**TRACK A YOTO DRIFTER**

**TEACHERS KEY**

**1. LEARNING HOW TO USE LATITUDE AND LONGITUDE TO PLOT DRIFTER
POSITIONS ON A CHART.**

A. Listed below are pairs of latitude and longitude, can you find these
locations on the [YOTO Drifter Tracking Chart.]{.underline}

  ----------------- ----------------- -----------------------------------
  **Latitude**      **Longitude**     **Where are you?**

  26°N              80°W              **Miami, FL**

  15°N              90°W              **Guatemala**

  42°20'N           71°W              **Boston, MA**
  ----------------- ----------------- -----------------------------------

B. Listed below are some places on the tracking chart, use latitude and
longitude to describe their location.

  ----------------------- ----------------------- -----------------------
  **Place**               **Latitude**            **Longitude**

  New Orleans, Louisiana  **30°N**                **90°W**

  The island of           **15°N**                **61°W**
  Martinique                                      

  Key West, Florida       **24°30' N**            **81°50'W**
  ----------------------- ----------------------- -----------------------

**2. PLOTTING DRIFTER POSITIONS AND DRAWING TRACKS**

**Before using real-time YOTO data, practice with data from drifters
used in the past.**

Drifter #1 - **Distance can be measured directly on tracking chart where
1 cm = roughly 150 nm (in this case the answers will probably be
[+]{.underline} 20 the answers given below) or they can be calculated
using 1 degree of latitude or longitude (as an estimate here) = 60 nm.**

+-------+---------+---------+-------+----------+----------+---------+
| Date  | L       | Lo      | Time  | Distance | Speed    | Di      |
|       | atitude | ngitude | Int   |          |          | rection |
|       | (°N)    |         | erval | (nm)     | (mph)    |         |
|       |         | (°W)    | (     |          |          |         |
|       |         |         | days) |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 8-    | 15      | -74     | 0     |          |          |         |
| 25-96 | °32'00" | °49'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 8-    | 14      | -75     | 3     | **81**   | **1**    | **SW**  |
| 28-96 | °40'00" | °48'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 9     | 14      | -76     | 3     | **60**   | **0.83** | **W**   |
| -2-96 | °14'00" | °45'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 9     | 14      | -77     | 3     | **63**   | **0.88** | **W**   |
| -5-96 | °07'00" | °50'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 9     | 15      | -79     | 3     | **115**  | **1.6**  | **NW**  |
| -8-96 | °12'00" | °10'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 9-    | 16      | -80     | 3     | **98**   | **1.4**  | **NW**  |
| 11-96 | °44'00" | °04'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 9-    | 17      | -81     | 3     | **86**   | **1.2**  | **NW**  |
| 14-96 | °49'00" | °03'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 9-    | 18      | -82     | 3     | **86**   | **1.2**  | **NW**  |
| 17-96 | °53'00" | °01'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 9-    | 19      | -82     | 3     | **59**   | **0.82** | **NW**  |
| 20-96 | °40'00" | °47'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 9-    | 20      | -82     | 3     | **38**   | **0.53** | **NW**  |
| 23-96 | °02'00" | °58'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+

Drifter #2

+-------+---------+---------+-------+----------+----------+---------+
| Date  | L       | Lo      | Time  | Distance | Speed    | Di      |
|       | atitude | ngitude | Int   |          |          | rection |
|       | (°N)    |         | erval | (nm)     | (mph)    |         |
|       |         | (°W)    | (     |          |          |         |
|       |         |         | days) |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 10    | 28      | -80     | 0     |          |          |         |
| -4-96 | °12'00" | °00'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 10    | 30      | -80     | 3     | **125**  | **1.7**  | **N**   |
| -7-96 | °20'00" | °02'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 10-   | 30      | -79     | 4     | **36**   | **0.38** | **NE**  |
| 11-96 | °51'00" | °49'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 10-   | 32      | -77     | 3     | **154**  | **2.1**  | **NE**  |
| 14-96 | °18'00" | °55'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 10-   | 32      | -78     | 3     | **28**   | **0.39** | **NW**  |
| 17-96 | °23'00" | °01'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 10-   | 33      | -77     | 3     | **74**   | **1.03** | **NE**  |
| 20-96 | °01'00" | °06'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 10-   | 33      | -77     | 3     | **11**   | **0.15** | **NE**  |
| 23-96 | °18'00" | °03'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 10-   | 35      | -74     | 3     | **192**  | **2.67** | **NE**  |
| 26-96 | °17'00" | °53'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 10-   | 37      | -69     | 3     | **331**  | **4.6**  | **NE**  |
| 29-96 | °54'00" | °54'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 11    | 37      | -67     | 3     | **139**  | **1.93** | **SE**  |
| -1-96 | °00'00" | °39'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+

**3. CALCULATING DRIFTER SPEED AND DIRECTION**

Practice calculating speed for the examples given below.

