Spatial and Temporal Features of Synoptic and Mesoscale Variability of the Baltic Sea Level

The spatial and temporal features of synoptic and mesoscale variability of the Baltic Sea level are studied using long-term hourly data. The spectral analysis revealed significant difference in the structure of the sea level spectra between the Gulf of Bothnia and the Gulf of Finland. The maximum variance of the synoptic sea level variability is observed at the head of the Gulf of Bothnia and in the southwestern part of the Baltic Sea, whereas the maximum variance of mesoscale variability is registered at the head of the Gulf of Finland and in the southwestern part of the sea. The minimum variance of synoptic sea level variability was observed in the Gulf of Bothnia in the 1950s–1960s, and the maximum was recorded at the beginning and at the end of the 20th century. The series of interdecadal variability of synoptic sea level fluctuations have a weak negative trend up to ?0.11 cm²/year in Kungsholmfrost. A significant qualitative and quantitative correlation was detected between the interannual variability of variance of mesoscale sea level variations in the Gulf of Finland (Gornyi Institut) and the Gulf of Riga (Parnu) and the interannual variability of the NAO index.     

Retrospective and prospective model simulations of sea level rise impacts on Gulf of Mexico coastal marshes and forests in Waccasassa Bay, Florida

The State of Florida (USA) is especially threatened by sea level rise due to extensive low elevation coastal habitats (approximately 8,000?km²?<?1?m above sea level) where the majority of the human population resides. We used the Sea Level Affecting Marshes Model (SLAMM) simulation to improve understanding of the magnitude and location of these changes for 58,000?ha of the Waccasassa Bay region of Florida??s central Gulf of Mexico coast. To assess how well SLAMM portrays changes in coastal wetland systems resulting from sea level rise, we conducted a hindcast in which we compared model results to 30?years of field plot data. Overall, the model showed the same pattern of coastal forest loss as observed. Prospective runs of SLAMM using 0.64?m, 1?m and 2?m sea level rise scenarios predict substantial changes over this century in the area covered by coastal wetland systems including net losses of coastal forests (69%, 83%, and 99%, respectively) and inland forests (33%, 50%, and 88%), but net gains of tidal flats (17%, 142%, and 3,837%). One implication of these findings at the site level is that undeveloped, unprotected lands inland from the coastal forest should be protected to accommodate upslope migration of this natural community in response to rising seas. At a broader scale, our results suggest that coastal wetland systems will be unevenly affected across the Gulf of Mexico as sea level rises. Species vulnerable to these anticipated changes will experience a net loss or even elimination.     

Comparison of three methods for estimating the sea level rise effect on storm surge flooding

Two linear methods, including the simple linear addition and linear addition by expansion, and numerical simulations were employed to estimate storm surges and associated flooding caused by Hurricane Andrew for scenarios of sea level rise (SLR) from 0.15 m to 1.05 m with an interval of 0.15 m. The interaction between storm surge and SLR is almost linear at the open Atlantic Ocean outside Biscayne Bay, with slight reduction in peak storm surge heights as sea level rises. The nonlinear interaction between storm surges and SLR is weak in Biscayne Bay, leading to small differences in peak storm surge heights estimated by three methods. Therefore, it is appropriate to estimate elevated storm surges caused by SLR in these areas by adding the SLR magnitude to storm surge heights. However, the magnitude and extent of inundation at the mainland area by Biscayne Bay estimated by numerical simulations are, respectively, 22–24 % and 16–30 % larger on average than those generated by the linear addition by expansion and the simple linear addition methods, indicating a strong nonlinear interaction between storm surge and SLR. The population and property affected by the storm surge inundation estimated by numerical simulations differ up to 50–140 % from that estimated by two linear addition methods. Therefore, it is inappropriate to estimate the exacerbated magnitude and extent of storm surge flooding and affected population and property caused by SLR by using the linear addition methods. The strong nonlinear interaction between surge flooding and SLR at a specific location occurs at the initial stage of SLR when the water depth under an elevated sea level is less than 0.7 m, while the interaction becomes linear as the depth exceeds 0.7 m.     

The influence of momentum advection on the Baltic Sea dynamics

Contribution of momentum advection to the formation of the low frequency fields of the Baltic Sea levels and currents is estimated using numerical experiments with a hydrodynamic model and statistical analysis of the experimental results. It is found that momentum advection has a significant influence on the formation of the mean level and its seasonal and synoptic variability in Neva Bay of the Gulf of Finland. The results show that nonlinear effects associated with advective accelerations can essentially contribute to the Neva River flood formation.     

