Long baroclinic Rossby waves with periods of about 500d near 20°N in the northwest Pacific Ocean

1IntroductionThe oceanic Rossby waves play an importantrole in the large-scale oceanic circulations.In the o-ceans baroclinic Rossby waves have surface manifes-tations of just a fewcentimeters,and wavelengths atmid-latitudes of hundreds to thousands of ki…     

Numerical modeling of wind and waves for Typhoon Betty (8710)

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Sensitivity of the half-life time of water exchange in coastal waters

A three-dimensional model was established to investigate water exchange in coastal waters, and applied to Qinzhou Bay(QZB) in the South China Sea. Given the strong tidal current in QZB, a half-life time was calculated for water exchange by filtering the tidal signal from the concentrations of a conservative substance. In a control run driven by the tide, without external inputs and an open boundary concentration of zero, it was estimated that the average half-life time in QZB was 54.8 d. Numerical experiments showed that wind accounted for an 11.9% reduction in the half-life time to 48.3 d. When rivers were included in the model, the half-life time decreased by 74.6% to 13.9 d. Sensitivity experiments showed that the half-life time for water exchange was greatly affected by the concentration of the conservative substance which was used at the open boundary. In response to 10,20, 30, and 40% increases in the boundary concentration, the half-life time increased to 91.5, 168.3, 186.2, and 229.1 d,respectively. Results also suggested that for coastal bays with large intertidal areas such as QZB, consideration of the wet and dry processes produced more accurate simulations of the hydrodynamics and the half-life times. Simulations, which did not incorporate wet and dry processes, were more than likely to have overestimated or underestimated the half-life times for water exchange.     

Energy budget of surface waves in the global ocean

Mechanical energy input from atmosphere and losses from wave-breaking dissipation of sea surface waves are estimated by a direct scheme. This scheme is based on the integration in the wavenumber space of the wind input and breaking dissipation source functions of the MASNUM wave model. The global amount of wind energy input, averaged in 2005, is about 57 TW, and the wave-breaking dissipation summed in deep-water is about 33 TW, over a half of the wind energy input. The residual may be dissipated by beach processes. Global distributions of the energy input and breaking dissipation concentrate in the westerlies of the Southern Hemisphere.     

全球海洋碳循环三维数值模拟研究

基于海洋环流模式POP和生物地球化学模型OCMIP-2,建立了全球海洋碳循环模式,并用于对全球海洋碳循环的模拟研究。该模式在大气CO₂为283×10-6条件下,积分3 100 a,达到工业革命前的平衡态。在此基础上,用历史时期观测的大气CO₂浓度进行强迫,模拟了历史时期的海洋碳循环。模拟的无机碳浓度、总碱度与基于观测得到的结果基本一致,模式能够较好地模拟全球碳循环过程。模拟结果表明,在北半球中高纬度和南半球的中纬度,海洋是大气CO₂的主要汇区;在赤道南北纬20°之间和南大洋50°S以南,海洋表现为大气CO₂的源区。在1980s海洋吸收CO₂速率(以C计)为1.38 Pg/a,1990s为1.55 Pg/a。海洋中人为碳在北大西洋含量最大,向下到达海底并向南输运到30°N附近;在南极附近,浓度较小,深度达到3 000 m;在中纬度,人为碳被限制在温跃层以上。     

误差订正对2018年夏季次季节尺度海冰预测的作用

北极海冰次季节尺度预测在针对破冰船和商船的实际服务中十分重要,但常常受制于气候模拟的模拟能力。本研究提出了一种误差订正方法并分别应用到两个气候模式：海洋一所地球系统模式（FIOESM）和美国国家环境预报中心（NCEP）的气候预报系统（CFS）,来改善北极海冰60天尺度的预测。本研究的预测工作是中国第9次北极科学考察和2018年夏季中远集团北极商业航行的业务化海冰服务保障的重要部分。模式起报时间分别是2018年7月1日、8月1日和9月1日,预报时效均是60天。结果显示,FIOESM整体上低估了海冰密集度的数值,平均偏差可达30%。误差订正对海冰密集度（SIC）的均方根偏差（RMSE）的改进比例可达27%,对海冰外缘线（SIE）的整体偏差（IIEE）的改进比例为10%。而对于CFS,SIE在边缘区域的过高估计是其主要特点。误差订正导致了SIC的RMSE改进了7%,而对SIE的IIEE改进了17%。在海冰范围预测方面,FIOESM预测的最小范围数值和时间点都和观测接近,而CFS的预测结果偏差较大。另外和其他S2S模式的结果比较发现,本研究提出的误差订正方法对存在较大偏差的预测结果改进更为有效。     

