Satellite science improves storm surge forecasting around the world

A new online resource which will help coastguards, meteorological organisations and scientific communities predict future storm surge patterns has been created. The freely-accessible database of storm surge data has been compiled through the multi-partner, international eSurge project, which was launched in 2011 with the aim of making available observational data to improve the modelling and forecasting of storm surges around the world using advanced techniques and instruments.  

The freely-accessible database of storm surge data has been compiled through the multi-partner, international eSurge project, which was launched in 2011 with the aim of making available observational data to improve the modelling and forecasting of storm surges around the world using advanced techniques and instruments.
Coastal altimetry, which provides detailed wave and sea level data in the coastal zone captured by specialist instruments called radar altimeters on board satellites, is at the heart of the project and scientists from NOC have been at the cutting-edge of this technique.
Raw data collected from altimeters have been re-processed and collated with wind speed data from scatterometers and sea level measurements from tide gauges, to show the spatial structure of each storm. With eSurge, forecasters and scientists can now download these enhanced data and use them for validating their storm surge models and for mapping future storms more accurately.
Dr Paolo Cipollini from NOC explained: "When a satellite altimeter overpasses the area affected by a surge, it gives us a unique profile of the water surface level from offshore to the coast, as well as concurrent measurements of wave height. This information is extremely useful to validate the surge models used for forecasts. Even when there doesn't happen to be an overpass at surge time, the statistics of sea level that we got from more than 20 years of repeated altimetric observations in the area can still be combined with data from nearby tide gauges to improve the forecasts of the expected surge."
This is the first time that such a detailed level of storm information has been collated and demonstrated as one comprehensive online resource. Data from around 200 storms spanning more than 10 years is now accessible, including major events such as Hurricane Katrina, which devastated New Orleans in the USA in 2005, Typhoon Haiyan in the Philippines -- one of the strongest tropical cyclones ever recorded -- and the major winter storm that caused widespread flooding in the UK in December 2013.
The eSurge project, which is funded by the European Space Agency, has also demonstrated the feasibility of offering near-real time data about recent and predicted storms, which can be viewed on the new eSurgeLive web page.
Findings of the three year project were presented at a symposium hosted in the Netherlands in January 2015. The partners are now looking at the possibility of extending the project and further developing the eSurge resource into a fully-operational, permanent service in the future.
As well as providing and analysing data for the eSurge project, NOC has also played a key role in opening up the findings to a wider global audience. In addition to providing data, scientists at NOC have also helped to build an online storm surge community, which enables scientists, storm modellers and users around the world to be better connected.
Head of Marine Physics and Ocean Climate (MPOC) at NOC, Professor Kevin Horsburgh, added: "Storm surges are a global hazard that pose a threat to thousands of lives, and coastal flood forecasting systems can save lives and protect property. Satellite altimetry methods developed at NOC play a crucial role in helping improve storm surge models and map out regional changes in mean sea level."
NOC is one of five international organisations involved in the eSurge project, which also includes CGI (UK), the Danish Meteorological Institute (DK), the Coastal and Marine Research Centre (IRL) and the Royal Dutch Meteorological Institute (NL).

This story is taken from Science Daily

Greenland Ice: The warmer it gets the faster it melts

Melting of glacial ice will probably raise sea level around the globe, but how fast this melting will happen is uncertain. In the case of the Greenland Ice Sheet, the more temperatures increase, the faster the ice will melt, according to computer model experiments by geoscientists. 

