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On Tue, 5 Dec 2006, HansPeter Roesli wrote: > Hi Rob and Don > > Sorry for my earlier email. There must have gone something wrong here. > Now you should get my response loud and clear. > > I am sorry to have confused you with my naive cropping of the grb files > with a word processor. Obviously the second set was okay. I just checked > them with IDV and the outcome looks quite reasonable(even with the > correct table being applied as hinted in Simon's email). In particular > Simon and me looked at the CLAI product which stand for CLoud Analysis > Image. The content reflects its intent, but geographical-wise the image > is flipped vertically (W<->E) and does not project on the selected HP, I fixed this yesterday. the scanning mode process was not invoked on the image, thus it was flipped. the projection part still needs fixed, John is out of town for a couple of weeks and he's the one who works on that code. robb... > projection (it depicts just a disk). May I assume that this still is > work in progress? > > Enjoy the snow (still no traces over here!), HP > > > Robb Kambic wrote: > > On Fri, 17 Nov 2006, Simon Elliott wrote: > > > >> Hi all, > >> > >> WHen I look at the file attached by HansPeter (HP GRIB.001) it looks > >> fine to me. The GRIB part can be found after the first 899 bytes. The > >> remaining part (GRIB to 7777, inclusive) is 803521 bytes long, which is > >> as indicated in octets 9 to 16 of Section 0. > > > > Hi Simon, > > > > First, let me thank you for your time. There's no problem decoding the > > (HP GRIB.001) file with my decoder that is 803521 bytes long. The file > > that was originally sent was not 803521 bytes, but 804420 bytes long. > > When the file was edited, the editor inserted extra bytes into the > > file. This caused the decoder to get confused and it could not extract the > > data. As you know the GRIB format is very rigid, so one extra byte can > > change the course of action of the decoder. There was some confusion about > > the acquistion of the file and I was unawared that the file was edited, so > > I assumed that there was some EUMETSAT changes in the file. Since the > > EUMETSAT datasets are very important to our community, I made an > > effort to decode the file with the extra bytes. When debugging, I added > > some code to accomodate the extra bytes but the decoder still got confused > > about the data extraction process. When I got an uncorrupted file, my > > decoder work without a problem. > > > > > > There is one question, the level information is using level 0, is that > > correct? > > > > First Surface Type : 0 Reserved > > First Surface value : 0.0 > > Second Surface Type : 0 Reserved > > Second Surface value : 0.0 > > > > I have never run across a model using these values before, can you give > > some insight? > > > > Thanks, > > Robb... > > > > Here's a dump of the Header information of the file, is there an problem > > here? > > > > -------------------------------------------------------------------- > > Header : GRIB2 > > Discipline : 3 Space products > > GRIB Edition : 2 > > GRIB length : 803521 > > Originating Center : 254 EUMETSAT Operation Centre > > Originating Sub-Center : 0 > > Significance of Reference Time : 3 Observation time > > Reference Time : 2006-01-02T11:45:00Z > > Product Status : 1 Operational test products > > Product Type : 6 Processed satellite observations > > Number of data points : 1530169 > > Grid Name : 90 Space View Perspective or Orthographic > > Grid Shape: 3 Earth oblate spheroid with axes > > specified by > > producer > > Oblate earth major axis: 6378.14 > > Oblate earth minor axis: 6356.7554 > > Number of points along parallel: 1237 > > Number of points along meridian: 1237 > > Latitude of sub-satellite point: 0.0 > > Longitude of sub-satellite pt: 0.0 > > Resolution & Component flags : 0 > > i direction increment : 1188.0 > > j direction increment : 1187.0 > > X-coordinate of sub-satellite : 619.0 > > Y-coordinate of sub-satellite : 619.0 > > Scanning mode : 192 > > Basic angle : 0 > > Altitude of the camera : 7.4533146E8 > > X-coordinate of origin : 0.0 > > Y-coordinate of origin : 0.0 > > Product Definition : 30 Satellite product > > Parameter Category : 1 Quantitative_products > > Parameter Name : 2 Cloud_Top_Height > > Parameter Units : m > > Generating Process Type : 8 Observation > > ForecastTime : 0 > > First Surface Type : 0 Reserved > > First Surface value : 0.0 > > Second Surface Type : 0 Reserved > > Second Surface value : 0.0 > > -------------------------------------------------------------------- > > Header : GRIB2 > > Discipline : 3 Space products > > GRIB Edition : 2 > > GRIB length : 803521 > > Originating Center : 254 EUMETSAT Operation Centre > > Originating Sub-Center : 0 > > Significance of Reference Time : 3 Observation time > > Reference Time : 2006-01-02T11:45:00Z > > Product Status : 1 Operational test products > > Product Type : 6 Processed satellite observations > > Number of data points : 1530169 > > Grid Name : 90 Space View Perspective or Orthographic > > Grid Shape: 3 Earth oblate spheroid with axes > > specified by > > producer > > Oblate earth major axis: 6378.14 > > Oblate earth minor axis: 6356.7554 > > Number of points along parallel: 1237 > > Number of points along meridian: 1237 > > Latitude of sub-satellite point: 0.0 > > Longitude of sub-satellite pt: 0.0 > > Resolution & Component flags : 0 > > i direction increment : 1188.0 > > j direction increment : 1187.0 > > X-coordinate of sub-satellite : 619.0 > > Y-coordinate of sub-satellite : 619.0 > > Scanning mode : 192 > > Basic angle : 0 > > Altitude of the camera : 7.4533146E8 > > X-coordinate of origin : 0.0 > > Y-coordinate of origin : 0.0 > > Product Definition : 30 Satellite product > > Parameter Category : 1 Quantitative_products > > Parameter Name : 3 Cloud_Top_Height_Quality_Indicator > > Parameter Units : > > Generating Process Type : 8 Observation > > ForecastTime : 0 > > First Surface Type : 0 Reserved > > First Surface value : 0.0 > > Second Surface Type : 0 Reserved > > Second Surface value : 0.0 > > > > > >> The users who have been looking at the data have received it via > >> EUMETCast, and also via ftp from me. Maybe some got data from the > >> UMARF, but I don't get to hear about them. I think that as long as a > >> decoder looks through a file and pulls out GRIB (or BUFR) messages > >> before decoding, then it doesn't matter how they are packed into files. > >> > >> Simon > >> > >> Dr Simon Elliott > >> Product Implementation Manager > >> Operations Department > >> EUMETSAT > >> tel: (+49) 6151 807385 > >> fax: (+49) 6151 807304 > >> > >> > >>>>> HansPeter Roesli <address@hidden> 17/11/2006 09:37:39 >>> > >> Hi Simon and Robb > >> > >> After having read Simon's first reaction I got a slight doubt about > >> what > >> I did. Actually, the file Robb is mentioning is not the original file > >> as > >> retrieved from EUMETSAT's archive U-MARF (you find that now attached). > >> > >> The original file is refused right away by IDV. Therefore, I chopped > >> off > >> the ASCII header with an editor and that is the file Robb is using. > >> Might be that my editor changed things inside the GRIB-7777 clause when > >> > >> I was pruning the file. So, Robb please check again with the attached > >> file which has leading bytes (EUMETSAT's ASCII header) before the bytes > >> > >> spelling GRIB. > >> > >> Also, Simon, when you are saying that other centres are not having > >> decoding problems, are they getting the data from EUMETCast/GTS or from > >> > >> U-MARF. I am using exclusively U-MARF retrieved products. Might be > >> there > >> is a problem with archived data? > >> > >> HP > >> > >> Simon Elliott wrote: > >>> Hello Robb, > >>> > >>> HansPeter has asked me to contact you directly as I am responsible > >> for > >>> the generation of the GRIB2 data from EUMETSAT. I am interested to > >> read > >>> about the extra characters you found inside hte message. As I'm > >> sure > >>> you can imagine, we have exchanged the data with other centres using > >>> different software and they have yet to spot this problem. > >>> > >>> I suspect either (i) the GRIB data have been chopped up for > >>> dissemination and not been properly re-assembled into the original > >>> message, or (ii) at some stage the data have been transferred with > >> ASCII > >>> FTP ... this happens quite often. > >>> > >>> If you could send me the file you mention, or make it availabel for > >> FTP > >>> transfer, I would be happy to investigate. > >>> > >>> Regards, > >>> > >>> Simon > >>> > >>> Dr Simon Elliott > >>> Product Implementation Manager > >>> Operations Department > >>> EUMETSAT > >>> tel: (+49) 6151 807385 > >>> fax: (+49) 6151 807304 > >>> > >>> > >>>>>> Robb Kambic <address@hidden> 14/11/2006 22:50:35 >>> > >>> HansPeter, > >>> > >>> i investigated the problem with Grib2 decoder not being able to > >> decode > >>> the > >>> space products, ie > >>> MSG1-SEVI-MSGCLTH-0100-0100-20060102114500.000000000Z-12774_GRIB.grb > >>> > >>> at first it seemed to be a table problem but that's not the case. > >>> the products do not follow the standard Grib encoding, there are > >>> extra characters inserted between the Grib format sections that's > >> the > >>> problem. i had the same problem with the Grib 1 format from some of > >>> the > >>> european centers. i tried the Grib 1 format fix then the decoder was > >>> able to > >>> decode the first 5 sections of the product but then the 6th section > >>> didn't begin at the correct position. at this time, i could some > >> help > >>> in > >>> finding out the format of the product, so i can modify the decoder. > >> i > >>> did a > >>> quick look for the product information but was unable to get the > >>> information > >>> i needed. Could you contact the data provider to get the structure > >> of > >>> the > >>> product? or get a contact person for this product? > >>> > >>> thanks, > >>> robb... > >>> > >>> > >>> > >>> > >>> > > > > =============================================================================== > > Robb Kambic Unidata Program Center > > Software Engineer III Univ. Corp for Atmospheric > > Research > > address@hidden WWW: http://www.unidata.ucar.edu/ > > =============================================================================== > > > > > > =============================================================================== Robb Kambic Unidata Program Center Software Engineer III Univ. Corp for Atmospheric Research address@hidden WWW: http://www.unidata.ucar.edu/ ===============================================================================