| 1 | MODULE mucorr_mod |
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| 2 | |
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| 3 | IMPLICIT NONE |
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| 4 | |
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| 5 | CONTAINS |
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| 6 | |
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| 7 | SUBROUTINE mucorr(npts,pdeclin, plat, pmu, pfract,phaut,prad) |
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| 8 | IMPLICIT NONE |
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| 9 | |
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| 10 | c======================================================================= |
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| 11 | c |
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| 12 | c Compute equivalent solar angle and fraction of day whithout |
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| 13 | c diurnal cycle. |
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| 14 | c |
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| 15 | c parmeters : |
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| 16 | c ----------- |
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| 17 | c |
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| 18 | c Input : |
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| 19 | c ------- |
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| 20 | c npts number of points |
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| 21 | c pdeclin solar declinaison |
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| 22 | c plat(npts) latitude |
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| 23 | c phaut thickness of atmosphere |
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| 24 | c prad planet radius |
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| 25 | c |
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| 26 | c Output : |
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| 27 | c -------- |
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| 28 | c pmu(npts) equivalent cosine of the solar angle |
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| 29 | c pfract(npts) fractionnal day |
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| 30 | c |
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| 31 | c======================================================================= |
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| 32 | |
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| 33 | c----------------------------------------------------------------------- |
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| 34 | c |
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| 35 | c 0. Declarations : |
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| 36 | c ----------------- |
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| 37 | |
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| 38 | c Arguments : |
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| 39 | c ----------- |
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| 40 | INTEGER,INTENT(IN) :: npts |
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| 41 | REAL,INTENT(IN) :: plat(npts) |
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| 42 | REAL,INTENT(IN) :: phaut,prad,pdeclin |
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| 43 | REAL,INTENT(OUT) :: pmu(npts), pfract(npts) |
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| 44 | c |
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| 45 | c Local variables : |
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| 46 | c ----------------- |
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| 47 | INTEGER j |
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| 48 | REAL pi |
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| 49 | REAL z,cz,sz,tz,phi,cphi,sphi,tphi |
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| 50 | REAL ap,a,t,b, tp |
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| 51 | REAL alph |
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| 52 | |
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| 53 | c----------------------------------------------------------------------- |
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| 54 | |
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| 55 | pi = 4. * atan(1.0) |
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| 56 | z = pdeclin |
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| 57 | cz = cos (z) |
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| 58 | sz = sin (z) |
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| 59 | |
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| 60 | DO j = 1, npts |
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| 61 | |
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| 62 | phi = plat(j) |
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| 63 | cphi = cos(phi) |
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| 64 | if (cphi.le.1.e-9) cphi=1.e-9 |
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| 65 | sphi = sin(phi) |
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| 66 | tphi = sphi / cphi |
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| 67 | b = cphi * cz |
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| 68 | t = -tphi * sz / cz |
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| 69 | a = 1.0 - t*t |
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| 70 | ap = a |
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| 71 | |
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| 72 | IF(t.eq.0.) then |
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| 73 | tp=0.5*pi |
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| 74 | ELSE |
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| 75 | IF (a.lt.0.) a = 0. |
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| 76 | t = sqrt(a) / t |
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| 77 | IF (t.lt.0.) then |
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| 78 | tp = -atan (-t) + pi |
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| 79 | ELSE |
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| 80 | tp = atan(t) |
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| 81 | ENDIF |
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| 82 | ENDIF |
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| 83 | t = tp |
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| 84 | |
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| 85 | pmu(j) = (sphi*sz*t) / pi + b*sin(t)/pi |
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| 86 | pfract(j) = t / pi |
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| 87 | IF (ap .lt.0.) then |
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| 88 | pmu(j) = sphi * sz |
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| 89 | pfract(j) = 1.0 |
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| 90 | ENDIF |
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| 91 | IF (pmu(j).le.0.0) pmu(j) = 0.0 |
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| 92 | pmu(j) = pmu(j) / pfract(j) |
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| 93 | IF (pmu(j).eq.0.) pfract(j) = 0. |
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| 94 | |
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| 95 | ENDDO |
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| 96 | |
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| 97 | c----------------------------------------------------------------------- |
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| 98 | c correction de rotondite: |
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| 99 | c ------------------------ |
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| 100 | |
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| 101 | alph=phaut/prad |
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| 102 | DO j=1,npts |
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| 103 | c !!!!!! |
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| 104 | pmu(j)=sqrt(1224.*pmu(j)*pmu(j)+1.)/35. |
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| 105 | c $ (sqrt(alph*alph*pmu(j)*pmu(j)+2.*alph+1.)-alph*pmu(j)) |
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| 106 | ENDDO |
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| 107 | |
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| 108 | END SUBROUTINE mucorr |
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| 109 | |
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| 110 | END MODULE mucorr_mod |
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