Extreme Wind Speeds Software: Fortran Code for Daily
Maximum Wind Speeds Data Sets
This page describes a Fortran-77 code that can be used to
analyze the daily maximum wind speeds
data sets. These data sets are from cities in which
hurricanes and tropical storms are not expected. This code
is freely downloadable (see below). The computed quantities
are saved in an ASCII file that can be imported into other
programs for plotting and further analysis.
We provide a pre-compiled executable for Windows 2000/XP
platforms. You can compile this code yourself for other
platforms if you have a Fortran-77/90/95 compiler available.
If you have a Fortran-77/90/95 compiler, you can modify this
code with minimal effort to analyze other data sets.
What the Program Computes
Given an input file, xxxx.xx, this program generates the
following two files:
This file contains a table for each value of the
threshold parameter. This table contains:
- The DeHaan estimates for the shape and scale
parameters of the generalized Pareto
- The wind speeds corresponding to a set of
specified mean return intervals.
- The maximum wind speed for the fitted
- Load factors corresponding to each of the mean
For each value of the threshold, the following
values are written to the file:
- the threshold value
- the number of values above the threshold
- the estimate of the shape parameter
- the estimate of the standard deviation of the
- the wind speeds corresponding to each of the
- the maximum possible wind speed
- the load factors corresponding to a return
return interval of 50 years
This file is provided to make it convenient to read the
values into another program for further analysis (e.g.,
a program for plotting the data).
Example under Windows
This section describes how to run the program under the
Windows 2000/XP operating system.
For the sake of discussion, let us assume that you have created
the directory "C:\WINDDHN" and that you have copied the
data file "abilene.tx" (which contains the data for Abilene,
TX) and the program executable "WINDDHN.EXE" to this
To run the program:
The program will then run. After it completes, the following
two files are created:
- Open a command prompt window.
- When you are prompted for the input file name, enter
- When you are prompted for the size of the interval,
Since these files contain daily data, there may be
significant autocorrelation (and therefore, the input
data are not independent) in the data since days
close to each other can result from the same storm.
To minimize this autocorrelation, the data is split
into intervals of x days where x is
typically set to either 4 or 8 (the program will
accept values for the interval size from 1 to 16).
The revised data then consists of the maximum wind
speeds of each of the intervals.
- The program then prompts you for the desired mean
return intervals. If you enter either a 0 or a
-1, default pre-selected choices will be used. If
any other value is entered, the program will prompt
for the specific values (up to 10 return intervals can
be specified). If a return value of 50 years is not
entered, it will automatically be added since this is
used to calculate the load factor.
See the above section for a description of what these files
These files can be viewed using Notepad (or any other suitable
For non-Windows platforms, the instructions are similar.
Just open a terminal window, initiate the program, and
enter the desired data file, interval size, and return
You can download the following:
You can download these files to whatever directory is
convenient for you. These files require no additional
Description of the Source Code
We provide a brief technical overview for those who want to
adapt this Fortran-77 program to other data sets.
Note that we have modified the code from the version that
was previously available on the NIST ftp site. The output
generated from the program is the same. However, the
program was rewritten to be easier to adapt to other
The program contains the following subroutines.
In summary, to adapt this code to your own data sets, do
This is the driver program. Although you should not
need to modify the basic structure of this routine,
you may want to tweak a few of the PARAMETER
statements to accomodate your own data sets. In
addition, you can set the desired number of iterations
for the threshold (the program uses 25).
This routine reads the input data file. This
routine will need to be modified if you are
adapting this code to your own data sets.
This routine generates the DeHaan estimates.
This routine opens the input/output files. This
routine also prompts for the desired interval size
and the desired mean return intervals.
This subroutine splits the data into intervals and
then extracts the maximum of each interval to form
the revised data set.
This is a utility subroutine used by INTRVL.
This subroutine performs a sort of the data using
the QuickSort algorithm. Although you can replace
this with your own sort routine, this is an excellent
sort algorithm and there is little to be gained by
- Modify the GETDAT routine to read your own data files.
- Check the WINDDHN routine to set the desired
- Compile the code on your system.
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Date created: 05/02/2005
Last updated: 11/30/2018
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