After the successful recovery and refurbishment of several bottom profilers, moorings, and surface buoys, the first transect of the PEACH (Processes Driving Exchange at Cape Hatteras; NSF Award: 1559476) cruise was undertaken this evening and into the early morning hours. The transect spaced 7 stations along 60km of ocean from a few kilometers off of the NC Outer Banks to the continental shelf break. To collect sub-surface data, scientists utilized shipboard CTD, the workhorse of physical oceanographers.
At each station, scientists and crew deployed the CTD package utilizing a winch that took it to within a few meters of the seafloor and then was pulled back onto the ship. The CTD takes several measurements per second that include ocean temperature, salinity, and depth. This allows oceanographers to understand gradients, such as density, that are essential to greater understanding of currents throughout the entire water column. In addition, each water type has a certain fingerprint of temperature and salinity, allowing researchers to determine where exactly a layer of water originated. A transect is formed when you deploy several CTDs over a line, allowing a complete representation of the ocean depth along a line.
All of the CTDs were successful in collecting this data with the last CTD brought onboard at 2:30am. A pod of over two dozen curious dolphins were spotted circling the last CTD as it surfaced.
After the CTD was secured, the R/V Neil Armstrong headed south, near Diamond Shoals. Tomorrow will feature more equipment servicing there during the day, followed by a another CTD transect across the Gulf Stream at night. Stay tuned to the OOMG blog for updates from Dr. Joe Zambon while he is at sea. Also, track the R/V Neil Armstrong here.
Dr. Joe Zambon and over a dozen scientists and PIs making up the PEACH (Processes Driving Exchange at Cape Hatteras; NSF Award #1559476) project departed the frozen waters of Woods Hole, MA on Monday morning (8-January) for Cape Hatteras onboard the R/V Neil Armstrong. The first day of travel was difficult with high seas and crashing waves. The anticipated transit time is 36 hours from Woods Hole, MA to offshore Cape Hatteras, NC.
Upon arrival, dive teams will attempt to retrieve moorings to replace broken equipment and change depleted batteries. This equipment, including bottom-mounted current profilers, deep ocean moorings and meteorological buoys, was deployed during the first cruise of the PEACH project in April 2017.
While the refurbishment of this equipment represents the highest priority to the science party, the next couple weeks will include investigating a number of physical parameters in the Gulf Stream to determine the mechanisms causing Gulf Stream fluctuations and air-sea interaction.
Stay tuned as Joe will provide updates when time and internet connectivity permit.
On Saturday, Dr. Joe Zambon arrived in New England to board the R/V Neil Armstrong for a journey down to offshore Cape Hatteras, NC. The study is part of the PEACH, Processes Driving Exchange at Cape Hatteras, grant sponsored by NSF (Award: 1559476). The next day will be spent mobilizing and retrofitting equipment onto the vessel for meteorological rawindsonde balloon deployments, a first for the R/V Neil Armstrong.
After a short mobilization period in the frozen waters of Woods Hole harbor, the scientists and crew onboard will repair and replace moorings deployed in the first research cruise of the project back in April 2017. In addition, measurements will be taken to help characterize and better understand the meandering nature of the Gulf Stream as it bends out to sea at Cape Hatteras.
In addition to the 15 scientists onboard, the group will be communicating with dozens of researchers back on shore to determine the best areas of deployment utilizing observations and numerical models.
The cruise is scheduled to begin on 8-January and wrap up around 22-January. Keep an eye on our blog for updates from the R/V Neil Armstrong!
Dr. He visited Nagoya University in Japan in December 2017 to promote collaboration on western boundary current dynamics and prediction. Just as the U.S. is adjacent to the strong Atlantic Ocean western boundary current called the Gulf Stream, Japan abuts the Pacific Ocean’s Kuroshio Current (see the post on Why Western Boundary Currents Exist).
Nagoya faculty Professor Joji Ishizaka, Associate Professor Hidenori Aiki, and Assistant Professor Yoshihisa Mino, as well as post docs and graduate students, met with Dr. He. We are grateful for travel support from the Harry C. Kelly Memorial Fund for U.S.-Japan Scientific Cooperation.
“The National Academies of Sciences, Engineering, and Medicine undertook a study to identify existing knowledge gaps about the Loop Current System and to develop a list of recommended efforts to fill those gaps. The resulting report, released today, calls for an international, multi-institutional campaign of complementary research, observation, and analysis activities that would help improve understanding and prediction of the Loop Current System.”
— from the News site of the National Academies of Sciences, Engineering, and Medicine. Read more.
Dr. He is a member of the National Academies’ Committee on Advancing Understanding of Gulf of Mexico Loop Current Dynamics, which produced this report.
