Contrasting Hydrodynamic Responses to Atmospheric Systems with Different Scales: Impact of Cold Fronts vs. That of a Hurricane

Wei Huang,Chunyan Li

doi:10.3390/jmse8120979

Abstract

In this paper, subtidal responses of Barataria Bay to an atmospheric cold front in 2014 and Hurricane Barry of 2019 are studied. The cold fronts had shorter influencing periods (1 to 3 days), while Hurricane Barry had a much longer influencing period (about 1 week). Wind direction usually changes from southern quadrants to northern quadrants before and after a cold front’s passage. For a hurricane making its landfall at the norther Gulf of Mexico coast, wind variation is dependent on the location relative to the location of landfall. Consequently, water level usually reaches a trough after the maximum cold front wind usually; while after the maximum wind during a hurricane, water level mostly has a surge, especially on the right-hand side of the hurricane. Water level variation induced by Hurricane Barry is about 3 times of that induced by a cold front event. Water volume flux also shows differences under these two weather types: the volume transport during Hurricane Barry was 4 times of that during a cold front. On the other hand, cold front events are much more frequent (30–40 times a year), and they lead to more frequent exchange between Barataria Bay and the coastal ocean.

Highlights

The coast of Louisiana in the northern Gulf of Mexico (NGOM) is characterized by semi-enclosed bays with exchange flows of water through multiple inlets, such as Lake Pontchartrain, Calcasieu Lake, Vermillion Bay, and Barataria Bay
The NGOM has several major environmental processes that are determined by hydrodynamics, those related to the exchange of water and sediment between estuaries and shelf water, e.g., the significant land loss around lower Mississippi River basin associated with processes that cause erosion and sediment transport [1,2,3,4,5,6]
During the cold front event in January 2014, the results indicate that water volume flux through Barataria Pass was the largest

Summary

Introduction

The coast of Louisiana in the northern Gulf of Mexico (NGOM) is characterized by semi-enclosed bays with exchange flows of water through multiple inlets, such as Lake Pontchartrain, Calcasieu Lake, Vermillion Bay, and Barataria Bay. A recent study [50] investigated the weather-induced exchange flows through multiple inlets of the Barataria Bay in a few months period in 2013, 2014, and 2015 with 51 atmospheric cold fronts passing the Louisiana coast. These events are apparently very common: an analysis [51] covering a period of 40 years identified more than 1600 atmospheric frontal events, with an average of ~41.2 ± 4.7 per year excluding the months between May and August for much weaker activities of this kind. The goals are to (1) compare the hydrodynamic responses to different weather systems (cold front and hurricane), (2) examine water exchange between Barataria Bay and coastal ocean through multiple inlets under the different weather systems, and (3) assess the quasi-steady state balance under different weather systems

Study Site and Data

Model Setup

Model Validation

Conclusions