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PROCESS_LONLATMONTH

PROCESS_LONLATMONTH

Name


    PROCESS_LONLATMONTH

Purpose


    This procedure returns a processed version of the input lon-lat-month data
    set. Processing includes lon-lat interpolation masking, taking anomalies,
    and taking averages.

Category


    GEOGRAPHICAL

Calling Sequence


    process_lonlatmonth, data

Inputs


    Data: A array of data to be processed. Of dimensions N_LON*N_LAT*N_TIME.
        Missing data should be denoted by NaN. Returns the processed data
        array.
    ANOMALY, DATA_MEAN, DESEASONALISE, FRAC_INTERPOLATE_THRESH,
        FRAC_BASE_THRESH, FRAC_SEASON_THRESH, LAT, LEN_SEASON, LON, MASK_DATA,
        MASK_LON, MASK_LAT, PERIOD_BASE, SEASON, TIME

Keyword Parameters


    ANOMALY: If set then anomalies with respect to the PERIOD_BASE
        climatology are returned. If set to 'absolute' then the absolute
        anomalies are returned. If set to 'fractional' then the fractional
        anomalies are returned. The default is not set (no anomalies).
    COVERAGE: An optional input floating array containing the fractional data
        coverage of each element in Data. Returns an altered array according
        to interpolation and masking operations. Of same dimensions as Data.
    DATA_MEAN: Returns an array of the temporal average of Data over the
        PERIOD_BASE period. Of size N_LON_OUT*N_LAT_OUT. This is if
        DATA_MEAN is set or if ANOMALY is set.
    DESEASONALISE: If set then the seasonal cycle is removed from the data
        before the seasonal values are calculated. See months_to_seasons.pro
        for more information.
    FRAC_COVERAGE_THRESH: The minimum fraction of (weighted) data that must
        be defined (i.e. not NaN) in order to proceed with an integration
        command. If the criterion is not met then a NaN is returned from that
        calculation. The default is 0.
    FRAC_INTERPOLATE_THRESH: The threshold fraction of the area in a new
        spatial cell with non-missing data in the old spatial cells being
        interpolated required for the interpolation to be carried out (as
        against being counted as missing data). The default is 0.
    FRAC_BASE_THRESH: The fraction of time steps in the base period required
        to have non-missing (non-NaN) values in order for the base value to be
        calculated. If this criterion is not satisfied then a NaN is
        recorded. The default is 0.
    FRAC_SEASON_THRESH: The fraction of the season that needs non-missing
        data in order to be averaged when seasonal averaging is selected. The
        default is 0.
    INTEGRATE: A string array containing integration instructions to run in
        array_total.pro through the Instruct keyword. See array_total.pro for
        further details. 'mean=1,2' gives the spatial average, 'total=1'
        gives the zonal total, 'mean=2' gives the meridional average, 'mean=3'
        gives the temporal average.
    INTERPOLATE_TOTAL: If set then when interpolating to the MASK_LAT and/or
        MASK_LON coordinates the area-weighted total of all values in the new
        grid cells that are overlapping the area in the new grid cell is
        taken. The default is to return the area-weighted average.
    LAT: A vector of latitude values for Data. Of length N_LAT. Returns the
        vector of latitude values for the returned processed Data, length
        N_LAT_OUT.
    LEN_SEASON: The length of the season for returning seasonal data. See
        months_to_seasons.pro (SEASONLEN) for more information.
    LON: A vector of longitude values for Data. Of length N_LON. Returns
        the vector of longitude values for the returned processed Data, of
        length N_LON_OUT.
    MASK_DATA: A masking array of dimensions N_LON_MASK*N_LAT_MASK or
        N_LON_MASK*N_LAT_MASK*N_TIME. Values are 1 (keep) or NaN (discard).
    MASK_LAT: A vector of the latitude coordinates for the mask. Of length
        N_LAT_MASK. If not given then MASK_LAT is assumed to equal LAT.
    MASK_LON: A vector of the longitude coordinates for the mask. Of length
        N_LON_MASK. If not given then MASK_LON is assumed to equal LON.
    MEAN_AREA: If set then the spatial mean is returned. The default is not
        set.
    MEAN_LAT: If set then the zonal mean is returned. The default is not set.
    MEAN_LON: If set then the meridional mean is returned. The default is
        not set.
    PERIOD_BASE: A vector of length two defining the climatological base
        period. The first/second elements give the first/last year of the
        period. The default value is the full period in TIME.
    SEASON: If a value is given, then the function returns seasonal mean or
        total data for the desired season of length LEN_SEASLON. See
        months_to_seasons.pro for more information.
    TIME: A vector of time values for Data. Of length N_TIME. Returns the
        vector of time values for the returned processed Data, of length
        N_TIME_OUT.
    WEIGHT: An array size N_LON_OUT*N_LAT_OUT*N_TIME_OUT of weightings to use
        when taking an average over one or more dimensions, as requested in
        INTEGRATE or MEAN_*. Note this should not include the area weightings
        for a polar grid, which are included automatically.

Outputs


    Data
    COVERAGE, DATA_MEAN, LAT, LON, TIME

Uses


    add_dim.pro
    array_total.pro
    mask_lonlattime.pro
    months_to_season.pro

Procedure


Example


Modification History


    Written by: Daithi A. Stone (stoned@atm.ox.ac.uk), 2008-03-26, adapted
        from mask_lonlatmonth.pro
    Modified: DAS, 2008-04-14 (Added WEIGHT keyword; added default base
        period to averaging section; added NGOOD=1 to months_to_season.pro
        call for time)
    Modified: DAS, 2009-04-07 (Corrected bug to allow anomaly calculation of
        one-dimensional data)
    Modified: DAS, 2011-03-30 (Fixed bug in recording lon and lat from
        mask_lonlattime.pro when COVERAGE is undefined; modified formating;
        added description for COVERAGE)



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