SOLPOS.H

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/*============================================================================
*
*    NAME:  solpos.h
*
*    Contains:
*        S_date       (computes the date from the day number)
*            INPUTS:     S_year, S_daynum
*            OUTPUTS:    S_year, S_month, S_day
*
*        S_solpos     (computes the solar position and intensity 
*                      from time and place) 
*            INPUTS:     S_month, S_day, S_latitude, S_longitude, S_timezone
*            OPTIONAL:   
*                            S_year    DEFAULT 2001   (non-leap)
*                            S_hour    DEFAULT   12   (noon)
*                            S_minute  DEFAULT    0   ( "  )
*                            S_second  DEFAULT    0   ( "  )
*                            S_press   DEFAULT 1013.0 (standard pressure)
*                            S_temp    DEFAULT   10.0 (standard temperature)
*                            S_tilt    DEFAULT    0.0 (horizontal panel)
*                            S_aspect  DEFAULT  180.0 (South-facing panel)
*
*            OUTPUTS:    S_daynum, S_amass, S_ampress, S_azim, S_cosinc, 
*                        S_elevref, S_etr, S_etrn, S_etrtilt, S_prime,
*                        S_sbcf, S_sunrise, S_sunset, S_unprime, S_zenref
*
*    Usage:
*         In calling program, along with other 'includes', insert:
*
*              #include "solpos.h"
*
*    Martin Rymes
*    National Renewable Energy Laboratory
*    25 March 1998
*----------------------------------------------------------------------------*/

/***** ALPHABETICAL LIST OF COMMON VARIABLES *****/
                           /* Each comment begins with a 1-column letter code:
                              I:  INPUT variable
                              O:  OUTPUT variable
                              T:  TRANSITIONAL variable used in the algorithm,
                                  of interest only to the solar radiation
                                  modelers, and available to you because you
                                  may be one of them */
/***** INTEGERS *****/

extern int   S_day;        

extern int   S_daynum;     

extern int   S_hour;       

extern int   S_minute;     

extern int   S_month;      

extern int   S_second;     

extern int   S_year;       

/***** FLOATS *****/

extern double S_amass;      
extern double S_ampress;    
extern double S_aspect;     
extern double S_azim;       
extern double S_cosinc;     
extern double S_dayang;     
extern double S_declin;     
extern double S_eclong;     
extern double S_ecobli;     
extern double S_ectime;     
extern double S_elevref;    
extern double S_eqntim;     
extern double S_erv;        
extern double S_etr;        
extern double S_etrn;       
extern double S_etrtilt;    
extern double S_gmst;       
extern double S_hrang;      
extern double S_julday;     
extern double S_latitude;   
extern double S_longitude;  
extern double S_lmst;       
extern double S_mnanom;     
extern double S_mnlong;     
extern double S_rascen;     
extern double S_press;      
extern double S_prime;      
extern double S_sbcf;       
extern double S_solcon;     
extern double S_ssha;       
extern double S_sunrise;    
extern double S_sunset;     
extern double S_temp;       
extern double S_tilt;       
extern double S_timezone;   
extern double S_tst;        
extern double S_tstfix;     
extern double S_unprime;    
extern double S_utime;      
extern double S_zenetr;     
extern double S_zenref;     

/*============================================================================
*    Integer function S_date, adapted from the NREL VAX solar libraries
*
*    This function calculates the month and day of month, given the 
*    day number (number of day in year, sometimes confusingly called 
*    the "Julian Day", but I know that you will never call it that).
*
*    Requires:
*        Year and day number:
*            S_year           NOTE:  2-digit year "xx" is assumed "19xx"
*                             DEFAULT S_year = 2001
*            S_daynum         RANGE: -1 to a large positive integer
*
*    Returns:
*        Year, month, day:
*            S_year
*            S_month
*            S_day
*----------------------------------------------------------------------------*/
 extern int S_date (void);


/*============================================================================
*    Integer function S_solpos, adapted from the NREL VAX solar libraries
*
*    This function calculates the apparent solar position and intensity
*    (theoretical maximum solar energy) based on the date, time, and 
*    location on Earth.\n
*
*    Requires:
*        Date and time:
*            S_year      DEFAULT 2001
*            S_month
*            S_day
*            S_hour      DEFAULT 12
*            S_minute    DEFAULT  0
*            S_second    DEFAULT  0
*        Location:
*            S_latitude
*            S_longitude
*        Location/time adjuster:
*            S_timezone
*        Atmospheric pressure and temperature:
*            S_press     DEFAULT 1013.0 mb
*            S_temp      DEFAULT 10.0 degrees C
*        Tilt of flat surface that receives solar energy:
*            S_aspect    DEFAULT 180 (South)
*            S_tilt      DEFAULT 0 (Horizontal)
*
*    Returns:
*        everything defined at the top of this listing.
*----------------------------------------------------------------------------*/ extern int S_solpos (void);