Intensity fluctuations in Hurricane Irma (2017) during a period of rapid intensification

Intensity fluctuations observed during a period of rapid intensification of Hurricane Irma (2017) between 04 September and 06 September were investigated in a detailed modelling study using an ensemble of Met Office Unified Model (MetUM) convection permitting forecasts. These intensity fluctuations consisted of alternating weakening and strengthening phases. During weakening phases the tropical cyclone temporarily paused its intensification. It was found that weakening phases were associated with a change in the potential vorticity structure, with a tendency for it to become more monopolar. Convection during strengthening phases was associated with isolated local regions of high relative vorticity and vertical velocity in the eyewall, while during weakening phases the storm became more azimuthally symmetric with weaker convection spread more evenly. The boundary layer was found to play an important role in the cause of the intensity fluctuations with an increase in the agradient wind within the boundary layer causing a spin--down just above the boundary layer during the weakening phases whereas during the strengthening phases the agradient wind reduces. This study offers new explanations for why these fluctuations occur and what causes them.

Integrating storm surge modeling with traffic data analysis to evaluate the effectiveness of hurricane evacuation

An integrated storm surge modeling and traffic analysis were conducted in this study to assess the effectiveness of hurricane evacuations through a case study of Hurricane Irma. The Category 5 hurricane in 2017 caused a record evacuation with an estimated 6.8 million people relocating statewide in Florida. The Advanced Circulation (ADCIRC) model was applied to simulate storm tides during the hurricane event. Model validations indicated that simulated pressures, winds, and storm surge compared well with observations. Model simulated storm tides and winds were used to estimate the area affected by Hurricane Irma. Results showed that the storm surge and strong wind mainly affected coastal counties in south-west Florida. Only moderate storm tides (maximum about 2.5 m) and maximum wind speed about 115 mph were shown in both model simulations and Federal Emergency Management Agency (FEMA) post-hurricane assessment near the area of hurricane landfall. Storm surges did not rise to the 100-year flood elevation level. The maximum wind was much below the design wind speed of 150–170 mph (Category 5) as defined in Florida Building Code (FBC) for south Florida coastal areas. Compared with the total population of about 2.25 million in the six coastal counties affected by storm surge and Category 1–3 wind, the statewide evacuation of approximately 6.8 million people was found to be an over-evacuation due mainly to the uncertainty of hurricane path, which shifted from south-east to south-west Florida. The uncertainty of hurricane tracks made it difficult to predict the appropriate storm surge inundation zone for evacuation. Traffic data were used to analyze the evacuation traffic patterns. In south-east Florida, evacuation traffic started 4 days before the hurricane’s arrival. However, the hurricane path shifted and eventually landed in south-west Florida, which caused a high level of evacuation traffic in south-west Florida. Over-evacuation caused Evacuation Traffic Index (ETI) to increase to 200% above normal conditions in some sections of highways, which reduced the effectiveness of evacuation. Results from this study show that evacuation efficiency can be improved in the future by more accurate hurricane forecasting, better public awareness of real-time storm surge and wind as well as integrated storm surge and evacuation modeling for quick response to the uncertainty of hurricane forecasting.

MDPrePost-Net: A Spatial-Spectral-Temporal Fully Convolutional Network for Mapping of Mangrove Degradation Affected by Hurricane Irma 2017 Using Sentinel-2 Data

Mangroves are grown in intertidal zones along tropical and subtropical climate areas, which have many benefits for humans and ecosystems. The knowledge of mangrove conditions is essential to know the statuses of mangroves. Recently, satellite imagery has been widely used to generate mangrove and degradation mapping. Sentinel-2 is a volume of free satellite image data that has a temporal resolution of 5 days. When Hurricane Irma hit the southwest Florida coastal zone in 2017, it caused mangrove degradation. The relationship of satellite images between pre and post-hurricane events can provide a deeper understanding of the degraded mangrove areas that were affected by Hurricane Irma. This study proposed an MDPrePost-Net that considers images before and after hurricanes to classify non-mangrove, intact/healthy mangroves, and degraded mangroves classes affected by Hurricane Irma in southwest Florida using Sentinel-2 data. MDPrePost-Net is an end-to-end fully convolutional network (FCN) that consists of two main sub-models. The first sub-model is a pre-post deep feature extractor used to extract the spatial–spectral–temporal relationship between the pre, post, and mangrove conditions after the hurricane from the satellite images and the second sub-model is an FCN classifier as the classification part from extracted spatial–spectral–temporal deep features. Experimental results show that the accuracy and Intersection over Union (IoU) score by the proposed MDPrePost-Net for degraded mangrove are 98.25% and 96.82%, respectively. Based on the experimental results, MDPrePost-Net outperforms the state-of-the-art FCN models (e.g., U-Net, LinkNet, FPN, and FC-DenseNet) in terms of accuracy metrics. In addition, this study found that 26.64% (41,008.66 Ha) of the mangrove area was degraded due to Hurricane Irma along the southwest Florida coastal zone and the other 73.36% (112,924.70 Ha) mangrove area remained intact.