+-----------------+-----------------+-----------------+-----------------+
| Object          | Distance        | Time            | Speed           |
+-----------------+-----------------+-----------------+-----------------+
| Airplane        | 700 miles       | 2 hours         | **350 mph**     |
+-----------------+-----------------+-----------------+-----------------+
| Snail           | 1.2 cm          | 1.5 hours       | **0.8 cm/h**    |
|                 |                 |                 |                 |
|                 |                 |                 | **(.0005 mph)** |
+-----------------+-----------------+-----------------+-----------------+
| Whale           | 25 nm           | 5 hours         | **5 mph**       |
+-----------------+-----------------+-----------------+-----------------+
| Cheetah         | 24 nm           | 15 minutes      | **96 mph**      |
|                 |                 |                 |                 |
|                 |                 | (.25 hours)     |                 |
+-----------------+-----------------+-----------------+-----------------+

  ----------------------- -----------------------------------------------
  Whale                   **Arrow should be 0.5 cm long**

  Cheetah                 **Arrow should be 9.6 cm long**
  ----------------------- -----------------------------------------------

If a direction is between 2 of the major directions (N, S, E, and W),
then the directions are combined. An arrow pointing to a direction
between North and East, would be pointing Northeast (NE). What direction
are the arrows below pointing, write it below each arrow.

![](media/image1.wmf){width="1.4159722222222222in"
height="0.6243055555555556in"}East ![](media/image2.emf)
![](media/image3.emf){width="0.9715277777777778in"
height="0.9715277777777778in"}

a\. **North** b. **Southeast**

Example

For each of the arrows below, measure its length and using a scale of 1
cm = 10 mph, determine what speed it represents and name the direction
it is pointing (this is its velocity).

![](media/image4.wmf){width="1.31875in" height="0.5833333333333334in"}
![](media/image5.wmf){width="0.6111111111111112in"
height="0.6111111111111112in"}
![](media/image6.wmf){width="0.49930555555555556in"
height="1.582638888888889in"}

a West (20 mph) b. **Southwest (10 mph)** c. **South (23 mph)**

Draw arrows which represent the speed and direction for the following
velocities.

![](media/image3.emf){width="0.49930555555555556in"
height="0.7784722222222222in"}**2 cm long arrow**
![](media/image3.emf){width="0.9020833333333333in"
height="0.9020833333333333in"}**3 cm long arrow**

a\. 20 mph, south b. 30 mph, southwest

**4. AVERAGING AND DRIFTER TRACKS**

Drifter #1

+-------+---------+---------+-------+----------+----------+---------+
| Date  | L       | Lo      | Time  | Distance | Speed    | Di      |
|       | atitude | ngitude | Int   |          |          | rection |
|       | (°N)    |         | erval | (nm)     | (mph)    |         |
|       |         | (°W)    | (     |          |          |         |
|       |         |         | days) |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 8-    | 15      | -74     | 0     |          |          |         |
| 25-96 | °32'00" | °49'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 9     | 14      | -76     | 6     | **137**  | **0.95** | **SW**  |
| -2-96 | °14'00" | °45'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 9-    | 16      | -80     | 9     | **256**  | **1.19** | **NW**  |
| 11-96 | °44'00" | °04'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+

Drifter#2

+-------+---------+---------+-------+----------+----------+---------+
| Date  | L       | Lo      | Time  | Distance | Speed    | Di      |
|       | atitude | ngitude | Int   |          |          | rection |
|       | (°N)    |         | erval | (nm)     | (mph)    |         |
|       |         | (°W)    | (     |          |          |         |
|       |         |         | days) |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 10    | 28      | -80     | 0     |          |          |         |
| -4-96 | °12'00" | °00'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 10-   | 30      | -79     | 7     | **147**  | **0.86** | **NE**  |
| 11-96 | °51'00" | °49'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+
| 10-   | 35      | -74     | 15    | **298**  | **0.83** | **NE**  |
| 26-96 | °17'00" | °53'00" |       |          |          |         |
+-------+---------+---------+-------+----------+----------+---------+

**ANALYSIS OF RESULTS**

1\. These Drifters are tracking ocean currents. What is the general
location of these currents and what is the main direction they are
moving? Is the direction of daily drift different from the direction
over a longer time scale ?

