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Homogenization in NorwayE. Lundstad, H. M. Gjelten, O.E. Tveito
Norwegian Meteorological Institute
Norwegian Meteorological Institute2
Outline
- Challenges
TEMPERATURE- Daily homogenization of temperature data from 5 cities in Norway.
PRECIPITATION- Homogeneity testing of precipitation data:
- Seasonal/monthly data. Have finished testing 1 of 13 regions.
- Objectives and Methods- Problems and Opportunities- Conclusion
Norwegian Meteorological Institute3
Challenges in Norway
Norwegian Meteorological Institute4
Norwegian Meteorological Institute5
Daily homogenization
Norwegian Meteorological Institute6
Norwegian Meteorological Institute7
Norwegian Meteorological Institute8
Norwegian Meteorological Institute9
Norwegian Meteorological Institute10
Norwegian Meteorological Institute12
Norwegian Meteorological Institute14
Reasons for breaks, from metadata (%)
Source: Ø. Nordli (1997) & L. Andresen (2011), MET NO
37
24
16
7
11
8
6
RelocationSolar radiation on screenInstrumental correctionScreenObserverObservation hourOthersUnknown
TEMPERATURE
Norwegian Meteorological Institute15
Temperature
Norwegian Meteorological Institute17
Precipitation
Norwegian Meteorological Institute18
Reasons for breaks, from metadata (%)
47
18
9
3
3
21
Relocation of gaugeChanged environmentInstallation of a windshieldNew observerOther known reasonsUnknown
Source: I. Hanssen-Bauer & E. Førland (1994), MET NO
PRECIPITATION
Norwegian Meteorological Institute19
Norwegian Meteorological Institute20
Færder 1977
Norwegian Meteorological Institute21
Challenges with the methods- especially precipitation
HOMER
Norwegian Meteorological Institute22
Precipitation
· Original goal: Homogenize monthly precipitation data.
· Current goal: Homogenize seasonal precipitation data. Monthly: too much noise?
· Software: Homer for quality control, MASH for homogenization.
· Recently finished the testing of the first of thirteen regions.
Norwegian Meteorological Institute23
The southeastern region· 94 stations, all with length > 70 years
Norwegian Meteorological Institute24
Norwegian Meteorological Institute25
Mash - Breaks
·1926: 1.02/ 1928: 1.02/ 1929: 1.01/ 1930: 1.03/ 1931: 0.97/ 1932: 0.96/ 1936: 0.94/ 1941: 1.04/ 1946: 1.04/
Norwegian Meteorological Institute27
The southeastern region, results
Norwegian Meteorological Institute28
Opportunities
· Wind screens were intoduced around 1907 at many stations might not detect this break possible underestimation of precipitation in the first part of the period
Norwegian Meteorological Institute30
Summary and Conclusion
· Daily homogenization is a challenge
· Homer is good for temperature
· Mash gives to many breaks and we can not find these breaks in the Meta data
· Some breaks are easy to find
· Urbanization is important to investigate
· Around 50 % of the precipitation stations are homogeneous
Norwegian Meteorological Institute31
Norwegian Meteorological Institute
+47 96 31 [email protected]@nile_2011
T.E.Twitter.
Thanks for your attention!
Norwegian Meteorological Institute