Biogeochemical responses of a highly polluted tropical coastal lagoon after the passage of a strong hurricane (Hurricane Irma)

Laguna Larga (Cayo Coco, Cuba) is a eutrophic coastal lagoon due to tourism development. As part of long-term monitoring of Laguna Larga, we were able to follow the lagoon's water quality from 2015 to 2018 and could assess the impacts of Hurricane Irma (September 8–9, 2017) by intensifying our sampling frequency. Physicochemical parameters (salinity, pH, dissolved oxygen, dissolved inorganic nitrogen, dissolved reactive silicate and total nitrogen) exhibited significant variations associated with hurricane Irma. Salinity decreased due to the extraordinary rainfall of the hurricane (339.8 mm/24 h, a new record for Cayo Coco). The water level in the lagoon rose 0.85 m. Strong hurricane winds and intense runoff drove organic matter and sediment resuspension. Anoxia and an increase of nutrients occurred throughout the lagoon. The main biogeochemical impact was that it boosted these eutrophic conditions of the lagoon, to levels that lasted for several months. A significant correlation among nutrients, salinity and dissolved oxygen was found. After 6 months, water quality in the lagoon had recovered to conditions similar to those before the hurricane. The case of Laguna Larga sustains those coastal systems under anthropic pressure that can take longer to recover after extreme climatic events, and highlights the need for long-term monitoring of tropical coastal ecosystems.

Comprehensive Analyses of Twitter for Hurricane Irma

This study sheds new light on the sentiment analysis of Twitter for Hurricane Irma with respect to the US states and different periods based on comprehensive analyses. This study finds that tweets are highly related to Florida since the state is the most damaged state with respect to Hurricane Irma. This study also finds that people in other regions posted numerous tweets regarding praying for the people who are damaged by the hurricane and trying to assist in some disaster relief. Next, this study shows that the proportion of tweets is differentiated by periods and regions. In the pre-hurricane period, tweets are heavily concentrated in the South region. In the hurricane period, tweets are highly located in the Southeast and the Northeast regions. In the post-hurricane period, tweets are more posted in the Northeast region. Lastly, this study highlights that people upload numerous tweets including keywords related to regions, such as “Florida”, “Miami”, and keywords related to the hurricane, such as “safe”, “prepare”, and “evacuate”. People are also highly interested in the US president’s action to cope with the Hurricane Irma.

Health Effects of Power Loss After Hurricane Irma on Nursing Home Residents in Florida

Previous research establishes that hurricanes adversely affect nursing home (NH) resident health but specific causal pathways are still unclear. We combined power outage data with Medicare claims to determine the effects of power loss from Hurricane Irma(2017) among NH residents in Florida. Out of 580 facilities, 289 reported power loss. These facilities had higher star ratings; higher beds counts, and were preferentially in the Southeast region of Florida compared to facilities without outages. There were 27,767 residents living in a NH without power. They were comparable in characteristics to residents that did not lose power (N=26,383). We ran adjusted generalized linear models with robust standard errors, clustering for NH. We found power loss was associated with a trend towards increased odds of mortality within 7-days (OR:1.12, 95% CI:0.96, 1.30) and 30-days (OR:1.10, 95% CI:1.00, 1.21) post-storm, but not with hospitalization. Future research should investigate the time-specific effects of power outages.

