1 | !********************************************************************** |
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2 | ! Copyright 1998,1999,2000,2001,2002,2005,2007,2008,2009,2010 * |
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3 | ! Andreas Stohl, Petra Seibert, A. Frank, Gerhard Wotawa, * |
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4 | ! Caroline Forster, Sabine Eckhardt, John Burkhart, Harald Sodemann * |
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5 | ! * |
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6 | ! This file is part of FLEXPART. * |
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7 | ! * |
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8 | ! FLEXPART is free software: you can redistribute it and/or modify * |
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9 | ! it under the terms of the GNU General Public License as published by* |
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10 | ! the Free Software Foundation, either version 3 of the License, or * |
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11 | ! (at your option) any later version. * |
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12 | ! * |
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13 | ! FLEXPART is distributed in the hope that it will be useful, * |
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14 | ! but WITHOUT ANY WARRANTY; without even the implied warranty of * |
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15 | ! MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * |
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16 | ! GNU General Public License for more details. * |
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17 | ! * |
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18 | ! You should have received a copy of the GNU General Public License * |
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19 | ! along with FLEXPART. If not, see <http://www.gnu.org/licenses/>. * |
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20 | !********************************************************************** |
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21 | |
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22 | real function obukhov(ps,tsurf,tdsurf,tlev,ustar,hf,akm,bkm) |
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23 | |
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24 | !******************************************************************** |
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25 | ! * |
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26 | ! Author: G. WOTAWA * |
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27 | ! Date: 1994-06-27 * |
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28 | ! * |
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29 | ! Update: A. Stohl, 2000-09-25, avoid division by zero by * |
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30 | ! setting ustar to minimum value * |
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31 | ! * |
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32 | !******************************************************************** |
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33 | ! * |
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34 | ! This program calculates Obukhov scale height from surface * |
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35 | ! meteorological data and sensible heat flux. * |
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36 | ! * |
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37 | !******************************************************************** |
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38 | ! * |
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39 | ! INPUT: * |
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40 | ! * |
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41 | ! ps surface pressure [Pa] * |
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42 | ! tsurf surface temperature [K] * |
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43 | ! tdsurf surface dew point [K] * |
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44 | ! tlev temperature first model level [K] * |
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45 | ! ustar scale velocity [m/s] * |
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46 | ! hf surface sensible heat flux [W/m2] * |
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47 | ! akm ECMWF vertical discretization parameter * |
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48 | ! bkm ECMWF vertical discretization parameter * |
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49 | ! * |
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50 | !******************************************************************** |
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51 | |
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52 | use par_mod |
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53 | |
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54 | implicit none |
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55 | |
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56 | real :: akm(nwzmax),bkm(nwzmax) |
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57 | real :: ps,tsurf,tdsurf,tlev,ustar,hf,e,ew,tv,rhoa,plev |
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58 | real :: ak1,bk1,theta,thetastar |
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59 | |
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60 | |
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61 | e=ew(tdsurf) ! vapor pressure |
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62 | tv=tsurf*(1.+0.378*e/ps) ! virtual temperature |
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63 | rhoa=ps/(r_air*tv) ! air density |
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64 | ak1=(akm(1)+akm(2))/2. |
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65 | bk1=(bkm(1)+bkm(2))/2. |
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66 | plev=ak1+bk1*ps ! Pressure level 1 |
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67 | theta=tlev*(100000./plev)**(r_air/cpa) ! potential temperature |
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68 | if (ustar.le.0.) ustar=1.e-8 |
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69 | thetastar=hf/(rhoa*cpa*ustar) ! scale temperature |
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70 | if(abs(thetastar).gt.1.e-10) then |
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71 | obukhov=theta*ustar**2/(karman*ga*thetastar) |
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72 | else |
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73 | obukhov=9999 ! zero heat flux |
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74 | endif |
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75 | if (obukhov.gt. 9999.) obukhov= 9999. |
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76 | if (obukhov.lt.-9999.) obukhov=-9999. |
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77 | |
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78 | end function obukhov |
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