Simulations of Hurricane Katrina (2005) under sea level and climate conditions for 1900

Global warming may result in substantial sea level rise and more intense hurricanes over the next century, leading to more severe coastal flooding. Here, observed climate and sea level trends over the last century (c. 1900s to 2000s) are used to provide insight regarding future coastal inundation trends. The actual impacts of Hurricane Katrina (2005) in New Orleans are compared with the impacts of a similar hypothetical hurricane occurring c. 1900. Estimated regional sea level rise since 1900 of 0.75 m, which contains a dominant land subsidence contribution (0.57 m), serves as a ‘prototype’ for future climate-change induced sea level rise in other regions. Landform conditions c. 1900 were estimated by changing frictional resistance based on expected additional wetlands at lower sea levels. Surge simulations suggest that flood elevations would have been 15 to 60 % lower c. 1900 than the conditions observed in 2005. This drastic change suggests that significantly more flood damage occurred in 2005 than would have occurred if sea level and climate conditions had been like those c. 1900. We further show that, in New Orleans, sea level rise dominates surge-induced flooding changes, not only by increasing mean sea level, but also by leading to decreased wetland area. Together, these effects enable larger surges. Projecting forward, future global sea level changes of the magnitude examined here are expected to lead to increased flooding in coastal regions, even if the storm climate is unchanged. Such flooding increases in densely populated areas would presumably lead to more widespread destruction.     

Crossings of ice-bound sea surfaces in history

Seven more-or-less well documentated cases of the use made of icebound sea areas in winter for the purposes of warfare are reviewed. The sea-ice crossings took place in 1495, 1577, 1581, 1658, 1809, 1940, and 1943, i.e. the first five occurred during the Little Ice Age. A book authored by a prominent Swedish personality (Archbishop Olaus Magnus) and published in 1555 says that warfare on frozen sea areas in winter by the Muscovites (Russians) and Swedes was as common as warfare by ships on the open seas in summer. There are indications of some crossings of ice-bound seas prior to 1495 and not necessarily for warlike activities. It seems that the Vikings too did some sea-ice crossings.The crossings of 1495, 1577, 1581, and 1940 involved the Gulf of Finland, that of 1809 the Gulf of Bothnia and the Aaland Islands area of the Baltic, that of 1658 the Danish Belts, and that of 1943 the Gulf of Taganrog in the Sea of Azov. In the first three cases the powers concerned were Muscovy (Russia) and Sweden which for centuries were fighting for supremacy in the Baltic and over the routes from the inner Baltic (Gulf of Finland and Bay of Riga) to western Europe. The case of 1809 involved, again, Russia and Sweden, though in the background of the conflict between the two were wider European issues of the Napoleonic wars. The 1658 crossing of the frozen-over Danish Belts was accomplished by the Swedes, forcing the Danes into submission: In the ensuing Peace Treaty Sweden for the first time in her history achieved her present territorial extent in the Scandinavian Peninsula. The case of 1940 was connected with the 1939–40 Winter War of Soviet Russia against Finland. The crossing of 1943 was made by German forces retreating from the Caucasus under the pressure of Soviet forces in World War II.The crossings of 1577, 1581, 1658, 1809, 1940, and 1943 took place between late in January and late in March; the case of 1495 appears to have taken place early in the winter season: probably late in November. Since in the period 1931–60 no part of the Gulf of Finland froze over before about the middle of December, the early date of the crossing of 1495 is possibly one of the many indications of cold winters during the Little Ice Age.     

On the problem of the Neva river flood waves identification

Based on the analysis of the measurements of hydrometeorological characteristics, the identification is corroborated of the Neva River flood waves as the baroclinic topographic waves. It is demonstrated that during the formation and maximum development of the most significant sea level rises in the Neva Bay, the stratification in the Gulf of Finland still remains pronounced despite the storm conditions. The baroclinic nature of the flood wave is indicated by the significant changes in the dispersion of currents with depth with their direction changing to the reverse one as it occurs in the first baroclinic mode wave. Directions of major axes of the standard deviation ellipses are oriented not along the isobaths as it should be in case of long gravity waves (being the longitudinal ones) but are extended across the bottom topography contours that is typical of gradient-vorticity waves assigned to the class of horizontal transverse waves.     