Nurse Staffing in Nursing Homes During Hurricane Irma

Little is known about the effect of hurricanes on nurse staffing in nursing homes. Hurricane Irma made landfall on September 10th, 2017 in Florida. This study examined daily nurse staffing levels from September 3rd-24th, 2017 in 653 nursing homes; 81 facilities evacuated and 572 facilities sheltered-in-place. Data from Payroll-Based Journaling (PBJ), Certification and Survey Provider Enhanced Reports (CASPER), and Florida’s health providers’ emergency reporting system were used. Among all facilities, we found significant increases in staffing for licensed practical nurses (p=.02) and certified nursing assistants (p<.001), but not for registered nurses (p=.10) before Hurricane Irma made landfall. In comparison to facilities that sheltered-in-place, evacuating facilities increased staffing levels of all nurse types (all p<.001). From one week before landfall to two weeks after landfall, an additional estimated $2.41 million was spent on nurse staffing. Policymakers attempting to reduce the burden of natural disasters on nursing homes should reimburse staffing-related expenses.

Excess Mortality Attributed to Hurricane Irma Among Assisted Living Residents With Chronic Conditions in Florida

Little is known about the impact of hurricanes on residents in assisted living communities (ALs), especially among individuals with chronic conditions that increase their risk of death after storms. We examined how the association between exposure to Hurricane Irma in 2017 and mortality differed by select chronic conditions. With Medicare data, we identified cohorts of AL residents in 2015 (n= 30,712) and 2017 (n= 29,842 ) and compared their rates of 30-day and 90-day and mortality. We adjusted rates for demographic characteristics and other comorbidities. AL residents with diabetes were at highest risk of death after the storm; between 2015 and 2017 they experienced a 50% increase in their 30-day mortality rates (0.6% in 2015, 0.9% in 2017) and a 43% increase in their 90-day mortality rates (2.1% in 2015, 3.0% in 2017). Policy makers should consider strategies to ensure that diabetic residents maintain continuity of medical care during disasters.

The Difference LTC Corporate Ownership Makes in Collaborations With Emergency Operation Centers During Disasters

Collaboration between nursing homes (NHs) and assisted living communities (ALCs) with state and local entities (e.g., emergency operation centers (EOCs)) is critical during a disaster. The corporate structure of NHs and ALCs can make a difference in their ability to collaborate with these entities during a disaster. This mixed-method study examines differences in satisfaction with collaboration with state and local entities during Hurricane Irma in Florida in 2017 between corporate-owned NHs (N=24), larger (25+ beds) ALCs (N=38) and smaller ALCs (N=30). We also explore collaboration in Florida NHs (N=35) and ALCs (N=123) specific to COVID19. Scaled 1-5 survey data results indicate that small ALCs are the least satisfied (M=2.90) with EOC collaboration, compared to NHs (M=3.04) and larger ALCs (M=3.33) during Irma. Smaller ALCs were more dissatisfied with COVID19 mandates compared to larger ALCs and NHs. Ways to improve collaboration during a disaster, especially for smaller ALCs, will be discussed.

Multiple Perspectives on Disaster Preparedness in Long-Term Care: From Heat to Hospice

Preparedness of residents in long-term care (LTC) exposed to disasters continues to warrant concern. Prior work by our research team highlights explicit evidence of the profound vulnerability of Florida nursing home (NH) residents exposed to Hurricane Irma in 2017. This research adds to our knowledge of the profound effect of disasters on long term care residents. This symposium will utilize mixed methodologies to discuss the varied effects of Hurricane Irma on vulnerable older adults residing in Florida NHs and Assisted Living communities (ALCs). Using a novel methodology for identifying a cohort of ALC residents, the first presentation will present the morbidity and mortality effects of Hurricane Irma on Florida ALC residents and identify high risk groups by health condition. The second presentation will document the effect of Hurricane Irma on NH Residents previously enrolled in Hospice and expound on the effect of the disaster on hospice enrollment after the storm. The third presentation will present qualitative results of interviews with ALC administrators highlighting the effect of the storm on both large and small (<25 beds) facilities. The fourth presentation will address the issue of heat exposure in the days after Hurricane Irma and consider the preventative effect of generators on morbidity and mortality. Finally, a fifth presentation will examine NH staffing level variation in the days leading to the hurricane. To conclude, this symposium offers a multi-faceted view of a disaster’s effects on LTC residents across Florida, including novel data from the NH environment and lesser-examined ALCs.