"Although lots of people have thought about sea level rise from the ice sheets, we don't really know how fast that will happen," said Patrick Applegate, research associate, Penn State's Earth and Environmental Systems Institute.
If all the ice in the Greenland Ice Sheet melts, global sea level would rise by about 24 feet. In the last 100 years, sea level in the New York City area has only increased by about one foot. However, storm surges from hurricanes stack on top of this long-term increase, so sea level rise will allow future hurricanes to flood places where people are not ready for or used to flooding. A vivid example occurred during Hurricane Sandy when parts of the New York City subway tunnel system flooded.
Greenland might be especially vulnerable to melting because that area of Earth sees about 50 percent more warming than the global average. Arctic sea ice, when it exists, reflects the sun's energy back through the atmosphere, but when the sea ice melts and there is open water, the water absorbs the sun's energy and reradiates it back into the air as heat. Arctic sea ice coverage has decreased over the last few decades, and that decrease will probably continue in the future, leading to accelerated temperature rise over Greenland. Floating ice does not add to sea level, but the Greenland Ice Sheet rests on bedrock that is above sea level.
Feedbacks in the climate system cause accelerated temperature rise over the Arctic. Other feedbacks in the Greenland Ice Sheet that contribute to melting include height-melting feedback. A warm year in Greenland causes more melt around the edges of the ice sheet, lowering the surface. The atmosphere is warmer at lower altitudes, so the now lower surface experiences even more melting. This process can lead to accelerated ice melt and sea level rise.
Another form of feedback occurs because ice sheets are large masses that want to spread. This spreading can either help preserve the ice sheet by allowing it to adjust to increased temperature or accelerate ice melting by moving ice to lower, warmer, places.
"Many studies of sea level rise don't take into account feedbacks that could cause rapid sea level rise," said Applegate. "We wanted to look at the effects of those feedbacks."
The researchers looked at two models of the Greenland ice sheet that include some of the important feedbacks. The first model is a three-dimensional ice sheet model. The second model looks at a transect across the island and was developed by Byron Parizek, associate professor of geosciences and mathematics, Penn State Dubois. To run both models, Robert Nicholas, research associate, EESI, estimated how much warming might take place over Greenland using results from global climate models.
Both the three-dimensional and transect models showed that the time necessary for ice mass loss from the Greenland ice sheet decreases steeply with increases in temperature. Shorter time scales -- faster melting -- imply faster sea level rise. The interplay between the height-melting feedback and ice flow causes this acceleration.
"Our analysis suggests that the benefits of reducing greenhouse gas emissions, in terms of avoided sea level rise from the Greenland Ice Sheet, may be greatest if emissions reductions begin before large temperature increases have been realized," the researchers state in a recent issue of Climate Dynamics.
Currently, about a billion people live in areas that would be flooded by a three-foot sea level rise.
"If we are going to do something to mitigate sea-level rise, we need to do it earlier rather than later," said Applegate. "The longer we wait, the more rapidly the changes will take place and the more difficult it will be to change."

This story is taken from Science Daily

Global warming skeptics unmoved by extreme weather

What will it take to convince skeptics of global warming that the phenomenon is real? Surely, many scientists believe, enough droughts, floods and heat waves will begin to change minds. But a new study throws cold water on that theory. 

But a new study led by a Michigan State University scholar throws cold water on that theory.
Only 35 percent of U.S. citizens believe global warming was the main cause of the abnormally high temperatures during the winter of 2012, Aaron M. McCright and colleagues report in a paper published online today in the journal Nature Climate Change.
"Many people already had their minds made up about global warming and this extreme weather was not going to change that," said McCright, associate professor in MSU's Lyman Briggs College and Department of Sociology.
Winter 2012 was the fourth warmest winter in the United States dating back to at least 1895, according to the National Oceanic and Atmospheric Administration. Some 80 percent of U.S. citizens reported winter temperatures in their local area were warmer than usual.
The researchers analyzed March 2012 Gallup Poll data of more than 1,000 people and examined how individuals' responses related to actual temperatures in their home states. Perceptions of warmer winter temperatures seemed to track with observed temperatures.
"Those results are promising because we do hope that people accurately perceive the reality that's around them so they can adapt accordingly to the weather," McCright said.
But when it came to attributing the abnormally warm weather to global warming, respondents largely held fast to their existing beliefs and were not influenced by actual temperatures.
As this study and McCright's past research shows, political party identification plays a significant role in determining global warming beliefs. People who identify as Republican tend to doubt the existence of global warming, while Democrats generally believe in it.
The abnormally warm winter was just one in an ongoing series of severe weather events -- including the 2010 Russian heat wave, Hurricane Sandy in 2012 and the 2013 typhoon in the Philippines -- that many believed would help start convincing global warming skeptics.
"There's been a lot of talk among climate scientists, politicians and journalists that warmer winters like this would change people's minds," McCright said. "That the more people are exposed to climate change, the more they'll be convinced. This study suggests this is not the case."

This story is taken from Science Daily

Hurricanes helped accelerate spread of lionfish

Just when you thought hurricanes couldn't get any scarier, think again. Their names roll of the tongue like a rogues' gallery: Floyd, Frances, Irene, Wilma and Andrew. But these aren't the names of notorious criminals; rather, they are just a few of the hurricanes since 1992 that have helped spread invasive marine species throughout the Florida Straits. Researchers have discovered that storms don't only have a dramatic impact on land; they have an equally dramatic effect on ocean currents, which helps the spread of marine invasive species throughout a region.

