January 9, 2010 – At Sea, 48º 57’S, 057º 51’W
By Herb McCormick
Late this morning, as Ocean Watch continued to gobble up the miles toward our next port of call – Port Stanley, Falkland Islands – at a prodigious rate of speed, my watch mate, Dave Logan, tilted his nose toward the sky and said, “I smell dirt.” It looked like fun: I tried it too. No, I couldn’t catch a whiff of anything (and have my doubts about Logan), but the sky did have a haze of sorts that we hadn’t detected earlier on this mostly glorious run from Mar del Plata, Argentina. Logan dove below to grab an instrument we have aboard called a Microtops Sun Photometer. We’d heard that the after effects of a dust storm in Patagonia might be drifting our way, and on behalf of scientists a half a world away, we were poised to help discover if the rumor was true.
The Around the Americas expedition has always aimed to be a voyage of discovery, and a large part of that mission has been to carry forth not only scientists themselves, but also recording instruments and data-collection tools to help other scientists conduct research and experiments from their landlocked labs and classrooms in institutions across the United States. In fact, in several different iterations, it happens onboard ever day. But today, as Ocean Watch closed to within a day of the Falklands, a couple of interesting things were going on that helps cast a light on how our offshore journeys aid shore-side science.
Yesterday, oceanographer Michael Reynolds – our longest standing onboard scientist, currently taking a break to work back home in Seattle – forwarded an email from a NASA scientist, Dr. Santiago Gasso, who specializes in atmospheric aerosols and is based in Greenbelt, Maryland. Here’s a portion of Dr. Grasso’s note:
“I’ve been in contact with you before regarding my interest in dust storms in Argentina and how they advect to the ocean. So, I want to let you know that a moderate dust storm is occurring right now between the cities of Bahia Blanca and Viedma (41º S)…and there is also dust activity in the coastal city of Comodor Rivadavia (46º S). There is strong wind from the W too.
“The dust cloud should advect SE towards the general area where you are located. Since I know you have a Microtops sun photometer, you may be aware of probably increases in aerosol optical depth in the next 24-48 hours. I do not expect you to see much dust (with the) naked eye; if you do I would appreciate if you could take some photographs. I heard from local fishermen that they have seen abundant dust deposited over the water, so…proof of it would be very helpful. It would greatly help to compare with the satellite.
“Also, I’ve been watching the area from space every day and right N of the Malvinas (Falkland) Islands, there is a huge bloom of coccolithophores and it would be great if you describe it and maybe take some pictures.”
Okay, a few things are going on here. Let’s start with the aerosols and dust.
A story from www.sciencemag.org describes succinctly what we mean by aerosols: “Human activities are releasing tiny particles (aerosols) into the stratosphere. These human-made aerosols enhance scattering and absorption of solar radiation. They also produce brighter clouds that are less efficient at releasing precipitation.
“These in turn lead to large reductions in the amount of solar irradiance reaching Earth’s surface, a corresponding increase in solar heating of the atmosphere, changes in the atmospheric temperature structure, suppression of rainfall, and less efficient removal of pollutants. These aerosol effects can lead to a weaker hydrological cycle, which connects directly to availability and quality of fresh water, a major environmental issue of the 21st century.”
Dr. Gasso has specialized in dust observation in the Patagonia region and the study of the long-range transport from there into the Southern Ocean and Antarctica. “Detection of dust in this area is very difficult because dust tends to be mixed with clouds and the satellite algorithms get confused in such scenes and dust detection in this area is poorly characterized,” he writes. Readings from devices like the Sun Photometer, then, can be highly useful.
Both photographer David Thoreson and Logan spent the morning recording data. The unit itself is tricky to master, particularly on the rolling deck of a sailboat. The very general idea is to point the device skyward and pinpoint the sun in the bulls-eye of the target; it’s not unlike the old hand game where you roll little stainless-steel balls into divots in a plastic-encased toy. As Logan squinted and gave the photometer a little body English, I mentioned that kids weaned on PlayStation might be pretty good at it.
“The skills gained in video-gamesmanship could certainly apply to this scientific instrument,” he said. I was sorry I’d brought it up.
While Logan shot the sun, our current onboard scientist, Dr. Warren Buck, took cloud observations and photographs for our ongoing NASA S’COOL program. Meanwhile, our 360º Ladybug camera, erected on the aft antenna arch, continued to collect and download the tens of thousands of images it records every day.
“This might be one of the really key times for the Ladybug,” noted Michael Reynolds. And that brings us to the cocolitophore bloom.
We’d been noticing as we’ve traveled south that the water’s color has been changing constantly, and dramatically, and today was a beautiful greenish blue. We’ve also seen occasional milky patches, and the bird sightings have been off the charts. We’ve also been noting some very strange surface-water readings on our fishfinder/depthsounder. Do any or all of the above have anything to do with this algae bloom? Frankly, we’re not sure. We’ve just sent Dr. Reynolds a long list of questions of our own. But here’s what we do know, courtesy of an article sent along by the good doctor:
“Coccolithophores are single-celled algae (plankton) distinguished by special calcium carbonate plates (or scales) of uncertain function. They’re almost exclusively marine and are found globally in large numbers throughout the oceanic surface waters, the euphotic (good sunlight) zone of the ocean.”
As plants, they need sunlight for photosynthesis, and thus live near the surface.
“Coccolithophores have long been thought to respond to increased ocean acidity, caused by increasing CO2 levels, by becoming less calcified,” the article continues. “Scientists were recently surprised to learn that in fact the opposite can happen in at least some circumstances, with the model species E. huxleyi becoming 40% heavier and more abundant in waters of CO2 concentration.”
See the attached NASA image showing the common locations of coccolithophore blooms.
Ocean acidification is clearly a major threat to our seas, and it appears coccolithophores may be an important link in our chain of knowledge. The ongoing education of the crew of Ocean Watch, obviously, continues. We’ve certainly learned a lot on our travels Around the Americas. Along the way, we’ve been honored and privileged to perhaps help our partners in science learn a few things, too.
- Herb McCormick with photographs by David Thoreson