Re: two time dimension

Hi Ahmed,
This is the result of a problem that has been fixed in NCL 6.1.0-beta. From the "What's New" page:

======
Changes to GRIB1/GRIB2 reader

        • Added support for complex packing in GRIB1. (It's already available for GRIB2 files.)

        • GRIB1 changes
Time range indicator 10, which indicates that time parameter P1 occupies 2 bytes, is now treated the same as time range indicator 0 for the purposes of generating the forecast time dimension. This means that GRIB1 variable names that used to have '_10' appended no longer will. And, in a very small number of cases, two forecast time dimensions may be concatenated into a single dimension that is the union of the two.
======

I think you can safely use the GRIB2 version of the file.
 -dave

On Jun 22, 2012, at 2:40 PM, ahmed lasheen wrote:

> Hello
> I am trying to plot the output of the WRF model .
> before using the NCL, i write small script to just cut the variables that I would plot like MSLP,TEMP
> I found that when I write ncl_filedump for the file that i got , i found that there is two time although there is just
> one time dimension . and after I convert the file into grib2 using the cnvgrib , I found that the second dimension disappear .
> the output of the ncl_filedump for the grib1 file is
> dimensions:
> forecast_time0 = 256
> lv_ISBL1 = 6
> g0_lat_2 = 61
> g0_lon_3 = 145
> forecast_time4 = 417
> variables:
> float TMP_GDS0_ISBL ( forecast_time0, lv_ISBL1, g0_lat_2, g0_lon_3 )
> center : US National Weather Service - NCEP (WMC)
> long_name : Temperature
> units : K
> _FillValue : 1e+20
> level_indicator : 100
> gds_grid_type : 0
> parameter_table_version : 2
> parameter_number : 11
> model : North Pacific Hurricane Wave Model
> initial_time : 11/02/2010 (00:00)
>
> float TMP_GDS0_ISBL_10 ( forecast_time4, lv_ISBL1, g0_lat_2, g0_lon_3 )
> center : US National Weather Service - NCEP (WMC)
> long_name : Temperature
> units : K
> _FillValue : 1e+20
> level_indicator : 100
> gds_grid_type : 0
> parameter_table_version : 2
> parameter_number : 11
> model : North Pacific Hurricane Wave Model
> initial_time : 11/02/2010 (00:00)
>
> float R_H_GDS0_ISBL ( forecast_time0, lv_ISBL1, g0_lat_2, g0_lon_3 )
> center : US National Weather Service - NCEP (WMC)
> long_name : Relative humidity
> units : %
> _FillValue : 1e+20
> level_indicator : 100
> gds_grid_type : 0
> parameter_table_version : 2
> parameter_number : 52
> model : North Pacific Hurricane Wave Model
> initial_time : 11/02/2010 (00:00)
>
> float R_H_GDS0_ISBL_10 ( forecast_time4, lv_ISBL1, g0_lat_2, g0_lon_3 )
> center : US National Weather Service - NCEP (WMC)
> long_name : Relative humidity
> units : %
> _FillValue : 1e+20
> level_indicator : 100
> gds_grid_type : 0
> parameter_table_version : 2
> parameter_number : 52
> model : North Pacific Hurricane Wave Model
> initial_time : 11/02/2010 (00:00)
>
> integer forecast_time4 ( forecast_time4 )
> long_name : Forecast offset from initial time
> units : hours
>
> float g0_lat_2 ( g0_lat_2 )
> long_name : latitude
> GridType : Cylindrical Equidistant Projection Grid
> units : degrees_north
> Dj : 0.33
> Di : 0.33
> Lo2 : 52.917
> La2 : 37.372
> Lo1 : 5.397
> La1 : 17.572
>
> float g0_lon_3 ( g0_lon_3 )
> long_name : longitude
> GridType : Cylindrical Equidistant Projection Grid
> units : degrees_east
> Dj : 0.33
> Di : 0.33
> Lo2 : 52.917
> La2 : 37.372
> Lo1 : 5.397
> La1 : 17.572
>
> integer lv_ISBL1 ( lv_ISBL1 )
> long_name : isobaric level
> units : hPa
>
> integer forecast_time0 ( forecast_time0 )
> long_name : Forecast offset from initial time
> units : hours
>
> and after i convert the file from grib1 to grib2 (cnvgrib -g12 file_grib1 file_grib2), i found that the second time disappear and it became part of the first time .
> dimensions:
> forecast_time0 = 673
> lv_ISBL0 = 6
> lat_0 = 61
> lon_0 = 145
> variables:
> float TMP_P0_L100_GLL0 ( forecast_time0, lv_ISBL0, lat_0, lon_0 )
> center : US National Weather Service - NCEP (WMC)
> production_status : Operational products
> long_name : Temperature
> units : K
> _FillValue : 1e+20
> grid_type : Latitude/longitude
> parameter_discipline_and_category : Meteorological products, Temperature
> parameter_template_discipline_category_number : ( 0, 0, 0, 0 )
> level_type : Isobaric surface (Pa)
> initial_time : 11/02/2010 (00:00)
>
> float RH_P0_L100_GLL0 ( forecast_time0, lv_ISBL0, lat_0, lon_0 )
> center : US National Weather Service - NCEP (WMC)
> production_status : Operational products
> long_name : Relative humidity
> units : %
> _FillValue : 1e+20
> grid_type : Latitude/longitude
> parameter_discipline_and_category : Meteorological products, Moisture
> parameter_template_discipline_category_number : ( 0, 0, 1, 1 )
> level_type : Isobaric surface (Pa)
> initial_time : 11/02/2010 (00:00)
>
> float lat_0 ( lat_0 )
> long_name : latitude
> grid_type : Latitude/Longitude
> units : degrees_north
> Dj : 0.33
> Di : 0.33
> Lo2 : 52.917
> La2 : 37.372
> Lo1 : 5.397
> La1 : 17.572
>
> float lon_0 ( lon_0 )
> long_name : longitude
> grid_type : Latitude/Longitude
> units : degrees_east
> Dj : 0.33
> Di : 0.33
> Lo2 : 52.917
> La2 : 37.372
> Lo1 : 5.397
> La1 : 17.572
>
> float lv_ISBL0 ( lv_ISBL0 )
> long_name : Isobaric surface
> units : Pa
>
> integer forecast_time0 ( forecast_time0 )
> long_name : Forecast offset from initial time
> units : hours
>
> I don't know if my problem is with the NCL or with dealing with grib1 and grib2 .
> Have i to convert the files from grib1 to grib2 to see just one time dimension.
> I contacted the WRF help , and they advise me to contact the NCL support for this , and they told me that my file is ok.
> thanks in advance
>
> --
> ===============
> Ahmed Lasheen
> Junior researcher at Cairo Numerical Weather Prediction Center (CNWPC)
> Egyptian Meteorological Authority(EMA)
> Cairo,Egypt
> ===============
>
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Received on Fri Jun 22 14:56:43 2012