Journal
CHINA OCEAN ENGINEERING
Volume 34, Issue 3, Pages 299-313Publisher
CHINA OCEAN PRESS
DOI: 10.1007/s13344-020-0028-2
Keywords
meteorological tide; atmospheric fronts; particle excursion; quasi-steady state; northern Gulf of Mexico; estuarine exchange flows
Funding
- National Science Foundation [NSF-NERC 1736713, NSF-NERC 1737274]
- Natural Environment Research Council [NSF-NERC 1736713, NSF-NERC 1737274]
- Bureau of Ocean Energy Management [M15AC000015]
- Northern Gulf Institute by NOAA's Office of Ocean and Atmospheric Research [NOAA-NOS-IOOS-2016-2004378]
Ask authors/readers for more resources
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 (approximate to 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 approximate to 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; and as a result, a regression model is established which can be very useful for predicting the weather produced quasi-periodic motions.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available