1.   Purpose and objectives

     This program computes statistics for mean daily simulated and observed  discharges.

2.   Description

     Equations are used to compute simulated and observed mean daily  discharges; the per cent bias between simulated and observed daily flows; the monthly bias in runoff (millimeters); the maximum error between simulated and observed daily flows, their per cent average absolute error and daily average absolute error; percent root mean square error, the daily root mean square error; the correlation coefficient for daily flows, and the regression line of best fit. Certain statistics are computed for 
several years of simulated and observed data. These are the maximum monthly volume error, and the per cent average absolute monthly volume error; the percent monthly volume root mean square error; the twenty-five largest daily error values and the twelve largest monthly volume errors (cubic meters per second per day) as 1) a per cent of the total square deviation, and 2) the per cent reduction of daily root mean square if error equals 
zero.

3.   Input

     Required input are time series of simulated and observed mean daily discharges. Time series are stored in files.

4.   Output

     Printed output as described above.

5.   Operational requirements and restrictions

     a) One person with knowledge and experience in hydrological processes, 
        models and statistics, and a grasp of the elements of river
        forecasting and basic understanding and familiarity with computer
        and software can run the program.

     b) With the qualifications described above, 1 day of training is
        required.

     c) Program is written for use on HP workstations; but could be
        modified to run on other computers having large storage

        capabilities and scratch work space. The program runs as part of
        NWSRFS-MCP3 (see component J15.3.01).

     d) Maximum array sizes are variably dimensioned and are specified by
        the user in the MCP3 program.

6.   Form of presentation

     Program is written in FORTRAN 77 and is obtained only as part of the National Weather Service River Forecast System (NWSRFS).

7.   Operational experience

     Has been applied throughout the USA with good results; regular usage in U.S. by National Weather Service; implementation is difficult, but not complex.

8.   Originator and technical support

     Michael Smith, Hydrologic Research Laboratory, NOAA-NWS.

9.   Availability

     From the HOMS National Reference Centre for USA.

10.  Conditions on use

     Free.