patterns from Tree-Ring Data" are available from: University of Arizona Press, 1230 North Park Avenue, Suite 102, Tucson, AZ 8571, USA.


Harold C. Fritts, DendroPower, 5703 North Lady Lane, Tucson, AZ 85704-2905, USA.

For questions about this disk, or for additional tree ring and other paleoclimate data sets, please contact: Mr. Bruce Bauer, Paleoclimate Group, National Geophysical Data Center, 325 Broadway, EGC, Boulder, CO 80303, USA, - Phone: (303) 497-6280, email: bab@NGDC1.NGDC.NOAA.GOV, BAB@PALEOSUN.NGDC.NOAA.GOV.

If you wish, you can download the READMEDF.ZIP file first and decompress it.

Then download the DIFMAP.ZIP archive which contains all information needed to run the program. Extract the files by entering PKUNZIP DIFMAP.ZIP *.* as explained in the Difmap Read Me file.

If your Web browser will not allow downloads of this kind, use an FTP client program to download the files from our anonymous FTP site, ftp.LTRR.Arizona.EDU, which will also allow you to download individual files (be sure to set binary mode before downloading the.ZIP or .EXE files if you are using your own FTP program and beware of using many Web browsers as your FTP client, since they don't work with our FTP server).

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Prepared by Harold C. Fritts hfritts@LTRR.arizona.edu -- Last updated March 29, 2000