“I noticed a pattern in the model today,” Zuzu’s Mom said.

“Really?” Zuzu answered.

Before dinner, Mom liked to talk about her work at the Coastal Physical Oceanography Lab. To her daughter Zuzu, it was pretty boring stuff, but it seemed important to Mom. Although a little old for cartoons, to make it more fun, Zuzu made up animated characters to act out what Mom was talking about. In her mind, Professor Mom was narrating an animation.

“The data are telling us something. In one location in the Southern Ocean something odd is happening. Phytoplankton don’t just grow there, maintaining their population, they thrive. In this one spot we are studying, they really bloom. I can’t draw a conclusion yet. I need to insert more variables and run the mathematical model a few more times to understand what the data are telling me,” Mom went on.

“Variables,” Zuzu thought. “Boring. How about: Helpers. Lab Assistants. Laboratory Underlings... Lablings.”

“What could the lablings be?” Zuzu wondered. “Hmm, what do they have a lot of in the Antarctic? Plankton, icebergs, how about krill? Yeah! The many lablings would be swarmsof krill,” Zuzu imagined.

Mom interrupted Zuzu’s mental movie casting. “Honey, is shrimp stir fry OK for dinner?”

1 2

Zuzu tried to appear interested. Mom came home a few weeks ago rambling on and on about ice melting underwater and rising to the surface. She called it an ice pump. When Mom is that excited, it usually means she will be preoccupied with writing, reading, running experiments on computers at the lab, and presenting her research at conferences. Last time, she had to address the U.S. Congress. Zuzu looked back at her book, she thought she had finished this page. Better read it again.

“Is it because of your discovery?” Zuzu asked.

3

Mom answered, “Well yes, in part. The ice pump is just that, a naturally occurring pump. It brings the mineral-rich water to the surface. The Antarctic ice sheet sits on bedrock, some 750 - 1000 meters below the surface of the Amundsen Sea. The water typically gets warmer as you go deeper, so the warmest water, about 3 degrees Celsius above the freezing point of sea water, is under the ice shelf. The shelf ice melts there and the water rises to the surface, bringing the mineral-rich water with it.”

Mom’s cell phone chirped with a text message. “That ring tone is weird,” Zuzu complained.

Mom shot over, grabbed her phone, and said. “A text from Chey, my lab assistant. Look honey, some exportedimages from our computer model showing the ice pump’s effect on dissolved nutrients such as iron at 100 meters depth.”shown at right

While Mom was talking, Zuzu invented Professor Pierre Penguin and a floating Antarctic lab built inside an iceberg.

Zuzu closed her book. She had covered the same page four times but she couldn’t remember it. “Why are the minerals so important?” she said, accepting that she was now engaged in the conversation. This seemed kind of cool.

4

“Minerals like iron are essential to life in the ocean and really to life in general. We have to think about the dissolved iron from three perspectives: as a limiting nutrient, as a forcing nutrient, and as a micro-nutrient,” Mom began. Zuzu imagined Professor Pierre’s iceberg lab as somewhat more realistic now. “Iron is considered a limiting nutrient. The food web would exist at some level without iron, but when we introduce iron,algal production is healthier.”

“Like when we put fertilizer on the lawn to make it grow better,” Zuzu confirmed. “Algae is like tiny grass floating in the water, isn’t it?”

5

“Exactly. We also consider iron a forcing agent, like light or temperature. Increased sunlight, warmer water, and greater concentrations of iron improve conditions for phytoplankton production.”

“They force growth?” Zuzu added.

“That’s right, Dear. Finally, we have to remember that it is a micro-nutrient, because iron is found and needed in such small quantities. Abundant nutrients, such as nitrogen, are considered macro-nutrients because they occur in large concen-trations. Iron may be found in magnitudes so small that scien-tists measure its concentration in nanomoles. One nanomole of iron is about 1 teaspoon of iron in 185 million gallons of water.”

“Mom! In science we use the metric system!” Zuzu corrected sharply. “Teamwork. I’ll convert water, you do iron,” Zuzu offered, grabbing her cell phone and typing feverishly.

“Collaboration,” Mom suggested, smiling then adding, “A teaspoon is about 40 grams of iron—actually 0.7 mole.”

