Predicting the intensity of hurricanes

Thu, 10/15/2020 - 5:15pm

University of Rhode Island Professor of Oceanography Isaac Ginis is a leading figure in predicting the power and intensity of hurricanes. Ginis has been researching their complex powers for over 30 years using computer-based models, with his studies resulting in improvements in hurricane forecasts and providing perspective on the hazards and impacts that arise from hurricanes.

One project Ginis is currently leading, funded by the U.S. Department of Homeland Security, is developing hurricane scenarios for Rhode Island to capture accurate representation of hurricane hazards and impacts, and will serve to better emergency preparedness in the state.

Block Island Times reporter Rosemary Connelli spoke to Ginis about his studies.

Q: Can you tell me a little bit about yourself and how you became involved in the study of hurricanes?

A: I’m a Professor of Oceanography at the Graduate School of Oceanography at URI. I have been at URI for 27 years, and I have been focusing my research on hurricanes for a long time, more than 30 years. I do computer modeling of hurricanes, which is essentially using computer models to predict hurricanes and their intensity. In particular, I have been focusing on the physical processes in hurricanes to better understand what controls the intensity of hurricanes — how strong they are going to be. One of the aspects about hurricanes that we know is that they draw energy from the ocean, particularly from the warm water. That’s the main reason that they develop in the summertime or in the tropics. The warmer the water is, the stronger the storms become. But what was less known is that hurricanes themselves change the temperature of the water. This cooling that hurricanes produce when they move over the ocean is very important to predicting hurricane intensity. What I have been working on to understand is how hurricanes interact with the ocean, and how to predict how the ocean temperature changes underneath the hurricanes. We developed a new model for predicting hurricanes that includes the hurricane model itself, an atmospheric model, but also an ocean model that is attached to the hurricane model. That was developed 20 years ago and that model was adopted by the National Hurricane Center for hurricane predictions. Since then I have been continuing to do research in improving computer models that are used by National Oceanic and Atmospheric Administration, National Hurricane Center, and the US Navy, and continue to work with graduate students and research associates.

Q: When did you become interested in pursuing hurricane studies?

A: I was completing my undergraduate degree in Applied Mathematics back in the Soviet Union — I am originally from Ukraine, which is now an independent country — and one day I heard a lecture someone gave at the university about tropical cyclones. We need to use a lot of mathematical equations [to predict tropical storms], in fact, the computer model is a bunch of mathematical equations. It was very fascinating and I decided to pursue my PhD in studying tropical cyclones. For my PhD, I actually did work studying typhoons in the Pacific Ocean.

Q: Can you describe to me some examples of hurricane hazards and impacts on coastal communities?

A: Hurricanes are known to produce very strong winds and heavy rainfall, and when they come ashore, the wind is one of the most significant hazards, so we need to predict how strong the wind is going to be at different locations. Wind is the main reason for power outages and damages to houses and structures. Now what the wind also does when a hurricane moves ashore, is that it produces the storm surge: the wind blows towards the land, and that causes the water to move ashore from the ocean. Essentially, the water from the sea can get up to 10 to 20 feet, and this is one of the main concerns for coastal flooding and coastal impacts. But, also worrying now more than before is rainfall and the inland flooding that is caused by rain runoff and flash flooding. Over the last several years, we are seeing that the hurricanes that made landfall in the US had slowed down after they came ashore. When a hurricane slows down, it produces even more rain... Most people die in hurricanes from water, not from wind. Flooding is extremely dangerous and unfortunately many people don’t realize how dangerous the water is.

Q: Due to climate change and warming temperatures, do you expect to see the intensity and scale of hurricanes to increase in the future?

A: Yes, definitely. I mentioned that the hurricanes are very much linked to the temperature of the ocean. When the ocean gets warmer, the hurricanes will get more energy, more fuel. We may not see a greater number of storms, but the storms will become more intense. And the hurricanes will also produce more rain because rain comes from the evaporation of the water from the ocean, and so it is also directly linked to the temperature of the ocean. Some people may be skeptical about climate change impact, and ask how scientists know. It’s just a law of physics. This is the same law of physics that we apply to storms now and the same law of physics that we will apply with respect to climate change. We know that the temperature increase of the ocean leads to stronger hurricanes. We know that the high temperature of the water produces more evaporation and more moisture supply into the atmosphere.

Q: Right now, this is the time period for hurricane season in the Atlantic Ocean. Do you think the duration of the hurricane season will extend into the future because of climate change?

