Contribution of Surface Waves to Sea Surface Temperatures in the Arctic Ocean

The aim of our study was to examine the contribution of surface waves from WAVEWATCH-III(WW3)to the variation in sea surface temperature(SST)in the Arctic Ocean.The simulated significant wave height(SWH)were validated against the products from Haiyang-2B(HY-2B)in 2021,obtaining a root mean squared error(RMSE)of 0.45 with a correlation of 0.96 and scatter index of 0.18.The wave-induced effects,i.e.,wave breaking and mixing induced by nonbearing waves resulting in changes in radiation stress and Stokes drift,were calculated from WW3,ERA-5 wind,SST,and salinity data from the National Centers for Environmental Prediction and were taken as forcing fields in the Stony Brook Parallel Ocean Model.The results showed that an RMSE of 0.81℃ with wave-induced effects was less than the RMSE of 1.11℃ achieved without the wave term compared with the simulated SST with the measurements from Argos.Considering the four wave effects and sea ice freezing,the SST in the Arctic Ocean decreased by up to 1℃ in winter.Regression analysis revealed that the SWH was linear in SST(values without subtraction of waves)in summer and autumn,but this behavior was not observed in spring or winter due to the presence of sea ice.The interannual variation also presented a negative relationship between the difference in SST and SWH.

Analysis of Sea Surface Temperature Cooling in Typhoon Events Passing the Kuroshio Current

The aim of this study is to investigate the sea surface temperature(SST) cooling as typhoons pass the Kuroshio Current.A numerical circulation model,denoted as the Stony Brook Parallel Ocean Model(sbPOM),was used to simulate the SST,which includes four wave-induced effect terms(i.e.,radiation stress,nonbreaking waves,Stokes drift,and breaking waves) simulated using the third-generation wave model,called WAVEWATCH-Ⅲ(WW3).The significant wave height(SWH) measurements from the Jason-2 altimeter were used to validate the WW3-simulated results,yielding a root mean square error(RMSE) of less than 0.50 m and a correlation coefficient(COR) of approximately 0.93.The water temperature measured from the Advanced Research and Global Observation Satellite was applied to validate the model simulation.Accordingly,the RMSE of the SST is 0.92℃ with a COR of approximately 0.99.As revealed in the sbPOM-simulated SST fields,a reduction in the SST at the Kuroshio Current region was observed as a typhoon passed,although the water temperature of the Kuroshio Current is relatively high.The variation of the SST is consistent with that of the current,whereas the maximum SST lagged behind the occurrence of the peak SWH.Moreover,the Stokes drift plays an important role in the SST cooling after analyzing four wave-induced terms in the background of the Kuroshio Current.The sensitivity experiment also showed that the accuracy of the water temperature was significantly reduced when including breaking waves,which play a negative role in the inside part of the ocean.The variation in the mean mixing layer depth(MLD) showed that a typhoon could enhance the mean MLD in the Kuroshio Current area in September and October,whereas a typhoon has little influence on the mean MLD in the Kuroshio Current area in May.Moreover,the mean MLD rapidly decreased with the weakening of the strong wind force and wave-induced effects when a typhoon crossed the Kuroshio Current.

“一带一路”区域气候变化事实、影响及可能风险

“一带一路”区域国家经济、政治发展极不平衡,随着全球气候变暖,区域内的自然环境、气候资源、水资源等都将面临着显著而复杂的变化,并且干旱、洪涝等多种气候灾害是“一带一路”区域可持续发展和重大基础设施建设面临的重大威胁之一。目前,“一带一路”倡议已经进入实质性建设阶段,沿线地区的气候变化及其灾害风险关乎“一带一路”倡议能否顺利实施及亚投行的投资安全。在此背景下,2016—2018年中国科学院地球科学学部实施了“‘一带一路’区域气候变化问题”咨询评议项目,项目针对该区域气候变化的事实、未来变化预估、气候变化的可能影响以及带来的潜在风险等问题进行了系统的调研,并开展了若干分析和研究。经过两年的努力,项目组完成了有关进展报告四份,包括一份总报告和三份分报告。本文扼要地概括和介绍了项目取得的主要成果。

