Surface pH

This resource is a map of Surface pH and comes from from a simulation that uses the multi-model mean forcings from RCP8.5 projection to drive an ocean eddy-resolving model (OFAM3). Insights for Warming and AcidificationIncreased frequency and duration of marine heatwaves increase the likelihood of more frequent and severe coral bleaching events.Tasman Sea approaches a permanent marine heatwave state by GWL3. Great Barrier Reef and Ningaloo Reef will experience annual conditions for extreme bleaching by GWL3. Acidity at GWL3: Southern Ocean surface waters south of 60S will drop below an annual mean aragonite saturation state of 1. Values above 1.0 are required to produce calcareous shells or skeletons optimally. Values below 1 are considered corrosive, and skeletons and shells may be subject to dissolution. The ocean environment will become more stressful for marine organisms and ecosystems.The references for the simulations are:Feng, M., Zhang, X., Oke, P., Monselesan, D., Chamberlain, M. A., Matear, R. J., & Schiller, A. (2016). Invigorating ocean boundary current systems around Australia during 19792014: As simulated in a near-global eddy-resolving ocean model. Journal Of Geophysical Research-Oceans.Hayashida, H., Matear, R. J., & Strutton, P. G. (2020). Background nutrient concentration determines phytoplankton bloom response to marine heatwaves. Global Change Biology, 26(9), 48004811. https://doi.org/10.1111/gcb.15255Hayashida, H., Matear, R. J., Strutton, P. G., & Zhang, X. (2020). Insights into projected changes in marine heatwaves from a high-resolution ocean circulation model. Nature Communications, 11(1), 19. https://doi.org/10.1038/s41467-020-18241-xMatear, R. J., Chamberlain, M. A., Sun, C., & Feng, M. (2015). Climate change projection for the western tropical Pacific Ocean using a high-resolution ocean model: Implications for tuna fisheries. Deep Sea Research Part II: Topical Studies in Oceanography, 113(0), 2246.Matear, R. J., Chamberlain, M. A., Sun, C., & Feng, M. (2013). Climate change projection of the Tasman Sea from an Eddy-resolving Ocean Model. Journal Of Geophysical Research-Oceans, 118(6), 29612976.Zhang, X., Oke, P. R., Feng, M., Chamberlain, M. A., Church, J. A., Monselesan, D., et al. (2016). A near-global eddy-resolving OGCM for climate studies. Geoscientific Model Development Discussions.DiagnosticsThe key ocean diagnostics are displayed according to Global Warming Levels (GWLs) using the 20 year period that define a given GWL. The key ocean diagnostics are:1. Sea Surface Temperature monthly climatology2. Surface Aragonite Saturation State monthly climatology3. Surface pH monthly climatology4. Intensity of Marine Heat Wave5. Duration of Marine Heat Wave6. NPP monthly climatology (N mol/m^2/s)7. Degree Heating Weeks (average of the annual maximum value dhw_amax, maximum (dhw_max) and minimum (dhw_max) annual value over GWL period8. Bottom Temperature9. Full ocean depth temperature (note simulation used restoring to T and S below 2000m)10. Magnitude of Bottom Stress (bmf)10. Bottom aragonite saturation state Data/confidence Confidence: high confidence in the direction of change, medium confidence in the magnitude of change and low confidence in the ecological consequence of the changes. (consistent with IPCC AR6)Limitation: ocean simulations that are not well suited for representing the high-resolution dynamics and features of the Australian coastal areas.https://github.com/AusClimateService/hazard_ocean/blob/main/README.md

本数据集为海洋表层pH分布图，其依托典型浓度路径8.5（Representative Concentration Pathway 8.5, RCP8.5）情景下的多模式平均强迫场，驱动海洋涡旋分辨模式OFAM3完成模拟构建。