OOMG member Dr. Joe Zambon tested a balloon-carried radiosonde with the help of NCSU’s Dr. Matt Parker from the roof of Jordan Hall. After filling the large balloon with helium, Joe and Matt zip-tied it closed, then attached the unwinder.
Between the balloon and the radiosonde, the unwinder gently spools out 10 m of string so that the radiosonde is far enough below the balloon to get a clear signal from GPS satellites.
The lightweight radiosonde connects to the unwinder and bears an antenna for satellite and ground communication and an instrument that takes measurements as it travels through the atmosphere.
Joe will be launching a dozen radiosondes from the deck of the R/V Neil Armstrong during the January 2018 PEACH research cruise to collect data on the atmosphere while other instruments are collecting data on the ocean. Ocean-atmosphere interactions are critical to understanding ocean conditions. The radiosonde will record conditions such as humidity, temperature, and pressure as it rises. A small battery in the radiosonde enables it to transmit data back to the ground in real time. The balloon may carry the instrument through the troposphere (~ 17 km above the Earth’s surface), eventually bursting due to low atmospheric pressure.
OOMG welcomes its newest member, visiting graduate student Yangyang Liu. She comes to NC State from her home institution Xiamen University located in China’s Fujian Province. While at NC State she will be working on modeling solar radiation in the upper water column and its impact on the large scale ocean dynamics.
Her advisor, Zhongping Lee, is a graduate of the University of South Florida’s Marine Science program, along with OOMG Director Ruoying He.
The group took Yangyang to sample NC State’s renowned Howling Cow ice cream at Talley Student Union. Howling Cow has been made at NC State for over fifty years and is a facet of campus life as well as a popular attraction the North Carolina State Fair.
Marine, Earth and Atmospheric Sciences (MEAS) PhD Student and OOMG member Laura McGee delivered a talk at the first ever Climate Lightning Talks: Apocalypse Now? How Extreme Weather is Affecting the Southeast and the Globe. Her talk was titled, “Hurricanes Cause Asymmetric Phytoplankton Blooms” and explained how phytoplankton activity is enhanced along the right side of hurricane tracks in the North Hemisphere.
McGee won the Grand Prize after a warm reception by the audience. The Lightning Talks were hosted by USGS Southeast Climate Science Center & NC State University and were held at the David Clark Labs Auditorium.
The event featured twelve speakers from eight departments spread throughout the university. The talks spanned topics from the intricacies of geophysical fluid dynamics to intergenerational conversations about climate change. Speakers ranged from professors to postdoctoral associates to graduate students. The complete list included:
Robert Scheller, Dept. Forestry and Environmental Resources
Ted Simons, Dept. of Applied Ecology
Danielle Lawson, Dept. of Parks, Recreation, & Tourism Management
Laura McGee, Dept. of Marine, Earth, and Atmospheric Sciences
Bill Hoffmann, Dept. of Plant and Microbial Biology
Samuel Flake, Dept. Plant and Microbial Biology
Eleanor Lahr, Dept. of Entomology & Plant Pathology
James Madden, Dept. of Marine, Earth, and Atmospheric Sciences
Zamani Atefeh, Dept. of Civil, Construction, and Environmental Engineering
Yuhao Ba, Dept. of Public Administration
Okan Pala, Center for Geospatial Analytics
Bethany Cutts, Dept. of Parks, Recreation, & Tourism Management
Fellow MEAS participant James Madden gave a talk explaining how future extreme rainfall events similar to the storm that flooded Crabtree Creek in Raleigh on July 16th, 2016 could be affected and enhanced by climate change.
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An interesting phenomena has been observed in the wake of Hurricane Irma as it moves along the west Florida coastline. Several images have been put on social media of water drastically receding away from the coastline, whereas tropical storms usually result in surge as they make landfall.
This phenomenon is largely due to 2 factors. First, the winds ahead of Irma are westward and offshore. This has the effect of pushing water offshore. Second, the bathymetry on the West Florida Shelf is characterized by shallow sloping, meaning that a 1 or 2 meter decrease in sea level would result in long stretches of dry seabed.
As this is dynamically driven, it can be observed in our CNAPS model. The included animation shows offshore winds in advance of Irma’s eye which quickly whip around to onshore. Offshore winds result in a modeled 2+ meter decrease in sea level, but once the eye passes, sea level rises with a combination of returning coastal water and storm surge. The National Hurricane Center has been sending out dire warnings to people in the path of the returning surge to stay away temporarily dry seabeds. Further up the coast, in Tampa Bay, water levels are rising rapidly and surge is already exceeding the Mean Higher High Water (MHHW) levels.
