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Hi Brian: After examining wgrib and gempak code, i think that my code is handling the nbit=0 case incorrectly. I am working on a fix. The fix will be in 4.5.3, and we may backport to 4.3.23, but im not sure. Thanks very much for reporting this problem. John > Hi Brian: > > This is what Ive found so far: > > file: https://aws1.pemdastech.com/tests/1420921000300.grib2 > > variable: CICEP_P0_L1_GLC0 aka "Categorical_Ice_Pellets_surface" > > record: only has 1 record, starts at pos 498311562 > > a dump of the drs( section 5 ) type 3 has these values (note that type 3 > inherits type 2 and type 0 values): > > Type0{referenceValue=0.0, binaryScaleFactor=0, decimalScaleFactor=0, > numberOfBits=0, originalType=0} > Type2{splittingMethod=1, missingValueManagement=0, primaryMissingValue=0.0, > secondaryMissingValue=0.0, numberOfGroups=0, referenceGroupWidths=4, > bitsGroupWidths=1, referenceGroupLength=1905141, lengthIncrement=1, > lengthLastGroup=-112001040, bitsScaledGroupLength=0} > Type3{orderSpatial=2, descriptorSpatial=1} > > my code has the logic that if numberOfGroups=0, then set all data equal to > missing value, in this case primaryMissingValue=0.0. This would explain why > NCL gives all zeroes. > > however, my code has the additional operation that if the data is missing, > set them to NaNs. So, it may be possible that "set to missing value" is the > way that GRIB-2 drs=3 sets a constant field. For sure, 0.0 is a valid value, > given that the unit description is "Categorical ice pellets (yes=1 no=0)" > > Another possibility is that numberOfGroups=0 should not mean "set to missing > values", but rather "this is a constant field, set to the reference value", > which is also 0.0. Im leaning towards this at the moment. > > I will investigate more tommorrow. > > John > > > > Thanks John, > > Here's a link to the HRRR forecast model output grib2 (500MB) file: > > https://aws1.pemdastech.com/tests/1420921000300.grib2 > > > > When I decode the file using NCL or wgrib2 I get "0" for the following > > fields (NCL names): > > CICEP_P0_L1_GLC0 > > CFRZR_P0_L1_GLC0 > > > > I also notice that I get the same issue for some lower sigma levels of > > cloud cover(NCL names): > > TCDC_P0_L100_GLC0 > > > > When I decode either of those with netCDF-Java, I get NaN. > > > > I didn't expect to have explicitly missing data for the HRRR model output > > and, using wgrib2, I looked at the grib2 file code table 5.5 to examine the > > missing value management and it returned a value indicating there were no > > explictly encoded missing values in the grib2 file. > > > > Thanks for your help! > > --- > > Brian Griffith, Ph.D. > > Senior Research Scientist & Site Lead > > PEMDAS Technologies & Innovations > > Phone: 828-398-8000 > > address@hidden<mailto:address@hidden> > > > > [cid:3FE592C7-C041-4CEB-8A81-855478D05A7E@hsd1.co.comcast.net.] > > CONFIDENTIALITY NOTICE: This email message and all attachments transmitted > > with it may contain legally privileged and confidential information > > intended solely for the use of the addressee. If the reader of this message > > is not the intended recipient, you are hereby notified that any reading, > > dissemination, distribution, copying, or other use of this message or its > > attachments is strictly prohibited. If you have received this message in > > error, please notify the sender immediately and delete this message from > > your system. Thank you. > > > > On Aug 20, 2014, at 1:56 PM, Unidata netCDF Java Support > > <address@hidden<mailto:address@hidden>> wrote: > > > > Hi Brian: > > > > Netcdf-Java typically sets missing values to NaNs, sounds like NCL does not > > . > > > > If you can send me a sample file (and as much detail as needed to > > reproduce) I can double check if anything more nefarious is going on. > > > > John > > > > Dear Sir, > > > > I am decoding NOAA ESRL HRRR model output in grib2 format and have > > encountered a conflict. > > > > I am decoding the categorical precipitation fields: > > CRAIN_P0_L1_GLC0 > > CFRZR_P0_L1_GLC0 > > CICEP_P0_L1_GLC0 > > CSNOW_P0_L1_GLC0 > > > > In particular, I am decoding CFRZR and CICEP and am getting an issue that > > when I use NCL to view the values of these parameters, I get values of "O". > > > > When I use netCDF-Java library 4.3.x or 4.5.2 (or NASA's Panoply tool which > > employs netCDF-Java libraries) to view the values of these parameters, I > > get values of "NaN". > > > > Can you explain what is happening here? Are the values in the grib2 file > > actually missing and being decoded in two different ways? How can I > > determine? > > > > Thanks, > > Brian > > --- > > Brian Griffith, Ph.D. > > Senior Research Scientist & Site Lead > > PEMDAS Technologies & Innovations > > Phone: 828-398-8000 > > address@hidden<mailto:address@hidden><mailto:address@hidden> > > > > [cid:3FE592C7-C041-4CEB-8A81-855478D05A7E@hsd1.co.comcast.net<mailto:address@hidden>.] > > CONFIDENTIALITY NOTICE: This email message and all attachments transmitted > > with it may contain legally privileged and confidential information > > intended solely for the use of the addressee. If the reader of this message > > is not the intended recipient, you are hereby notified that any reading, > > dissemination, distribution, copying, or other use of this message or its > > attachments is strictly prohibited. If you have received this message in > > error, please notify the sender immediately and delete this message from > > your system. Thank you. > > > > > > > > > > > > Ticket Details > > =================== > > Ticket ID: RGN-330338 > > Department: Support netCDF Java > > Priority: Normal > > Status: Open > > > > > > > > Ticket Details =================== Ticket ID: RGN-330338 Department: Support netCDF Java Priority: Normal Status: Open