Currents along the pacific coast of Canada

Abstract

A powerful storm passed over the coastal waters of eastern Canada on the 21 and 22 January 2000 causing significant damage to coastal infrastructure. The storm generated a large (>1.4 m) storm surge in the southern Gulf of St. Lawrence that unfortunately coincided with a high spring tide. This resulted in record high water levels in the southern Gulf of St. Lawrence (e.g., the highest level at Charlottetown since records began in 1911) and severe flooding around Prince Edward Island and along the eastern shore of New Brunswick.

During January 2000, a recently developed storm surge forecast system was running in pre‐operational mode at Dalhousie University. The core of the forecast system is a depth‐averaged, non‐linear, barotropic ocean model driven by forecast winds and air pressures produced by the Canadian Meteorological Centre's regional atmospheric forecast model. In this study we assess the forecast skill of the surge model for the 21 January storm by comparing its 24‐hour forecasts with two independent hourly dataseis: (i) sea levels recorded by 12 tide gauges located in eastern Canada and the north‐eastern United States, and (ii) depth‐mean currents recorded by an acoustic Doppler current profiler deployed on the outer Scotian Shelf. Overall, the forecasts of coastal sea level and depth‐mean currents are reasonable and have forecast errors below about 0.1 m and 0.1 m s^?1 respectively.     

Sea level history of the northern Gulf of Mexico coast and sea level rise scenarios for the near future

The sea level history of the northern Gulf of Mexico during recent geologic time has closely followed global eustatic sea level change. Regional effects due to tectonics and glacio-isostasy have been minimal. Over the past several million years the northern Gulf coast, like most stable coastal regions of the globe, has experienced major swings of sea level below and above present level, accompanied by major shifts in shoreline position. During advances of the northern hemisphere ice sheets, sea level dropped by more than 100 m, extending the shoreline in places more than 100 km onto the shelf. For much of the period since the last glacial maximum (LGM), 20,000 years ago, the region has seen rates of sea level rise far in excess of those experienced during the period represented by long-term tide gauges. The regional tide gauge record reveals that sea level has been rising at about 2 mm/year for the past century, while the average rate of rise since the LGM has been 6 mm/year, with some periods of abrupt rise exceeding 40 mm/year. During times of abrupt rise, Gulf of Mexico shorelines were drowned in place and overstepped. The relative stability of modern coastal systems is due primarily to stabilization of sea level approximately 6,000 years ago, resulting in the slow rates of rise experienced during historic time. Recent model projections of sea level rise over the next century and beyond may move northern Gulf coastal environments into a new equilibrium regime, more similar to that experienced during the deglaciation than that which has existed during historic time.     

辽宁省蓝莓潜在适生区

依据蓝莓生物学特性和环境要求,建立起包含地形、土壤、气候三方面共11个指标的辽宁省蓝莓潜在适生区评价指标体系,综合运用层次分析法、地理信息系统空间分析技术、系统聚类分析法,开展辽宁省蓝莓潜在适生区划研究。结果表明：①基于地形、土壤、气候条件的辽宁省蓝莓种植适生区面积分别占辽宁省总面积的81.68%、60.86%、78.16%,土壤条件对蓝莓潜在分布具有明显的限制作用;②从综合区划来看,辽宁省蓝莓适生区面积约为7.628×104km2,占辽宁省总面积的51.54%,主要分布于辽东半岛、辽河平原大部地区以及辽东湾西部沿海地区,其中辽河平原地区作为粮食主产区,不建议大规模发展蓝莓产业,建议将辽东半岛和辽东湾西部沿海地区作为辽宁省蓝莓产业发展的重点地区;③运用系统聚类法,将辽宁省59个县（市）区进行了二级区划,分为潜在适生区3个亚区和非适生区2个亚区,其中潜在适生区第1亚区在自然条件上具备明显的种植优势,非适生区第2亚区蓝莓种植条件最不理想。区划结果与现有蓝莓种植区较为吻合,可为辽宁省蓝莓产业规划提供科学依据。     

Assessment of temporal and spatial inhomogeneity of waters in the Nevskaya Guba Bay and Eastern Gulf of Finland from hydrochemical indicators

Hydrochemical inhomogeneity of waters in the Nevskaya Guba Bay and adjoining water areas of the Gulf of Finland is assessed with a principal component method. The application of the method made it possible to beforehand divide the period of study (1978–1996) into stages and then to single out hydrochemical zones that are formed under the impact of the main factors that take into account the interrelations of 17 water quality indicators. It is demonstrated that spatial water area inhomogeneity at different stages of construction of special structures to protect the city against floods, increased volumes of biologically treated waste waters, and changed sizes of dumping of polluted subsoil is related to various hypothetical factors reflecting different processes in the water body. Whereas before 1993 natural processes of organic matter production and destruction were leading in zone formation, at later stages it was the composition of treated waste waters and processes of the secondary water pollution with phosphate, lead, and cadmium.     