Update: Parts of this story were published on Sept. 12th in the scientific blog Live Science.
Our coupled models, initialized at 8pm on September 7th, have completed and are now able to resolve Irma making landfall in Florida sometime between 2am and 5am Sunday morning. As a result, both the 3 and 7 day runs are capable of resolving the storm and currently point the landfall as occurring between Miami and Homestead (where Andrew made landfall in August 1992). This is in agreement with last night’s National Hurricane Center (NHC) forecast. The forecast track has shifted back slightly west since then, but is still within the NHC track forecast cone.
In addition to the 7-day animation shown, here is a KMZ file showing the predicted storm impact on southern Florida 54-hours into our forecast period (early Sunday morning). Included in the KMZ file are 10m wind + direction, sea level pressure (SLP) + wind direction, sea surface temperature (SST), significant wave height, estimated 1-hr precipitation, and simulated radar reflectivity for 06Z (2am EDT) Sunday morning. Load the files into Google Earth (available for free) to visualize the data.
We will continue to update as the storm progresses.
Many, many thanks to NC Sea Grant and NC Space Grant for their gracious support and funding for my upcoming project, Investigation of Marine Physical-Biogeochemical Interactions During Storm Conditions Off of the North Carolina Coast. This work will use long-term satellite observations, in-situ data, and numerical model analysis to examine and quantify phytoplankton blooms and air-sea carbon exchange due to hurricanes in the North Carolina coastal ocean. Hurricanes induce two competing mechanisms that exchange carbon: first, strong ocean mixing causes the ocean to release CO2 to the atmosphere, in a process called outgassing. Second, hurricanes induce phytoplankton blooms by upwelling deep ocean nutrients to the upper water column. These phytoplankton blooms, through photosynthesis, move CO2 from the atmosphere to the ocean. By examining the contributions of these two mechanisms, my research seeks to shed light on the role of hurricanes on ocean acidification and climate change.
NC Sea Grant has released a news statement about the fellowship here.
Thank you, NC Sea Grant/Space Grant, and I look forward to working on this exciting research!
Over the last few days, the 7-day forecast experiment upgrade has been working well. Our output from forecasts initialized on the 6th and 7th are largely in line with the forecast models that the National Hurricane Center (NHC) has been favoring in their forecast tracks. We have been utilizing additional resources provided by the High Performance Computing (HPC) center at NC State for our experimental 7-day simulations. However, the operational 3-day model simulations are our first priority to assess immediate hazards, so these experimental 7-day products take longer to develop.
As Irma moves closer to land and becomes a hazard to the mainland U.S. within our normal 72-hour forecast window, we will provide analysis on both products.
Over the last few weeks, we have been working to expand the current CNAPS forecast from 3 to 7 days. With the appearance of Hurricanes Harvey and Irma, and the peak of the hurricane season on September 10, we were graciously allocated additional computing power from the High Performance Computing (HPC) Center at North Carolina State University to perform some experimental simulations of a 7-day forecast. We now have a framework to run our CNAPS nowcast/forecast for 168 hours quasi-operationally.
This forecast, initialized at 00Z on September 5, shows Irma entering the CNAPS domain near the Leeward Islands in the Caribbean, moving along the northern coast of Cuba, abruptly making a turn to the north to bisect the state of Florida, then weakening over the southeast U.S. This is in line with several of the national forecast models run at the same time.
Our usual 72-hour CNAPS forecast will run as normal, and we will provide additional experimental analysis and products about Irma as it threatens the U.S. Stay tuned for more updates.
Dr. Roy He served on the PhD committee of Ann Kristin Sperrevik at the University of Bergen, in Norway, and attended her defense in June 2017. Her thesis title is “Modeling coastal circulation in Norway using a high-resolution 4D-Var ocean assimilation system.” Also serving on Ms. Sperrevik’s committee were Dr. Anthony T. Weaver of CERFACS, France, and Dr. Tor Eldevik of the University of Bergen. Dr. Sperrevik defended successfully and is now on staff at the Norwegian Meteorological Institute.
The Kenan Institute of Engineering, Technology, and Science (KIETS) at NC State University has funded OOMG’s research on Dynamical Model Downscaling of Climate Change and Its Impacts on Marine Environmental Conditions Off North Carolina. Support for this research into the slowdown on the Atlantic meridional overturning circulation (AMOC) will enable OOMG to refine fine-scale modeling of the Gulf Stream near North Carolina, and leverage other funding to enhance our programs. Together, KIETS and OOMG will provide important information to benefit coastal stakeholders and communities.
We thank KIETS for their support and look forward to a productive relationship.