Tag Archive | "rosenstiel school of marine and atmospheric science"

Study Pinpoints Onset of Modern Monsoons

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Study Pinpoints Onset of Modern Monsoons


Study has important implications to understanding future climate changes and sea-level rise

Special to UM News

Anna Ling, a Ph.D. candidate in marine geosciences, catalogs core samples aboard the research vessel JOIDES Resolution. Photo by Gregor EberlI

UM’s Anna Ling, a Ph.D. candidate in marine geosciences, catalogs core samples aboard the research vessel JOIDES Resolution. Photo by Gregor EberlI

MIAMI, Fla. (July 26, 2016)—A new study by an international team of scientists reveals the exact timing of the onset of the modern monsoon pattern in the Maldives 12.9 million years ago, and its connection to past climate changes and coral reefs in the region. The analysis of sediment cores provides direct physical evidence of the environmental conditions that sparked the monsoon conditions that exist today around the low-lying island nation and the Indian subcontinent.

In November 2015, Rosenstiel School of Marine and Atmospheric Science geoscientist Gregor Eberli, along with co-chief scientist Christian Betzler of Germany, and an international team of 31 scientists from 15 countries, embarked on an eight-week expedition to the Maldives aboard the research vessel JOIDES Resolution. The scientific team on International Ocean Discovery Program (IODP) Expedition 359, which included UM geochemist Peter Swart and sedimentologist Anna Ling, extracted 3,097 meters of sediment cores that contain the history of the monsoon that is the most intense annually recurring climatic element on Earth. The monsoon system supplies moisture to the Indian subcontinent, which is important for the human population and vegetation in the region, as well as the marine ecosystem in the surrounding seas.

The Maldives are a string of island atolls built on coral reefs in the middle of the Indian Ocean. The waters around the low-lying archipelago have steadily risen and fallen for millions of years in sync with the changing climate. A new climatic phase heightened by human influence has these waters rising again, endangering the existence of the popular island paradise.

“They are at the center of the storm for sea-level rise,” said Rosenstiel School Professor Gregor Eberli, a senior author on the study published in Scientific Reports.

The low-lying island nation offers the scientists a unique opportunity to reconstruct climate conditions during previous periods of varying sea levels to help scientists better understand how future climate change will the effect the 1,000 kilometer-long archipelago and low-lying coastal areas around the world.

Today, the monsoon winds bring moisture to the Indian subcontinent but also drive the ocean currents across the Maldives. These currents carry sediment to the Maldives that is deposited along their shores and between the atolls. These sediments hold historic records of climate change and monsoon activity during the last 15 million years. At the same time, these same sediments also bury ancient reef buildups that flourished before the monsoon started. These reefs hold the key to the sea-level changes that took place before the onset of the monsoon.

Most scientists agree that the South Asian Monsoon is linked to the initial uplift, or birth, of the Himalayas, but the timing and other environmental drivers at play are still in question. During Expedition 359, Eberli’s team drilled seven holes along the Maldives Archipelago to collect sediments that hold records of past sea level and environmental changes during the Neogene, a geological time period that began 23 million years ago. The information can help pinpoint the timing and environmental conditions that supported the development of the modern day ocean currents and monsoon conditions.

“We have unraveled the physical evidence of the monsoon and now know the exact timing of when the modern monsoon pattern began, and have shown what consequences the onset of the monsoon had on the coral reefs of the Maldives,” said Beztler, the co-chief scientist for Expedition 359, from the CEN at University of Hamburg in Germany. “The scientific results of this expedition will give answers to many fundamental questions of the monsoon and the climate in general.”

In the Maldives, the monsoon and sea level have an intimate history. During what geoscientists called the Miocene Climate Optimum, roughly 15 million years ago when temperatures and CO2 levels were higher than today, the reefs around the Maldives atolls were flourishing. When the climate began to cool and sea levels dropped, the atolls become exposed, only to be flooded again during the subsequent rise. However, with the onset of the monsoon, the new ocean circulations patterns began to emerge that were not favorable to the islands’ coral reefs.

The team found evidence for a period of global cooling that preceded the onset of the monsoon. During this cooling period the atmospheric circulation began producing seasonal wind changes that were ripe for the development of a winter and summer monsoon. These winds also started to generate ocean currents, which in combination with the expansion of an oxygen minimum zone caused several of the atolls to be submerged.

This global cooling led to an expansion of the West Antarctic Ice Sheet that caused global sea level to fall, exposing many of the Maldives’ reefs. The currents also caused local upwelling that was again detrimental to the corals. At three of the eight drill sites, these drowned reefs were found covered by current deposits.

