PowerPointPrsentation

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The CERA-2 TaxonomiesTOPIC and LOCATION
Frank ToussaintMax-Planck-Institut für
MeteorologieHamburg
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Contexts

• The importance of the context
• a falling apple gives us different ideas in
  different contexts
• the head of some person changes the context and
  the meanings ...
• the heads of the users change the context and
  the meanings ...

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Ontological Dynamics

• What changes undergoes an Ontology ?
• NEW . . .
• semantics
• meta data structures. . . BY . . .
• new persons (working group / group leader)
• new persons (new collaborations)
• new data types
• new research fields
• any new idea !
• NO ONTOLOGY IS STABLE IN SPACETIME

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Care about the Ontology
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Ontologies' Requirements

• What are the Requirements of a CERA Ontology?
• contents satisying the institutes' needs,
  extensible
• structure flexible, changeable, good DB
  performance
• structure and contents understandable for the
  user --- KEEP THINGS SIMPLE ---
• Do not try to map the colloquial language of
  your colleagues into your DB table structure!

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GCMD Taxonomy

• Hierarchical levels of different dynamics
• high level low dynamics low level high
  dynamics
• Global Change Master Directory (GCMD)provides us
  with ...
• hierarchical ... Þ ... for efficiency
• fairly stable ... Þ mainly new topics added
• widly used ... Þ for collaborations
• earth science contents ... Þ social sciences
  not included
• for the high levels ... Þ 3 levels
  populatedof our ontology (taxonomy) .

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Ontololgies in CERA

• Which Ontologies does CERA-2 have ?
• table TOPIC CERA's ontology of
  parameters, quantities
• table LOCATION CERA's ontology of
  countries, regions
• table GENERAL_KEY simple linear keyword list
• no thesauri, i.e., no synonyms

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TOPIC LOCATION Structure

• Structure of tables TOPIC and LOCATION
• hierarchical (taxonomies)
• recursive
• additionally
• some common SQL tools
• views for each hierarchy level
• equivalent to tables for each level and one
  view TOPIC, merging the tables

TOPIC TOPIC_ID NUM TOPIC_NAME CHAR TOPIC_ACR
ONYM CHAR TOPIC_DESCR CHAR TOPIC_POINTER NUM TOPIC
_LEVEL NUM
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G C M D

• The Global Change Master Directory (GCMD)
• ... offers 10 different keyword lists
  athttp//gcmd.nasa.gov/Resources/valids/index.htm
  l
• CERA takes 1244 Science Keywords table
  TOPIC 356 Locations (countries, continents,
  etc.) table LOCATION
• not in CERA Source/Sensor keyword lists and
  other

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TOPIC LOCATION Contents

• Contents of table TOPIC
• first 3-4 levels of GCMD parameter valids
• lower levels institute specific
• at PIK social science keyword list in
  addition
• Contents of table LOCATION
• GCMD location valids on levels 1-3
• lower levels institute specific

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Extension of CERA Topic Parameter CODE

• Tables CODE and ALIAS as local extensions
• climate models widely use code numbers (0..255)
  for physical parameters mapping TOPIC vs. CODE

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Extension of CERA TopicNet Structure

• From the Hierarchy to the Netreferencing from
  Topic to Topic
• additional relation TOPIC_CONNECT

TOPIC TOPIC_ID NUM TOPIC_NAME CHAR
TOPIC_ACRONYM CHAR TOPIC_DESCR CHAR
TOPIC_POINTER NUM TOPIC_LEVEL NUM
TOPIC_CONNECT TOPIC1_ID NUM TOPIC2_ID NUM
DESCR CHAR
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Summary

• SummaryStructure
• taxonomies are intuitive, easy to handle
• net structures and thesauri need much more care,
  but give easier access for the user
• Content
• GCMD is a good basis for an earth system
  taxonomy (compatibility for meta data
  exchange, stability, elaborated in its branch)
• ... has to be extended