南海海平面对两类El Nino的不同响应

利用ECMWF ORAS4重构数据,分析了南海海平面异常(SLA)对东部型(EP)El Ni?o和中部型(CP)El Nino的不同响应特征。南海SLA在两类El Nino期间表现出不同的时空演变规律。对于东部型El Nino,南海空间平均的SLA在发展年的秋、冬季显著下降,最低可达-2 cm,并在次年开始上升,至次年冬季可达2 cm。空间分布上,在发展年秋、冬季,除越南东南部海域存在一个正异常中心外,在南海绝大部分海域,SLA均表现为显著的负异常;从次年春季开始,SLA负异常减弱,而越南东南部的正异常开始发展,直至冬季南海大部分海域以正异常为主。对于中部型El Nino,南海SLA在整个El Nino发展和衰退期间均表现为显著负异常,异常值始终维持在-2 cm左右,并且在空间上表现为全海盆一致的负异常模态。相比于传统的经验正交分解(EOF),季节EOF(S-EOF)能够更好地刻画南海SLA在两类El Nino期间的时空演变特征,S-EOF的第一模态表现为中部型El Nino模态,而第二模态更多地表现为南海SLA在东部型El Nino期间的演变特征。南海海平面在两类El Nino期间的不同变化主要是由于海峡通道处的热量平流输运异常所产生的热比容效应导致的,但是比容海平面的贡献主要集中在南海内区和南海东部等深水海域,对于南海西部等近岸海域,海平面的变化机制还有待进一步深入研究。

Evaluation of Typhoon Waves Simulated by Wave Watch-Ⅲ Model in Shallow Waters Around Zhoushan Islands

In this study, we simulated typhoon waves in the shallow waters around the Zhoushan Islands using the WaveWatch-Ⅲ(WW3) model version 5.16, the latest version released by the National Oceanic and Atmospheric Administration. Specifically, we used in-situ measurements to evaluate the performance of seven packages of input/dissipation source terms in the WW3 model. We forced the WW3 model by wind fields derived from a combination of the parametric Holland model and high-resolution European Center for Medium-Range Weather Forecasts(ECMWF) wind data in a 0.125? grid, herein called H-E winds. We trained the H-E winds by fitting a shape parameter B to buoy-measured observations, which resulted in a smallest root mean square error(RMSE) of 3 m s^(-1) for B, when treated as a constant 0.4. Then, we applied the seven input/dissipation terms of WW3, labelled ST1, ST2, ST2+STAB2, ST3, ST3+STAB3, ST4, and ST6, to simulate the significant wave height(SWH) up to 5 m during typhoons Fungwong and Chan-hom around the Zhoushan Islands. We then compared the SWHs of the simulated waves with those measured by the in-situ buoys. The results indicate that the simulation using ST2 performs best with an RMSE of 0.79 m for typhoon Fung-wong and an RMSE of 1.12 m for typhoon Chan-hom. Interestingly, we found the simulated SWH results to be relatively higher than those of the observations in the area between Hangzhou Bay and the Zhoushan Islands. This behavior is worthy of further investigation in the future.

Global Sea Level Change and Thermal Contribution

The global long-term sea level trend is obtained from the analysis of tide gauge data and TOPEX/Poseidon data. The linear trend of global mean sea level is highly non-uniform spatially, with an average rate of 2.2 mmyear^-1 in T/P sea-level rise from October 1992 to September 2002. Sea level change due to temperature variation （the thermosteric sea level） is discussed. The results are compared with TOPEX/Poseidon altimeter data in the same temporal span at different spatial scales. It is indicated that the thermal effect accounts for 86% and 73% of the observed seasonal variability in the northern and southern hemispheres, respectively. The TOPEX/Poseidon observed sea level lags behind the TSL by 2 months in the zonal band of 40%-60% in both the northern and southern hemispheres. Systematic differences of about 1-2 cm between TOPEX/Poseidon observations and thermosteric sea level data are obtained. The potential causes tbr these differences include water exchange among the atmosphere, land, and oceans, and some possible deviations in thermosteric contribution estimates and geophysical corrections to the TOPEX/Poseidon data.

