Observing and Modeling the Response of Placentia Bay to an Extratropical Cyclone

Guangjun Xu,Brad Deyoung,Guoqi Han,Jingsong Yang,Changming Dong

doi:10.3390/atmos10110724

Abstract

An extratropical cyclone reported to have the largest wind speed in Newfoundland in morethan a decade landed on the island of Newfoundland on 11 March 2017. The oceanic responses inPlacentia Bay on the southeast coast of Newfoundland to the winter storm were examined usingobserved data and the Finite-Volume Community Ocean Model (FVCOM). The peak non-tidal waterlevel increase, i.e., storm surge, reached 0.85mat St. Lawrence and 0.77mat Argentia on Placentia Bay.Sea surface temperature slightly decreased after the storm passage according to buoy and satellitemeasurements. Root mean square dierences (RMSD) of the magnitude of storm surge between modelresults and observations are 0.15 m. The model sea surface temperature showed a small decrease,consistent with observations, with RMSDs from 0.19 to 0.64 C at buoy stations. The simulatedsurface current changes agree with buoy observations, with model-observation velocity dierenceratios (VDR) of 0.75–0.88. It was found that, at Argentia (St. Lawrence), the peak storm surge inPlacentia Bay was dominantly (moderately) associated with the inverse barometric eect, and thesubsequent negative surge was mainly due to the wind eect at both stations. The sea surface coolingwas associated with oceanic heat loss. In the momentum balance, the Coriolis, pressure gradient,and advection terms were all important during the storm, while the first two terms were predominantbefore and after the storm.

Highlights

Tropical cyclones and extratropical cyclones can generate strong winds and high coastal storm surges
We consider a storm for further study based on the following criteria: (i) there is a closed low pressure contour with central air pressure less than 1005 hPa, which is generated in the extratropical region from 25◦ N to 55◦ N; (ii) the low-pressure system lasts for at least 24 h; and (iii) the storm track is from southwest to northeast
In the morning of 11 March 2017, the extratropical cyclone arrived on the southwestern Newfoundland Shelf and headed north toward Placentia Bay

Summary

Introduction

Tropical cyclones (such as hurricanes) and extratropical cyclones can generate strong winds and high coastal storm surges. The combination of storm surge and wind waves can produce significant inundation and cause severe damage in coastal zones [1,2]. Placentia Bay is located on the southeast coast of Newfoundland in the northwestern Atlantic. Ocean, bordered by the Avalon Peninsula to the east and the Burin Peninsula to the west It supports essential fisheries such as Atlantic cod [3] and emerging aquaculture. It is an important marine transport route, especially for crude oil tankers. It is important to Atmosphere 2019, 10, 724; doi:10.3390/atmos10110724 www.mdpi.com/journal/atmosphere

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