渤海风驱-潮致Lagrange余流的数值模拟与季相时空变异

The spatial distribution and seasonal variation of the tide-induced Lagrangian Residual Circulations (LRC hereafter), wind-driven LRC, and the coupling dynamic characteristics were simulated using ECOM, given the Hellerman and Rosenstein global monthly-mean wind stresses. The results showed that the tide-induced LRC of the harmonic constituent M2 bears an identical pattern in four seasons in the Bohai Sea: the surface one is weak with random directions; however, there exist a southeast current from the Bohai Strait to the Laizhou bay, and a weakly anticlockwise gyre in the south of the Bohai Strait for the bottom layer LRC. The magnitude of bottom layer tide-induced LRC is larger than the surface one, and moreover, it contributes significantly to the whole LRC in the Bohai Sea. Unlike the identical structure of the tide-induced LRC, the wind driven LRC varies seasonally under the prevailing monsoon. It forms a distinct gyre under the summer and winter monsoons in July and January respectively, but it seems weak and non-directional in April and September.     

A model, study on seasonal spatial-temporal variability of the Lagrangian Residual Circulations in the Bohai Sea

1 IntroductionThe BohaiSea is a sem i-closed shallow sea w ith a m ean depth ofaround 20 m ,com posed oftheLiaodong Bay,the BohaiBay,the Laizhou Bay and the BohaiBasin,and connected to the N orthY ellow Sea through a latitudinal strait. The tidal dynam ic…     

A model study on seasonal spatial-temporal variability of the Lagrangian Residual Circulations in the Bohai Sea

The spatial distribution and seasonal variation of the tide-induced Lagrangian Residual Circulations (LRC hereafter), wind-driven LRC, and the coupling dynamic characteristics were simulated using ECOM, given the Hellerman and Rosenstein global monthly-mean wind stresses. The results showed that the tide-induced LRC of the harmonic constituent m2 bears an identical pattern in four seasons in the Bohai Sea: the surface one is weak with random directions; however, there exist a southeast current from the Bohai Strait to the Laizhou bay, and a weakly anticlockwise gyre in the south of the Bohai Strait for the bottom layer LRC. The magnitude of bottom layer tide-induced LRC is larger than the surface one, and moreover, it contributes significantly to the whole LRC in the Bohai Sea. Unlike the identical structure of the tide-induced LRC, the wind driven LRC varies seasonally under the prevailing monsoon. It forms a distinct gyre under the summer and winter monsoons in July and January respectively, but it seems weak and non-directional in April and September.     

Numerical simulation on seasonal transport variations and mechanisms of suspended sediment discharged from the Yellow River to the Bohai Sea

Based on sediment and discharge flux data for the Yellow River, realistic forcing fields and bathymetry of the Bohai Sea, a suspended sediment transport module is driven by a wave-current coupled model to research seasonal variations and mechanisms of suspended load transport to the Bohai Sea. It could be concluded that surface sediment concentration indicates a distinct spatial distribution characteristic that varies seasonally in the Bohai Sea. Sediment concentration is rather high near the Yellow River estuary, seasonal variations of which are controlled by quantity of sediment from the Yellow River, suspended sediment concentration reaches its maximum during summer and fall. Furthermore, sediment concentration decreases rapidly in other seas far from the Yellow River estuary and maintains a very low level in the center of the Bohai Sea, and is dominated by seasonal variations of climatology wind field in the Bohai Sea. Only a small amount of sediments imported from the Yellow River are delivered northwestward to the southern coast of the Bohai Bay. Majority of sediments are transported southeastward to the Laizhou Bay, where sediments are continuously delivered into the center of the Bohai Sea in a northeastward direction, and part of them are transported eastward alongshore through the Bohai Strait. 69% of sediments from the Yellow River are deposited near the river delta, 31% conveyed seaward, within which, 4% exported to the northern Yellow Sea through the Bohai Strait. Wind wave is the most essential contributor to seasonal variations of sediment concentration in the Bohai Sea, and the contribution of tidal currents is also significant in shallow waters when wind speed is low.     

黄河入海悬沙季节输送变化与输送机制的数值研究(英文)

Based on sediment and discharge flux data for the Yellow River, realistic forcing fields and bathymetry of the Bohai Sea, a suspended sediment transport module is driven by a wave-current coupled model to research seasonal variations and mechanisms of suspended load transport to the Bohai Sea. It could be concluded that surface sediment concentration indicates a distinct spatial distribution characteristic that varies seasonally in the Bohai Sea. Sediment concentration is rather high near the Yellow River estuary, seasonal variations of which are controlled by quantity of sediment from the Yellow River, suspended sediment concentration reaches its maximum during summer and fall. Furthermore, sediment concentration decreases rapidly in other seas far from the Yellow River estuary and maintains a very low level in the center of the Bohai Sea, and is dominated by seasonal variations of climatology wind field in the Bohai Sea. Only a small amount of sediments imported from the Yellow River are delivered northwestward to the southern coast of the Bohai Bay. Majority of sediments are transported southeastward to the Laizhou Bay, where sediments are continuously delivered into the center of the Bohai Sea in a northeastward direction, and part of them are transported eastward alongshore through the Bohai Strait. 69% of sediments from the Yellow River are deposited near the river delta, 31% conveyed seaward, within which, 4% exported to the northern Yellow Sea through the Bohai Strait. Wind wave is the most essential contributor to seasonal variations of sediment concentration in the Bohai Sea, and the contribution of tidal currents is also significant in shallow waters when wind speed is low.     

