Conditions météorologiques et leur mesure: précipitations, température, évapotranspiration, vitesse et direction du vent.
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Historical versions of the theme definition are found in the INSPIRE IMS and Scoping papers:
• Weather conditions and their measurements; precipitation, temperature, evapotranspiration, wind. (INSPIRE IMS, 2003)
• Weather conditions and their measurements; precipitation, temperature, evapotranspiration, wind speed and direction (INSPIRE Scoping, 2004) In order to place into context the range of spatial data types relevant to this theme, we consider the typical 'forecast cycle' of a national meteorological service (NMS).
(a) collect meteorological observations over (say) a six-hour interval,
(b) 'assimilate' these into a numerical model to produce an estimate of the current atmospheric state,
(c) use this analysis as the initial condition for a model forecast run forward in time (typically out to several days).
Four broad types of data are involved at different phases of the cycle:
1. Observations: around 11000 surface stations globally make up the Global Observing System, reporting such atmospheric parameters as weather, cloud, temperature, humidity, wind, visibility, pressure. A subset of these stations make 'climate observations' which include daily temperature minimum and maximum, sunshine hours, rainfall amount etc. In addition, around 1000 'upper-air' stations make radiosonde (free-rising balloon) observations of pressure, wind, temperature and humidity. Voluntary observing ship and drifting buoys make marine observations including sea surface temperature, and wave height and period. Several hundred thousand reports per day of pressure, winds and temperature are made from aircraft observations.
2. Synoptic analysis: Gridded wind, temperature, humidity, geopotential height, precipitation, etc. Also, 'sensible weather' elements (fronts, cloud, thunderstorm activity etc) will be analysed.
3. Forecasts: Numerous forecast products are produced operationally. A conventional weather forecast contains similar elements to the synoptic analysis.
4. Climatological data: Long-term time-series' of data (either observations or analyses) may be analysed statistically to create climatologies (e.g. 20th century decadal averages, seasonal/monthly minimum or maximum, etc.). There is considerable overlap and ambiguity between the themes 'Atmospheric conditions' and 'Meteorological geographical features' – e.g. weather conditions ('Meteorological geographical features') including precipitation, temperature, wind etc. are precisely components of the atmospheric state ('Atmospheric conditions').
Numerous suggestions have been made by stakeholders to resolve this ambiguity. They include:
• merging the themes (it is impossible to amend the Directive, but it would be sensible to consider the themes jointly during data specification development)
• distinguishing 'field-based data' (Atmospheric conditions) from 'point-based data' (Meteorological geographical features)
• distinguishing 'time-series & near-real-time data' (Atmospheric conditions) from 'gridded climate data' (Meteorological geographical features)
• distinguishing 'climate data' (Atmospheric conditions) from 'observations and forecasts' (Meteorological geographical features).
To resolve the ambiguity between themes, we consider the multi-level approach to data needs assessment applied in the INSPIRE 'Environmental Thematic User Needs Position Paper' (2002). Data at local or regional level are often needed for management and policy implementation, while lower resolution ('smaller scale') data are often required for reporting and policy development/evaluation. The latter includes summaries and integrated data products.
The scope of 'Meteorological geographical features' thematic data should be limited to local-level high-resolution (weather-related) data, typically observations.
• This includes synoptic observations from stations making up the WMO RA VI (European) Regional Basic Synoptic Network. The WMO operates a dedicated network (the Global Telecommunications System) to distribute observations and data products. Data exchange is governed by WMO Resolution 40, which provides for free and unrestricted exchange of observational data 'essential' for forecast activities. 'Additional' nominated data and products may be provided with charge, while all data must be supplied free of charge (excluding costs of reproduction and delivery) for research and education. The ECOMET Catalogue (http://www.meteo.oma.be/ECOMET/Categories of data and products.htm) provides a 'one-stop shop' index of both 'essential' and chargeable data and product offerings from European NMSs. A similar catalogue is available for the European Centre for Medium-range Weather Forecasting (ECMWF) (http://www.ecmwf.int/products/catalogue/).