The fundamental characteristics of current in the Bering Strait and the Chukchi Sea from July to September 2003

The characteristics of current in the Bering Strait and the Chukchi Sea areanalyzed based on the two current data on the mooring stations during the Second National ArcticResearch Expedition of China in 2003. The tidal currents of the principal diurnal and semidiurnalellipses rotate clockwise in the upper layer, except for N_2, S_2, and Q_1 at Sta. ST. In the BeringStrait (Sta. ST), the major semi-axis of tidal current constituent M_2 is 2.9 cm/s in the upperlayer, which is much smaller than that of semi-monthly oscillation (11.8 cm/s); and the mean currentflows northwestward at the amplitude of about 20 cm/s and varies a little with depth. During thecruise, the current has significant semi-monthly oscillation at the two mooring stations. Thespectra analyses of the air pressure gradient and the wind stress show that there are thesemi-monthly oscillations in these two data series. The near-inertial current, approximately 4 cm/s,presents almost the same magnitude of the principal tidal currents in the Bering Strait.

台风期间浮标和潜标上ADCP的空间变化、数据误差及校正

基于南海北部浮标和潜标的声学多普勒流速剖面仪(ADCP)数据,通过一套几何算法计算了台风海鸥(1415)期间ADCP的空间变化和流速误差,并进行数据校正。浮标上,台风过后ADCP的水平位移最大可达2.61 km,水平流速误差最大可达0.27 m/s,垂向流速误差最大仅为5×10^(-4) m/s;温跃层流速校正值在台风过后显著大于流速测值,这表明水平校正对于温跃层流速的质量控制很重要。潜标上,ADCP最大垂向位移增量为179 m,最大绳子倾角为35°,最大水平位移为1.5 km;ADCP水平流速误差和倾角误差都很小,在数据校正中可忽略不计,但对台风过后中层流速的垂向校正不能忽略。

Assessing the global averaged sea-level budget from 2003 to 2010

A global mass balance （Greenland and Antarctica ice sheet mass loss, terrestrial water storage） and differ- ent sea-level components （observed sea-level from satellite altimetry, steric sea-level from Ishii data, and ocean mass from gravity recovery and climate experiment, GRACE） are estimated, in terms of seasonal and interannual variabilities from 2003 to 2010. The results show that a detailed analysis of the GRACE time series over the time period 2003-2010 unambiguously reveals an increase in mass loss from the Greenland ice sheet and Antarctica ice sheet. The mass loss of both ice sheets accelerated at a rate of （392.8±70.0） Gt/a during 2003-2010, which contributed （1.09±0.19） mm/a to the global mean sea-level during this time. The net terrestrial water storage （TWS） trend was negative over the 8 a time span, which gave a small positive contribution of （0.25±0.12） mm/a. The interannual variability of the global mean sea-level was at least part- ly caused by year-to-year variability of land water storage. Estimating GRACE-based ice sheet mass balance and terrestrial water storage by using published estimates for melting glaciers, the results further show that the ocean mass increase since 2003 has resulted half from an enhanced contribution of the polar ice sheets, and half from the combined ice sheet and terrestrial water storage loss. Taking also into account the melt- ing of mountain glaciers （0.41 mm/a） and the small GRACE-based contribution from continental waters （0.25 mm/a）, a total ocean mass contribution of （1.75±0.57） mm/a from 2003 to 2010 is found. Such a value represented 75% of the altimetry-based rate of sea-level rise over that period. The contributions to steric sea-level （i.e., ocean thermal expansion plus salinity effects） are estimated from： （1） the difference between altimetry-based sea-level and ocean mass change and （2） the latest Ishii data. The inferred steric sea-level rate from （1） （1.41 mm/a from 2003 to 2010） did not agree well with the Ishii-based value also estimated here （0.44 mm/a from 2003 to 2010）, but phase. The cause for such a discrepancy is not yet known but may be related to inadequate sampling of in situ ocean temperature and salinity measurements.

Prediction of China's Submerged Coastal Areas by Sea Level Rise due to Climate Change

Based on the simulation with the Ocean-Atmosphere Coupled Model CCSM and Ocean Model POP under the green- house gas emission scenario of the IPCC SRES A2 （IPCC, 2001）, and on the earth crust subsidence and glacier melting data, the relative sea level change is obtained along the coast of China in the 21 st century. Using the SRTM elevation data the submergence of coastal low land is calculated under the extreme water level with a 100-year retum period. The total flooding areas are 98.3× 10^3 and 104.9× 10^3 km2 for 2050 and 2080, respectively. For the three regions most vulnerable to extreme sea level rise, i.e., the coast of Bohai Bay, the Yangtze River Delta together with neighboring Jiangsu Province and northern Zhejiang Province, and the Pearl River Delta, the flooded areas are 5.0× 10^3, 64.1×10^3 and 15.3 × 10^3 km2 in 2050 and 5.2 × 10^3, 67.8×10^3 and 17.2 × 10^3 km2 in 2080, respectively.

