Transcript Site Classification at the Norwegian Meteorological Institute (P3.8) Mareile Wolff, Nina Larsgård, Hildegunn Nygård, Ted Torfoss Status • Started working with the classification scheme.

Site Classification at the Norwegian
Meteorological Institute (P3.8)
Mareile Wolff, Nina Larsgård, Hildegunn Nygård, Ted Torfoss
Status
• Started working with the classification scheme as recommended from CIMO in 2010
• Translation of the document, both as a simplified and a complete version.
• Suitable tools for field measurements were considered and tested. For the present,
a laser distance meter with tilt function was chosen (though not perfect).
• Classification of manual precipitation stations started in 2012, ca. 20-25% of the
manual precipitation stations will be classified by the end of the year.
• That work will continue, eventually including the automated precipitation stations,
classification for wind, temperature & humidity, and radiation.
Benefits
• a more objective method to characterize the exposure of a site
• Improvement communication, both internal and external
• possible to follow development of a station
• easy to identify measures to improve the exposure of a site, also motivation
• a quality measure to differentiate between stations of the Norwegian
Meteorological Institute and stations of cooperation partners, see poster P3(6).
• also applicable for finding new places for station
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Challenges & Questions
• Finding good tools which are easy to use and accurate enough (Disto not perfect)
• Difficulties to judge if the natural relief is representative or not (”does a move of
the station by 500m change the class obtained?”)*
• How accurate is the description of natural shielding (”surrounded by obstacles of
uniform height, seen under an elevation angle between 14° to 26°”)* : Class jump
from 1 to 3 when surrounding trees higher than 26.5°
• The shading duration due to one obstacle depends on its width and its location.
That aspect is especially important for locations with high variation of sun
elevation and azimuth throughout a year (high latitude countries)
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Weighting of shadowing effect by itself?
Weighting of effect compared to distance of heat source/water extent
• It is recommended to determine the roughness index for 30°-sectors; how to
“average” the overall roughness length? 2 km? 300m?
• Simplification for the actual fieldwork is needed….Schemes, diagrams, Smartphone
apps, Excel sheets - What are you using?
• Complete classification of an existing network will take a couple of years if no
extra ”classification resources” are available
• Archiving and maintaining good and usable documentation of classification results
needs good planning and extra resources
• Finding the right balance between improving the scheme (i.e. sector classes for
wind) and overloading it
• Quantifying the effect of different classes – how large is the error (Japan Mariko
Kumamoto – more studies? planned studies?)
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