Changes between Version 1 and Version 2 of Scripts/FluxnetValidation/DataProcessing


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Timestamp:
01/07/13 17:10:42 (9 years ago)
Author:
nvuilsce
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  • Scripts/FluxnetValidation/DataProcessing

    v1 v2  
    22FLUXNET_DATA is a set of Python scripts that aim at generating meteorological ORCHIDEE input file (.nc file) from FLUXNET site data (.csv file).[[BR]] 
    33Additionally, the file stores other monitored variables that may serve for model/data comparison.[[BR]] 
    4 The main feature of FLUXNET_DATA is to fill the gaps in the meteorological time series thanks to ERA-interim 6-hourly product.  
     4The main feature of FLUXNET_DATA is to fill the gaps in the meteorological time series thanks to ERA-interim 3-hourly product.  
    55 
    66== Input requirements ==  
     
    2222the location of the ERA-interim products (name_path_reanalysis) 
    2323the directory where we want to store the ORCHIDEE input files (name_path_out) 
    24 the shortest gap for which we use the reanalysis for filling gaps (gapmax). Below gapmax length, we use a linear interpolation . It is expressed in time step of the in-situ data and its default value is 12 (= 6 hours)  
     24the shortest gap for which we use the reanalysis for filling gaps (gapmax). Below gapmax length, we use a linear interpolation . It is expressed in time step of the in-situ data and its default value is 6 (= 3 hours)  
    2525 
    2626== Functioning == 
    2727FLUXNET_DATA creates half-hourly time-series of Air Temperature, Rainfall, Snowfall, Shortwave and Longwave down radiation, surface pressure, surface specific humidity, North-dir and East-dir wind speed from available FLUXNET data (Air Temperature, Precipitation,  Shortwave and Longwave down radiation, Vapour pressure deficit, Wind speed) and ERA-interim products when FLUXNET data are not available or not original data.[[BR]] 
    28 In order to fill the gaps with ERA-interim data, we first compare FLUXNET and ERA-interim data at 6-hour time resolution when both datasets are available and correct for systematic bias in order to use non-bias ERA-interim data when gaps.[[BR]] 
     28In order to fill the gaps with ERA-interim data, we first compare FLUXNET and ERA-interim data at 3-hour time resolution when both datasets are available and correct for systematic bias in order to use non-bias ERA-interim data when gaps.[[BR]] 
    2929Variables that are compared are : 
    3030 - Air Temperature 
    3131 - Shortwave and longwave down radiation 
    32  - Vapour pressure deficit 
     32 - Water vapour pressure 
    3333 - Precipitation 
    3434 - Wind speed 
     
    4040Vapour pressure deficit from ERA-interim products is calculated by using the Magnus Tetens relationship based on Air water deficit, Air temperature and Surface pressure (Murray, 1967, http://cires.colorado.edu/~voemel/vp.html).  
    4141 
    42 When there are gaps in the Fluxnet time-series, 6-hourly non-bias ERA-interim data are used and consequently interpolate to match the half-hourly time resolution of the Fluxnet data. 'Air Temperature', VPD, 'Wind speed', 'Longwave down Radiation' and 'Pressure' are linearly interpolated. 6-hourly precipitation are spread at half-hourly resolution using the observed mean frequency of precipitation. For the shortwave down radiation interpolation, we account for the solar angle evolution over the 6-hourly time period. 
     42When there are gaps in the Fluxnet time-series, 3-hourly non-bias ERA-interim data are used and consequently interpolate to match the half-hourly time resolution of the Fluxnet data. 'Air Temperature', 'Water Vapour Pressure', 'Wind speed', 'Longwave down Radiation' and 'Pressure' are linearly interpolated. 3-hourly precipitation are spread at half-hourly resolution using the observed mean frequency of precipitation. For the shortwave down radiation interpolation, we account for the solar angle evolution over the 3-hourly time period. 
    4343 
    4444Last, in order to agree with the required meteorological fields by ORCHIDEE, precipitation is split into Rainfall and Snowfall by using a 0°C threshold and VPD is converted in 'Air specific humidity' using the Magnus Tetens relationship.