FUTURE CHANGES IN SPECTRAL WAVE CLIMATE AROUND JAPAN UNDER GLOBAL WARMING

Future projections of ocean wave climate related with global warming has been conducted for the assessment of climate change impacts on coastal disaster, beach morphology, and coastal structure design. In this study, we conduct the high-resolution future wave climate projection in the East Asia region and detail analysis on wave climate based on two-dimensional wave spectra in addition to conventional wave statistics (significant wave height). Future changes in wave height, period and direction can be discussed consistently owing to analysis on the mean wave spectra.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/FEYPZFRr5SQ

ENSEMBLE WAVE CLIMATE PROJECTIONS BASED ON CMIP5 MODELS

A warming climate has the potential to not only raise sea level but also exacerbate coastal hazards due to changes in storm frequency and intensity. Along open coasts where wave energy is often the dominant process dictating shoreline positions, changes in mean and extreme wave conditions are likely to alter long-term geomorphic evolution patterns. The Coordinated Ocean Wave Climate Project (COWCLIP) is to provide infrastructure to support a systematic, community-based framework that allows for validation and inter-comparison of wave projections. Here, the primary aims are to 1) present quantitative evaluations of projected global scale wave conditions and 2) to present the framework and preliminary results of regional wave modeling that will provide projections of nearshore wave conditions for use in long-term geomorphic change analyzes.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/Y6BEHq5wZXw

Climate-induced variability in South Atlantic wave direction over the past three millennia

Through alteration of wave-generating atmospheric systems, global climate changes play a fundamental role in regional wave climate. However, long-term wave-climate cycles and their associated forcing mechanisms remain poorly constrained, in part due to a relative dearth of highly resolved archives. Here we use the morphology of former shorelines preserved in beach-foredune ridges (BFR) within a protected embayment to reconstruct changes in predominant wave directions in the Subtropical South Atlantic during the last ~ 3000 years. These analyses reveal multi-centennial cycles of oscillation in predominant wave direction in accordance with stronger (weaker) South Atlantic mid- to high-latitudes mean sea-level pressure gradient and zonal westerly winds, favouring wave generation zones in higher (lower) latitudes and consequent southerly (easterly) wave components. We identify the Southern Annular Mode as the primary climate driver responsible for these changes. Long-term variations in interhemispheric surface temperature anomalies coexist with oscillations in wave direction, which indicates the influence of temperature-driven atmospheric teleconnections on wave-generation cycles. These results provide a novel geomorphic proxy for paleoenvironmental reconstructions and present new insights into the role of global multi-decadal to multi-centennial climate variability in controlling coastal-ocean wave climate.

Variations in Winter Ocean Wave Climate in the Japan Sea under the Global Warming Condition

Future variations in the ocean wave climate caused by global warming could affect various coastal issues. Using a third-generation wave model, this study produced projections of the ocean wave climate for winter around Japan, focusing on the Japan Sea side. Wave simulation forcing (sea surface wind) was generated through five different global warming experiments. More than half the future wave projections showed an increasing tendency of the climatological mean significant wave height during winter. However, the maximum significant wave height did not show any clear tendency in future variation. The top 1% of significant wave heights and mean wave periods showed apparent increases in frequencies of higher/longer waves in three out of the five future projections. Frequency distributions of significant wave height, mean wave period, mean wavelength and wave direction showed various future variations (reduction of small ocean waves, increasing frequency of waves from the west). There are large uncertainties in future variations of wave climate in the Japan Sea, but the high probability of variations in daily wave climate is recognized, based on the future wave projections. Variations in daily wave climate are important because they could affect the topography and environment of the coast through long-term repetitive actions.

UNMANNED AERIAL SYSTEM LIDAR SURVEY OF TWO BREAKWATERS IN THE HAWAIIAN ISLANDS

The U.S. Army Corps of Engineers (USACE), Honolulu District (POH) is responsible for the operation and maintenance of 26 navigation projects within the State of Hawaii and the U.S. Pacific territories. The majority of these deep-draft and small-boat harbors include breakwaters that are consistently exposed to a substantial and varied Pacific Ocean wave climate, requiring POH to maintain a rigorous structure condition inspection program to ensure safe and efficient operations at all of its navigation projects. As part of its constant efforts to improve the quality and efficiency of this inspection program, POH has joined with the USACE Cold Regions Research and Engineering Laboratory (CRREL) Remote Sensing and GIS Center of Expertise to utilize an Unmanned LiDAR Scanning (ULS) system to collect LiDAR (Light Detection and Ranging) spatial data and co-registered imagery of breakwaters at Hilo Deep Draft Harbor on the island of Hawaii, and Kaumalapau Deep Draft Harbor on the island of Lanai.

Seasonally Variation of Significant Wave Height for 25 Year Period Based on JMA/MRI-AGCM3.2 Wind Climate Data

The global ocean wave climate has long been of interest to the ocean engineering community because of the need for accurate operational wave data for applications such as vessel design, design of offshore and coastal structures or naval operations. Recently, there has been a major interest in wave climate changes as a result of global warming. Therefore, studies on predicting the effect of global warming on ocean wave climate are required. The objectives of this study are to analyze the accuracy and variability of global significant wave height hindcast for the 25 year period 1979-2003. This study describes the 25 year global significant wave height simulation derived from the Japan Meteorology Agency/Meteorology Research Institute (JMA/MRI)-AGCM3.2 wind climate data. The wind climate data were input into ocean wave model WAM with a global grid of spacing 1o in latitude by 1o in longitude. In situ wind and wave data sets from National Data Buoy Center (NDBC)-National Oceanic and Atmospheric Administration (NOAA) database were used to evaluate the hindcast accuracy. The validation showed good agreement both wind and waves data. The wave hindcast analysis show that the seasonal variability of significant wave height in the Northern Hemisphere is greater than in the Southern Hemisphere. Meanwhile, most of the equatorial regions are in calm condition all year.