To download the zipped code for the Climate module,
right click on the following link and choose "Save Link As..."

ClimateChange.zip

This file will need to be unzipped in WinZip before it can be compiled.
If you would rather download the unzipped code and edit out the additional characters (^M) due to file transfer, click here



Click here to see an example of the Climate module's output.




....INSTRUCTIONS FOR USE

  1. Save the ClimateChange.cpp code in a directory named "Climate" (or whatever you prefer). Compile the code. (On a Sun Solaris 7, an example compile command is "CC ClimateChange.cpp -o climate". This will generate the output "climate," which is a compiled program ready to run.)

  2. Make sure your 1-km2 ascii files are also in this same directory. These files are the ones you generated for each land class and should have names such as urb87.asc, ag87.asc, wat87.asc, urb96.asc, etc. You should have created these files from the SLEUTH land use maps following the instructions at the "Data Preparation" link.

  3. Be sure that you know the number of columns and rows for the resampled 1-km2 output. You will be asked to input the number of columns specifically.

  4. The module will initialize the climate variables for each 1-km2 land parcel for the first year of interest. This is typically the year that you used to start the growth cycle in the SLEUTH model. Be sure that you know the names of all the land uses' 1-km2 ascii files for this initialization year. The initial climate variables are based on the percentage of developed land within the land parcel, as well as the nature of the remaining land (whether it's predominantly agricultural or wooded). For irregular boundaries, such as those of watersheds or counties, the land use percentages for the 1-km squares along the border are based strictly on the total number of classified pixels. When examining edge areas, keep this fact in mind.

  5. The climate variables used in this module are:

    tstar
    This is a scaled radiant surface temperature, as derived from satellite data. Its values range from 0 to 1, indicating the degree to which the temperature resembles that of a wet, vegetated surface (0) or a dry, bare surface (1).
    fr
    This is the fractional vegetation cover and ranges from 0 (unvegetated) to 100 (completely vegetated). It was also derived in the original analyses from satellite data.
    etrn
    This is the evapotranspiration fraction. It represents the fraction of net radiant energy (rn) being used in transpiration by plants or in evaporation of moisture from the surface. Ranging from 0 (dry) to 1 (wet), it can be considered an index of surface moisture. In the original analyses, this parameter was determined by coupling a surface energy balance model with the satellite-derived tstar and fr parameters.


  6. Before running the module, you should note the general sequence that you plan to use in your climate predictions.Each time step will require an initial year and a final year. The module requires the climate fields for the initial year, as well as the change in development that occurs over the time interval. You will be prompted for the various files that contain these inputs. Beforehand, though, you may want to make a table with your time steps. For example:

    1. initialize in 1996
    2. predict from 1996 to 2000
    3. predict from 2000 to 2005
    4. predict from 2005 to 2010
    5. predict from 2010 to 2015, etc.

  7. You will need to know the names for the 1-km2 ascii files for the URBAN class for all of the years involved.

  8. In the module you will be given a choice for the level of impact that the development will have on the vegetation. Determine whether you want the growth scenarios to have:

    1. a decrease in vegetation equal to the increase in development (high impact)
    2. a decrease in vegetation equal to 1/2 the increase in development (moderate impact)
    3. no decrease in vegetation (no impact)
    4. an increase in vegetation equal to 1/2 the increase in development ('friendly')

  9. Run the ClimateChange program (just type the name of the program that came out of compiling). All required inputs will be requested through prompts within the module. Be sure to pay close attention to what exactly the prompt is asking you for. Specifically, be sure to note the YEAR that is required for a given prompt's response. If you mess up the input names at any point, the module typically gives you two chances to enter the filenames. Keep in mind that the module is trying to read in the number of names it is seeking. If you want to prematurely exit, repeatedly enter this number of nonsense names until the module exits on its own. Using CNTRL-C could cause the module to dysfunction when you try to run it again. (You can deal with this by recompiling the code.)

  10. At each time step, the module determines which 1-km2 land parcels have a percentage of developed land in the second year that is at least the first year's value plus 10. These parcels' climate variables are updated based on the initial climatic state of the parcel, as well as the amount and type of development that has occurred. The remaining land parcels retain the value of their climate variables from the first year in the given time step.

  11. Internal to the module are two files (temp.asc and temp2.asc) that you can delete at the end of a run if you wish. These keep track of where development has exceeded the threshold level such that the climate fields are then updated. If the threshold level is not exceeded within a time step, then the initial percentage of urban land within the parcel is carried over to serve again as the next step's first year comparison value. In this way, parcels that take several time steps to grow beyond the development threshold are still able to participate. Once the threshold is reached, however, the climate fields are updated, and the growth comparisons start over based on the new percentage of urban land within the 1-km2 land parcel.

  12. The output consists of a tstar, fr and etrn layer for each year at 1-km2 resolution. The files for the initialization year will have the form init_tstar.asc, init_fr.asc, init_etrn.asc. The files in the following years have the form tstarxx.asc, frxx.asc, etrnxx.asc where "xx" represents the last two digits of the particular year. These files contain the raw, unaltered data. An alternative format is provided for the conversion of the output to gif images. These files have the same naming structure as the original files except "_forgif" is added to the name before the .asc extension. Instructions at the "Data Preparation" link explain how to convert these ascii files to gif images for visualization purposes. Keep in mind that the values in these images have been multipled by 100 (tstar and etrn) and/or been truncated (tstar, etrn and fr).