1 | real function photo_O1D(sza) |
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2 | |
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3 | !***************************************************************************** |
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4 | ! * |
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5 | ! * |
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6 | ! Author: A. Stohl * |
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7 | ! * |
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8 | ! Nov 2014 * |
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9 | ! * |
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10 | ! * |
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11 | !***************************************************************************** |
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12 | ! * |
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13 | ! INPUT: * |
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14 | ! sza solar zenith angle (degrees) * |
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15 | ! * |
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16 | ! OUTPUT: * |
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17 | ! photo_O1D J(O1D) photoylsis rate * |
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18 | ! * |
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19 | !***************************************************************************** |
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20 | |
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21 | implicit none |
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22 | |
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23 | integer :: iz,ik |
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24 | real :: sza |
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25 | real :: z1,z2,zg,f1,f2,dummy |
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26 | real :: photo_NO2 |
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27 | integer, parameter :: nzenith=11 |
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28 | real, parameter :: pi=3.1415927 |
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29 | real, dimension(nzenith) :: zangle,fact_photo |
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30 | |
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31 | ! zangle: zenith angles for which fact_photo is tabulated |
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32 | ! fact_photo: conversion of photolysis rate of NO2 to photolysis |
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33 | ! rate of O3 into O1D as a function of solar zenith angle |
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34 | |
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35 | zangle=(/0.,10.,20.,30.,40.,50.,60.,70.,78.,86.,90.0001/) |
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36 | fact_photo=(/0.4616E-02,0.4478E-02,0.4131E-02,0.3583E-02,0.2867E-02,& |
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37 | &0.2081E-02,0.1235E-02,0.5392E-03,0.2200E-03,0.1302E-03,0.0902E-03/) |
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38 | |
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39 | if (sza.lt.90.) then |
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40 | do iz=1,nzenith-1 |
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41 | if(sza.ge.zangle(iz)) ik=iz |
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42 | end do |
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43 | z1=1./cos(zangle(ik)*pi/180.) |
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44 | z2=1./cos(zangle(ik+1)*pi/180.) |
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45 | zg=1./cos(sza*pi/180.) |
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46 | dummy=(zg-z1)/(z2-z1) |
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47 | f1=alog(fact_photo(ik)) |
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48 | f2=alog(fact_photo(ik+1)) |
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49 | photo_NO2=1.45e-2*exp(-0.4/cos(sza*pi/180.)) |
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50 | photo_O1D=photo_NO2*exp(f1+(f2-f1)*dummy) |
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51 | else |
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52 | photo_O1D=0. |
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53 | endif |
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54 | |
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55 | return |
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56 | |
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57 | end function photo_O1D |
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58 | |
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59 | |
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