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1.
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. 相似文献
2.
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. 相似文献
3.
V. S. Nikiforovskaya 《Russian Meteorology and Hydrology》2009,34(12):810-817
The results of mathematical modeling of the unsteady water motion in the Tom River over the section between the town of Tomsk
and the river mouth, when it is under pressure head of the Ob River flood waves, are presented. The research is performed
based on the analysis of field materials, numerical computation results of field and hypothetical hydrological regimes simulating
the process of interaction of long waves of the Ob and Tom rivers in the region of their confluence. Mathematical modeling
is performed with the help of mathematical models of the river channel “Tom” and “Confluence” in order to reveal a possible
formation on the Tom River of a counterflow under extreme conditions connected with the joint impact of anthropogenic and
natural factors. 相似文献
4.
1998年长江流域降水致洪的评估 总被引：6，自引：2，他引：4
通过１９５１年以来长江流域１０个大水年的降水量手对比,对１９９８年长江流域降水致洪进行了评估。结果表明,１９９８年长江大水与１９５４年一样,是一次全流域性的大水年,降水总量接近１９５４年,强于其它大水库。 相似文献
5.
E. A. Zakharchuk A. S. Kudryavtsev V. N. Sukhachev 《Russian Meteorology and Hydrology》2014,39(2):100-108
The features of the spatiotemporal variability of the sea level in the North and Baltic seas during the periods of formation of major Baltic inflows are investigated using the analysis of satellite altimetry data. It is demonstrated that dramatic drops in the sea level between the Baltic and North seas are observed during a few weeks before major inflows. A process of intensive inflows of the North Sea water to the Baltic Sea is accompanied not only by horizontal motions but also by vertical ones manifested in the increase in convergent flows in the North Sea and divergent flows in the Baltic Sea. A pronounced feature of the low-frequency dynamics of water of the North and Baltic seas is its wave structure. In both seas, low-frequency waves with the periods of 14–36 days propagate with the eastern component of the phase velocity along the isobaths and are identified as barotropic topographic Rossby waves. Phase velocities and lengths of low-frequency waves in the Baltic Sea are smaller by several times than those in the North Sea. Using the data of the analysis of meteorological information, a resonance-wave mechanism of generation of major Baltic inflows is studied. 相似文献
6.
E. S. Nesterov Z. K. Abuzyarov G. A. Grigor’eva I. N. Davidan V. I. Dymov T. A. Pasechnik 《Russian Meteorology and Hydrology》2011,36(10):669-676
An estimate of the computation accuracy of wind waves is obtained on the basis of three mathematical models used for the diagnosis and forecast of wind waves at the Hydrometcenter of Russia, US National Weather Service, and European Centre for Medium-Range Weather Forecasts. The accuracy estimation was carried out for the whole year 2006 by means of the comparison of model computations based on different wind fields with hourly instrumental observations of waves at 16 buoys in the North Atlantic. The computation accuracy was estimated on the basis of six statistical characteristics. Besides, the estimates for various wave height ranges for months and seasons of the year are made for all buoys and grouped into three geographical areas: the coasts of the United States, Canada, and Great Britain. The essential differences are revealed in the accuracy of model-based computation of waves in the areas of the ocean with different wind wave regimes, in different seasons of the year, and within various wave height ranges. The obtained results indicate the necessity to improve the present-day methods of diagnosis and forecast of wind waves. 相似文献
7.
M. V. Shmakova 《Russian Meteorology and Hydrology》2012,37(2):145-147
A mathematical model of water and solid matter motion is proposed in a three-dimensional formulation. Interrelated calculation
of variables describing the state of the water flow and the flow of solid matter is presented. Bottom sediment resistance
to the flow motion is presented by such characteristics of the soil as the coefficient of internal friction of the soil and
cohesive force of the soil at shear. Computation results for 60-km reach of the Neva River are given as an example of model
calculation. 相似文献
8.
The water dynamics in the straits between the North and Baltic seas during two major Baltic inflows that took place in the January of 1993 and 2003 is investigated using satellite altimetry data. It is found that the water mass surge to the eastern coast of the North Sea occurs before the beginning of the major Baltic inflow, and the sea level difference between the two seas is ~60 cm. Low-frequency fluctuations in the sea level and its wave parameters are studied. The wavelet analysis and the frequency-directed spectral analysis reveal the wave nature of the mechanisms leading to major Baltic inflows. The empirical characteristics of the obtained low-frequency waves are compared with the theoretical dispersion relations for the gradient-vorticity waves. Sea level variations during major Baltic inflows in the Danish Straits are identified as baroclinic Rossby waves. The analysis of cyclonic activity in the Northern Hemisphere demonstrated that stationary cyclones were observed during the inflows; this proves the feasibility of the resonance mechanism of the generation of major Baltic inflows. 相似文献
9.
