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Contents of /trunk/models/johnpye/nrel/spa.h

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Wed Apr 11 21:23:18 2012 UTC (10 years, 2 months ago) by jpye
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Add calculation of Julian Day within ASCEND model.
1 /*
2 THIS CODE COMES FROM APPENDIX A.6 OF REPORT NREL/TP-560-34302
3 WHICH WAS OBTAINED FROM
4 http://www.osti.gov/bridge/servlets/purl/15003974-iP3z6k/native/15003974.PDF
5 */
6
7 /////////////////////////////////////////////
8 // HEADER FILE for SPA.C //
9 // //
10 // Solar Position Algorithm (SPA) //
11 // for //
12 // Solar Radiation Application //
13 // //
14 // May 12, 2003 //
15 // //
16 // Filename: SPA.H //
17 // //
18 // Afshin Michael Andreas //
19 // afshin_andreas@nrel.gov (303)384-6383 //
20 // //
21 // Measurement & Instrumentation Team //
22 // Solar Radiation Research Laboratory //
23 // National Renewable Energy Laboratory //
24 // 1617 Cole Blvd, Golden, CO 80401 //
25 /////////////////////////////////////////////
26
27 ////////////////////////////////////////////////////////////////////////
28 // //
29 // Usage: //
30 // //
31 // 1) In calling program, include this header file, //
32 // by adding this line to the top of file: //
33 // #include "spa.h" //
34 // //
35 // 2) In calling program, declare the SPA structure: //
36 // spa_data spa; //
37 // //
38 // 3) Enter the required input values into SPA structure //
39 // (input values listed in comments below) //
40 // //
41 // 4) Call the SPA calculate function and pass the SPA structure //
42 // (prototype is declared at the end of this header file): //
43 // spa_calculate(&spa); //
44 // //
45 // Selected output values (listed in comments below) will be //
46 // computed and returned in the passed SPA structure. Output //
47 // will based on function code selected from enumeration below. //
48 // //
49 // Note: A non-zero return code from spa_calculate() indicates that //
50 // one of the input values did not pass simple bounds tests. //
51 // The valid input ranges and return error codes are also //
52 // listed below. //
53 // //
54 ////////////////////////////////////////////////////////////////////////
55
56 #ifndef __solar_position_algorithm_header
57 #define __solar_position_algorithm_header
58
59
60 //enumeration for function codes to select desired final outputs from SPA
61 enum {
62 SPA_ZA, //calculate zenith and azimuth
63 SPA_ZA_INC, //calculate zenith, azimuth, and incidence
64 SPA_ZA_RTS, //calculate zenith, azimuth, and sun rise/transit/set values
65
66 SPA_JD, // just calculate the julian day and return
67 SPA_ZA_JD, // as SPA_ZA but don't calculate julian day afresh
68 SPA_ZA_INC_JD, // as SPA_ZA_INC but don't calculate julian day afresh
69 SPA_ZA_RTS_JD, // as SPA_ZA_RTS but don't calculate julian day afresh
70
71 SPA_ALL, // calculate all SPA output values from datetime inputs
72 };
73
74 typedef struct
75 {
76 //----------------------INPUT VALUES------------------------
77
78 int year; // 4-digit year, valid range: -2000 to 6000, error code: 1
79 int month; // 2-digit month, valid range: 1 to 12, error code: 2
80 int day; // 2-digit day, valid range: 1 to 31, error code: 3
81 int hour; // Observer local hour, valid range: 0 to 24, error code: 4
82 int minute; // Observer local minute, valid range: 0 to 59, error code: 5
83 int second; // Observer local second, valid range: 0 to 59, error code: 6
84
85 double delta_t; // Difference between earth rotation time and terrestrial time
86 // It is derived from observation only and is reported in this
87 // bulletin: http://maia.usno.navy.mil/ser7/ser7.dat,
88 // where delta_t = 32.184 + (TAI-UTC) + DUT1
89 // valid range: -8000 to 8000 seconds, error code: 7
90
91 double timezone; // Observer time zone (negative west of Greenwich)
92 // valid range: -18 to 18 hours, error code: 8
93
94 double longitude; // Observer longitude (negative west of Greenwich)
95 // valid range: -180 to 180 degrees, error code: 9
96
97 double latitude; // Observer latitude (negative south of equator)
98 // valid range: -90 to 90 degrees, error code: 10