“These atolls basically drowned, which opened seaways across the Maldives that increased the monsoon activity,” said Eberli. “This partial drowning of the atolls is very interesting as it shows that the combination of rising sea level and ocean current can be detrimental to coral growth.”

Upwelling of nutrient-rich waters and the strengthening of the currents sweeping over the reef flats were detrimental to the islands’ coral reef foundation.

Eberli suggests that the abrupt development of the modern-day monsoon conditions were not only due to the uplift of the Himalayas, which is a prerequisite, but ultimately the result of the cooling after the Miocene Climate Optimum, which initiated the formation of the bipolar ocean circulation that is still in existence today.

The study, titled “The abrupt onset of the modern South Asian Monsoon winds,” was published in the July 20 issue of the journal Scientific Reports.

 

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Marine Geoscientist Named 2016 AGU Fellow

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Marine Geoscientist Named 2016 AGU Fellow


Peter K. Swart recognized for his pioneering research in marine geochemistry

Special to UM News

Peter Swart

Peter Swart

MIAMI, Fla. (July 26, 2016)—Peter K. Swart, professor and chair of the Department of Marine Geosciences at the Rosenstiel School of Marine and Atmospheric Science, has been elected a fellow of the American Geophysical Union (AGU), the nation’s leading professional society for scientists in the earth and space sciences. The award will be presented during the 2016 AGU Fall Meeting in San Francisco.

A pioneer in marine geochemistry who has been at UM since 1983, Swart, the Lewis G. Weeks Professor of Marine Geology and director of UM’s Stable Isotope Laboratory, is best known for his work on isotopes in geochemistry, carbonate diagenesis (physical and chemical changes occurring during the conversion of sediment to sedimentary rock), paleoclimatology, and hydrology.

“I am pleased that Peter is being recognized by AGU for his pioneering geochemistry research,” said Roni Avissar, dean of the Rosenstiel School. “This is a well-deserved and long-overdue recognition of Peter’s achievements.”

Swart pioneered the use of geochemistry in other areas such as extra-terrestrial materials, hydrology, and carbonates. His 1982 paper in Science was the first to reveal the presence of highly enriched C-13 phases in meteorites, offering clues to the origin of the solar system.

“To be elected a Union Fellow is a tribute to those AGU members who have made exceptional contributions to earth and space sciences as valued by their peers and vetted by section and focus group committees,” according to the AGU.

Throughout his career Swart has been supported through a variety of sources, including the National Science Foundation, the National Oceanographic and Atmospheric Administration, the Environmental Protection Agency, the U.S. Department of Energy, and the U.S. Department of the Interior, as well as several global corporations. He is one of the principal investigators in the Comparative Sedimentology Laboratory (CSL), a consortium of petroleum companies, and the former editor of the highly regarded journal Sedimentology. In 2011, his work with Rosenstiel School Professors Kenny Broad and Amy Clement on the dating and isotopic analysis of stalagmites to reconstruct past climate changes was featured as part of a cover story in National Geographic.

Swart is a fellow of the American Association for the Advancement of Science and the Geological Society of America. He is also a member of the American Geophysical Union, the Coral Reef Society, the Geological Society of America, the Geochemical Society, and the International Association of Sedimentologists.

Swart has an impressive record of scholarly accomplishments, with more than 190 published papers, book chapters, editorials, and special publications that have garnered over 5,000 citations. He also teaches regularly and has served as a Ph.D. and Master’s dissertation committee chair for more than 30 students.

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Hurricane Researchers Honored for Best Paper

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Hurricane Researchers Honored for Best Paper


Dave Nolan

David Nolan

Special to UM News

MIAMI—The Rosenstiel School of Marine and Atmospheric Science research team led by Professor David Nolan has been awarded the American Meteorological Society’s (AMS) prestigious Banner Miller Award, which recognizes outstanding contributions to the science of hurricane and tropical weather forecasting published in an international journal during the previous four years.

Nolan, whose research focuses on the dynamics of hurricanes and the improvement of hurricane forecasts, and his team received the biannual award during the AMS Hurricanes and Tropical Meteorology meeting, held recently in San Juan, Puerto Rico, for an article, “Development and validation of a hurricane nature run using the Joint OSSE nature run and the WRF model,” which appeared in the Journal of Advances in Modeling Earth Systems in 2013.

The article describes the development of an extremely realistic computer simulation of an Atlantic hurricane and its validation by comparisons to observations in real hurricanes. This “nature run” computer simulation is currently used by more than a dozen research groups in various Observing System Simulation Experiments (OSSE). OSSEs are used to determine the effectiveness of new instruments, such as new satellites or unmanned aircraft, in improving hurricane forecasts before they are actually deployed, which potentially saves millions of dollars.

