Transcript ESIP_Winter_2012_-_Wenli_Yang_

ArcGIS and NASA EOS Data
NASA GES DISC Team:
Aijun Chen, Wenli Yang, Peisheng Zhao, Long Pham,
Chris Lynnes, Gail Wade
NASA ESDIS:
Ross Bagwell, Francis Lindsay
ESIP Winter Meeting, January 4, 2012 - Washington DC
Introduction
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Most NASA EOS data products are archived in HDF-EOS
format.
Some data centers provides additional format support,
especially netCDF and GeoTiff (e.g., GES DISC’s OPeNDAP
and WCS services).
ArcGIS is one of the most frequently used GIS software
packaged in the GIS community.
Enabling direct data access from ArcGIS to NASA EOS data is
greatly desirable.
We’ll briefly introduce the status ArcGIS’ support for NASA
EOS data and demonstrate how NASA GES DISC’s
atmospheric data products, archived in HDF-EOS and
available as times-series in netCDF via WCS service, can be
visualized in ArcGIS.
ArcGIS Support for
HDF4-Based HDF-EOS Data
• Level 3 HDF4- based HDF-EOS are directly supported.
• Some minor issues:
• The ArcMap interface only allows to add a maximum of 29
fields, which may not adequate for some of our products, such as
the AIRS standard retrievals).
• The interface does not display the entire field name when a field
name is long (about 55 characters including array size, data type
info). This could be a problem for a field with a very long name.
• Once added into ArcMap, the field name is not carried into the
layer name (but with a field number), which makes it difficult to
know which layer is which field. But this could be manually
fixed, although tedious, because the field name can be viewed
from the layer properties.
ArcGIS Support for
Non-Grid EOS4 and Native HDF
• For other levels of HDF-EOS4 and native, data are treated as arrays
without geolocation information (some may cause software crash,
e.g., MLS-Aura_L2).
• Difficult to define axes for spatial dimensions, e.g., AIRS L1B
radiance array stored in Y/X/Channel array (i.e., BIP in
135x90x2378) is imported in ArcMap as having X-rows and Channel
columns (i.e., BSQ).
180x360
90x2378
ArcGIS Support for
HDF5-Based HDF-EOS
• For HDF5-based HDF-EOS, the “he5” file extension not included
default.
• They can be added by changing the settings (in ArcCatalog, add extension
name and description in ArcCatalog->Customize->ArcCatalogOptions->FileTypes->New
Type; in ArcMap, Customize->ArcMapOptions->File Formats and check the extension
name is associated to hdf5).
• However, the geolocation information is not correctly read and the
data is essentially treated as generic rasters.
Level 2 HDF Files
• Level 2 HDF-EOS, either 4- or 5-based, treated as native raster.
• AIRS L2 in HDF-EOS4:
AIRS.2011.10.17.098.L2.RetStd.v5.2.2.0.G11290152649.hdf
• OMI L2G in HDF-EOS5:
OMI-Aura_L2G-OMTO3G_2011m0815_v0032011m0816t062855.he5
CF-netCDF Data Format
• nc extension not included in ArcCatalog and can be added in the
same way as the hdf.
• In ArcMap, netCDF data must be imported using ArcToolBox>MultiDimensionTools.
• The nc extension not viewable in ArcMap even “All-supported
format” is selected in Customize->ArcMapOptions->Raster >FileFormats.
• CF-netCDF file can be imported as
• Raster
• Feature
• Table.
CF-netCDF Data Format
• When a CF-netCDF file is made to a raster, only one variable can be
selected in the interface but all fields are actually added.
• Use the netCDF menu in the
Properties to select the layer
to be shown.
• Don’t need to put in “Band”
information otherwise
nothing will be added. This
is perhaps due to not
allowing variable selection,
i.e., “bands” vary for
different variables.
• For OPeNDAP output,
renaming the _FillValue
attribute causes the value not
being recognized.
CF-netCDF as Raster: OMI Examples
• OMDOAO3e: Cloud Fraction (top), ColumnAmountO3 (bottom)
• Selected in the
Properties.
• Window to small to
show variable names.