Role of surface warming in the northward shift of tropical cyclone tracks over the South China Sea in November

Tropical cyclones （TCs） formed in the Northwest Pacific Ocean （NWP） can cross the South China Sea （SCS） sometimes. It is found that the TC tracks in the SCS in November are shifted to the north after 1980 compared with those before 1980. Both data analyses and numerical simulations show that the surface warming in the SCS may contribute to this more northward shift. The warming produces a cyclonic atmosphere circulation anomaly in the northwestern SCS and an associated southerly in the central SCS steering the TCs to the north.

Validation of significant wave height retrieval from co-polarization Chinese Gaofen-3 SAR imagery using an improved algorithm

Chinese Gaofen-3（GF-3） is the first civilian satellite to carry C-band（5.3 GHz） synthetic aperture radar（SAR）.During the period of August 2016 to December 2017, 1 523 GF-3 SAR images acquired in quad-polarization（vertical-vertical（VV）, horizontal-horizontal（HH）, vertical-horizontal（VH）, and horizontal-vertical（HV）） mode were recorded, mostly around China＇s seas. In our previous study, the root mean square error（RMSE） of significant wave height（SWH） was found to be around 0.58 m when compared with retrieval results from a few GF-3 SAR images in co-polarization（VV and HH） with moored measurements by using an empirical algorithm CSARWAVE. We collected a number of sub-scenes from these 1 523 images in the co-polarization channel,which were collocated with wind and SWH data from the European Centre for Medium-Range Weather Forecasts（ECMWF） reanalysis field at a 0.125° grid. Through the collected dataset, an improved empirical wave retrieval algorithm for GF-3 SAR in co-polarization was tuned, herein denoted as CSARWAVE2. An additional 92 GF-3 SAR images were implemented in order to validate CSARWAVE2 against SWH from altimeter Jason-2, showing an about 0.52 m RMSE of SWH for co-polarization GF-3 SAR. Therefore, we conclude that the proposed empirical algorithm has a good performance for wave retrieval from GF-3 SAR images in co-polarization.

Role of ocean upper layer warm water in the rapid intensification of tropical cyclones: A case study of typhoon Rammasun(1409)

Rammasun intensified rapidly from tropical storm to super typhoon in the northern South China Sea（NSCS）before its landfall on Hainan Island. Analysis of observed data shows that the anomalous ocean upper layer warm water（WW） is important to the rapid intensification of Rammasun. During the period of Rammasun, sea surface temperature（SST） in the NSCS was much warmer than the climatological SST. The anomalous WW supplied more energy to Rammasun, resulting in its rapid intensification. Numerical simulations further confirm that the NSCS WW plays an important role in the rapid intensification of Rammasun. As the WW is removed, the intensification of Rammasun is only 25 h Pa, which is 58.1% of that in the original SST-forced run.

Responses of estuarine salinity and transport processes to sea level rise in the Zhujiang(Pearl River) Estuary

Understanding the changes of hydrodynamics in estuaries with respect to magnitude of sea level rise is important to understand the changes of transport process. Based on prediction of sea level rise over the 21st century, the Zhujiang（Pearl River） Estuary was chosen as a prototype to study the responses of the estuary to potential sea level rise. The numerical model results show that the average salt content, saltwater intrusion distance, and stratification will increase as the sea level rises. The changes of these parameters have obvious seasonal variations. The salt content in the Lingdingyang shows more increase in April and October（the transition periods）. The saltwater intrusion distance has larger increase during the low-flow periods than during the highflow periods in the Lingdingyang. The result is just the opposite in Modaomen. The stratification and its increase are larger during the low-flow periods than during the high-flow periods in Lingdingyang. The response results of transport processes to sea level rise demonstrate that：（1） The time of vertical transport has pronounced increase.The increased tidal range and currents would reinforce the vertical mixing, but the increased stratification would weaken the vertical exchange. The impact of stratification changes overwhelms the impact of tidal changes. It would be more difficult for the surface water to reach the bottom.（2） The lengthways estuarine circulation would be strengthened. Both the offshore surface residual current and inshore bottom residual current will be enhanced.The whole meridional resident flow along the transect of the Lingdingyang would be weakened. These phenomena are caused by the decrease of water surface slope（WWS） and the change of static pressure with the increase of water depth under sea level rise.