“In about 700 million liters of water,” Zuzu finished. “Wow! That tiny amount of iron makes such a difference?”

6

Mom flipped through images on her phone, stopping on a NASA image showing phytoplankton growth in the Southern Ocean in summer. shown below “See the boxed region? It can make that much difference. Phytoplankton production in the surrounding ocean is about 0.1 - 0.3 milligrams chlorophyll per cubic meter (mg-chl m-3). In this area of the Amundsen Sea, production is 10 to 30 times greater than average” Mom noted.

Zuzu asked, “You’re sure the ice pump is responsible?”

“Well, we are considering it. We should know more tomorrow. We have 300 computers doing distributed calculations on the mathematical model right now—They have been running for a few days. Why don’t you stop by the lab tomorrow after school to see the results?” Mom asked.

7

“Cool!” Zuzu said, excited. “But what really is the mathematical model?”

Mom answered, “The model is a massive computer simu-lation of the real world. Imagine a multi-dimensional spread-sheet—a sort of database—of water temperatures, amounts of dissolved iron and other minerals at various depths from lots of locations, images and amounts of plankton at various depths from various locations, and lots more information. It’s all stored on computers and all linked together.” screen capture below shows a list of data in the model

“Are the measurements from your trips to Antarctica used in the model? Did you use remote sensing?” Zuzu asked.

“The research brought back from Antarctic cruises— hundreds and hundreds of measurements, contributed to building the model,” Mom said.

“But our work just contrib-uted to a larger database of information that scientists have been building for over forty years,” Mom added. “Come to the lab tomorrow and see for yourself.”

8

“Is it the ice pump?” Zuzu burst into the lab. “Hi Dr. Chey.”

“Hi Zuzu,” Mom said. “These are images Chey plotted from exported data from the model. See what you think.”

“Hi Zuzu,” Dr. Chey replied.

Zuzu pointed at one of the images noting, “This one doesn’t seem to show much iron. Same with this one.” She pointed at another image. Then pointing to the last image she said, “This one looks most like the Observations image.”

“We think so too,” Dr. Chey added. “It confirms the ice pump and the ice shelf melt water play a significant role in bringing the iron to the surface.”

Zuzu summarized, “So the ice pump brings the iron to the surface where the water can get sunlight and phytoplankton grow.”

“They don’t just grow, Zuzu. This is a huge bloom of algae,” Mom clarified.

“So there is algae in the water. Other than making the seawater green and using up the iron and minerals, why is the algae in the Antarctic so important?” Zuzu asked.

10

Initial Condition (Control)

Vertical Mixing Only

Melting Ice Shelf

Observations(Sherrell et al. 2015)

9

“Phytoplankton aren’t the only living things that occur here, Zuzu. When the phytoplankton bloom, then krill, zooplankton, and small fish show up in great numbers to graze on the phytoplankton. These organisms stay around, eat, and reproduce, also in great numbers, which attract larger fish, birds, seals, penguins, and whales. It’s a great food web of consumers all triggered by the algae bloom,” Mom continued.

“And all started by the ice pump,” Zuzu concluded.

“Well, the ice pump delivers the iron, but other factors contribute,” Dr. Chey added.

“...like macro-nutrients such as nitrogen and phosphorous, forcing agents such as light and temperature, as well as micro-nutrients such as iron!” Zuzu boasted.

“Wow,” Dr. Chey concluded, “were you reading your Mom’s articles?”

“Mom and I were discussing this the other day. Say, how did you even know to look for the ice pump?” Zuzu asked.

Dr. Chey pulled up a satellite image on his computer. “Images like these from NASA showed us areas of interest around Antarctica.” shown below, clouds and ice appear black

“Mom showed me an image like that on her phone, but what do you do with it?” Zuzu asked.