FY-3C微波成像仪海上大气可降水产品质量检验

中国自主研制的第二代极轨气象卫星的首颗业务星风云三号C星(FY-3C)于2013年9月23日发射升空。微波成像仪(MWRI)作为FY-3C上携带的重要微波载荷之一,能够实现对大气、海洋和陆地的全天时监测。其中,MWRI海上大气可降水量(TPW)产品在数值预报模式以及气候变化研究中具有很重要的应用价值,但是应用效果的好坏往往受产品精度的制约。使用长达4年的卫星观测资料,通过MWRI TPW业务产品和无线电探空及专用传感器微波成像仪(SSMIS) TPW业务产品的比较,对MWRI TPW产品(包括轨道产品、日产品和月产品)的质量进行检验。结果表明,轨道产品和地面实际观测的探空数据的平均相对误差在7%左右,均方根误差为2.6 mm;日产品和SSMIS日产品的均方根误差约为3 mm,和探空日产品的均方根误差小于2.1 mm;月产品和SSMIS月产品的均方根误差小于1.3mm。表明FY-3C MWRI TPW业务产品长期以来一直稳定运行且精度较高,具备实际应用潜力。     

Development of Climate and Earth System Models in China: Past Achievements and New CMIP6 Results

The Earth-Climate System Model (ECSM) is an important platform for multi-disciplinary and multi-sphere integration research, and its development is at the frontier of international geosciences, especially in the field of global change. The research and development (R&D) of ECSM in China began in the 1980s and have achieved great progress. In China, ECSMs are now mainly developed at the Chinese Academy of Sciences, ministries, and universities. Following a brief review of the development history of Chinese ECSMs, this paper summarized the technical characteristics of nine Chinese ECSMs participating in the Coupled Model Intercomparison Project Phase 6 and preliminarily assessed the basic performances of four Chinese models in simulating the global climate and the climate in East Asia. The projected changes of global precipitation and surface air temperature and the associated relationship with the equilibrium climate sensitivity under four shared socioeconomic path scenarios were also discussed. Finally, combined with the international situation, from the perspective of further improvement, eight directions were proposed for the future development of Chinese ECSMs.     

Historical simulation and twenty-first century prediction of oceanic CO2 sink and pH change

A global ocean carbon cycle model based on the ocean general circulation model POP and the improved biogeochemical model OCMIP-2 is employed to simulate carbon cycle processes under the historically observed atmospheric CO 2 concentration and different future scenarios (called Rep- resentative Concentration Pathways, or RCPs). The RCPs in this paper follow the design of Inter- governmental Panel on Climate Change (IPCC) for the Fifth Assessment Report (AR5). The model results show that the ocean absorbs CO 2 from atmosphere and the absorbability will continue in the 21st century under the four RCPs. The net air-sea CO 2 flux increased during the historical time and reached 1.87 Pg/a (calculated by carbon) in 2005; however, it would reach peak and then decrease in the 21st century. The ocean absorbs CO 2 mainly in the mid latitude, and releases CO 2 in the equator area. However, in the Antarctic Circumpolar Current (ACC) area the ocean would change from source to sink under the rising CO 2 concentration, including RCP4.5, RCP6.0, and RCP8.5. In 2100, the anthropogenic carbon would be transported to the 40 S in the Atlantic Ocean by the North Atlantic Deep Water (NADW), and also be transported to the north by the Antarctic Bottom Water (AABW) along the Antarctic continent in the Atlantic and Pacific oceans. The ocean pH value is also simulated by the model. The pH decreased by 0.1 after the industrial revolution, and would continue to decrease in the 21st century. For the highest concentration sce- nario of RCP8.5, the global averaged pH would decrease by 0.43 to reach 7.73 due to the absorption of CO 2 from atmosphere.     

两种湍流参数化方案针对水体温度演变过程的模拟与比较

依据山东跋山水库的观测数据,采用MY2.5参数化方案和κ-ε参数化方案在不同的表面边界条件下模拟观测的温度剖面演化过程。模拟结果显示,在风应力强迫的表面边界条件下,采用这两种参数化方案的模拟结果差别不大;当考虑Mellor和Blumberg的波浪破碎表面边界条件时,采用MY2.5参数化方案的模拟结果没有明显的改善,但采用κ-ε参数化方案的模拟结果有明显的改善,得到与观测相符的模拟结果。