Spatio-temporal variability of oceanographic conditions in the Exclusive Economic Zone of Cuba

In this work we assessed the spatio-temporal variability of the oceanographic conditions in the period 1998–2017 in four sectors of the Exclusive Economic Zone (EEZ) of Cuba, referred to as the northwest, northeast, southwest and southeast sectors (i.e., NWS, NES, SWS and SES, respectively). We relied upon remote-sensing observations of wind speed, sea surface temperature (SST), sea surface height anomaly (SSHA) and chlorophyll-a (chl-a) concentration along with model predictions of mixed layer depth (MLD), nitrate concentration and net primary production (NPP). We found evidence of the spatially heterogeneous oceanographic conditions of the EEZ of Cuba, since the analysed variables fluctuated spatially with meridional and zonal gradients. Overall, the southern sectors were warmer and less productive than the northern ones, thereby showing the influence of the Caribbean Sea. The NWS showed the highest variability of the physical and biological variables analysed, given the convergence of the Caribbean and the Gulf of Mexico waters and the Loop Current variability. The NES was strongly influenced by coastal conditions given its limited area and long coast line. Besides, a significant decadal increase in SSHA was linked to that in SST. Still, this warming trend was not reflected in the chl-a concentration and NPP trends, which is consistent with the fact that there has been no change over the studied 20 years in mean wind regime and MLD. Furthermore, the strong El Niño Southern Oscillation events of 1997–1998 and 2015–2016 appear to have considerably impacted the surface chl-a concentration, which was partially governed by the variability of the MLD

The Impact of Hurricanes on the Oceanographic Conditions in the Exclusive Economic Zone of Cuba

In this work, we analysed the satellite-based responses of sea surface temperature (SST) and chlorophyll-a (chl-a) concentration in the waters of the Exclusive Economic Zone (EEZ) of Cuba to hurricanes that crossed the EEZ between 1998 and 2016. We considered two spatial scales to capture the spatially heterogeneous nature of the effects of hurricanes. A first more fine-grained one where we considered 120 km radius disks centered at every consecutive hurricane position within the EEZ (scale 1) and a second more coarse grained one enclosing the entire EEZ (scale 2). We conclude that the hurricanes induced a weak cooling since 75 and 85% of the SST anomalies at scale 1 and 2, respectively, were smaller than -1{\deg}C. The cooling was mainly caused by the wind, inducing mixing and/or upwelling of subsurface cool waters. The maximum chl-a responses were recorded in the first and second post-storm weeks, with 60% ranging between -0.01 and 0.04 mg m$^{-3}$ at scale 1, and between -0.07 and 0.02 mg m$^{-3}$ at scale 2. During those post-storm weeks SST and chl-a anomalies were 18 and 44% higher at scale 1 than at scale 2, respectively. We argue that the transport of chl-a from the deep chlorophyll maximum and/or the rich coastal waters are the dominant mechanisms determining the post-storm chl-a response in the EEZ. We also found that the magnitude of the Island Mass Effect in the EEZ after the passage of the hurricanes was 89% higher than before its passage.Comment: 33 pages, 14 figures. Submitted to Remote Sensing of Environmen

Oceanic response to the consecutive Hurricanes Dorian and Humberto (2019) in the Sargasso Sea

Understanding the oceanic response to tropical cyclones (TCs) is of importance for studies on climate change. Although the oceanic effects induced by individual TCs have been extensively investigated, studies on the oceanic response to the passage of consecutive TCs are rare. In this work, we assess the upper-oceanic response to the passage of Hurricanes Dorian and Humberto over the western Sargasso Sea in 2019 using satellite remote sensing and modelled data. We found that the combined effects of these slow-moving TCs led to an increased oceanic response during the third and fourth post-storm weeks of Dorian (accounting for both Dorian and Humberto effects) because of the induced mixing and upwelling at this time. Overall, anomalies of sea surface temperature, ocean heat content, and mean temperature from the sea surface to a depth of 100 m were 50 %, 63 %, and 57 % smaller (more negative) in the third-fourth post-storm weeks than in the first-second post-storm weeks of Dorian (accounting only for Dorian effects), respectively. For the biological response, we found that surface chlorophyll a (chl a) concentration anomalies, the mean chl a concentration in the euphotic zone, and the chl a concentration in the deep chlorophyll maximum were 16 %, 4 %, and 16 % higher in the third-fourth post-storm weeks than in the first-second post-storm weeks, respectively. The sea surface cooling and increased biological response induced by these TCs were significantly higher (Mann-Whitney test, p < 0.05) compared to climatological records. Our climatological analysis reveals that the strongest TC-induced oceanographic variability in the western Sargasso Sea can be associated with the occurrence of consecutive TCs and long-lasting TC forcing

The impact of hurricanes on the oceanographic conditions in the Exclusive Economic Zone of Cuba

In this work, we analysed the satellite-based responses of sea surface temperature (SST) and chlorophyll-a (chl-a) concentration in the waters of the Exclusive Economic Zone (EEZ) of Cuba to hurricanes that crossed the EEZ between 1998 and 2016 as well as the environmental drivers governing the post-storm responses. We considered two spatial scales to capture the spatially heterogeneous nature of the effects of hurricanes. A first more fine-grained one where we considered 120 km radius disks centered at every consecutive hurricane position within the EEZ (scale 1) and a second more coarse grained one enclosing the entire EEZ (scale 2). We conclude that the hurricanes induced a weak cooling since 75 and 85% of the SST anomalies at scale 1 and 2, respectively, were smaller than -1 degrees C. The sea surface cooling was mainly caused by wind-driven processes. The maximum chl-a responses were recorded in the first and second post-storm weeks, with 60% ranging between -0.01 and 0.04 mg m(-3) at scale 1, and between -0.07 and 0.02 mg m(-3) at scale 2. During those post-storm weeks SST and chl-a anomalies were 18 and 44% higher at scale 1 than at scale 2, respectively. We argue that the transport of chl-a from the deep chlorophyll maximum and/or the rich coastal waters are the dominant mechanisms determining the post-storm chl-a response in the EEZ. We also found that the magnitude of the Island Mass Effect (i.e., increase of chl-a concentration in waters surrounding islands) after the passage of the hurricanes was 89% higher in the EEZ than before its passage