| 1 |
greg |
1.2 |
{ RCSid $Id$ } |
| 2 |
greg |
1.1 |
{* |
| 3 |
|
|
* SOLAR CALCULATIONS |
| 4 |
|
|
* |
| 5 |
|
|
* 7/25/84 |
| 6 |
|
|
* 10/10/86 |
| 7 |
|
|
* |
| 8 |
|
|
*} |
| 9 |
|
|
|
| 10 |
|
|
RLAT = 0.66; {* Site latitude (radians) *} |
| 11 |
|
|
|
| 12 |
|
|
RLON = 2.13; {* Site longitude (radians) *} |
| 13 |
|
|
|
| 14 |
|
|
RSM = 120 * PI/180; {* Standard meridian (radians) *} |
| 15 |
|
|
|
| 16 |
|
|
|
| 17 |
|
|
stadj(jd) {* solar time adjustment (hours) *} |
| 18 |
|
|
{ jd is days into year } |
| 19 |
|
|
= |
| 20 |
|
|
0.170 * sin( 4*PI/373 * (jd - 80) ) - |
| 21 |
|
|
0.129 * sin( 2*PI/355 * (jd - 8 ) ) + |
| 22 |
|
|
12*(RSM-RLON)/PI |
| 23 |
|
|
; |
| 24 |
|
|
|
| 25 |
|
|
|
| 26 |
|
|
sdec(jd) {* solar declination angle (radians) *} |
| 27 |
|
|
{ jd is days into year } |
| 28 |
|
|
= |
| 29 |
|
|
0.4093 * sin( 2*PI/368 * (jd - 81) ) |
| 30 |
|
|
; |
| 31 |
|
|
|
| 32 |
|
|
|
| 33 |
|
|
salt(sd, st) {* solar altitude (radians) *} |
| 34 |
|
|
{ sd is solar declination, st is solar time (hours) } |
| 35 |
|
|
= |
| 36 |
|
|
asin( sin(RLAT) * sin(sd) - cos(RLAT) * cos(sd) * |
| 37 |
|
|
cos(st*PI/12) ) |
| 38 |
|
|
; |
| 39 |
|
|
|
| 40 |
|
|
|
| 41 |
|
|
sazi(sd, st) {* the solar azimuth (radians) *} |
| 42 |
|
|
{ sd is solar declination, st is solar time (hours) } |
| 43 |
|
|
= |
| 44 |
|
|
-atan2( cos(sd) * sin(st*PI/12), |
| 45 |
|
|
-cos(RLAT)*sin(sd) - |
| 46 |
|
|
sin(RLAT)*cos(sd)*cos(st*PI/12) ) |
| 47 |
|
|
; |
| 48 |
|
|
|
| 49 |
|
|
|
| 50 |
|
|
SAZI = sazi(SDEC, STIME) * 180/PI; |
| 51 |
|
|
|
| 52 |
|
|
SALT = salt(SDEC, STIME) * 180/PI; |
| 53 |
|
|
|
| 54 |
|
|
SDEC = sdec(JDATE); |
| 55 |
|
|
|
| 56 |
|
|
STIME = TIME + stadj(JDATE); |
| 57 |
|
|
|
| 58 |
|
|
JDATE = DAY + select(MONTH,0,31,59,90,120,151,181,212,243,273,304,334); |
