Navigation : Top / Research / Projection of Future Wave Climate for Coastal Environment Prediction
* 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
± 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 sealevel
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
models based on the high-resolution atmospheric General
Circulation Model (GCM) developed by the Japanese
Meteorological Research Institute and Japan Meteorological
Agency (MRI-JMA) and the global wave model. The
averaged and extreme ocean wave climate changes on both
global and regional scales are discussed.

This project is part of [[Innovative Program of Climate Change Projection for the 21st Century:]] which is supported by Japanese government.

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

** Research period [#pfbee87d]
This project started in 2008 and supported by [[Innovative Program of Climate Change Projection for the 21st Century:]] supported by Japanese government.

* Results [#j248bb2f]
** Direct projection of sea surface wind and wave climate change [#cf25dea8]
Following netcdf data set are one of our results based on the latest version of MRI/JMA AGCM model. If you want to know in detail please ask me directly.
These data set are basically free but please refer to following references when you use the data set.
*** Hs [#h02273a5]
- Annual averaged data
- 50 years return period data
*** U10 [#a0dd6ecc]

* References [#bc14d3c8]
+ 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.