The Characteristics of Near-surface Velocity During the Upwelling Season on the Northern Portugal Shelf

Observations made on the northern Portugal mid-shelf between May 13 and June 15,2002 were used to characterise the near-surface velocity during one upwelling season. It was found that in the surface mixed layer,the 'tidal current' was diurnal,but the tidal elevation was semi-diurnal. Both the residual current and the major axes of all tidal constituents were nearly perpendicular to the isobaths and the tidal current ellipses rotated clockwise;the major axis of the major tidal ellipse was about 3 cm s-1. The extremely strong diurnal current in the surface layer was probably due to diurnal heating,cooling,and wind mixing that induced diurnal oscillations,including the diurnal oscillation of wind stress. This is a case different from the results measured in the other layers in this area. The near-inertial spectral peaks occurred with periods ranging from 1 047 min to 1 170 min,the longest periods being observed in deeper layers,and the shortest in the surface layer. Weak inertial events appeared during strong upwelling events,while strong inertial events appeared during downwelling or weak subinertial events. The near-inertial currents were out of phase between 5 m and 35 m layers for almost the entire measurement period,but such relationship was very weak during periods of irregular weak wind. Strong persistent southerly wind blew from May 12 to 17 and forced a significant water transport onshore and established a strong barotropic poleward jet with a surface speed exceeding 20 cm s-1. The subinertial current was related to wind variation,especially in the middle layers of 15 m and 35 m,the maximum correlation between alongshore current and alongshore wind was about 0.5 at the 5 m layer and 0.8 at the 35 m layer. The alongshore current reacted more rapidly than the cross-shore current. The strongest correlation was found at a time lag of 20 h in the upper layer and of 30 h in the deeper layer. The wind-driven surface velocity obtained from the PWP model had maximum amplitude of about 7 cm s-1,corresponding to a wind stress at 0.1 Pa,and the horizontal velocity shear due to thermal wind balance had the order of 3 cm s-1. So the local wind and thermal wind would only explain a part of the strong surface velocity variations.

Global Distribution of Thermosteric Contribution to Sea Level Rising Trend

The sea level derived from TOPEX/Poseidon （T/P） altimetry data shows prominent long term trend and inter-annual variability. The global mean sea level rising rate during 1993-2003 was 2.9mm a^-1. The T/P sea level trend maps the geographical variability. In the Northern Hemisphere （15°-64°N）, the sea level rise is very fast at the mid-latitude （20°-40°N） but much slower at the high-latitude, for example, only 0.5 mm a^-1 in the latitude band 40°-50°N. In the Southern Hemisphere, the sea level shows high rising rate both in mid-latitude and high-latitude areas, for example, 5.1 mm a^-1 in the band 40°- 50°S. The global thermosteric sea level （TSL） derived from Ishii temperature data was rising during 1993-2003 at a rate of 1.2 mm a^-1 and accounted for more than 40% of the global T/P sea level rise. The contributions of the TSL distribution are not spatially uniform; for instance, the percentage is 67% for the Northern Hemisphere and only 29% for the Southern Hemisphere （15°-64°S） and the maximum thermosteric contribution appears in the Pacific Ocean, which contributes more than 60% of the global TSL. The sea level change trend in tropical ocean is mainly caused by the thermosteric effect, which is different from the case of seasonal variability in this area. The TSL variability dominates the T/P sea level rise in the North Atlantic, but it is small in other areas, and shows negative trend at the high-latitude area （40°-60°N, and 50°-60°S）. The global TSL during 1945-2003 showed obvious rising trend with the rate of about 0.3 mm a-l and striking inter-annual and decadal variability with period of 20 years. In the past 60 years, the Atlantic TSL was rising continuously and remarkably, contributing 38% to the global TSL rising. The TSL in the Pacific and Indian Ocean rose with significant in- ter-annual and decadal variability. The first EOF mode of the global TSL from Ishii temperature data was the ENSO mode in which the time series of the first mode showed steady rising trend. Among the three oceans, the first mode of the Pacific TSL presented the ENSO mode; there was relatively steady rising trend in the Atlantic Ocean, and no dominant mode in the Indian Ocean.