A: Our hurricane season now starts officially on June 1, and ends on November 30, although we have seen tropical storms before June and later than November. But with global warming and the temperature of the ocean increasing, we most likely will see the extension of the hurricane season possibly start in May and extend into December. In fact in 2005, we had a hurricane in the Atlantic that developed late in December. It is very likely that we will see longer hurricane seasons and also the temperature will get warmer more to the north. What that means for Rhode Island — hurricanes that will move in our direction to the north will be able to maintain their intensity longer and that would imply that we might see stronger hurricanes in Southern New England. In the historical context, the warmest temperature of the ocean is in the tropics, near Florida and the Gulf of Mexico. When hurricanes move to the north, they experience the colder water and so hurricanes will typically get weaker. The strongest hurricane we have seen in the state was a Category 3 hurricane — intensity goes from Category 1 to Category 5, with 5 being the highest. We have seen Category 3 the highest, but it is very possible that we will see stronger than Category 3 in the future. That’s another concern for us in New England.

Q: What years would you say have been the worst years for hurricanes in Rhode Island?

A: We don’t see hurricanes often in Southern New England, but the last Category 3 hurricane that made landfall in R.I. was Hurricane Carol in 1954, and more recently, we got a pretty significant impact from Hurricane Sandy in 2012. Although the storm made landfall in New Jersey and New York [in 2012], the storm size was so huge that here we had very strong winds. As a result, we had coastal flooding in Matunuck and Westerly, and significant storm surge and damage from beach erosion. We certainly need to be prepared — we are well overdue, statistically speaking, for a significant hurricane impact in R.I. I am particular in emphasizing to the emergency managers in R.I. that we should not look at historical storms and use those storms as an example of what to expect in the future. We do already see the impact from climate change on hurricanes, but also storms have a tendency to slow down. Storms like Hurricane Carol in 1938 were intense but they moved relatively fast through R.I. But we could experience a storm that would slow down and get stuck over R.I. for a day and produce a significant amount of rain. In R.I., our rivers are relatively short and shallow — they could fill up quickly and produce the flooding with a significant amount of rain.

Q: Have any of your studies looked at the impacts of storms on island communities?

A: There are other scientists at URI that have done some work in the past looking at beach erosion… but certainly on the south shore of R.I. This is certainly a very important issue and I think we need to better understand the impact of extreme storms. Not just hurricanes, but Nor’easters. With Block Island, it is exposed to the open ocean and long, high waves. I actually do have another project that is funded by the National Park Service, looking at the impact of Nor’easters on New England parks. We are looking at three parks: Cape Cod National Seashore, Boston Harbor Islands park, and Acadia National Park in Maine. One of the concerns about the climate change that we experience already is that sea level rise will continue, and the combination of sea level rise and storm surge will produce more flooding and impact on coastal communities. We are simulating different sea level rise projections in the future, and will communicate what we find in terms of our simulations to the park managers on how to better prepare for future storms.

Q: Can you briefly explain to me the difference between a Nor’easter and a tropical storm?

A: What we call tropical cyclones are the storms that develop in the tropics during the summertime when the water is warm, and those storms draw their energy from the ocean. Nor’easters, or extra tropical cyclone storms, develop typically in the wintertime and they draw their energy from essentially the differences between the temperature over the land.

The main difference is where they get their energies, because cyclones get their energy from the warm waters of the ocean and Nor’easters get their energy based on the differences in temperature. In terms of hurricanes, Nor’easters are much larger in size and move much slower. That means, they could produce significant damage, power outage, and snow storms. We remember the 1978 famous storm that paralyzed the entire state, and highway I-95 had become a parking lot.

Q: It appears that the type of storms produced depend on the environment, and the temperatures in those environments.

A: Right, it’s also since we are a coastal state and we are right at the boundary between the land and the water — there are temperature differences. When we have cold air sliding down from Canada, the ocean is still much warmer even in the winter time. And this temperature difference is what creates this instability in the atmosphere that triggers the storms.

I was recently asked a question on how climate change could lead to more snow, and the reason is that snow comes from the moisture in the atmosphere. In the summertime, it produces rain, and in the winter it produces snow. But the moisture still comes from the ocean. Essentially, the same moisture that leads to more rainfall in hurricanes is the same moisture that will lead to more snow in the winter in Nor’easters. That’s another connection to climate change. We all enjoy living on the coast, but sometimes we pay a price for enjoying most of it. I think the most important thing for us is to understand what is happening and make sure that we can make predictions ahead of the time for people to better prepare, and for the planning purposes when we build new structures and houses — we need to think about elevating houses, and moving away from the shore.

Q: Did you have any final thoughts or comments you would like to share on your research and the future of hurricanes?

A: I think the main thing I want to convey is that the science we do is not only an academic exercise, but it can be very helpful in terms of future preparation for storms. It’s interesting that my research is very much related to mathematics, physics and computer science — computer models are so complex, and there is a lot of computer engineering and software engineering involved to make the computer models.

Q: Thank you for taking the time to chat with me, Isaac!

A: You’re welcome.