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Wave atlas along the south-eastern coast of Sweden : A 6-year simulation of waves using local wind measurements from meteorological stations around the Baltic Sea

Irminger Street, Sebastian LU (2011) VVR820 20111
Division of Water Resources Engineering
Abstract
A wave atlas describing the monthly wave climate at 5 locations along the Swedish SE coast was desired. Using the WAM wave model to hindcast the waves between Jan 1st 2004 and Dec 31st 2009 the parameters significant wave height, direction of wave propagation and spectral wave peak period were extracted from the time series and assembled in a wave atlas. The model was forced with point source wind measurements from meteorological stations in coastal areas around the southern Baltic Sea. To accommodate for differences in winds on land and over water the wind measurements were compensated through a logarithmic expression deriving from experiments at the American Great Lakes. Validation of the model results against buoy measurements showed... (More)
A wave atlas describing the monthly wave climate at 5 locations along the Swedish SE coast was desired. Using the WAM wave model to hindcast the waves between Jan 1st 2004 and Dec 31st 2009 the parameters significant wave height, direction of wave propagation and spectral wave peak period were extracted from the time series and assembled in a wave atlas. The model was forced with point source wind measurements from meteorological stations in coastal areas around the southern Baltic Sea. To accommodate for differences in winds on land and over water the wind measurements were compensated through a logarithmic expression deriving from experiments at the American Great Lakes. Validation of the model results against buoy measurements showed that the chosen approach was able to reproduce the general trends of the wave climate, even if single events could be misrepresented. The larger wave heights were generally underestimated.
The resulting wave atlas showed April-Aug as a calmer period with average HS 0.7-1 m while Nov- Feb was a period of higher waves with average HS 1-1.5 m. Waves for rough conditions, determined as the average of the top 10% of HS for every month, were in the range 1.2-2 m and 2-2.7 m for the respective periods, while the maximum values were in the range of 2-4 m and 2.9-4.6 m, respectively. The high waves during the calmer period were due to reoccurring storms in June around the southern tip of Sweden.
Wave propagations, determined as the direction in which the waves travelled, were mainly in the range N/NE/E from June-Dec. During the late winter and early spring there was an increase in westerly waves, culminating around March/April.
Model results of wave peak periods were difficult to interpret due to large scatter. The average monthly peak period showed only minor annual variations, with values for all months being between 4-6 seconds. Maximum peak periods varied a little more, between 7.5-11 seconds. Through visual comparison of measurement values and model results the average values of Tp are considered trustworthy, but the large scatter of the results make the maximum values of Tp less certain
The resulting wave atlas is primarily intended for practical applications and as guidelines for design in and around the 5 selected locations. The results can also be used as input to more detailed computer models of the surf zone. (Less)
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author
Irminger Street, Sebastian LU
supervisor
organization
course
VVR820 20111
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Baltic Sea, wave modelling, WAM, forcing through wind measurements, wave climate
report number
TVVR 11/5007
ISSN
1101-9824
language
English
id
2334336
date added to LUP
2012-02-01 08:59:07
date last changed
2012-02-01 08:59:07
@misc{2334336,
  abstract     = {A wave atlas describing the monthly wave climate at 5 locations along the Swedish SE coast was desired. Using the WAM wave model to hindcast the waves between Jan 1st 2004 and Dec 31st 2009 the parameters significant wave height, direction of wave propagation and spectral wave peak period were extracted from the time series and assembled in a wave atlas. The model was forced with point source wind measurements from meteorological stations in coastal areas around the southern Baltic Sea. To accommodate for differences in winds on land and over water the wind measurements were compensated through a logarithmic expression deriving from experiments at the American Great Lakes. Validation of the model results against buoy measurements showed that the chosen approach was able to reproduce the general trends of the wave climate, even if single events could be misrepresented. The larger wave heights were generally underestimated.
The resulting wave atlas showed April-Aug as a calmer period with average HS 0.7-1 m while Nov- Feb was a period of higher waves with average HS 1-1.5 m. Waves for rough conditions, determined as the average of the top 10% of HS for every month, were in the range 1.2-2 m and 2-2.7 m for the respective periods, while the maximum values were in the range of 2-4 m and 2.9-4.6 m, respectively. The high waves during the calmer period were due to reoccurring storms in June around the southern tip of Sweden.
Wave propagations, determined as the direction in which the waves travelled, were mainly in the range N/NE/E from June-Dec. During the late winter and early spring there was an increase in westerly waves, culminating around March/April.
Model results of wave peak periods were difficult to interpret due to large scatter. The average monthly peak period showed only minor annual variations, with values for all months being between 4-6 seconds. Maximum peak periods varied a little more, between 7.5-11 seconds. Through visual comparison of measurement values and model results the average values of Tp are considered trustworthy, but the large scatter of the results make the maximum values of Tp less certain
The resulting wave atlas is primarily intended for practical applications and as guidelines for design in and around the 5 selected locations. The results can also be used as input to more detailed computer models of the surf zone.},
  author       = {Irminger Street, Sebastian},
  issn         = {1101-9824},
  keyword      = {Baltic Sea,wave modelling,WAM,forcing through wind measurements,wave climate},
  language     = {eng},
  note         = {Student Paper},
  title        = {Wave atlas along the south-eastern coast of Sweden : A 6-year simulation of waves using local wind measurements from meteorological stations around the Baltic Sea},
  year         = {2011},
}