The regularities of changes in the parameters of the hydrological regime of the Lower Volga are considered using data of routine observations at gaging stations and data of field studies carried out by the specialists of Zubov State Oceanographic Institute in 2006–2017. The main modern trends are revealed for runoff and water level, water temperature, and ice phenomena as well as for the duration of flooding of the Volga-Akhtuba floodplain during the spring flood. The parameters are compared for natural and regulated Volga River runoff conditions. It is shown that considerable variation in the duration of flooding of floodplains, in water temperature, and heat flow during the spring flood under modern conditions is caused both by runoff operation and by increase in the anthropogenic load on the area of the Volga-Akhtuba floodplain in the recent decades. 相似文献
10.
Considered is a dangerous ice phenomenon developing in the Neva River during its freezing, the formation of the intrawater
ice resulting in the corking of water intakes, and ice jams causing a sharp water runoff decrease downstream of them and floods.
Described are the forecasting techniques of the intrawater ice formation intensity, peak ice jam water levels, and thickness
of ice jams. 相似文献
11.
利用蒲河流域内所有国家气象站以及区域自动气象站共28站逐小时降水实况、过程降水量、数字高程模型、土地利用、土壤类型等资料,采用FloodArea水动力模型,对2020年6月19日21时-22日20时出现的历史罕见暴雨洪涝过程进行洪水淹没模拟及效果检验。模拟结果表明：1)全过程模拟水位与实测水位整体拟合度较高,确定性系数DC达93.22%;2)蒲河上游来水较小,持续性强降水是造成此次洪涝水位偏高的主要原因,模拟显示蒲河流域中上游水位上涨明显,其中石角水文站模拟的最大上涨水位达7.61米,与实测上涨水位7.14米较为一致;3)FloodArea水动力模型能够较准确地反演出蒲河流域暴雨致洪个例的淹没进程,能够直观地反映出淹没范围、淹没深度的空间差异,且淹没深度与逐小时实测水位的确定性系数较高,淹没深度的突增对洪峰的预报预警具有一定的指示意义。 相似文献
12.
A. V. Rozhdestvenskii V. A. Buzin T. L. Shalashina 《Russian Meteorology and Hydrology》2010,35(1):54-61
The genesis of the formation of maximum water levels of the Lena River near Yakutsk is considered. Recovery techniques of
series of hydrological characteristics is briefly stated. Observational data on maximum water levels are reduced to the long-term
period, an estimation of their homogeneity and stationarity is carried out. The recomputation of maximum water levels of 1%
probability taking account of extreme historical levels is executed. As a result, the mark of calculated 1% maximum water
level (97.34 m, Baltic System) is obtained, which is 0.98 m higher than the one given in hydrological handbooks [1, 6]. 相似文献
13.
It is demonstrated that the greatest influence of the variations in the groupiness of storm waves in the Baltic Sea concerns the highest waves. The variations in the height of less high waves are defined by wind speed. It is revealed that the height of 3% of the highest waves depends on their bandwidth: higher and lower waves are characterized by the larger and smaller set of frequencies, respectively. The significant wave height does not almost depend on the bandwidth. It is found that the spectrum of storm waves in the southwestern part of the Baltic Sea has a multi-peak structure which reflects the complex structure of waves consisting of several wave systems. Envelopes and individual waves of different frequency ranges superimpose, and extreme waves are generated. The probability of occurrence of extreme waves is maximum at the moments of the maximum development of wave groupiness. 相似文献
14.
利用1951—2004年我国740站逐日降水资料对夏季长江中下游典型旱涝年季节内振荡周期、强度和位相等特征进行合成对比分析发现:长江中下游涝年降水季节内振荡周期较旱年长, 涝年以30~60 d周期为主, 而旱年以10~30 d周期为主。旱涝年长江中下游地区夏季降水的10~30 d振荡整体上均强于30~60 d振荡; 10~30 d及30~60 d振荡, 涝年的强度都大于旱年。季节内振荡在旱年的北传较涝年强, 能达到50°N附近; 而涝年不仅有明显的季节内振荡从低纬度地区向北传播, 同时还有弱的振荡从中高纬度地区向南传播, 两者汇合于长江流域形成强的振荡中心。影响我国低频降水的低频异常环流分布模态在旱涝年是一致的, 但涝年的低频环流强于旱年, 而这种低频环流场的差异正是造成涝年的低频降水强于旱年的原因之一。 相似文献
15.
