Navigation : Top / Research / Projection of Future Wave Climate for Coastal Environment Prediction

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* Introduction [#pf140555]

Research of global climate change due to greenhouse
effects on the earth's environment is changing from
understanding phenomena to impact assessment, mitigation
and adaptation strategies for future development of human
society. Sea-level rise has been observed at a rate of 1.7 mm
plus minus 0.3 mm/yr from 1870 to 2004 and a significant acceleration
of sea-level rise was observed in the last ten years (Church
and White, 2006). The major source of the sea-level rise is
thermal expansion of sea water temperature increase, thus
the sea-level rise is a static side issue of climate change
influence. Sea-level rise greatly impacts human activity near
the coastal zone (IPCC, 2007) and simply exacerbates the
vulnerability of coastal regions to other physical processes
(e.g. storm surges, storm waves). Another direct influence
of sea-level rise is the inundating of low level coastal areas
which is of concern.

On the other hand, ocean waves and storm surges of
future climate are also expected to change characteristics
from the present climate and are the dynamic side issue of
climate change. It is necessary to seriously consider the
impacts of these dynamic phenomena for coastal disaster
prevention and reduction, if extreme weather events will
become stronger than those in the present climate. For
example, the North Atlantic observed wave data shows 5
cm/yr increase of annual maxima for the last 40 years (Wang
and Swail, 2002). The wave hindcasts in the Atlantic Ocean
show more significant wave height increase in the region
off the Canadian coast and the northwest of Ireland but less
significant change in the North Sea and in the region off
the Scandinavian coast (Wang and Swail, 2002). In addition,
long-term changes of storm waves and surges are important
for infrastructures near the coastal zone. For example, a
coastal breakwater design is basically determined by the
wave pressure of the maximum wave condition, the so-called
design wave, for durable period and the wave pressure is
proportional to the wave height. Moreover, coastal erosion
is another critical issue, where more than 70% of sandy
beaches around the world are presently erosional.
Equilibrium condition of coastal beach profile depends on
seasonal or annual wave height, period and direction. The
projection of future change on coastal erosion is insufficient
due to information deficiencies on changes in waves and
coastal currents. Therefore, future ocean wave climate
change will have significant impacts on extreme and daily
coastal environments. These influences will be at greatest
risk at coastal areas, especially in the heavily populated
mega delta regions of East, South-East and South Asia. The
future coastal environmental changes give a big influence
to these regions, directly.

The future wave climate projection has been conducted
by a few researchers (e.g. Hemer et al., 2006). These studies
have shown an increase in wave height due to increased
wind speeds associated with mid-latitude storms in many
regions of the mid-latitude oceans. Zhang et al. (2004) and
Wang and Swail (2006) made statistical projections of global
wave height from the empirical relationships between sea level
pressure and significant wave height. Furthermore, the
dynamical regional wave climate projections has been
carried out in Europe and North America but there is no
dynamical global wave climate projection at present.

This study projects future wave climate and analyzes
differences between present and future ocean wave climate
The averaged and extreme ocean wave climate changes on both
global and regional scales are discussed.

This project is coupled with [[Projection of Tropical Cyclone and Storm Surge>Research/Projection of Tropical Cyclone and Storm Surge]]
and is a part of [[Innovative Program of Climate Change Projection for the 21st Century:]] which is supported by Japanese government.

** Collaborators [#bd1bc906]
- Hajime Mase, DPRI
- Tomohiro Yasuda, DPRI
- Sota Nakajo, DPRI
- Sota Nakajo, Kumamoto University
- Tomya Shimura, DPRI

* Outline [#j248bb2f]
** Direct projection of sea surface wind and wave climate change [#cf25dea8]
This research uses the product of global climate
projections on the basis of 20 km high-resolution GCM
developed by [[Meteorological Research Institute (MRI)/ Japan Meteorological Agency (JMA) AGCM model:]] (denoted by GCM for simplicity hereafter). 
The 20 km high-resolution MRI-JMA GCM is
the single atmospheric GCM with T959L60 resolution
following A1B scenario and is newly developed for the
Kakushin (2007) program (Kitoh et al., 2009).
-- [[Kitoh et al. (2009) Projection of changes in future weather extremes using super-high-resolution global and regional atmospheric models in the KAKUSHIN Program: Results of preliminary experiments, Hydrological Research Letters:]]

The global wave climate projections for the three periods
were simulated by the SWAN (Simulating WAves
Nearshore) model (Booij et al., 1999) using sea surface wind
at 10 m height U10 of the GCM. 
The long-term wave climate changes were analyzed both for the global scale and
regional oceans.
The analysis of computed future wave climate change from the present climate are conducted in detail.


Ratio of averaged wave height change from the present (1978-2004) to future (2075-2099) climate conditions. The positive means increased wave height from the present climate.


Regional changes of averaged and extreme wave height from the present to future climate conditions (NA:The North Atlantic, NP:The North Pacific, JP:Around Japan).

* Data Archive [#oaeddfa9]
Following netcdf data set are one of our results based on this project. 
These data set are basically free for academic purpose but please refer to following references when you use the data set.
If you want to know in detail please ask me directly.
*** Data source [#tfe14c14]
The data is [[NetCDF:]] formatted and the mean and extreme values are included.
- [[Hs: Average and 50 years return period data:]]
- [[Hs: Average and 50 years return period data:]]
- [[U10: Average and 50 years return period data:]]

&color(blue){Please exclude Florida area for the analysis following validation results.}; This is due to misconfiguration and will be refined next release.
&color(blue){The wave data has been updated in 2012/08/22.}; 
It improved data quality around the Florida. Please use the latest data for research purpose.

* Joint Research [#ne17a1e0]
-  Coordinated Ocean Wave Climate Projections
-- [[COWCLIP:]]

* References [#bc14d3c8]
** Journal paper published [#iabc8725]
+ Mori, N., T. Yasuda, H. Mase, T. Tom and Y. Oku (2010)
[[Projection of extreme wave climate change under the global warming:]], 
[[Hydrological Research Letters:]], Vol.4, pp.15-19. 
** Conference proceedings [#dbdcd93c]
+ Mori, N., T. Yasuda, R. Iwashima, T. H. Tom, H. Mase and Y. Oku (2009) Impact of global climate change on wave climate, Coastal Dynamics 2009, CD-ROM, No.135.
+ Mori, N., T. Yasuda, H. Mase, R. Iwashima (2009) T. H. Tom and Y.Oku, Prediction of global sea surface wind and wave climate change based on MRI-JMA GCM, Proceedings of 33rd IAHR Congress, No.10980, 8p.