“Part of the success of this project is that we made the nature run freely available for anyone to download,” said Nolan, professor and chair of the Department of Atmospheric Sciences. “In addition to OSSEs, it has been used by several groups for basic research on hurricanes.”

Nolan’s coauthors include Rosenstiel School graduate students Kieran Bhatia and Lisa Bucci and Robert Atlas, director of the National Oceanic and Atmospheric Administration’s (NOAA) Atmospheric and Oceanic Marine Laboratory in Miami. The NOAA Office of Weather and Air Quality and its Hurricane Forecast Improvement Program supported their work. Bhatia is now a postdoctoral fellow at NOAA’s Geophysical Fluid Dynamics Laboratory in Princeton, New Jersey.

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Study Shows After-Effects of Oil Spill

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Study Shows After-Effects of Oil Spill


Study on mahi-mahi embryos and larvae shows toxic oil affects developing heart, eye, and neurological function

Special to UM News

mahi.mahi

This info graphic from the University of California, Riverside shows hexagonal shaped Polycyclic Aromatic Hydrocarbons (PAHs) in crude oil impairs development of the heart, eye, and neurological function in the early life stages of mahi-mahi.

MIAMI (July 12, 2016)—A research team led by scientists at the University of California, Riverside, and the University of Miami’s Rosenstiel School of Marine and Atmospheric Science has found that ultraviolet light is changing the structure of the oil components from the Deepwater Horizon (DWH) oil spill into something more toxic, further threatening numerous commercially and ecologically important fishes. The 2010 DWH explosion, which spilled more than 3 million barrels of crude oil into the northern Gulf of Mexico, is the worst oil disaster in U.S. history, contaminating the spawning habitats for many fishes.

“Ours is the first experiment evaluating the effects of DWH oil on the genetic responses of mahi-mahi embryos and larvae,” said Daniel Schlenk, a professor of aquatic ecotoxicology at UC Riverside, who led the study published in Environmental Science and Technology. “It is also the first experiment of this nature on a lifestage and species that was likely exposed to the oil. We found that the weathering of oil had more significant changes in gene expression related to critical functions in the embryos and larvae than the un-weathered oil. Our results predict that there are multiple targets of oil for toxicity to this species at the embryonic life stage.”

For their study, the researchers exposed the fish embryos to the oils at three different time points: 24 hours post fertilization, 48 hours post fertilization, and 96 hours post fertilization. (Hatching to larvae in mahi-mahi occurs at 48 hours post fertilization; the researchers bracketed this time point at 24 hours post fertilization and 96 hours post fertilization.) Then, the researchers collected transcripts of all the genetic information at each time point and evaluated these transcripts using novel bioinformatic methods. Finally, they evaluated the toxicity and heart functions in animals using the embryos’ gene expression to predict biochemical, cellular, and tissue targets where the oil was causing an effect.

For their experiments, Schlenk and Rosenstiel School scientists caught the mahi-mahi off the coast of Miami, and exposed embryos to two types of oil: one set was exposed to slick oil (weathered) from the spill, while another set was exposed to oil that came from the source of the spill. The researchers carried out the experiment this way because fish in the northern Gulf of Mexico had been exposed during the spill to both types of oil. The study attempted to understand which of the two oils—slick oil or source oil—is worse for the fish and how oil affects development.

“This study exemplifies a fruitful collaboration between UC Riverside and the UM Rosenstiel School to identify molecular targets for oil toxicity,” said Rosenstiel School Professor Martin Grosell, lead of the RECOVER (the Relationship of Effects of Cardiac Outcomes in Fish for Validation of Ecological Risk) consortium and co-author of the study. “In addition to impacts on heart development and function, the gene expression results illustrate the peripheral components of the nervous system involved in sensory function are impaired by oil exposure during early development.”

Sensory function is important for prey detection and predator avoidance.

“We found that the heart, eye, and neurological function were affected,” Schlenk said. “In collaboration with other consortia members from the Universities of Miami, Texas, and North Texas, we are now following up on these results. Previous studies have shown that the heart is the primary target for oil. Our study shows that in addition to heart function, risk and recovery should also examine eye and neuronal function.”

The approximately four-month study was expedited by a unique software, On-RAMP, that the researchers used to identify the gene signatures from the fish.

“Normally, it can take months to annotate the genes and identify the regulatory directions of expression,” Schlenk explained. “But by using On-RAMP, we could identify the genomic responses in a matter of weeks, allowing pathway analyses with sophisticated software normally only used for human/mice responses.”

