NCAR Command Language (NCL) is an interpreted language designed for sceintific data analysis and visualization with high quality graphics, espeially for atmospherice scince. NCL has been support NetCDF 3/4, GRIB 1/2, HDF-SDS, HDF_EOS, shapefiles, binary, and ASCII files for years. Now HDF-EOS5 is the released version, and HDF5 in beta-test stage. Now NCL team are developing NCL to write HDF5 files, and to read HDF-EOS5 data with OPeNDAP. NCL team will share with people their experience to visualize and analyze HDF-EOS5 and HDF5 data.

1. Visualizing and Analyzing of
HDF-EOS and HDF data with NCL
Wei Huang, Dave Brown, Mary Haley,
Rick Brownrigg
CISL/NCAR
Dennis Shea, Adam Philips
CGD/NCAR
huangwei@ucar.edu

2. What is NCL
◦ NCL stands for NCAR Command Language
 http://www.ncl.ucar.edu for more information
◦ NCL is developed at CISL/NCAR, for
scientific data analysis and visualization
◦ Free available as binaries, open source
◦ Supports NetCDF (3 and 4), GRIB (1 and 2),
HDF, HDF-EOS 2 and 5 (as Spring of 2010)
◦ Newly added HDF5 and OpenDap (in 2010)
◦ High quality graphics
◦ Lots of example scripts
02/17/14
CISL/NCAR

3. HDF-EOS5 Released April, 2010
HDF-EOS5
included NCL
◦ 5.2.0 released in April, 2010
◦ 5.2.1 released in July, 2010
HDF,
and HDF-EOS2/5 Examples
◦ http://www.ncl.ucar.edu/Applications/HDF.shtml
◦ Use “ncl_filedump” to check variables in HDF, and
HDF-EOS2/5 files
◦ Use “ncl_convert2nc” to convert HDF-EOS2/5 and
HDF files to NetCDF files
02/17/14
CISL/NCAR

4. HDF-EOS5 Sample
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CISL/NCAR

5. HDF-EOS5 Sample (continue)
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CISL/NCAR

6. HDF-EOS5 Sample (continue)
Reflectivity of the ground pixel
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CISL/NCAR

7. HDF5 in Beta Release
02/17/14
CISL/NCAR

8. Sample Script to Read HDF5

f = addfile(”./data/MOD13A2A.h5", "r”)
◦ printVarSummary(f)

grps = getfilegroups(f, "/", 0)
◦ print(grps)

grps2 = getfilegroups(f, "/MODIS_Grid_16DAY_1km_VI", 0)
◦ print(grps2)

v1 = f->1_km_16_days_red_reflectance
◦


printVarSummary(v1)
vn = grps2(0)+"/1 km 16 days blue reflectance”
v2 = f->$vn$
◦ printVarSummary(v2)
02/17/14
CISL/NCAR

9. Group in HDF5 and Sample Script

f = addfile(”./data/NISESSMI.h5", "r")
◦ print(f)


gn = "/Northern Hemisphere”
g1 = f=>$gn$
◦ print(g1)


g2n = "/Northern Hemisphere/Data Fields”
g2 = g1=>$g2n$
◦ print(g2)


vn = "/Northern Hemisphere/Data Fields/Age"
v1 = g1->$vn$
◦ printVarSummary(v1)

v2 = g2->$vn$
◦
printVarSummary(v2)
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CISL/NCAR

10. HDF5 Sample Plot
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CISL/NCAR

11. HDF5 Sample Plot (continue)
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CISL/NCAR

12. HDF5 Sample Plot (continue)
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CISL/NCAR

13. HDF5 Sample Plot (continue)
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CISL/NCAR

14. Read Compound data from HDF5
 fn
= "K1VHR_23SEP2008_2330_L02_SST.h5”
 f = addfile(fn, "r”)
◦ print(f)
 lon1d
= f->/SST/SST_Composite.Longitude
 lat1d = f->/SST/SST_Composite.Latitude
 sst1d = f->/SST/SST_Dataset.SST
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CISL/NCAR

15. Print-out





filename:
K1VHR_23SEP2008_2330_L02_SST
file global attributes:
dimensions:
DIM_000 = 36381
variables:

group </PRODUCT_INFORMATION>

group </PRODUCT_METADATA>

group </PRODUCT_METADATA/PRODUCT_DETAILS>

group </PRODUCT_METADATA/PROJECTION_PARAMETERS>

group </SST>

compound <SST_Composite> (Latitude, Longitude, SST) (DIM_000)

compound <SST_Dataset> (Latitude, Longitude, SST) (DIM_000)

group </SST/GP_PARAM_INFO>
02/17/14
CISL/NCAR

16. 02/17/14
CISL/NCAR

17. HDF-EOS5 OpenDap
Using
liboc-dap-0.0.2
In Alpha Version
02/17/14
CISL/NCAR

18. HDF-EOS5 OpenDap -- a sample script




url = "http://acdisc.gsfc.nasa.gov/opendap/HDFEOS5/Aura_OMI_Level3/OMAEROe.003/2010/"
filename = url + "OMI-Aura_L3-OMAEROe_2010m0712_v0032010m0714t203639.he5”
f = addfile(filename,"r”)
◦ print(f)
vis_aerosol = f->SingleScatteringAlbedoPassedThresholdMean
◦ printVarSummary(vis_aerosol)


lat = f->Latitude
◦ printVarSummary(lat)
lon = f->Longitude
◦ printVarSummary(lon)
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CISL/NCAR

19. HDF-EOS5 OpenDap –sample plot
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CISL/NCAR

20. Conclusion
HDF-EOS5
is already released
◦ 5.2.0 in April, 2010
◦ 5.2.1 in July, 2010
HDF5
will be released soon
◦ Being tested with lots of data
◦ In Beta Version
HDF-EOS5
OpenDap is on the way
◦ With limited test
◦ In Alpha Version
02/17/14
CISL/NCAR

21. Questions?
Thank You!
02/17/14
CISL/NCAR

22. Write HDF5 with NCL
Write
HDF5 with Options:
◦ Compression
 At File Level
 At Variable Level
◦ Chunking
 At File Level
 At Variable Level
02/17/14
CISL/NCAR

23. Sample Script to Write HDF5
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CISL/NCAR