Scale analyses for long wave, zonal ultralong wave (with zonal scale of disturbance L1~104 km and meridional scale L2~103 km) and meridional ultralong wave (L1~103 km, L2~104 km) are carried out and a set of approximate equations suitable for the study of these waves in a dry tropical atmosphere is obtained. Under the condition of sheared basic current, frequency analyses for the equations are carried out. It is found that Rossby waves and gravity waves may be separated for n ≥ l where n is the meridional wave number, whereas for n = 0 and L1~1000 km, the mixed Rossby-gravity wave will appear. Hence it is confirmed that the above results of scale analyses are correct. The consistency be-tween frequency analysis and scale analysis is established.The effect of shear of basic current on the equatorial waves is to change their frequencies and phase velocities and hence their group velocities. It increases the velocity of westward travelling Rossby waves and inertia-gravity and mixed waves, but decelerates the eastward inertia-gravity waves and the Kelvin wave. The recently observed low-frequency equatorial ocean wave may be interpreted as an eastward Kelvin wave in a basic current with shear. 相似文献
16.
The river ice regime is considered a sensitive indicator of climate change and within this study long term changes (in case of River Daugava starting from 1530, but for other studied rivers starting from first half of twentieth century) river ice regimes in the Baltic region have been studied. The ice cover duration on the rivers (17 rivers) in the Baltic countries and Belarus has decreased during the recent decades. In addition to this, long term observational records of ice break on the rivers of the studied region exhibit a pattern of periodic changes in the intensity of ice regime. Both the ice regime and the seasonal river discharge are shown to be strongly influenced by large-scale atmospheric circulation processes over North Atlantic that manifests through close correlation with North Atlantic Oscillation index. 相似文献
17.
对流层上层斜压波包活动与2003年江淮流域梅雨的关系 总被引：7，自引：3，他引：4
利用NCEP/NCAR再分析和中国740站逐日降水资料, 研究了2003年淮河流域梅雨期间对流层上层斜压波动的传播情况。结果发现, 斜压波组织成波包向下游传播且具有明显的下游频散效应。波动起源于巴尔喀什湖西北侧, 沿着西北－东南向的路径向东南传播, 传至江淮流域大约需要3天。斜压波包所带来的扰动能量为江淮流域暴雨的发生发展提供了必要的能量积聚。通过与1998和1997年这两个梅雨年份的比较, 发现1998年异常强梅雨年的斜压波包的活动特征与2003年的相似, 但在梅雨降水非常偏少的1997年, 未发现有明显的斜压波包向下游的传播。 相似文献
18.
19.
A system of hydrographs’ quantitative parameters for the flood discharges and stages in the Lower Volga River and its delta
was developed. Water releases from the Volzhskaya Hydropower Plant and floods in the upper sections of the Volga River delta
caused by those releases were identified and grouped in accordance with their water content; their parameters were computed
for the entire period of the runoff managing (i.e., since 1961). In addition, parameters of typical hydrographs, which were
averaged for different categories of water content, were computed and their graphical models were plotted. Quantitative and
qualitative estimates of changes in shape of the discharge hydrographs in the Lower Volga were obtained for different flood
types, while for the water stage hydrographs in the Lower Volga and its delta, only quantitative estimation was carried out. 相似文献
20.
夏秋季长江、黄河流量长期变化的主要特征 总被引：18，自引：0，他引：18
利用20世纪后50 a或更长时间的水文资料,研究长江、黄河夏秋季流量长期演变的主要特征。统计分析得出:长江、黄河夏秋季流量都占年总量的一半以上,月均流量和标准差均为其他月份的2.6倍或更大。长江夏秋季流量的标准差约为其多年平均流量的22.1％,黄河则为58.8％。长江夏秋季的平均流量约为黄河的15.7倍,相应标准差为5.9倍。二者相比,长江流量大而稳定,黄河流量比长江小1个量级,而相对变化幅度大一倍以上。黄河流量自20世纪30年代中期至1968年正距平为主,累积距平曲线持续上;而自1985年至今负距平占绝对优势,流量逐年下降,下游频频断流。利用Petitt计算变点的方法可以找出长江、黄河流量以往主要的显著变点。利用快速富利叶计算法,对黄河流量进行谐波分析,得出黄河流量在未来几年内将逐渐增加。 相似文献