Weather Induced Quasi-Periodic Motions in Estuaries and Bays:Meteoro-logical Tide

作     者：LI Chun-yan HUANG Wei WU Ren-hao Alex SHEREMET LI Chun-yan;HUANG Wei;WU Ren-hao;Alex SHEREMET

作者机构：College of the Coast and EnvironmentLouisiana State UniversityBaton Rouge 70803USA Virginia Institute of Marine ScienceCollege of William and MaryGloucester Pt.23062USA School of Atmospheric SciencesSun Yat-Sen UniversityZhuhai 519082China Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519082China Engineering School of Sustainable Infrastructure and EnvironmentUniversity of FloridaGainesville FL 32611USA 

出 版 物：《China Ocean Engineering》 (中国海洋工程（英文版）)

年 卷 期：2020年第34卷第3期

页      面：299-313页

核心收录：

学科分类：07[理学] 0707[理学-海洋科学] 

基　　金：The research was financially supported by the National Science Foundation and Natural Environment Research Council(Grant Nos.NSF-NERC 1736713 and NSF-NERC 1737274) Bureau of Ocean Energy Management(Grant No.M15AC000015) NOAA-NOS-IOOS-2016-2004378,through the Northern Gulf Institute by NOAA’s Office of Ocean and Atmospheric Research 

主　　题：meteorological tide atmospheric fronts particle excursion quasi-steady state northern Gulf of Mexico estuarine exchange flows 

摘      要：Influenced by weather, the estuaries and bays often exhibit recurring oscillations in flow and water level similar to astronomical tides. The weather impact however is less regular than tides and more difficult to predict. The spectrum of weather induced motions in estuaries and bays is mostly at the low-frequency end with time scales longer than those of diurnal tides. The repeated weather impact produces meteorological tide: the recurring flood and ebb and flushing of the estuaries and bays but at lower frequencies than those of tides. The variation in weather conditions is quasi-periodic and of large scale nature(~1000-3000 km) because of the alternating low-and high-atmospheric pressure systems of extra-tropical cyclones and anti-cyclones and associated fronts. By examining 40 years of data between Jan. 1, 1977 and Dec. 31, 2016, we identified 1648 frontal events(averaging ~41.2±4.7 per year)influencing the northern Gulf of Mexico for time periods in the spring, fall and winter. The late spring and summer months(May, Jun, July, and August) were not included in the calculation because of much weaker activities involving synoptic weather systems with fronts during these months. It is found that the number of frontal events reached the maximum in Jan. and Dec. while the minimum occurred in April and Sept. It is found that there is an increasing trend of number of fronts over the 40-year period. Our data show that the low pass filtered water level,velocity, and vorticity(velocity shear) all vary in response to the weather and appear as the meteorological tide. The particle excursions of meteorological tides are much larger than those from the astronomical tides. In addition, the irregular nature of the meteorological tide makes the inward flux and outward flux asymmetric in general and thus it has a significant implication to dispersion and transport of waterborne materials. A scaling analysis shows that the meteorological tide generally reaches quasi-steady state;a