Response And Recovery Of Sea Surface Temperature Near Puerto Rico To Hurricanes Irma and Maria, September 2017

Abstract:

In September 2017 Puerto Rico suffered the passage of two major hurricanes, Irma, and Maria. Both were Category 5 hurricanes at some point, however at landfall (Maria) and point of closest approach (Irma) they were Category 4 intensity. The purpose of this study is to examine the response/recovery of regional sea surface temperature (SST) associated with the two hurricanes.

Hurricane Maria made landfall at Yabucoa, Puerto Rico on September 20, 2017 at 1015 UTC. At landfall Hurricane Maria had wind speeds of 135 kt. and an eye diameter of 28 n mi. At 1800 UTC Maria emerged to the Atlantic Ocean with winds of 95kt. after passing across the island on a SE to NW trajectory.

The eye of Hurricane Irma tracked 50n mi to the North of Puerto Rico on September 6-7, 2017. The strongest winds reported on the island occurred at La Puntilla, in San Juan Bay. Winds were sustained at 48 kts with a gust to 64 kts.

SST data for each hurricane were obtained from the National Data Buoy Center (NDBC) website. Five National Ocean Service (NOS) water level stations (MISP4, MGIP4, SJNP4, ESPP4, and CLBP4) around the island and one Caribbean Regional Association for Coastal Ocean Observing (CARICOOS) metocean buoy (41115) provided continuous SST for the hurricane period.

Each hurricane showed a similar drop in SST of approximately 1.5- 2.5°C but had very different recovery times. After the passage of Hurricane Irma, SST recovered to pre-storm levels in approximately 3 days. Recovery to pre-storm levels took almost 7 days following Hurricane Maria.

Elementary heat flux calculations reveal evaporative fluxes similar to that calculated for Hurricane Harvey. Additional SST cooling can be attributed to upwelling.