modsolarcalc Module Reference

Functions/Subroutines
real(kind(1d0)) function	min_zenith (lat, doy)
real(kind(1d0)) function	local_apparent_time (lng, dectime)
subroutine	solar_angles (lat, lng, timezone, dectime, decl, zenith, azimuth)
subroutine	solar_times (lat, lng, timezone, dectime, sunrise, sunset, snoon)
real(kind(1d0)) function	kdown_surface (doy, zenith)
real(kind(1d0)) function	transmissivity_cd (p, td, g, zenith)
real(kind(1d0)) function	solar_esdist (doy)

Function/Subroutine Documentation

kdown_surface()

real(kind(1d0)) function modsolarcalc::kdown_surface	(	integer	doy,
		real(kind(1d0))	zenith )

Definition at line 344 of file suews_phys_estm.f95.

      ! Calculates ground level solar irradiance clear sky
      ! assuming transmissivity = 1
      ! let it report zero if zenith >= 90
      REAL(KIND(1D0)) :: zenith, Isurf
      INTEGER :: doy
      REAL(KIND(1D0)) :: Rmean, Rse, cosZ, Itoa
 
      rmean = 149.6 !Stull 1998
      rse = solar_esdist(doy)
      IF (zenith < pi/2.) THEN
         cosz = cos(zenith)
         itoa = 1370*(rmean/rse)**2 !top of the atmosphere
         isurf = itoa*cosz !ground level solar irradiance in W/m2
      ELSE
         isurf = 0.
      END IF
 

References mathconstants::pi, and solar_esdist().

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local_apparent_time()

real(kind(1d0)) function modsolarcalc::local_apparent_time	(	real(kind(1d0))	lng,
		real(kind(1d0))	dectime )

Definition at line 275 of file suews_phys_estm.f95.

      !Oke, 1989, equation of time elsewhere
      REAL(KIND(1D0)) :: lng, dectime, la_time
      REAL(KIND(1D0)) :: gamma, eqtime, lmst
 
      lmst = dectime - 4.*lng/60./1440.
      gamma = 2.*pi/365.*(lmst - 1.)
      eqtime = 229.18*(7.5e-5 + 1.868e-3*cos(gamma) - 0.032077*sin(gamma)&
           &    - 0.014615*cos(2.*gamma) - 0.040849*sin(2.*gamma))
      la_time = lmst + eqtime/1440.

References mathconstants::pi.

min_zenith()

real(kind(1d0)) function modsolarcalc::min_zenith	(	real(kind(1d0))	lat,
		integer	doy )

Definition at line 261 of file suews_phys_estm.f95.

      !returns max zenith
      !returns zenith in radians for lat, lng in degrees
      REAL(KIND(1D0)) :: lat, dectime, zmin
      REAL(KIND(1D0)) :: latr, decl
      INTEGER :: doy
      dectime = float(doy)
      latr = lat*dtr
      decl = 0.409*cos(2*pi*(dectime - 173)/365.25)
      zmin = pi/2.-asin(sin(latr)*sin(decl) - cos(latr)*cos(decl)*(-1))

References mathconstants::dtr, and mathconstants::pi.

solar_angles()

subroutine modsolarcalc::solar_angles	(	real, intent(in)	lat,
		real, intent(in)	lng,
		real, intent(in)	timezone,
		real, intent(in)	dectime,
		real(kind(1d0)), intent(out)	decl,
		real(kind(1d0)), intent(out)	zenith,
		real(kind(1d0)), intent(out)	azimuth )

Definition at line 288 of file suews_phys_estm.f95.

 
      REAL, INTENT(in) :: lat, lng, timezone, dectime
      INTEGER :: doy, hour, mn
      REAL(KIND(1D0)), INTENT(out) :: decl, zenith, azimuth
      REAL(KIND(1D0)) :: ha, latr, eqtime, tst, &
                         time_offset, gamma !!!!!FO!!!!! lngr, phi, theta
 
      latr = lat*pi/180.
      doy = floor(dectime)
      hour = floor((dectime - doy)*24.)
      mn = floor((dectime - doy - hour/24.)*60.) !!!Check this
 
      gamma = 2.*pi/365.25463*(doy - 1.+(hour - 12.)/24.)
      eqtime = 229.18*(7.5e-5 + 1.868e-3*cos(gamma) - 0.032077*sin(gamma)&
           &    - 0.014615*cos(2.*gamma) - 0.040849*sin(2.*gamma))
      decl = 6.918e-3 - 0.399912*cos(gamma) + 0.070257*sin(gamma)&
           &    - 0.006758*cos(2.*gamma) + 9.07e-4*sin(2.*gamma) - 2.697e-3*cos(3.*gamma)&
           &    + 1.48e-3*sin(3.*gamma)
      time_offset = eqtime - 4.*lng + 60.*timezone
      tst = hour*60.+mn + time_offset
      ha = (tst/4.) - 180.
      ha = ha*pi/180.
 
      zenith = acos(sin(latr)*sin(decl) + cos(latr)*cos(decl)*cos(ha))
      azimuth = pi + acos((sin(latr)*cos(zenith) - sin(decl))/(cos(latr)*sin(zenith)))
 
      RETURN

References mathconstants::pi.

solar_esdist()

real(kind(1d0)) function modsolarcalc::solar_esdist

(

integer

doy

)

Definition at line 457 of file suews_phys_estm.f95.

