Last change
on this file since 1579 was
135,
checked in by aslmd, 14 years ago
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CHANGEMENT ARBORESCENCE ETAPE 2 -- NON COMPLET
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File size:
2.1 KB
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1 | SUBROUTINE mufract(jjm,pdecli, plat, pmu, pfract) |
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2 | IMPLICIT NONE |
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3 | c |
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4 | c======================================================================= |
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5 | c |
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6 | c Calcul of equivalent solar angle and and fraction of day without |
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7 | c diurnal cycle. |
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8 | c |
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9 | c parmeters : |
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10 | c ----------- |
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11 | c |
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12 | c Input : |
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13 | c ------- |
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14 | c jjm number of points |
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15 | c pdecli solar declinaison |
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16 | c plat(jjm) latitude |
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17 | c |
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18 | c Output : |
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19 | c -------- |
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20 | c pmu(jjm) equivalent cosinus of the solar angle |
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21 | c pfract(jjm) fractionnal day |
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22 | c |
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23 | c |
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24 | c======================================================================= |
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25 | c |
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26 | c----------------------------------------------------------------------- |
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27 | c |
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28 | c 0. Declarations : |
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29 | c ----------------- |
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30 | c |
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31 | c Arguments : |
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32 | c ----------- |
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33 | |
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34 | INTEGER jjm |
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35 | REAL plat(jjm),pmu(jjm), pfract(jjm) |
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36 | REAL pdecli |
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37 | c |
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38 | c Local variables : |
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39 | c ----------------- |
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40 | |
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41 | INTEGER j |
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42 | REAL pi |
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43 | REAL z,cz,sz,tz,phi,cphi,sphi,tphi |
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44 | REAL ap,a,t,b |
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45 | c |
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46 | c======================================================================= |
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47 | c |
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48 | pi = 4. * atan(1.0) |
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49 | z = pdecli |
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50 | cz = cos (z*pi/180.) |
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51 | sz = sin (z*pi/180.) |
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52 | c |
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53 | DO 20 j = 1, jjm |
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54 | c |
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55 | phi = plat(j) |
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56 | cphi = cos(phi) |
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57 | if (cphi.le.1.e-9) cphi=1.e-9 |
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58 | sphi = sin(phi) |
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59 | tphi = sphi / cphi |
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60 | b = cphi * cz |
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61 | t = -tphi * sz / cz |
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62 | a = 1.0 - t*t |
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63 | ap = a |
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64 | IF(t.eq.0.) THEN |
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65 | t=0.5*pi |
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66 | ELSE |
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67 | IF (a.lt.0.) a = 0. |
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68 | t = sqrt(a) / t |
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69 | IF (t.lt.0.) THEN |
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70 | t = -atan (-t) + pi |
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71 | ELSE |
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72 | t = atan(t) |
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73 | ENDIF |
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74 | ENDIF |
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75 | pmu(j) = (sphi*sz*t) / pi + b*sin(t)/pi |
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76 | pfract(j) = t / pi |
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77 | IF (ap .lt.0.) THEN |
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78 | pmu(j) = sphi * sz |
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79 | pfract(j) = 1.0 |
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80 | ENDIF |
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81 | IF (pmu(j).le.0.0) pmu(j) = 0.0 |
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82 | pmu(j) = pmu(j) / pfract(j) |
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83 | IF (pmu(j).eq.0.) pfract(j) = 0. |
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84 | c |
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85 | 20 CONTINUE |
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86 | c |
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87 | RETURN |
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88 | END |
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89 | c |
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90 | c* end of mufract |
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91 | c======================================================================= |
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92 | c |
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