Changeset 6140 for trunk/DOC/TexFiles/Chapters/Chap_OBS.tex
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- 2015-12-21T12:35:23+01:00 (8 years ago)
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trunk/DOC/TexFiles/Chapters/Chap_OBS.tex
r4245 r6140 18 18 location and nearest model timestep. The resulting data are saved in a ``feedback'' file (or 19 19 files). The code was originally developed for use with the NEMOVAR data assimilation code, but 20 can be used for validation or verification of model orany other data assimilation system.21 22 The OBS code is called from \mdl{nemogcm .F90} for model initialisation and to calculate the model20 can be used for validation or verification of the model or with any other data assimilation system. 21 22 The OBS code is called from \mdl{nemogcm} for model initialisation and to calculate the model 23 23 equivalent values for observations on the 0th timestep. The code is then called again after 24 each timestep from \mdl{step .F90}. To build with the OBS code active \key{diaobs} must be25 set.24 each timestep from \mdl{step}. The code is only activated if the namelist logical \np{ln\_diaobs} 25 is set to true. 26 26 27 27 For all data types a 2D horizontal interpolator is needed to interpolate the model fields to … … 29 29 addition to provide model fields at the observation depths. Currently this only works in 30 30 z-level model configurations, but is being developed to work with a generalised vertical 31 coordinate system. Temperature data from moored buoys (TAO, TRITON, PIRATA) in the 32 ENACT/ENSEMBLES data-base are available as daily averaged quantities. For this type of 33 observation the observation operator will compare such observations to the model temperature 34 fields averaged over one day. The relevant observation type may be specified in the namelist 35 using \np{endailyavtypes}. Otherwise the model value from the nearest timestep to the 31 coordinate system. 32 33 Some profile observation types (e.g. tropical moored buoys) are made available as daily averaged quantities. 34 The observation operator code can be set-up to calculated the equivalent daily average model temperature fields 35 using the \np{nn\_profdavtypes} namelist array. Some SST observations are equivalent to a night-time 36 average value and the observation operator code can calculate equivalent night-time average model SST fields by 37 setting the namelist value \np{ln\_sstnight} to true. Otherwise the model value from the nearest timestep to the 36 38 observation time is used. 37 39 38 40 The code is controlled by the namelist \textit{nam\_obs}. See the following sections for more 39 details on setting up the namelist. 41 details on setting up the namelist. 40 42 41 43 Section~\ref{OBS_example} introduces a test example of the observation operator code including … … 59 61 60 62 \begin{enumerate} 61 \item Compile NEMO with \key{diaobs} set.62 63 \item Download some EN SEMBLES EN3data from64 \href{http://www. hadobs.org}{http://www.hadobs.org}. Choose observations which are63 \item Compile NEMO. 64 65 \item Download some EN4 data from 66 \href{http://www.metoffice.gov.uk/hadobs}{http://www.metoffice.gov.uk/hadobs}. Choose observations which are 65 67 valid for the period of your test run because the observation operator compares 66 68 the model and observations for a matching date and time. 67 69 68 \item Add the following to the NEMO namelist to run the observation 69 operator on this data. Set the \np{enactfiles} namelist variable to the 70 observation file name: 70 \item Compile the OBSTOOLS code using: 71 \begin{verbatim} 72 ./maketools -n OBSTOOLS -m [ARCH]. 73 \end{verbatim} 74 75 \item Convert the EN4 data into feedback format: 76 \begin{verbatim} 77 enact2fb.exe profiles_01.nc EN.4.1.1.f.profiles.g10.YYYYMM.nc 78 \end{verbatim} 79 80 \item Include the following in the NEMO namelist to run the observation 81 operator on this data: 71 82 \end{enumerate} 72 83 … … 77 88 Options are defined through the \ngn{namobs} namelist variables. 78 89 The options \np{ln\_t3d} and \np{ln\_s3d} switch on the temperature and salinity 79 profile observation operator code. The \np{ln\_ena} switch turns on the reading 80 of ENACT/ENSEMBLES type profile data. The filename or array of filenames are 81 specified using the \np{enactfiles} variable. The model grid points for a 90 profile observation operator code. The filename or array of filenames are 91 specified using the \np{cn\_profbfiles} variable. The model grid points for a 82 92 particular observation latitude and longitude are found using the grid 83 93 searching part of the code. This can be expensive, particularly for large … … 92 102 A number of utilities are now provided to plot the feedback files, convert and 93 103 recombine the files. These are explained in more detail in section~\ref{OBS_obsutils}. 104 Utilites to convert other input data formats into the feedback format are also 105 described in section~\ref{OBS_obsutils}. 94 106 95 107 \section{Technical details} … … 104 116 %------------------------------------------------------------------------------------------------------------- 105 117 106 Th is name list uses the "feedback" type observation file inputformat for107 profile, sea level anomaly and sea surface temperature data. All the118 The observation operator code uses the "feedback" observation file format for 119 all data types. All the 108 120 observation files must be in NetCDF format. Some example headers (produced using 109 121 \mbox{\textit{ncdump~-h}}) for profile
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