      !from Stull, 1998
      INTEGER :: doy
      REAL(KIND(1D0)) :: Rse
      REAL(KIND(1D0)) :: MA, nu, e, a
 
      e = 0.0167
      a = 146.457
 
      ma = 2.*pi*(doy - 3)/365.25463 !Mean anomaly
      nu = ma + 0.0333988*sin(ma) + .0003486*sin(2.*ma) + 5e-6*sin(3.*ma) !true anomaly
      rse = a*(1 - e*e)/(1 + e*cos(nu))
 

References mathconstants::pi.

Referenced by kdown_surface().

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solar_times()

subroutine modsolarcalc::solar_times	(	real(kind(1d0)), intent(in)	lat,
		real(kind(1d0)), intent(in)	lng,
		real(kind(1d0)), intent(in)	timezone,
		real(kind(1d0)), intent(in)	dectime,
		real(kind(1d0)), intent(out)	sunrise,
		real(kind(1d0)), intent(out)	sunset,
		real(kind(1d0)), intent(out)	snoon )

Definition at line 319 of file suews_phys_estm.f95.

      !  for sunrise and sunset ha = ha(zenith=90)
      !  timezone is offset to GMT e.g. -5 for EST
 
      REAL(KIND(1D0)), INTENT(in) :: lat, lng, timezone, dectime
      INTEGER :: doy
      REAL(KIND(1D0)), INTENT(out) :: sunrise, sunset, snoon
      REAL(KIND(1D0)) :: ha, latr, eqtime, gamma, zenith, decl
      latr = lat*dtr
      zenith = 90.833*dtr
      doy = floor(dectime)
      gamma = 2.*pi/365.*(float(doy) - 0.5) !fractional year
      eqtime = 229.18*(7.5e-5 + 1.868e-3*cos(gamma) - 0.032077*sin(gamma)&
           &    - 0.014615*cos(2.*gamma) - 0.040849*sin(2.*gamma))
      decl = 6.918e-3 - 0.399912*cos(gamma) + 0.070257*sin(gamma)&
           &    - 0.006758*cos(2.*gamma) + 9.07e-4*sin(2.*gamma) - 2.697e-3*cos(3.*gamma)&
           &    + 1.48e-3*sin(3.*gamma)
      ha = acos(cos(zenith)/(cos(latr)*cos(decl)) - tan(latr)*tan(decl))
      ha = ha*rtd
      sunrise = (720.-4.*(lng - ha) - eqtime)/60.-timezone
      sunset = (720.-4.*(lng + ha) - eqtime)/60.-timezone
      snoon = (720.-4.*lng - eqtime)/60.-timezone
      RETURN

References mathconstants::dtr, mathconstants::pi, and mathconstants::rtd.

transmissivity_cd()

real(kind(1d0)) function modsolarcalc::transmissivity_cd	(	real(kind(1d0))	p,
		real(kind(1d0))	td,
		real(kind(1d0))	g,
		real(kind(1d0))	zenith )

Definition at line 380 of file suews_phys_estm.f95.

      ! bulk atmospheric transmissivity (Crawford and Duchon, 1999)
      ! P = pressure (hPa)
      ! Td = dewpoint (C)
      ! G parameter is empirical value from Smith 1966 (JAM)
      ! zenith in radians
 
      !        integer         ::doy           !!!!!FO!!!!!
      REAL(KIND(1D0)) :: P, Td, zenith, G, trans
      REAL(KIND(1D0)) :: m, TrTpg, u, Tw, Ta, cosZ
      REAL(KIND(1D0)) :: Tdf
 
      IF (zenith > 80.*dtr) THEN
         cosz = cos(80.*dtr)
      ELSE
         cosz = cos(zenith)
      END IF
      tdf = td*1.8 + 32. !celsius to fahrenheit
      !  Transmission coefficients
      m = 35*cosz/sqrt(1224.*cosz*cosz + 1) !optical air mass at p=1013 mb
      trtpg = 1.021 - 0.084*sqrt(m*(0.000949*p + 0.051)) !first two trans coeff
      u = exp(0.113 - log(g + 1) + 0.0393*tdf) !precipitable water
      tw = 1 - 0.077*(u*m)**0.3 !vapor transmission coe3ff.
      ta = 0.935**m !4th trans coeff
      trans = trtpg*tw*ta !bulk atmospherics transmissivity

References mathconstants::dtr.