基于GIS和AIS的渤海海上船舶活动时空特征分析

基于2018年海上船舶自动识别系统(Automatic Identification System, AIS)数据,借助GIS空间分析方法,对渤海海上船舶位置及密度、船舶速度等空间分布特征以及船舶流量日、月和季节变化的时间特征进行分析,得到以下结论：① 渔业船舶多活动于近岸海域,呈团聚状分布;商业船舶多聚集在公共航道区,整体呈带状分布;货船数量占商业船舶总量的78.58%,主要为中型货船,客船与油轮以中小型船舶所占比重相对较大。② 渤海船舶速度以中低速为主,尤其是渔业船舶;较高速度的船舶主要是大中型货船和客船。③ 渔业船舶活动时间和季节变化特征显著,秋季休渔期结束后以及白天工作时间段渔船活动较频繁;与渔业船舶相比,渤海商业船舶活动受季节变化和昼夜交替影响较小。分析发现,渤海交通流密度高,船舶会遇频繁,发生船舶碰撞以及重大污染事故的风险较大;东西向和南北向的海上交通与渔业捕捞作业船舶之间存在较大的海域空间利用冲突,需要引起足够的重视。自然环境与资源条件、沿岸社会经济发展与港口建设、海域管制等因素影响海上船舶时空分布。     

近55年宁夏秋季降水的时空变化特征及其大尺度环流背景

利用1951-2005年宁夏秋季降水、SST、NCEP/NCAR全球再分析资料及74个环流特征量,使用REOF、小波变换、相关分析等多种统计方法,分析了宁夏秋季降水的时空变化特征及其与SST和北半球500 hPa高度场的遥相关.结果表明:近55年,宁夏秋季降水呈下降趋势,异常敏感区在宁夏北部和六盘山区;1979年前后发生突变,突变后降水明显减少,有显著的3年和6年左右周期变化;加利福尼亚西岸海区是影响宁夏秋季降水的SST关键区,3～5月是关键期,SST冷(暖)水位相与宁夏秋季降水偏多(少)相对应;3～5月加利福尼亚西岸海区SST在1979年前后发生突变,突变前后北半球中低纬度地区500 hPa高度场变化显著,新疆脊、西太平洋副高和印缅槽是宁夏秋季降水的主要影响系统.     

1950~2011年渤海地区海表风场的季节特征与多尺度变化分析

基于1950~2011年的NCEP/NCAR再分析资料,对渤海10 m风场的风速与风向变化进行多尺度分析。利用小波分析、交叉谱分析等方法对渤海海域的海表风速、风向的变化趋势以及周期进行研究。分析发现：渤海地区海表风的风向与风速除了存在显著的季节性变化特征外,在年际、年代际的变化尺度上也有明显的周期性。风向存在1 a、8.7 a、15.8 a的显著周期,风速存在1 a、6.3 a、15 a的显著周期。风向与风速在时间尺度分别为20 a、5.71 a、2.67 a时存在显著共振周期;共振周期受东亚季风、西太平副热带高压的年际、年代际变化的影响呈现出多尺度变化周期。     

近50年长江中下游地区夏季气温变化与环流异常

Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the middle and lower reaches of the Yangtze River (MLRYR) and the related circulation anomalies in the Eastern Hemisphere. Our results have demonstrated that a significantly increasing trend is observed in daily minimum temperature in the past 50 years. And in some regions in the Northern Hemisphere, the opposite scenarios are observed in circulation anomalies in lower and upper parts of the troposphere in the years when the temperatures are higher than normal, as compared to those in the years when the temperatures are lower than normal in the middle and lower reaches of the Yangtze River (MLRYR). Additionally, the anomalous circulation structure in vertical direction in both the high and lower temperature years are barotropic. It is found that the emergence and maintenance of the aforementioned anomalous circulations are related to three kinds of wave train teleconnection patterns. Further more, influences of the long wave surface radiation on the air temperature are stronger in the nighttime than that in the daytime. While both the maximum and minimum temperatures have negative relationships with the sensible heat flux but positive relationships with the latent heat flux. To some extent, the anomalous dynamic heating (cooling) caused by the vertical thermal advection as well as the diabatic heating (cooling) caused by diabatic processes can explain the formation of the high (low) temperature events in the middle and lower reaches of the Yangtze River (MLRYR) in boreal summer.     

Summertime temperature variations in the middle and lower reaches of Yangtze River and their related circulation anomalies in the past five decades

Using the daily data of temperature from China Meteorological Administration and the NCEP/NCAR reanalysis from 1960 to 2005, we have analyzed the relationships between the summertime high/low temperature events in the middle and lower reaches of the Yangtze River (MLRYR) and the related circulation anomalies in the Eastern Hemisphere. Our results have demonstrated that a significantly increasing trend is observed in daily minimum temperature in the past 50 years. And in some regions in the Northern Hemisphere, the opposite scenarios are observed in circulation anomalies in lower and upper parts of the troposphere in the years when the temperatures are higher than normal, as compared to those in the years when the temperatures are lower than normal in the middle and lower reaches of the Yangtze River (MLRYR). Additionally, the anomalous circulation structure in vertical direction in both the high and lower temperature years are barotropic. It is found that the emergence and maintenance of the aforementioned anomalous circulations are related to three kinds of wave train teleconnection patterns. Further more, influences of the long wave surface radiation on the air temperature are stronger in the nighttime than that in the daytime. While both the maximum and minimum temperatures have negative relationships with the sensible heat flux but positive relationships with the latent heat flux. To some extent, the anomalous dynamic heating (cooling) caused by the vertical thermal advection as well as the diabatic heating (cooling) caused by diabatic processes can explain the formation of the high (low) temperature events in the middle and lower reaches of the Yangtze River (MLRYR) in boreal summer.