浮车型五模块有轨电车质量均衡计算系统开发

车辆质量管理与计算是整车设计与制造的重要环节,车辆质量分配不均,将影响行车安全。浮车型五模块有轨电车结构特殊,轴重计算相对较复杂,文中首先针对浮车型五模块有轨电车的特殊机构,推导了轴重的计算公式。然后基于Visual Studio平台下C~#语言和SQL SERVER数据库,开发一款浮车型五模块有轨电车的质量均衡计算工具。将计算工具所得计算结果与实际测量数据进行了对比分析,得出计算方法合理,因此,该计算工具可作为浮车型五模块有轨电车设计过程中的质量管理和计算工具。

Current and Thermohaline Characteristics of the Arabian Sea During January 1998

Based on a ship survey during January 1998, the characteristics of the flow, the thermohaline properties and the volume transport of the Arabian Sea are discussed. A strong westward flow exists between 10.5?N and 11?N, part of which turns to the south as the Somali current near the coast at about 10?N and the rest turns north. At the passage between the African continent and the So- cotra Island, the northern branch separates into two flows: the left one enters the passage and the right one flows eastward along the southern slope of the island. Off the island the flow separates once more, most of it meandering northeast and a small fraction flow- ing southeast. Volume transport calculation suggests that the tidal transport is one or two orders of magnitude smaller than the total transport in this region and it becomes more important near the coast. The average velocity of the flow in the upper layer (0-150 m) is about 20 cm s-1, with a maximum of 53 cm s-1 appearing east of the Socotra Island, and the subsurface layer (200-800 m) has an aver- age velocity of 8.6 cm s-1; the velocity becomes smaller at greater depths. The depth of the seasonal thermocline is about 100 m, above which there is a layer with well mixed temperature and dissolved oxygen. High-salinity and oxygen-rich water appears near the surface of the northern Arabian Sea; a salinity maximum and oxygen minimum at 100 m depth along 8?N testifies the subduction of surface water from the northern Arabian Sea. Waters from the Red Sea and the Persian Gulf also influence the salinity of the area.

Establishment of ocean dumping area capacity assessment model

Dumping area capacity is mainly affected by the hydrodynamic process （tidal sediment, storm surge and wave, etc.） as well as the size and depth of dumping area. Based on three-dimensional ocean circulation model known as FVCOM （Finite Volume Coast and Ocean Model） and the stochastic dynamic statistical analysis model, taking advantage of dumping ground topography evolution and dumping quantity, the author aims to discuss the influence of hydrodynamic processes and dumping activity so as to built a new model of ocean dumping area capacity. With the data of depth and dumped amount in the dumping area, the changes of bottom topographic which caused by tidal current under the natural condition based on the FVCOM hydrodynamic and sediment module, the author strive to analyze the statistical relation of the changes for dumping amount, tidal current and bottom topographic. Through real data to fit revision coefficient values, which will be regarded as topographic changes reference value affected by wave and storm surges. Thus taking this evaluation as the long-term changes in the dumping capacity. In the premise of setting up the threshold of bottom topographic changes, the dumping area capacity is calculated. Take Yangtze Estuary No. 1 dumping area as an example, As the water depth reduces by 0.5 m annually, the dumping area capacity is about 6.7 million m3/a, the model results are in reasonable agreement with the actual amount. Then the model is validated in Luoyuan Bay dumping area, Shengsishangchuan Mountain dumping area, Dongding dumping area, Dongshan dumping area, and Wenzhou Port dumoin~ area. it is turns out the results are similar to that of the actual observations.

Preface:The variation of marine environment and climate effect in Indo-Pacific Ocean

In the backgroumd of global change,tbe vanibility of the marine eoviroument and the resulting climate effects in the Asia-Pacifc region and the Indian Ocean have become inceasingly prominent.Tbe research om climate effects has peat research siguificance and national needs.