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The impact of climate change on wind waves

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Fetches in 8 directions (N NE E SE S SW W NW) ... When prospecting new harbours and other constructions in the sea there is need ... – PowerPoint PPT presentation

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Title: The impact of climate change on wind waves


1
The impact of climate change on wind waves
Barry Broman SMHI
  • Using a simple model Hsf(wind,fetch,duration)
  • 1189 points (1020 resolution)
  • Fetches in 8 directions (N NE E SE S SW W NW)
  • Estimated wind fields from observations and sea
    level preasure 1980-2004 (hindcast)
  • Wind fields from RCMs (control, scenarios)

2
  • The wave climate is needed in order to classify
    routes for ships of different kinds. There are
    different classes depending on which wave height
    is exceeded during 10 of the time i.e. the 90th
    percentile.
  • When planning sea operations information of the
    wave climate is needed. A changing climate will
    have implications on such operations
  • Information on waves is also important for
    estimations of erosion on the shore and the sea
    bottom.
  • When prospecting new harbours and other
    constructions in the sea there is need to know
    the wave climate.

3
significant wave height Hsmean of 33 highest
waves
4
Nomogram Hsf(wind,fetch,duration)
5
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6
Fetches in 8 directions (N NE E SE S SW W NW)
7
1181 points (1020 resolution)
8
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9
Observed and estimated significant wave height
at Almagrundet 1984
10
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11
Significant wave heights (in m) in the control
climates RCAO-H (upper panels), RCAO-E (lower
panels), annual mean (left panels), and 90th
percentile (right panels).
12
Changes of 90th percentiles of the significant
wave height (in m) in the scenarios compared to
the control simulations RCAO-H (upper panels),
RCAO-E (lower panels), B2 (left panels), and
A2 (right panels).
13
Changes of annual mean significant wave heights
(in m) in the scenarios compared to the control
simulations RCAO-H (upper panels), RCAO-E
(lower panels), B2 (left panels), and A2 (right
panels).
14
Mean Hs(m) December 2004 Different models
Fetch
Hypne
SWAN
15
90th percentile Hs(m) December 2004 Different
models
Fetch
Hypne
SWAN
16
Areas used for represantive windstations
17
Hs (m) 90-level Calculated from representative
stations 1979-1994
October
November
December
18
Diagrams used for planning
19
Conclusions
  • Results from the two control runs give similar
    mean wave heights of 0-1.3 m
  • The corresponding 90th percentile shows waves of
    the order 0-2.5 m with the highest waves in the
    southern and eastern Baltic proper
  • The differences of the mean significant wave
    height and the 90th percentile of the wave height
    between control simulations (1961-1990) and hind
    cast simulation (1980-2004) are in the range of
    -0.2 and 0.2 m approximately
  • Changes of the 90th percentiles are significant
    larger in RCAO-E than in RCAO-H
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