The research was funded by the Gulf of Mexico Research Initiative, Grant No: SA-1520, as well as the Relationship of Effects of Cardiac Outcomes in Fish for Validation of Ecological Risk (RECOVER) consortium.

In addition to Schlenk and Grosell, other co-authors of the study include Elvis Genbo Xu, Graciel Diamante, and Juliane Freitas, from UC Riverside; Edward M. Mager, Christina Pasparakis, Lela S. Schlenker, John D. Stieglitz, and Daniel Benetti from the UM Rosenstiel School; and E. Starr Hazard, Sean M. Courtney, and Gary Hardiman at the Medical University of South Carolina.

Next, the research team will follow up with whole animal physiological and behavioral effects to see if the newly identified molecular responses can be linked to function.

Watch a video of the fish larvae at 48 hours.

 

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Study Follows  African Dust Across the Atlantic

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Study Follows African Dust Across the Atlantic


Special to UM News

The dust cloud is visible in this composite image from the Suomi National Polar-orbiting Partnership (NPP) satellite Visible Infrared Radiometer Suite (VIIRS)

Dust is visible in this composite image from the Suomi National Polar-orbiting Partnership satellite’s Visible Infrared Radiometer Suite.

MIAMI, Fla. (July 7, 2016) — Summer isn’t just hurricane season in Florida, it’s also dust season. And the two have a few things in common.

Scientists at the Rosenstiel School of Marine and Atmospheric Science are taking advantage of this year’s dust season to study the aging of these aerosol particles that travel across the Atlantic Ocean from Africa to Florida. The study, which began July 1 and runs through August, will help improve weather and climate forecasts, including our understanding of the early development of tropical storms.

Rosenstiel School Professor Emeritus Joseph Prospero is coordinating his studies with those of colleagues at the Izaña Observatory, atop an 8,000-foot mountain on Tenerife in the Canary Islands, 300 kilometers from the coast of West Africa. The Izaña team is studying dust as it emerges from Africa, and the Miami scientists will make an identical set of measurements on the island of Barbados in the Caribbean and in Miami as the same dusty air mass passes over these sites about a week later.

“By making coordinated measurements at Izaña Observatory in the eastern Atlantic and again at Barbados and Miami in the western Atlantic, we can develop a detailed picture of the properties of African dust and its impact on the atmospheric and ocean environment in this huge region,” said Prospero, who is known as the “grandfather of dust” for his pioneering research on African dust that began in 1965.

The researchers are looking for changes in the size and chemical composition of the dust as it travels across the Atlantic Ocean. These data will be incorporated in weather and climate models to see how well the models can simulate the processes of dust generation and transport and its effect on the environment.

African dust is carried in the Saharan air layer (SAL), a layer of hot, dry air that extends from about 3,280 feet (1,000 meters) to 3.7 miles (6 kilometers) in altitude and originates in the Saharan Desert. This dust is a major nutrient source in the tropical Atlantic Ocean, and plays an important role in the biological productivity of Atlantic and Caribbean ocean waters.

Of particular interest to the researchers is the role of African dust plumes on the formation and properties of tropical storms. The SAL moves west over the Atlantic in association with easterly waves, an area of relatively low air pressure associated with the development of tropical disturbances, some of which evolve into tropical storms. Scientists have estimated that nearly 85 percent of major hurricanes originate from easterly waves and that the SAL can suppress the development of hurricanes in the Atlantic.

The study is focusing on the changes in the SAL and the associated dust as it crosses the Atlantic since these changes can affect the impact that the dust has on meteorological processes.

“By developing a better understanding of the variability of dust storms and the properties of the transported dust, we can develop better hurricane and climate models,” said Prospero. “It will help us to anticipate how dust transport will change as our climate changes, which may have a huge impact on the climate in North Africa.”

Saharan dust also affects the quality of the air we breathe since the air contains high concentrations of particulate matter. For this reason, the U.S. Environmental Protection Agency and the World Health Organization (WHO) have set limits on the concentration of suspended particles in the air. During the summer months, African dust is the dominant particulate species in the atmosphere over the Caribbean Basin and Florida and often exceeds WHO concentration guidelines during the summer.

“In our study we eventually hope to be able to predict the occurrence of major dust outbreaks over the Caribbean Basin and the southern U.S. This would enable us to issue health alerts to susceptible populations, such as those with impaired respiratory systems, the elderly, and infants,” said Prospero.

The ongoing study is supported by grants from the National Science Foundation and NASA. UM Rosentiel School scientists Paquita Zuidema and Cassandra Gaston are also involved.

 

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