CF-netCDF as Raster:
AIRS L3 Example
• The L3 AIRXRET file in “nc” format obtained from OPeNDAP
(AIRS.2011.01.01.L3.RetStd001.v5.2.2.0.G11003131820.hdf.nc)
• The file contains more than 230 fields.
• Selecting field to display in the “Layer Properties” window.
CF-netCDF as Raster:
AIRS L3 Example
TRMM L3 Precipitation Products
• Native HDF doesn’t work well, especially with x-dim before ydim.
• 3B42, 3B43
• 3A12, 3B31 SurfacePrecipitation and RainWater
• 3A11
• 3A25
• OPeNDAP (http://disc2.nascom.nasa.gov/opendap/TRMM_L3/) produces CFnetCDF for 3B42 and 3B43 (but not for many others, e.g.,
3B31, 3A11, 3A12, 3A25, 3A26).
CF-netCDF L2G AIRS Examples
• A L2G file obtained from OPeNDAP:
AIRS.2011.01.01.001.L2.RetStd.v5.2.2.0.G11003114443.hdf.nc
• Data cannot be not added using the netCDF to raster tool (due to
variable spacing in coordinate variables), but can be added as a feature layer.
CF-netCDF as Feature
• Multiple variables in a CF-netCDF file can be imported as multiattribute feature.
• When treated as feature, data do not need to be georectified and thus
the unequally-distanced
values can be imported,
such as the previously
mentioned OMI SO2
and L1/L2 files.
• The feature table could be
very large, even though the
“_FillValue” cells are
excluded.
• Feature points can be
interpolated to a raster array.
Interpolation
• The Natural Neighbor (left) and IDW (right)
interpolations, from the non-FillValues, for
the totO3std variable in the previous
L2G AIRS data (totO3).
Interpolation
• Showing both original point values and the interpolated rasters.
The original values are shown with proportional symbology.
CF-netCDF Summary
• Level 3 data works fine with the ArcToolBox.
• The minor issues when importing as a raster include not allowing
selecting variables (and bands) during importing and not displaying
long variable names.
• Some OPenDAP converted files (OMI SO2 and OMAEROe) cannot
be added as a raster layer, with an error message showing unequal
spacing dimension variables.
• A possible reason might be due to the rounding errors in dimension
variables, such as longitude values being (179.87502, 179.62498,
179.37502,…). However, the OMTO3e product has the same
longitude value and works fine.
• Multiple variables can be added as feature layers. Each pixel is
treated as a point feature.
• For Level 2, or any non-rectified models, use feature model instead
of raster model.
Air Quality for US Metropolitan Areas
• US Metropolitan areas and their 200km and 400km buffer zones
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The next steps would be to calculate statistics (min/max/mean/std/etc) for each zone and its
buffer areas, and create tables/chart for time series of NO2, CO, etc.
However, zonal analysis often hangs or errors for both AIRS and OMI data. AIRS data is in
HDF4-based HDF-EOS and OMI is in netCDF (error message was not informative, e.g.,
background geoprocessing encountered a serious error. Need more tests).
Global O3: 2011/07/01 to 2011/12/31
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Acquired from the GES DISC WCS server and imported into ArcGIS. Movie created using the
ArcGIS Time Slider tool.
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http://acdisc.sci.gsfc.nasa.gov/daacbin/wcsL3?service=WCS&version=1.0.0&request=GetCoverage&Coverage=OMTO3e:ColumnAmountO3&CRS=C
RS:84&BBOX=-179.5,-89.5,179.5,89.5&resx=1.0&resy=1.0&Time=2011-07-01/2011-12-31&format=netcdf
Global O3: 2011/07/01 to 2011/12/31
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Acquired from the GES DISC WCS server and imported into ArcGIS. Movie created using the
ArcGIS Time Slider tool.
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http://acdisc.sci.gsfc.nasa.gov/daacbin/wcsL3?service=WCS&version=1.0.0&request=GetCoverage&Coverage=OMTO3e:ColumnAmountO3&CRS=C
RS:84&BBOX=-179.5,-89.5,179.5,89.5&resx=1.0&resy=1.0&Time=2011-07-01/2011-12-31&format=netcdf
Questions?