### 变暖与酸化相关研究进展
海洋热浪的发生频率与持续时长增加，将提升珊瑚白化事件频发且程度加剧的可能性。当升温达3℃全球升温阈值（Global Warming Level 3, GWL3）时，塔斯曼海将趋近于永久性海洋热浪状态；大堡礁与宁格罗礁届时将每年出现极端白化的环境条件。
GWL3情景下的海洋酸化情况：南纬60°以南的南大洋表层海水，其年均文石饱和状态将降至1以下。文石饱和值高于1.0时，海洋生物才能最优地形成钙质外壳与骨骼；若饱和值低于1，则海水具有腐蚀性，生物外壳与骨骼可能发生溶解。海洋环境对海洋生物与生态系统的胁迫程度将进一步加剧。

#### 模拟参考文献
1. Feng, M., Zhang, X., Oke, P., Monselesan, D., Chamberlain, M. A., Matear, R. J. & Schiller, A. (2016). 1979-2014年间澳大利亚周边海洋边界流系统的增强活动：基于近全球涡旋分辨海洋模式的模拟结果. 《地球物理研究杂志：海洋卷》(Journal Of Geophysical Research-Oceans).
2. Hayashida, H., Matear, R. J. & Strutton, P. G. (2020). 背景营养盐浓度决定浮游植物水华对海洋热浪的响应. 《全球变化生物学》(Global Change Biology), 26(9), 4800-4811. https://doi.org/10.1111/gcb.15255
3. Hayashida, H., Matear, R. J., Strutton, P. G. & Zhang, X. (2020). 基于高分辨率海洋环流模式的海洋热浪预估变化研究进展. 《自然·通讯》(Nature Communications), 11(1), 19. https://doi.org/10.1038/s41467-020-18241-x
4. Matear, R. J., Chamberlain, M. A., Sun, C. & Feng, M. (2015). 基于高分辨率海洋模式的西热带太平洋气候变化预估：对金枪鱼渔业的启示. 《深海研究第二部分：海洋学专题研究》(Deep Sea Research Part II: Topical Studies in Oceanography), 113(0), 2246.
5. Matear, R. J., Chamberlain, M. A., Sun, C. & Feng, M. (2013). 基于涡旋分辨海洋模式的塔斯曼海气候变化预估. 《地球物理研究杂志：海洋卷》(Journal Of Geophysical Research-Oceans), 118(6), 2961-2976.
6. Zhang, X., Oke, P. R., Feng, M., Chamberlain, M. A., Church, J. A., Monselesan, D. et al. (2016). 用于气候研究的近全球涡旋分辨海洋环流模式(OGCM). 《地球科学模式发展讨论》(Geoscientific Model Development Discussions).

#### 诊断指标说明
本数据集的核心海洋诊断指标基于全球升温阈值（Global Warming Levels, GWLs）进行展示，每个阈值对应一段20年的时段。核心海洋诊断指标包括：
1. 海表温度月气候态
2. 表层文石饱和状态月气候态
3. 表层pH月气候态
4. 海洋热浪强度
5. 海洋热浪持续时长
6. 净初级生产力（Net Primary Production, NPP）月气候态（单位：N mol/m²/s）
7. 升温周数（DHW）：GWL时段内年均最大值dhw_amax、年度最大值dhw_max与年度最小值dhw_min的平均值
8. 海底温度
9. 全海深温度（注：本模拟对2000米以深的温度与盐度采用恢复边界条件）
10. 海底应力强度（bmf）
11. 海底文石饱和状态

#### 数据可信度与局限性
**可信度**：变化趋势的可信度较高，变化幅度的可信度中等，变化带来的生态影响可信度较低（与政府间气候变化专门委员会第六次评估报告（IPCC AR6）的结论一致）。
**局限性**：本海洋模拟无法较好地还原澳大利亚近岸区域的高分辨率动力学过程与海洋特征。

本数据集详情可参考：https://github.com/AusClimateService/hazard_ocean/blob/main/README.md