Researchers at Nova Southeastern University's (NSU) Oceanographic Center have discovered that storms don't only have a dramatic impact on land; they have an equally dramatic effect on ocean currents, which helps the spread of marine invasive species throughout a region. More specifically, NSU researchers looked at the distribution of lionfish in the Florida Straits.
"This is the first-ever study that shows hurricane-altered ocean currents are able not only to help, but actually accelerate the invasion of non-native marine species of any kind," said Matthew Johnston, Ph.D., one of the research scientists at NSU's Oceanographic Center who conducted the study. "Lionfish are pretty sedentary, so this is like creating express lanes on a superhighway -- otherwise, that's a pretty long swim for lionfish babies."
The research, conducted by Johnston and NSU Oceanographic Center Professor Sam Purkis, Ph.D., focused on the explosion of lionfish populations in area waters. Their findings are being published in the journal Global Change Biology. Another NSU Oceanographic Center Professor, Richard Spieler, Ph.D., in the course of his research, was one of the first to see lionfish in Bahamian waters soon after their arrival.
Not to be too technical, Johnston said that the research focused on how large storms (i.e. hurricanes) affect the flow of water in the Florida Straits. Normally, the currents represent a potential barrier to the transport of lionfish eggs and larvae across the Florida Straits. The researchers found that as a hurricane passes, the flow of water shifts from a strong, northern flow to a strong, eastern flow.
It's these changes in flow direction and speed that likely carry lionfish larvae and eggs from Florida to the Bahamas and can explain how lionfish were able to cross the Gulf Stream so soon after their introduction to South Florida waters.
Johnston said that once they were established in the Bahamas, hurricanes allowed lionfish to spread quickly against the normal, northwestern direction of water flow in the area. In addition, the storms helped increase the spread of lionfish by approximately 45% and their population size by 15%.
"The study has broader implications in that global climate change may cause an increase in storm frequency and/or intensity, perhaps further accelerating the spread of marine invasives," Johnston said. "Given that South Florida is a hotspot for marine invasive species, the transport of marine larvae from Florida to the Bahamas on hurricane-altered water flow may become commonplace for invasive and native species alike."
Johnston indicated this research has two implications. First, we need to make a concerted effort to prevent marine introductions to begin with and second, we must implement vigorous, early-detection programs to remove these invasive species before they become a problem. Now the team wants to take this research concept and study similar situations in the South Pacific where typhoons are common.

This story is taken from Science Daily

Predicting which African storms will intensify into hurricanes

Most hurricanes over the Atlantic that eventually make landfall in North America actually start as intense thunderstorms in Western Africa one or two weeks earlier, research indicates. This research may help cities and towns better prepare for these hurricanes with far more warning. 

A new study published in Geophysical Research Letters by Tel Aviv University's Prof. Colin Price and his graduate student Naama Reicher of the Department of Geosciences at TAU's Faculty of Exact Sciences finds most hurricanes over the Atlantic that eventually make landfall in North America actually start as intense thunderstorms in Western Africa.
"85 percent of the most intense hurricanes affecting the U.S. and Canada start off as disturbances in the atmosphere over Western Africa," says Prof. Price. "We found that the larger the area covered by the disturbances, the higher the chance they would develop into hurricanes only one to two weeks later."
Watching the clouds gather
Using data covering 2005-2010, Prof. Price analyzed images of cloud cover taken by geostationary satellites, which orbit Earth at the precise speed of Earth's rotation and take pictures of cloud cover every 15 minutes. This enabled Prof. Price to track the variability in cloud cover blocking Earth's surface in West Africa between the months of June and November -- hurricane season.
The coverage of clouds acts as an indication of atmospheric disturbances. The more clouds in an area, the larger the disturbance. Using infrared cloud-top temperature data gathered from satellites, Prof. Price assessed the temperatures of the cloud tops, which grow colder the higher they rise. He then compared his cloud data with hurricane statistics -- intensity, date of generation, location, and maximum winds --from the same period using the National Hurricane Center data base.
"We first showed that the areal coverage of the cold cloud tops in tropical Africa was a good indicator of the monthly number of atmospheric disturbances -- or waves -- leaving the west coast of tropical Africa," said Prof. Price. "The disturbances that developed into tropical storms had a significantly larger area covered by cold cloud tops compared with non-developing waves."
What makes them special
According to Prof. Price, only 10 percent of the 60 disturbances originating in Africa every year turn into hurricanes. And while there are around 90 hurricanes globally every year, only 10 develop in the Atlantic Ocean.
"We wanted to know what was so special about these 10% of disturbances that develop into hurricanes. Was there something different about these storms at their genesis?" said Prof. Price. "By looking at each of these storms individually, we found again that the larger the cloud coverage originally in West Africa, the higher the value of the accumulated cyclone energy in a future hurricane. The conclusion, then, is that the spatial coverage of thunderstorms in West Africa can foretell the intensity of a hurricane a week later.
"If we can predict a hurricane one or two weeks in advance -- the entire lifespan of a hurricane -- imagine how much better prepared cities and towns can be to meet these phenomena head on," Prof. Price says. He is currently examining the thunderstorm clusters around the eyes of hurricanes to study the intensification process of those destructive phenomena.

