Abstract
Two proxies able to determine the sign of the atmospheric
stability in the absence of temperature
measurements were investigated using data from
four forested sites in Sweden. The results indicate
that the simple proxy based on the time of the day
when the measurement was taken was sufficient
to identify approximately 75% of the stable occurrences.
However, also during daytime, stable stratification
was not infrequent. A criterion based on a
combination of the local turbulence intensity and
shear exponent was therefore also investigated,
and the combination of the two criteria was able
to estimate approximately 90% of the overall stable
data.
When selecting data with mean wind speeds
over 5 m/s at 80 m height, the presented data sets
include mostly data where temperature effects are
small (near-neutral), followed by stable data. Only
few occurrences of unstable conditions were anyway
observed.
The investigated data sets show large variation
of shear and turbulence intensity with increasing
stability, indicating the need for proxies that also
can be used to characterize the degree of atmospheric
stability.
Original language | English |
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Title of host publication | Proceedings of EWEA 2014 |
Number of pages | 9 |
Publisher | European Wind Energy Association (EWEA) |
Publication date | 2014 |
Publication status | Published - 2014 |
Event | European Wind Energy Conference & Exhibition 2014 - Fira de Barcelona Gran Via, Barcelona, Spain Duration: 10 Mar 2014 → 13 Mar 2014 http://www.ewea.org/annual2014/ |
Conference
Conference | European Wind Energy Conference & Exhibition 2014 |
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Location | Fira de Barcelona Gran Via |
Country/Territory | Spain |
City | Barcelona |
Period | 10/03/2014 → 13/03/2014 |
Internet address |
Keywords
- Atmospheric stability
- Obukhov length
- Richardson number