A SEDRIS Representation of Atmospheric Data

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A SEDRIS Representation of Atmospheric Data
Louis A. Hembree Naval Research Laboratory 7
Grace Hopper Ave. Monterey, CA (831)
656-4787 hembree_at_nrlmry.navy.mil
Rob Cox SAIC 12479 Research Parkway Suite
600 Orlando, FL 32826 407-207-3609 ROBERT.M.COX_at_cp
mx.saic.com
Valerie Pastor SAIC 550 Camino El Estero Suite
205 Monterey, CA 93940 831-649-5242 valerie.l.pas
tor_at_cpmx.saic.com
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TOPICS

• SEDRIS TECHNOLGY COMPONENTS
• ATMOSPHERIC GRID MAPPING
• ATMOSPHERIC OBSERVATION MAPPING

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SEDRIS Technology Components

• Data Representation Model (DRM)
• Provides syntax and structural semantics for
  databases
• Environmental Data Coding Standard (EDCS)
• Provides object/thing level semantics
• Spatial Reference Model (SRM)
• Robust description of the coordinate systems,
  combined with an accurate, efficient, fast
  software implementation
• SEDRIS Transmittal Format (STF)
• Platform independent storage and transmission of
  databases
• Application Programmers Interface (API)
• Allows ease of access
• Lowers the barrier-to-entry in software
  development

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Gridded Data Mapping
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Relevant Parts of SEDRIS 3.0.3 DRM
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Atmospheric Gridded Forecast
METOC forecasts typically start at some base time
(analysis time) and forecast fields are created
at some interval (6 hrs) and extend for some
period (48 hours). The forecasts are run every
12 hours typically. Therefore, there can be
several overlapping forecasts available at a
given time.
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High Level Mapping
Aggregation
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Top Level Nested Time Related Geometry
Indicates significance of time
Environmental Root
Classes associated with the top level Time
Related Geometry
Classification_Data
tag EDCS_CC_BASE_FORECAST_TIME
Geometry_Time_ Constraints_Data
Geometry_Time_ Constraints_Data
hour 00 minutes 00 seconds 00
hour 06 minutes 00 seconds 00
Time_Related_Geometry
Times (base forecast times) for children of top
level Time Related Geometry
Lower level Time Related Geometry see next slide
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Locating Property Grid
From parent Time Related Geometry
Property_Grid_Hook_Point
Property_Grid_Hook_Point
GD_Location_3D
geodetic_latitude 29 geodetic_longitude
-160 elevation 0
Location of Property Grid Hook Point in specified
SRF
Grid location corresponding to hook point
Property_Grid
Property_Grid
data_table_type EDCS_CC_ATMOSPHERIC_ANALYSIS_VOL
UME spatial_axes_count 2 location_index
(0,0,0) srf_parms.is_2D SE_FALSE srf_parms.u.par
ms_3d.u.gd_parameters.horizontal_datum
SE_SPHERICAL_COA_HDATUM srf_parms.u.parms_3d.u
.gd_parameters.vertical_datum SE_SPHERICAL_CO
A_VDATUM srf_parms.u.parms_3d.u.gd_parameters.elev
ation_units
SE_UNITS_METERS
data_present SE_TRUE
data_table_type EDCS_CC_ATMOSPHERIC_
ANALYSIS_EARTH_SURFACE spatial_axes_count
2 location_index (0,0,0) srf_parms.is_2D
SE_FALSE srf_parms.u.parms_3d.u.gd_parameters.hori
zontal_datum SE_SPHERICAL_COA_HDATUM srf_parm
s.u.parms_3d.u.gd_parameters.vertical_datum
SE_SPHERICAL_COA_VDATUM srf_parms.u.parms_3d.u
.gd_parameters.elevation_units

