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Hi all:
1. The CFSR dataset is known to have grib encoding issues, so its possible we are seeing some of that and/or bugs in the software. in particular, the translation of grib1 to grib2 had bugs in it. ive been unable to get authoritative info on how to fix this, but i do have machinery to do so if we can figure out what to do. 2. The 4.3 software is completely different from 4.2. We are only going to fix 4.3 grib problems. 4.2 doesnt handle time interval coordinates correctly. 3. In this file: ftp://ftp.ncep.noaa.gov/pub/data/nccf/com/cfs/prod/cfs/cfs.20120927/00/monthly_grib_01/flxf.01.2012092700.201305.avrg.grib.grb2 I am seeing records like the one I have dumped below. statistic type is "Average" reference time is 2012-09-27T00:00:00.000Z the "end of overall time interval" is == 2012/09/27T0:0:0 forecast time is 8 months. we are interpreting the time interval coordinate as: (0.000000, 1.000000) == (2012-08-27T00:00:00.000Z, 2012-09-27T00:00:00.000Z) which seems wrong. ill have to look at this closer. 4. Note that this is an interval coordinate, meaning the "valid time" is a time interval. From this comment: "The forecasts from that model run are for the mean conditions over the months of May 2013" Im guessing the correct interval should be: (0.000000, 1.000000) == (2013-05-01T00:00:00.000Z, 2013-06-01T00:00:00.000Z) so: - we do have a bug - the dates are encoded wrong - have to figure out how to fix systematically. if theres a way to derive the correct answer from the info in the PDS below, can you see it? It will be unfortunate if we have to rely on the filename. --------- File=0 E:/data/work/ansari/flxf.01.2012092700.201305.avrg.grib.grb2 Header="" Grib2IndicatorSection Discipline = (0) Meteorological products Length = 64370 Grib2IdentificationSection Center = (7) US National Weather Service, National Centres for Environmental Prediction (NCEP) SubCenter = (0) null Master Table = 2 Local Table = 1 RefTimeSignif = 1 (Start of forecast) RefTime = 2012-09-27T00:00:00.000Z RefTime Fields = 2012-9-27 0:0:0 ProductionStatus = 0 (Operational products) TypeOfProcessedData = 1 (Forecast products) Grib2GridDefinitionSection hash=-1824839391 crc=4229097007 Length = 72 Source (3.0) = 0 (Specified in Code table 3.1) Npts = 72960 Template (3.1) = 40 (3.40) Grid definition template 3.40 - Gaussian latitude/longitude 1: GDS length == 72 5: Section == 3 6: Source of Grid Definition (see code table 3.0) == 0 (table 3.0: Specified in Code table 3.1) 7: Number of data points == 72960 11: Number of octects for optional list of numbers == 0 12: Interpretation of list of numbers == 0 (table 3.11: There is no appended list) 13: Grid Definition Template Number == 40 15: Shape of the Earth == 6 (table 3.2: Earth assumed spherical with radius of 6 371 229.0 m) 16: Scale factor of radius of spherical Earth == 0 17: Scaled value of radius of spherical Earth == 0 21: Scale factor of major axis of oblate spheroid Earth == 0 22: Scaled value of major axis of oblate spheroid Earth == 0 26: Scale factor of minor axis of oblate spheroid Earth == 0 27: Scaled value of minor axis of oblate spheroid Earth == 0 31: Ni - number of points along a parallel == 384 35: Nj - number of points along a meridian == 190 39: Basic angle of the initial production domain == 0 43: Subdivisions of basic angle used to define extreme longitudes and latitudes, and direction increments == 0 47: La1 - latitude of first grid point == 89277000 51: Lo1 - longitude of first grid point == 0 55: Resolution and component flags == 48 56: La2 - latitude of last grid point == -89277000 60: Lo2 - longitude of last grid point == 359062000 64: Di - i direction increment == 938000 68: N - number of parallels between a pole and the Equator == 95 72: Scanning mode == 0 73: List of number of points along each meridian or parallel. == -9999 Grib2ProductDefinitionSection Interval = (2012-08-27T00:00:00.000Z,2012-09-27T00:00:00.000Z) (4.8) Product definition template 4.8 - average, accumulation and/or extreme values or other statistically-processed values at a horizontal level or in a horizontal layer in a continuous or non-continuous time interval 1: PDS length == 58 5: Section == 4 6: Number of coordinates values after Template == 0 8: Product Definition Template Number == 8 10: Parameter category == 2 11: Parameter number == 17 12: Type of generating process == 2 (table 4.3: Forecast) 13: Background generating process identifier (defined by originating centre) == 0 (table ProcessId: Table ProcessId code 0 not found) 14: Analysis or forecast generating process identifier (defined by originating centre) == 98 (table ProcessId: Table ProcessId code 98 not found) 15: Hours after reference time of data cutoff == 0 17: Minutes after reference time of data cutoff == 0 18: Indicator of unit of time range == 3 (table 4.4: Month) 19: Forecast time in units defined by octet 18 == 8 23: Type of first fixed surface == 1 (table 4.5: Ground or water surface) 24: Scale factor of first fixed surface == 0 25: Scaled value of first fixed surface == 0 29: Type of second fixed surface == 255 (table 4.5: Missing) 30: Scale factor of second fixed surface == 0 31: Scaled value of second fixed surface == 0 35: Year - time of end of overall time interval == 2012 37: Month - time of end of overall time interval == 9 38: Day - time of end of overall time interval == 27 39: Hour - time of end of overall time interval == 0 40: Minute - time of end of overall time interval == 0 41: Second - time of end of overall time interval == 0 42: n - number of time range specifications describing the time intervals used to calculate the statistically-processed field == 1 43: Total number of data values missing in statistical process == 0 47: Statistical process used to calculate the processed field from the field at each time increment during the time range == 0 (table 4.10: Average) 48: Type of time increment between successive fields used in the statistical processing == 2 (table 4.11: Successive times processed have same start time of forecast, forecast time is incremented) 49: Indicator of unit of time for time range over which statistical processing is done == 3 (table 4.4: Month) 50: Length of the time range over which statistical processing is done, in units defined by the previous octet == 1 54: Indicator of unit of time for the increment between the successive fields used == 255 (table 4.4: Missing) 55: Time increment between successive fields, in units defined by the previous octet == 0 59: As octets 47 to 58, next innermost step of processing == -9999 71: Additional time range specifications, included in accordance with the value of n. Contents as octets 47 to 58, repeated as necessary == -9999 Grib2SectionDataRepresentation Template = 40 (Grid point data - JPEG 2000 code stream format) NPoints = 72960 Grib2SectionData Starting Pos = 196 Data Length = 64170 On 9/28/2012 11:45 AM, Steve Ansari wrote: Hi Jack, |