Implications of recent sea level rise science for low-elevation areas in coastal cities of the conterminous U.S.A.

Recently published work estimates that global sea level rise (SLR) approaching or exceeding 1 m by 2100 is plausible, thus significantly updating projections by the Fourth Assessment of the Intergovernmental Panel on Climate Change. Furthermore, global greenhouse gas (GHG) emissions over the 21st century will not only influence SLR in the next ??90 years, but will also commit Earth to several meters of additional SLR over subsequent centuries. In this context of worsening prospects for substantial SLR, we apply a new geospatial dataset to calculate low-elevation areas in coastal cities of the conterminous U.S.A. potentially impacted by SLR in this and following centuries. In total, 20 municipalities with populations greater than 300,000 and 160 municipalities with populations between 50,000 and 300,000 have land area with elevations at or below 6 m and connectivity to the sea, as based on the 1 arc-second National Elevation Dataset. On average, approximately 9% of the area in these coastal municipalities lies at or below 1 m. This figure rises to 36% when considering area at or below 6 m. Areal percentages of municipalities with elevations at or below 1?C6 m are greater than the national average along the Gulf and southern Atlantic coasts. In contrast to the national and international dimensions of and associated efforts to curb GHG emissions, our comparison of low-elevation areas in coastal cities of the conterminous U.S.A. clearly shows that SLR will potentially have very local, and disproportionate, impacts.     

中国沿海风能分布特征及其影响因子的数值模拟

利用欧洲中期天气预报中心0.75°×0.75°再分析资料,对中国海岸线两侧相邻区域内的风能、风速进行研究,讨论不同季节、不同区域风能、风速的分布特征;利用WRF(Weather Research Forecast)模式模拟海表面温度上升和城市化发展对中国东部沿海风能的影响。结果表明:1)中国沿海风能的时空分布不均一,季节变化明显。春季渤海湾区域风能明显大于其他三区(华东沿海、东南沿海和南海北部沿海区域)。夏季渤海湾区域风能显著小于其他三区,而华东沿海区域风能稍大。秋季东南沿海和南海北部沿海区域风能较大。冬季沿海四区风能大小接近。一般而言,秋冬季风能较大、春夏季风能较小,夏季风能显著小于冬季。2)不同区域、不同季节风速的年际变化存在明显差异。除冬季东南沿海区域风速有增大趋势外,其他区域各季节风速都呈缓慢减小趋势,但减小幅度很小。3)海表温度升高在不同季节对风速的影响不同。春季渤海湾和山东半岛、北部湾沿海及杭州湾风速随海温升高而增强。夏季海温升高幅度不同,则风速显著变化区域不同,但大部分沿海区域风速随海温升高而增强。秋冬季风速随海表温度升高而增强,影响区域较稳定:秋季东南沿海和华东沿海区域风速增强,冬季渤海湾和南海北部沿海区域风速增强。4)城市化发展增大了地表摩擦力,使得夏秋季登陆我国的热带气旋迅速减弱,沿海风速随之减小。     

The potential impacts of sea level rise on the coastal region of New Jersey,USA

This study presents an assessment of the potential impacts of sea level rise on the New Jersey, USA coastal region. We produce two projections of sea level rise for the New Jersey coast over the next century and apply them to a digital elevation model to illustrate the extent to which coastal areas are susceptible to permanent inundation and episodic flooding due to storm events. We estimate future coastline displacement and its consequences based on direct inundation only, which provides a lower bound on total coastline displacement. The objective of this study is to illustrate methodologies that may prove useful to policy makers despite the large uncertainties inherent in analysis of local impacts of climate and sea level change. Our findings suggest that approximately 1% to 3% of the land area of New Jersey would be permanently inundated over the next century and coastal storms would temporarily flood low-lying areas up to 20 times more frequently. Thus, absent human adaptation, by 2100 New Jersey would experience substantial land loss and alteration of the coastal zone, causing widespread impacts on coastal development and ecosystems. Given the results, we identify future research needs and suggest that an important next step would be for policy makers to explore potential adaptation strategies.     