SE_UNITS_METERS data_present SE_TRUE
?
?
Axes
Table_Property_Descriptions
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Specifying Contents of Property Grid
From parent Property Grid
?
Table_Property_Description
attribute_code EDCS_AC_AIR_TEMPERATURE value_uni
t SE_UNITS_PASCAL value_type SE_DT_FLOAT_32
Specifies contents of Property Grid
Table_Property_Description
Contains characteristics of the parameter
specified in the Table Property Description. Can
also include missing value flag among others.
attribute_code EDCS_AC_WIND_SPEED_U_COMPO
NENT value_unit SE_UNITS_METERS_PER_SECOND value
_type SE_DT_FLOAT_32
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Axes for Atmospheric Volume Grid
Axes classes are ordered with the spatial axes
coming first. The parent Property Grid had
spatial_axes_count 2, therefore the regular axes
are the spatial axes as they are the first two
axes.
From parent Property Grid
?
Regular_Axis
axis_type EDCS_AC_SPATIAL_GEODETIC_LATITUDE ax
is_unit SE_UNITS_DEGREES_ARC axis_value_count
231 interpolation_type SE_NOT_SUPPLIED first_
value 0. spacing .20 values_are_ints
SE_FALSE type_of_spacing SE_LINEAR_SPACING axis_
alignment SE_ALIGN_LOWER
Not a spatial axis.
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3
Regular_Axis
axis_type EDCS_AC_SPATIAL_GEODETIC_LONGITUDE a
xis_unit SE_UNITS_DEGREES_ARC axis_value_count
156 interpolation_type SE_NOT_SUPPLIED first
_value 0. spacing .20 values_are_ints
SE_FALSE type_of_spacing SE_LINEAR_SPACING axis_
alignment SE_ALIGN_LOWER
2
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GRIB Conversion Software
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Gridded Binary (GRIB) Format

• Converts gridded data from a set of GRIb messages
  to a STF
• GRIB is a World Meteorological Organization
  standard format for gridded data
• Binary format
• One level, time, parameter combination per
  message
• A set of GRIB messages contains no information
  about the relationship between the messages

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GRIB to STF Conversion Software

• Reads and analyzes the GRIB messages in a data
  set
• Maps the information to the gridded
  representation previously presented
• STF size is approximately the same size of
  smaller than the aggregate size of the GRIB files
• Conversion time is of the order of minutes
• Composed of two components
• sedcfg analyzes the GRIb files and produces the
  mapping
• grib2stf actually perform the conversion and
  produces the STF

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The sedcfg component

• Uses several external files in mapping process
• file used to map GRIB parameter IDs to EDCS
  Attribute Codes
• file used to map GRIB level IDs to EDCS
• file used to specify the appropriate horizontal
  and vertical datums
• GRIB tables (used by GRIB decoder)
• Metadata file information not included in GRIB
  file
• Produces a mapping file used by grib2stf

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The grib2stf Component

• Reads GRIB messages and mapping file and produces
  STF.
• Requires the following external files
• GRIB tables used by GRIB decoder same as used
  by sedcfg
• Mapping file produced by sedcfg
• Mapping of enumerations used in GRIB messages to
  EDCS enumerations. Required only if data set
  includes enumerations.

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Plot of Atmospheric STF Data
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Point DataSurface Observation Profiles Mappings
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Point Data
Data is located at arbitrary locations Example
Surface observations. Observations are assigned
to a specific hour, but can actually occur some
delta about the hour.
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Surface Observations
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Profiles --Radiosonde Data
Profile data located at arbitrary
locations. Same type of time information as for
surface observations. Radiosonde profiles also
contain surface observation data.
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Radiosonde

• Basic mapping same as for surface observations
• Classification data Radiosonde

Property_Value (station ID)
Location_3D
Point
Property_Value (station pressure)
Classes added to hold profile data
Property_Table (atmospheric profile)
Property_Value (station altitude)
Add Data_Table association to Point
One axis Atmospheric pressure levels
Table_Property_Description (air temperature)
Irregular_Axis (atmospheric pressure)
Table_Property_Description (wind speed)
Table_Property_Description (wind direction)
Table_Property_Description class used to specify
the parameters measured at each level of profile.
Table_Property_Description (relative humidity)
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Surface Obs Radiosondes
Transmittal_Root
Metadata
Environmental_Root
Transmittal_Summary
Spatial_Domain
Time_Related_Geometry
Note The order of these could be reversed.
Classification_Related_Geometry
Indicates type of data
Geometry_Classification_Data
Surface_Obs
Geometry_Classification_Data
Radiosonde
Union_of_Primitive_Geometry
Union_of_Primitive_Geometry
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Summary

• A detailed mapping for atmospheric gridded data
  was presented
• GRIB to STF Conversion program developed
• Surface observations and atmospheric profile
  mappings also presented
• SEDRIS can be used to represent atmospheric data
  and produces a compact representation