Dr. Chey pulled up a screen of commands on another computer. (screen capture shown below) “We run model experiments to better understand the measurements from Antarctica. We write programs such as this that analyze the data and model results. There is a lot to compute so we distribute the calculation load across a network of three hundred computers.”

load( ʻ/home/pierre/inspire/mwf_ts_cWW_v3_corr.matʼ); nsta = 88;

wvec = nan( nsta, 1 ); % kwat cvec = nan( nsta, 1 ); % kchl dvec = nan( nsta, 2 ); % Depth of 1% light ( observed, parameterized ) .

for ista = 1 : nsta% for ista = 26 : 26 % Station-29 of ASPIRE .

if ( ista == 3 || ista == 7 || ista == 17 || ista == 61 || ista == 86 ) continue end

% 2-depth (m), 11-Flour (mg/m3), 13-PAR, 14-SPAR

dept = cnv3( ista ).data(:, 2); flou = cnv3( ista ).data(:, 11); par = cnv3( ista ).data(:, 13); spar = cnv3( ista ).data(:, 14);

if ( max( dept(:) ) < 50. || dept(1) > 5.1 ) continue end

flou( find( flou < 0. ) ) = 0.;

if ( isnan( flou(1) ) ) good = find( ~ isnan( flou ) ); flou( 1 : good(1) - 1 ) = flou( good(1) ); clear good; end 12,0-1 2%

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“A supercomputer!” Looking at the code, Zuzu noticed something familiar, “Hey, this looks like a for loop with some if-then-else statements. I write code similar to this in robotics club for a microcontroller.”

Dr. Chey was surprised, “Wow, maybe we should get you an account on the supercomputer that you could access from your laptop. You could run your own tests on the mathematical model. You just need to know the equations and understand the calculations.”

“Start with studying for your math test,” Mom added.

Zuzu sighed, “Aw Mom.”

“How about we give Zuzu the URLs so she could look at all the NASA satellite images herself?” Dr. Chey offered proudly. “This QR code will take you right to the website.”

“Maybe I could find an area to study!” Zuzu said.14

This material is based upon work supported by the National Science Foundation under Grant No. 1443657. Any opinions, findings, and conclusions, or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.

ISBN: 978-0-692-96026-4 © 2017 Twarog, St-Laurent, Hofmann, Dickerson, & Brown

Cover Image: Composite image of simulated surface chlorophyll concentration (green) and sea ice (gray) along the coast of the Amundsen Sea in December 2010 (austral summer). The chlorophyll represents algae growing in ice-free regions and is from model simulations conducted at Old Dominion University. The sea ice is from satellite images (Scambos et al. 1996).

Consultants:Abbie H. Brown, Ph.D., Professor of Instructional Technology, East Carolina UniversityDaniel Dickerson, Ph.D., Associate Professor of Science Education, East Carolina UniversityE.E. Hofmann, Ph.D., Professor of Oceanography, Old Dominion UniversityP. St-Laurent, Ph.D., Research Associate, Old Dominion University

Image Credits:Front cover image (sea ice):Scambos, T., J. Bohlander, and B. Raup. 1996. Images of Antarctic Ice Shelves. MODIS Level-1B data for 20101224. Boulder, Colorado USA: National Snow and Ice Data Center, http://dx.doi.org/10.7265/N5NC5Z4N.

Image on page-6:Images of microalgae are from NSF-sponsored research conducted by Professor Gordon T. Taylor, School of Marine and Atmospheric Sciences, Stony Brook University.

Image on page-7:NASA Goddard Space Flight Center, Ocean Ecology Laboratory, Ocean Biology Processing Group. Moderate-resolution Imaging Spectroradiometer (MODIS) Aqua Chlorophyll Data; 2014 Reprocessing. NASA OB.DAAC, Greenbelt, MD, USA. doi:10.5067/AQUA/MODIS/L3M/CHL/2014, Accessed on 2014/03/24.

Image on page-9 (data used in “Observations”):Sherrell, R.M., M.E. Lagerstrom, K.O. Forsch, S.E. Stammerjohn and P.L. Yager, 2015, Elementa: Science of the Anthropocene, 3(000071), doi:10.12952/journal.elementa.000071.

Image on page-13:NASA Goddard Space Flight Center, Ocean Ecology Laboratory, Ocean Biology Processing Group. Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Chlorophyll Data; 2014 Reprocessing. NASA OB.DAAC, Greenbelt, MD, USA. doi: 10.5067/ORBVIEW-2/SEAWIFS/L3M/CHL/2014, Accessed on 2016/11/02.

Why do some areas of the Southern Ocean have massive algaeblooms every summer? What is an ice pump and is it responsible? Find answers to these questions as you and Zuzu explore satellite images, mathematical models, Antarctic food webs, marine photos, programming code and why krill invaded her mother’s kitchen!