基于CMIP5模式的中国地区未来洪涝灾害风险变化预估

利用22个CMIP5全球气候模式模拟结果,结合社会经济以及地形高度数据,分析了RCP8.5温室气体排放情景下21世纪近期（2016-2035年）、中期（2046-2065年）和后期（2080-2099年）中国洪涝致灾危险性、承灾体易损性以及洪涝灾害风险。结果表明,洪涝灾害危险等级较高的地区集中在中国的东南部,洪涝承灾体易损度高值区位于中国的东部地区。在RCP8.5情景下,未来我国洪涝灾害高风险区主要出现在四川东部、华东的大部分地区、华北的京津冀地区、陕西和山西的部分地区以及东南沿海部分地区。东北地区的各大省会城市面临洪涝灾害的风险也很高。与基准期（1986-2005年）相比,21世纪后期,虽然发生洪涝灾害的区域变化不大,但高风险区域有所增加。鉴于模式较粗的分辨率以及确定权重系数的方法学等问题,洪涝灾害风险的预估还存在较大的不确定性。     

广东后汛期季风槽暴雨天气形势特征分析

对1981-2002年广东后汛期季风槽暴雨期间的环流形势和天气系统进行了统计分析,结果发现,广东后汛期的季风槽暴雨多数发生在西太平洋副高位置偏东或偏南的情况下,并与中纬西风槽或ITCZ有直接联系;季风槽多数位于华南地区上空或华南沿岸海面;高层辐散覆盖广东全部或大部,中心在华南近海。西南季风向北推进源于西南和华南地区低压槽发展,或由于热带气旋登陆后北上而牵动西南季风深入华南陆地,也有些过程是副高西端的偏南气流引导南海季风北进。对流活动有从南海北部或北部湾附近向华南移动的趋势,并有昼夜变化。     

Simulation and Analysis of Sea Floods in the Don River Delta

Storm surges and wind waves in the Taganrog Bay (the Sea of Azov) are simulated with the ADCIRC+SWAN numerical model, and the mechanisms of the Don River delta flooding are analyzed. It is demonstrated that the most intensive flooding of the Don River delta occurs in case of southwestern wind with the speed of not less than 15 m/s. A storm surge leads to the intensification of wind waves in the whole Taganrog Bay due to the general sea level rise. As a result, the significant wave height near the Don River delta increases by 0.5–0.6 m.     

The stochastic weather model in the system of deterministic and stochastic modeling of runoff and nutrient load

The estimation is carried out of the distribution functions of annual runoff and nutrient load on the Russian part of the Gulf of Finland (the Baltic Sea) formed by different pollution sources. The stochastic weather model is used for the estimation.     

基于城市内涝仿真模型的天津风暴潮灾害评估

基于城市内涝仿真模型,根据天津沿海地区的地形、地貌特征以及排水系统等对城市内涝仿真模型进行改进,在沿海边界和河口设置时变水位,使得模型拓展到既能模拟暴雨产生的内涝,也能模拟由于风暴潮侵袭造成的淹没情景。该模型对天津沿海地区历史上典型风暴潮个例以及10年、20年、50年、100年一遇重现期风暴潮产生的积水范围和积水深度进行了模拟,并对2012年8月3日台风达维 (1210) 造成的天津沿海风暴潮进行了业务试应用。将历史风暴潮个例模拟结果以及2012年8月3日的评估结果与实际灾情进行对比,结果显示模型具有较好的模拟能力,可应用于风暴潮灾害的评估和预估业务中,为相关部门和行业提供决策参考。     

Seasonal variations of oceanic conditions near the southeastern coast of Sakhalin Island

Seasonal variations of hydrological conditions in the area adjoining the southeastern coast of Sakhalin Island are described based on the analysis of monthly mean temperature and salinity obtained over standard oceanic sections Makarov-Cape Georgii and Cape Svobodny-the sea and from nine oceanic surveys. The Poronai River runoff that promotes the formation of a warm surface layer with low salinity largely influences the water area of Terpeniya Bay in the northern part of the area studied. In spring, these waters primarily spread southward along the coast; in summer, they flow southeastward, forming a weak vortex structure at 144° E. In the fall, major changes occur below 20 m, where waters of the cold intermediate layer are replaced by warmer waters (4–6°C) of low salinity connected with the Amur River runoff. The destruction of the CIL core near the shelf edge at depths of about 100 m resulting from the fall intensification of the East Sakhalin Current is pronounced in the southern, abyssal part of the region. The coastal area is covered by waters with salinity below 32‰ connected with the Amur River runoff. The volume of low-salinity waters coming through the Cape Svobodny-the sea section into the southern part of the Sea of Okhotsk is estimated at 3000 km³ taking into account instrumental measurements of flow rates.