Posts Tagged ‘Hurricane Leslie’

Salinity Processes in the Upper Ocean Regional Study (SPURS): Of ship meals and science

September 10th, 2012 by Maria-Jose Viñas

By Eric Lindstrom

Saturday’s lunch menu at Chez Knorr.

Saturday, 8 September 2012 — Given the talk around the Knorr’s dinner table, you would have to say that oceanographic expeditions run on their stomachs. Key to surviving weeks away from home and family is good food and good moods. The food on the Knorr is excellent, so we are likely to have happier people and better results. Most people will come back a few pounds heavier. There is a gym on the ship but it can be dangerous to be on a treadmill or lifting weights in rolling seas…so, more than likely most will lose the weight battle to the dining experience!

Bobby, preparing for lunch.

Everyone has a mug.

Today was the day we passed in front of the predicted track of Hurricane Leslie. We felt a bit of the swell coming from the storm, but otherwise we had fine conditions. In the early afternoon, we slowed for a few minutes to deploy the first Argo float of the voyage. Deploying the floats is pretty easy since they have all been powered up and are ready to go right out of the box. We just have to slow the ship and lower the instrument over the stern and gently into the water.

We plan to deploy two Argo floats in front of the predicted hurricane track. They will measure temperature and salinity profiles before, during, and after storm passage. In addition the profiling instruments “listen” to ocean acoustics and can make an estimate of wind speed and rain rate based on the noise of those actions on the sea surface (pretty cool!) So, we especially wanted to see how the acoustic sensors deal with a big signal like a hurricane. Steve Riser at University of Washington is the Principal Investigator for the Argo floats in SPURS.

First Argo float deployment.

The float disappears over the stern.

I also received my first official science training of the voyage. We have a small device called an underway CTD  for measuring a profile of conductivity, temperature, and depth of seawater. Two people will work together to deploy and recover this instrument on an hourly basis throughout most of the experiment. The device is tethered to a small winch and boom (like a fishing rod and reel) at the stern of the vessel and dropped in the water to make measurements from the surface to 400 meters (about 1312 feet) depth while the ship is steaming at 10 knots. It finishes a profile in 100 seconds and is then reeled back aboard. It is kind of like hauling in a fish with an electrically-powered rod and reel. It takes 20 minutes to haul in the beast and then another few minutes to download the data from its internal memory to a laptop computer. We plan to deploy this instrument every hour once we begin normal operations in the SPURS region next Friday.

The latest wind and wave information from Hurricanes Leslie and Michael suggest that our path to the SPURS site is just about perfect for seeing the minimum impact from the storms. The seas are still lumpy, but Knorr looks to be slipping through the gap between the storms. Fingers crossed!

Salinity Processes in the Upper Ocean Regional Study (SPURS): Hurricanes, make way for Knorr!

September 7th, 2012 by Maria-Jose Viñas

By Eric Lindstrom

Cloudy skies over the Atlantic, with Hurricane Leslie in the distance.

We knew when we left Woods Hole yesterday that we had two hurricanes (Leslie and Michael) standing between us and our study site, far southeast of Woods Hole in the mid-Atlantic. How Captain Adam of the Knorr chooses to deal with this over the next days is a study in weather and ocean forecasting – and calculated risks. We considered at least three options: delay departure until the coast is clear, make a significant departure to the cruise track (sail far south, then east), or leave on time but travel quickly to the east and then south to miss the worst of the hurricane weather.

The last option is what we are doing. We abandoned plans to do test stations and do science training for a few days so we can make hast to the east, to the east side of Leslie’s track. Then we can make our way south and around Michael. Tom Farrar and Fred Bingham of the SPURS science team have provided the bridge with Gulf Stream analyses that we hope will help us take best advantage of ocean currents in our race eastward. We could easily have found ourselves in an eddy that would hinder our progress, and no one wants that with bad weather coming toward us! It was a fabulous start to the voyage to have the crew of the Knorr and the SPURS team working so closely on the strategy to both keep us safe and on schedule.

The Knorr's new track to avoid Hurricane Leslie.

It’s worth mentioning too that satellite data and the shore-based team play a crucial role in our cruise planning. Zhinjin Li and Michelle Gierach at the NASA Jet Propulsion Lab have been feeding us the latest satellite images from the Atlantic so we can better understand the wind, waves, and currents in our path. We rely on these contributions because it is difficult to surf the web from sea – we have Internet access, but it can be quite slow.

Today we feel the enormous forces of the tropical storms on the western Atlantic. There is a good swell running – speaking clearly of some strong wind at a distance. Some aboard are feeling seasick, but the mess is still full of hearty eaters and smiling faces!

SPURS scientist Fred Bingham goes through safety training.

One of the things you notice in these conditions are all the items that can shake, rattle, squeak, groan, or otherwise move and make noise. I have been up and down in my cabin a number of times during the night to silence rattling cupboard doors, toppling books, sliding glasses – it’s almost an endless battle. At sea you don’t just put something down – you secure something, wedge something, pad something, or it becomes something broken, lost, dangerous or just plain noisy! Sometimes one even has to wedge oneself in a place and just stop moving around! All of us have greater appreciation than most for the stability of land and the silence that stability brings. When things are shipshape, all is secure and in its place. We are living shipshape today.

Notes from the Field