Reflections on the theme of classifying, documenting
and exchanging meteorological data, and
some additional comments on agro meteorological and
biological data sets.
Tor Håkon Sivertsen The Norwegian Crop
Research Institute
The weather systems on the planet earth do not
respect the borders put up by the nations.
• The exchange of meteorological data sets connected to the man
made systems for making measurements and models for
predicting the global weather is a concern of international character.
I will look at a few related subjects:
• Classifying phenomena connected to weather and climate.
• Existing systems of exchanging meteorological data
• What challenges of exchanging data will appear in the future connected to real time exchange of data between monitoring systems and models.
• The place of agro meteorological and biological models in this.
• The different systems for making observations.
Classification of meteorological phenomena
and climate• Classification of clouds (Luke Howard)• Classification in synoptic meteorology• Classification of in cloud physics,
tropical meteorology, physical meteorology etc.
• Classification of climate (Wladimir Köppen in the years 1918-1936)
The idea of using the modern tool of object oriented analysis when constructing
classes of meteorological phenomena in numerical models of weather and
climate( COST718)The basic idea is that in each class or sub
class of a phenomenon quantitative parameters/ attributes is attached to the
phenomenon. Then we have a numerical sub model or a
numerical model.
The existing systems of exchanging meteorological data sets
in the frame of WMO( World Meteorological Organisation): CREX (Character form for the
Representation and EXchange of data)
BUFR (Binary Universal Form for Representation of meteorological
data).Gridded data sets, called GRIB
(‘GRIdded Binary’).
The CREX/BUFR system
A BUFR-message consist of six sections(of octets): ‘Indicator
section’ ‘Identification section’ ‘Optional section’ ‘Data description
section’ ‘Data section’ , ‘End section’ .
The metadata of the BUFR-system is contained in the sections 1,2 and 3.
The metadata is interpreted by several tables information about the ‘category’ of the data and the types
of quantitative information considered.
GRIB-systemA GRIB-record consists of six sections, ‘Indicator section’, ‘Product Definition Section (PDS)’ containing metadata on
the parameters considered, ‘Grid Description Section’ containing
information on the grid used (type projection of mapping used) etc., ‘Bit Map Section(BMS) –optional’ contains information of parameter fields not
defined in certain subsystems of the gridded model by a bit-map-
system,‘Binary Data Section (BDS)’ , ‘End section’ ‘7777’ (human readable
indication of the end of the record)
The metadata of the ‘GRIB’-system is mainly contained in section number ‘1’, and section number ‘2’ and the interpretation is given in
several tables. The ‘GRIB’-system is tailored for representation and
exchange of the content of numerical weather prediction models.
The metadata contained in the ‘BUFR’ and ‘GRIB’-systems is called
meteorological elements. According to ‘International
Meteorological Vocabulary’ a ‘meteorological element’ is defined
in the following manner:’Atmospheric variable which characterizes the state of the
weather at a specific place at a particular time (e.g. air
temperature, pressure, wind, humidity, thunderstorm and fog)’.
Attached to ‘BUFR’ and ‘GRIB’ there are several tables giving the
interpretation of the meteorological elements. This classification system consists of a mixture of phenomena
and parameters describing the phenomena, and the system is very
flexible and has great scope.But my message is: This meta data
part ought to be reconsidered according to the ideas put up above.
The term ‘parameter’ is often used to describe a quantitative property
of the atmosphere ( air pressure, air temperature, wind velocity, global
radiation etc.) The term ‘parameter’ is not
defined in The meteorological glossary , but the term
‘parametrization’ is defined in the following manner:
‘Approximate representation of subgrid-scale processes in a numerical model in terms of variables which are explicitly
calculated’.
The use of the term ‘parameterisation’ could be more
general. When a weather phenomenon is described by
attaching quantitative measurable attributes to it we call it ‘parameterisation’. The parameterisation of the
phenomena then has to be different on the different scales.
The work on quality and availability of data made in
COST718 ACTION• In agro meteorological contexts
the need of exchange of data often is for modelling purposes.
• Therefore the need for metadata and documentation is
connected to the modelling (crop growth as well as crop protection/ warning systems)
A Documentation System for Parameters
(a) Measured (b) In Models
• Name of the parameter
• Unit• Defintion• Method(s) for
measurement• Representativen
ess • CREX/BUFR
descriptors
• Name of the parameter
• Unit• Defintion• Representativeness
in model considered• Representativeness
of other models• CREX/BUFR
descriptors
I think this meta data discussion, and the discussion on exchange
of agro meteorological and biological data ought to be put in the frame set by the planning of a new COST action and the work in
the frame of work led by WMO and connected to weather
hazards, see THORPEX-project, A global atmospheric research
program.
A new COST action of agro meteorology probably will get the
name:’CLIMATE CHANGE AND IMPACT OF METEOROLOGICAL HAZARD ON AGRICULTURE’ .
In this connection I refer to the THORPEX-program of WMO , see session ‘NP 5.04
Weather hazards reduction(THORPEX)’ at the EGU-meeting in Vienna in April 2005.
What is probably possible to develop is a system for exchange of data and information in almost real
time between the observation systems on the ground (automated
stations, weather radar systems etc.) and the information from the
satellites and the different numerical weather prediction
systems running.
A question often raised to meteorologists is the following
question: Is it possible to replace the old ground based
meteorological stations with the measurements of the
meteorological parameters by remote sensing equipment like weather radars and satellites?
The work on ‘homogenisation’ of long data series of meteorological data is
connected to the observing systems. In studies on global change and climate change it is important to be able to refer to long homogenous series of
meteorological data.
My conclusion is very short: When looking at BUFR
and GRIB, what could be considered is making some sort of parallel work of
extending the biological and agro meteorological models to use the BUFR
and GRIB-protocols, but at the same time take a look at the metadata
systems of GRIB and BUFR first to see if the classification systems may be
constructed in a more logical way using methods from object oriented analysis of
the modern IT-world?
Thank you very much!
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