Hurricane Isaac storm surges off Florida observed by Jason-1 and Jason-2 satellite altimeters

Abstract

Storm surges can cause damage to properties and loss of life in coastal communities. Thus it is important to enhance our capabilities of observing, understanding and forecasting storm surges for mitigating damage and loss. Previous studies have shown that cross-shelf altimetric sea surface height profiles can be used to determine storm surge features. In this study we combine satellite altimetry with tide-gauge data to study storm surge features off Florida in the Gulf of Mexico during Hurricane Isaac 2012. Satellite observations show a storm surge of about 0.8 m near Cedar Key and Apalachicola decreasing westward and southward in the early morning of August 28, 2012 (UTC), consistent with tide-gauge measurements. Our analysis of satellite data reveals that the storm surge propagates northward from Naples to Cedar Key with a phase speed of 14–16m/s and a cross-shelf decay scale of 190–220km, in approximate agreement with the estimates from tide-gauge data. In contrast, an analysis of tide-gauge data reveals that the storm surge propagates westward from Apalachicola to Pensacola with a phase speed of 6–7m/s and a cross-shelf decay scale of about 85km. It is further shown that the post-storm sea level variations at these stations are associated with first-mode continental shelf waves. The present study shows that along-shelf altimetric sea surface height profiles can be useful to observe and understand storm surge features as cross-shelf ones demonstrated previously, of importance to improvement of storm surge forecasting. It suggests that a constellation of altimeter missions especially with wide-swath altimetry could be suited to monitor storm surges.