Global dynamical projections of surface ocean wave climate for a future high greenhouse gas emission scenario
Global dynamical projections of surface ocean wave climate for a future high greenhouse gas emission scenario
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DOI：
10.1016/j.ocemod.2012.09.008
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发表时间：
2013-10-01
期刊：
影响因子：
3.2
通讯作者：
Trenham, Claire E.
中科院分区：
文献类型：
--
作者：
Hemer, Mark A.;Katzfey, Jack;Trenham, Claire E.
使用立方共形大气模式（Cubic Conformal Atmospheric model）动态缩小到60公里的两个大气-海洋环流模式（aogcm: ECHAM5和CSIRO Mk3.5）的地表风强迫实现了光谱波模式WaveWatch III的全球1度实现。模拟了两个30年时间片：1979-2009年代表当前气候，2070-2099年代表高温室气体排放情景（SRES A2）下的未来气候情景。进一步的波浪模式模拟使用了1979-2009年NCEP气候预报系统再分析的强迫，使用与气候模式强迫运行相同的模式设置，作为评估气候模式衍生波场技能的基准后验。气候模式强迫对1979-2009年时间片的波浪模拟显示出相对于基准波浪气候的偏差，特别是对南大洋波浪产生的高估，这影响了太平洋的广大地区，这些地区将这些波浪作为膨胀接收。为了减少偏差，在对气候模式强迫风进行偏差调整后，重复进行了波浪模式运行，但模式模拟显著波高每月第99百分位的技能严重恶化。在SRES A2温室气体排放情景下，波浪气候（1979-2009年和2070-2099年）的预估未来变化对风的偏倚调整是否已经应用相对不敏感。从这两个气候模式集观测到的预估变化有两个强有力的特征，它们在质量上与以前的研究一致：预估南大洋波浪产生的增加导致南大洋平均有效波高（H-Sm）增加约10%，预估北大西洋波浪产生的减少，H-Sm的变化幅度相似。利用气候指数（南方涛动指数- SOI、北大西洋涛动- NAO和南环模- SAM）对月平均有效波高H-Sm的年际距平进行回归分析。在当前气候和预估气候之间，观察到波高变率与这些气候指数之间的关系存在显著差异。例如，在预测的未来气候中，NAO与西欧和西北非洲海岸的H-Sm异常之间从负相关到正相关的显著转变被注意到。作为对预测的未来气候情景的响应，风浪特征的潜在未来变化，以及风浪气候年际变率与确定的气候指数之间的变化关系，对沿海、近岸和近海环境的一系列过程和活动具有广泛的影响。爱思唯尔有限公司版权所有版权所有。
A global 1 degrees implementation of the spectral wave model, WaveWatch III, was forced with surface winds from two atmosphere-ocean general circulation models (AOGCMs: ECHAM5 and CSIRO Mk3.5), dynamically downscaled to 60 km using the Cubic Conformal Atmospheric Model. Two 30-yr time slices were simulated: 1979-2009 representing current climate, and 2070-2099 representing a future climate scenario under a high greenhouse gas emission scenario (SRES A2). A further wave model simulation with forcing from the NCEP Climate Forecast System Reanalysis for 1979-2009, using the same model settings as the climate model forced runs, serves as a benchmark hindcast to assess skill of climate-model-derived wave fields. Climate model forced wave simulations for the 1979-2009 time-slice display biases relative to the benchmark wave climate - notably an overestimation of wave generation in the Southern Ocean, which influences broad regions of the Pacific which receive these waves as swell. Wave model runs were repeated following bias-adjustment of the climate model forcing winds with the aim to reduce biases, but model skill to simulate the monthly 99th percentile of significant wave heights deteriorates severely.Projected future changes in wave climate (between 1979-2009 and 2070-2099) under the SRES A2 greenhouse gas emission scenario are relatively insensitive to whether bias-adjustment of winds has been applied. Two robust features of projected change are observed from the two climate model sets which are qualitatively consistent with previous studies: a projected increase of Southern Ocean wave generation leading to approximately 10% increase in Southern Ocean mean significant wave heights (H-Sm), and a projected decrease in wave generation in the North Atlantic, with changes in H-Sm of similar magnitude.Interannual anomalies of monthly mean significant wave height, H-Sm, were regressed against climate indices (Southern Oscillation Index - SOI; North Atlantic Oscillation - NAO and the Southern Annular Mode - SAM) over each time-slice. Significant differences in the relationships between wave height variability and these climate indices between current and projected climates are observed. For example, a significant shift from negative to positive correlation between the NAO and H-Sm anomalies along the western European and north-west African coasts in the projected future climate is noted. The potential future changes in wind-wave characteristics, and the changing relationships between interannual variability of wave climate with identified climate indices, as a response to projected future climate scenarios have broad implications for a range of processes and activities in the coastal, near-and-off-shore environments. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.