99
100 double elevation; // Observer elevation [meters]
101 // valid range: -6500000 or higher meters, error code: 11
102
103 double pressure; // Annual average local pressure [millibars]
104 // valid range: 0 to 5000 millibars, error code: 12
105
106 double temperature; // Annual average local temperature [degrees Celsius]
107 // valid range: -273 to 6000 degrees Celsius, error code; 13
108
109 double slope; // Surface slope (measured from the horizontal plane)
110 // valid range: -360 to 360 degrees, error code: 14
111
112 double azm_rotation; // Surface azimuth rotation (measured from south to projection of
113 // surface normal on horizontal plane, negative west)
114 // valid range: -360 to 360 degrees, error code: 15
115
116 double atmos_refract;// Atmospheric refraction at sunrise and sunset (0.5667 deg is typical)
117 // valid range: -5 to 5 degrees, error code: 16
118
119 int function; // Switch to choose functions for desired output (from enumeration)
120
121 //-----------------Intermediate OUTPUT VALUES--------------------
122
123 double jd; //Julian day
124 double jc; //Julian century
125
126 double jde; //Julian ephemeris day
127 double jce; //Julian ephemeris century
128 double jme; //Julian ephemeris millennium
129
130 double l; //earth heliocentric longitude [degrees]
131 double b; //earth heliocentric latitude [degrees]
132 double r; //earth radius vector [Astronomical Units, AU]
133
134 double theta; //geocentric longitude [degrees]
135 double beta; //geocentric latitude [degrees]
136
137 double x0; //mean elongation (moon-sun) [degrees]
138 double x1; //mean anomaly (sun) [degrees]
139 double x2; //mean anomaly (moon) [degrees]
140 double x3; //argument latitude (moon) [degrees]
141 double x4; //ascending longitude (moon) [degrees]
142
143 double del_psi; //nutation longitude [degrees]
144 double del_epsilon; //nutation obliquity [degrees]
145 double epsilon0; //ecliptic mean obliquity [arc seconds]
146 double epsilon; //ecliptic true obliquity [degrees]
147
148 double del_tau; //aberration correction [degrees]
149 double lamda; //apparent sun longitude [degrees]
150 double nu0; //Greenwich mean sidereal time [degrees]
151 double nu; //Greenwich sidereal time [degrees]
152
153 double alpha; //geocentric sun right ascension [degrees]
154 double delta; //geocentric sun declination [degrees]
155
156 double h; //observer hour angle [degrees]
157 double xi; //sun equatorial horizontal parallax [degrees]
158 double del_alpha; //sun right ascension parallax [degrees]
159 double delta_prime; //topocentric sun declination [degrees]
160 double alpha_prime; //topocentric sun right ascension [degrees]
161 double h_prime; //topocentric local hour angle [degrees]
162
163 double e0; //topocentric elevation angle (uncorrected) [degrees]
164 double del_e; //atmospheric refraction correction [degrees]
165 double e; //topocentric elevation angle (corrected) [degrees]
166
167 double eot; //equation of time [minutes]
168 double srha; //sunrise hour angle [degrees]
169 double ssha; //sunset hour angle [degrees]
170 double sta; //sun transit altitude [degrees]
171
172 //---------------------Final OUTPUT VALUES------------------------
173
174 double zenith; //topocentric zenith angle [degrees]
175 double azimuth180; //topocentric azimuth angle (westward from south) [-180 to 180 degrees]
176 double azimuth; //topocentric azimuth angle (eastward from north) [ 0 to 360 degrees]
177 double incidence; //surface incidence angle [degrees]
178
179 double suntransit; //local sun transit time (or solar noon) [fractional hour]
180 double sunrise; //local sunrise time (+/- 30 seconds) [fractional hour]
181 double sunset; //local sunset time (+/- 30 seconds) [fractional hour]
182
183 } spa_data;
184
185 //Calculate SPA output values (in structure) based on input values passed in structure
186 int spa_calculate(spa_data *spa);
187
188 //Calculate Julian Day, return #days.
189 double julian_day (int year, int month, int day, int hour, int minute, int second, double tz);
190
191 #endif

john.pye@anu.edu.au
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