This story is taken from Science Daily

Below-normal Atlantic Hurricane Season is likely this year

For the hurricane season, which officially runs from June 1 -- November 30, NOAA is predicting a 70 percent likelihood of 6 to 11 named storms (winds of 39 mph or higher), of which 3 to 6 could become hurricanes (winds of 74 mph or higher), including zero to 2 major hurricanes (Category 3, 4 or 5; winds of 111 mph or higher). 

For the hurricane season, which officially runs from June 1 -- November 30, NOAA is predicting a 70 percent likelihood of 6 to 11 named storms (winds of 39 mph or higher), of which 3 to 6 could become hurricanes (winds of 74 mph or higher), including zero to 2 major hurricanes (Category 3, 4 or 5; winds of 111 mph or higher). While a below-normal season is likely (70 percent), there is also a 20 percent chance of a near-normal season, and a 10 percent chance of an above-normal season.
"A below-normal season doesn't mean we're off the hook. As we've seen before, below-normal seasons can still produce catastrophic impacts to communities," said NOAA Administrator Kathryn Sullivan, Ph.D., referring to the 1992 season in which only seven named storms formed, yet the first was Andrew -- a Category 5 Major Hurricane that devastated South Florida.
"The main factor expected to suppress the hurricane season this year is El Niño, which is already affecting wind and pressure patterns, and is forecast to last through the hurricane season," said Gerry Bell, Ph.D., lead seasonal hurricane forecaster with NOAA's Climate Prediction Center. "El Niño may also intensify as the season progresses, and is expected to have its greatest influence during the peak months of the season. We also expect sea surface temperatures in the tropical Atlantic to be close to normal, whereas warmer waters would have supported storm development."
Included in today's outlook is Tropical Storm Ana, but its pre-season development is not an indicator of the overall season strength. Ana's development was typical of pre-season named storms, which often form along frontal boundaries in association with a trough in the jet stream. This method of formation differs from the named storms during the peak of the season, which originate mainly from low-pressure systems moving westward from Africa, and are independent of frontal boundaries and the jet stream.
With the new hurricane season comes a new prototype storm surge watch/warning graphic from NOAA's National Hurricane Center, intended to highlight areas along the Gulf and Atlantic coasts of the United States that have a significant risk of life-threatening inundation by storm surge from a tropical cyclone.
The new graphic will introduce the concept of a watch or warning specific to the storm surge hazard. Storm surge is often the greatest threat to life and property from a tropical cyclone, and it can occur at different times and at different locations from a storm's hazardous winds. In addition, while most coastal residents can remain in their homes and be safe from a tropical cyclone's winds, evacuations are often needed to keep people safe from storm surge. Having separate warnings for these two hazards should provide emergency managers, the media, and the general public better guidance on the hazards they face when tropical cyclones threaten.
Also new this season is a higher resolution version (2 km near the storm area) of NOAA's Hurricane Weather Research and Forecasting model (HWRF), thanks to the upgrades to operational computing. A new 40-member HWRF ensemble-based data assimilation system will also be implemented to make better use of aircraft reconnaissance-based Tail Doppler Radar data for improved intensity forecasts. Retrospective testing of 2015 HWRF upgrades demonstrated a five percent improvement in the intensity forecasts compared to last year.
"It only takes one hurricane or tropical storm making landfall in your community to significantly disrupt your life," said FEMA Deputy Administrator Joseph Nimmich. "Everyone should take action now to prepare themselves and their families for hurricanes and powerful storms. Develop a family communications plan, build an emergency supply kit for your home, and take time to learn evacuation routes for your area. Knowing what to do ahead of time can literally save your life and help you bounce back stronger and faster should disaster strike in your area."

This story is taken from Science Daily