Hi, Matt!
Finally, I added the CALIPSO VFM NCL example here:
http://hdfeos.org/zoo/index_openLaRC_Examples.php#CALIPSO
It uses "dim_gbits" function that Mary suggested.
Regards,
-- Are your big (Earth) data in HDF(-EOS)? On Tue, Jul 23, 2013 at 10:57 PM, Matthew Fearon <Matthew.Fearon@dri.edu> wrote: > Hi Mary, > > Thanks for the examples you sent; "dim_gbits" and hdfeos example page. I'll > take a look. In the meantime, I uploaded an hdf Calipso VFM, Vertical > Feature Mask, to ftp.cgd.ucar.edu/incoming. The file name is: > > CAL_LID_L2_VFM-ValStage1-V3-02.2011-12-31T23-18-11ZD.hdf > > I'm trying to correctly unpack the variable 'Feature_Classification_Flags' > which should be a one digit value. A discussion of the bit arrangement can > be found here: > > http://www-calipso.larc.nasa.gov/resources/calipso_users_guide/data_summaries/vfm/index.php > > It would be great to add an example of this to the applications page. I > believe it would help many users in the future. > > thank you in advance, > Matt > > > ________________________________ > From: Mary Haley [haley@ucar.edu] > Sent: Tuesday, July 23, 2013 8:45 PM > To: Matthew Fearon > Cc: H. Joe Lee; ncl-talk@ucar.edu > > Subject: Re: reading raw calipso data in NCL > > Hi Matt (and Joe), > > I didn't see this message before I sent you the other response. > > I think you want to check out our "dim_gbits" function, which allows you to > extract bits from an NCL data variable. > > After reading the description below, maybe Joe will have a better idea of > how to extract the bits that you need. We might be able to add some examples > of this on our applications page. > > Please look at example "hdf4eos_5.ncl" at: > > http://www.ncl.ucar.edu/Applications/HDF.shtml > > This example shows how to extra the bits you want and generate a contour > plot. > > Here's the "dim_gbits" function documentation: > > http://www.ncl.ucar.edu/Document/Functions/Built-in/dim_gbits.shtml > > The dim_gbits function requires that you know how the bits are written. > > If you do an ncl_filedump on the HDF file, you should see a description of > how > the bits are laid out. The description looks something like this: > > % ncl_filedump MOD05_L2.A2002161.1830.004.2003221153410.hdf | less > > . . . > > byte Cloud_Mask_QA ( Cell_Along_Swath_1km_mod05, > Cell_Across_Swath_1km_mod05 ) > long_name : MODIS Cloud Mask, First Byte > unit : none > scale_factor : 1 > add_offset : 0 > Parameter_Type : MODIS Input > Cell_Along_Swath_Sampling : ( 1, 2030, 1 ) > Cell_Across_Swath_Sampling : ( 1, 1354, 1 ) > Geolocation_Pointer : External MODIS geolocation product > description : > > bit field Description Key > --------- ----------- --- > > 0 Cloud Mask Flag 0 = not determined > 1 = determined > > 1-2 Unobstructed FOV Quality Flag 00 = cloud > 01 = 66% prob. > clear > 10 = 95% prob. > clear > 11 = 99% prob. > clear > PROCESSING PATH FLAGS > --------------------- > 3 Day / Night Flag 0 = Night / 1 = Day > 4 Sunglint Flag 0 = Yes / 1 = No > 5 Snow / Ice Background Flag 0 = Yes / 1 = No > 6-7 Land / Water Flag 00=Water/01=Coastal > 10=Desert/11=Land > valid_range : ( 0, -1 ) > _FillValue : 0 > hdf_name : Cloud_Mask_QA > . . . > > > --Mary > > On Jul 23, 2013, at 9:10 PM, Matthew Fearon <Matthew.Fearon@dri.edu> wrote: > > Hi, Joe > Thanks for your reply. At this time, I'm most interested in Calipso Vertical > Feature Mask (VFM) and reading the associated variable > 'Feature_Classification_Flags' from the hdf file, eg., > CAL_LID_L2_VFM-ValStage1-V3-02.2011-12-31T23-18-11ZD.hdf . NCL reads this > variable as an unsigned short. However, in order to extract the correct > flag, which should be a single value, it appears the data need to be bit > interpreted. I'm not sure how to do this correctly in NCL. If you have any > luck unpacking and or plotting up the data in NCL, please let me know. Right > now, I'm trying to setup a temporary workaround with Matlab, via the code > released by NASA, to extract the data correctly -- not an ideal solution. > > thanks again, > Matt > > > ________________________________________ > From: H. Joe Lee [hyoklee@hdfgroup.org] > Sent: Tuesday, July 23, 2013 7:13 PM > To: Matthew Fearon > Subject: Re: reading raw calipso data in NCL > > Hi, Matt! > > I'm also interested in plotting HDF CALIPSO data and post it under > our website [1] but I'm wondering if you could provide the specific > NASA HDF product name (e.g., > CAL_IIR_L1-Prov-V1-11.2008-08-20T01-40-12ZD.hdf) that you're mostly > interested in. > > Thanks, > > > [1] http://hdfeos.org/zoo > -- > HDF: Software that Powers Science > > > On Mon, Jul 22, 2013 at 2:56 PM, Matthew Fearon <Matthew.Fearon@dri.edu> > wrote: > > Dear NCL users: > > Just curious if anyone has developed an NCL script to read raw Calipso data, > particularly vertical feature mask, in hdf format and make a plot? I see > there are a couple examples here: > http://www.ncl.ucar.edu/Applications/calipso.shtml , but they are using a > processed form of the data. Any assistance would be much appreciated. > > thanks, > Matt > > > _______________________________________________ > ncl-talk mailing list > List instructions, subscriber options, unsubscribe: > http://mailman.ucar.edu/mailman/listinfo/ncl-talk > > _______________________________________________ > ncl-talk mailing list > List instructions, subscriber options, unsubscribe: > http://mailman.ucar.edu/mailman/listinfo/ncl-talk > > _______________________________________________ ncl-talk mailing list List instructions, subscriber options, unsubscribe: http://mailman.ucar.edu/mailman/listinfo/ncl-talkReceived on Fri Feb 14 09:21:12 2014
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