**One drifter is in the Caribbean Sea and the other is in the North
Atlantic Ocean just off the southeast U.S. coast (it is in the Gulf
Stream). The main current in the Caribbean Sea flows to the west,
becoming more northwesterly at the western side of the Sea. In the
southeastern U.S., the Gulf Stream flows principally north, becoming
more northeasterly near North Carolina.**

**The direction of daily drift may be different from that measured over
longer time periods. Small scale features such as eddies (circular
currents) or meanders (bends in a current stream) may effect the
relatively short-term drifter tracks, but their long term drift is
typically in the direction of the main or large-scale current system in
the region. The large scale current systems of the ocean are a function
of factors such as the distribution of land masses, climate, ocean
bathymetry, water density, global wind patterns, and the coriolis
force.**

2\. Do both Drifters behave the same or differently? What might make the
currents (drifters) speed up, slow down or change direction?

**The drifters do not behave the same because they are in different
ocean regions within different current systems. Regional ocean currents
are strongly dependent on local conditions such as the pattern of
larger-scale flow, bathymetry (depth), morphology of the region
(configuration of land masses), and wind. Wind at the surface can make
drifters speed up or slow down by intensifying currents (if the wind is
in the same direction as water movement) or reducing currents (when the
wind is in the opposite direction of water movement). Small eddies,
meanders or changes in depth can also make currents change speed or
direction.**

3\. Did the number of days used to calculate the speed and direction
make a big difference?

**Yes, the speed and direction of the drifter changes depending on how
many days are used in averaging. Using a greater number of days to
calculate your average means that you are determining longer term flows
(typically larger-scale currents). Small-scale features can be
recognized using smaller intervals for averaging of drifter positions.**

4\. Do you think you could predict the position of a Drifter in the
future, for instance 3 days after your last position plotted ?

**Sometimes**

5\. Give one example of why it is important to understand how ocean
currents flow.

**Transport of materials within the sea, such as larvae, sediment,
pollutants, and heat (climate), ship travel, etc. - see website**

**REAL TIME YOTO DRIFTER DATA**

Now that you are an expert at plotting ocean Drifters and their tracks,
click into the YOTO Drifter position and tracks or data to obtain
information on drifters deployed in 1998. Plot their positions,
calculate their speed, direction and try to predict where they are going
each day or week. Learn at the same time as real scientists where ocean
currents are flowing, and how sea surface temperatures are changing.

**YOTO Drifter Questions**

1\. These drifters are tracking ocean currents. What is the general
location of these currents and what is the main direction they are
moving? Is the direction of daily drift different from the direction
over a longer time scale ?

**See answer #1 above**

2\. Do the number of days used to calculate the speed and direction make
a big difference?

**Yes, same as #2 above**

3\. Go back to your chart and record the temperature next to each point.
Do you see any changes in temperature along the Drifter tracks? What
could cause temperature at the sea surface to change?

**Yes and No, sometimes the temperature changes along the drifter tracks
or between drifter positions. Sea surface temperatures typically
decrease from the Caribbean Sea and tropical Atlantic northward. On a
global scale, on the western side of an ocean basin surface currents
tend to transport warm water from southerly latitudes northward. As
surface water flows northward it is cooled by the surrounding air, which
becomes cooler as you move north toward higher latitudes. Sea surface
temperatures can also be decreased by wind mixing or through the
addition of cooler river water or other colder ocean waters.**

What role do sea surface temperatures play in climate and weather
patterns?

**The ocean plays a very important role in the Earth's climate and
weather patterns as dramatically illustrated by the 1997 - 1998 El Nino.
Ocean water has a high heat capacity, thus it tends to store heat. In
areas of warm sea surface temperatures, high evaporation and convection
often produce thunderstorms and rain over nearby land masses. Warm
currents like the Gulf Stream warm nearby coastal regions that otherwise
would be relatively cool and dry. Warm ocean waters are also an
important source of energy for developing hurricanes, this is one reason
why during the summer months, the tropical Atlantic ocean is a breeding
ground for hurricanes. When hurricanes move over cool water or land,
they tend to decrease in strength.**

4\. Many organisms in the sea have young that begin life as small
floating creatures, called plankton. Even those organisms who in their
adult forms are strong swimmers or live on the bottom, may begin as
plankton and drift with the ocean currents. Understanding ocean currents
is therefore very important to our ability to assess the population
size, location, and breeding grounds in numerous marine species. For
instance, the spiny lobster, an important species in reef environments
and a commercial fishery, begins its life as a small, flattened
skeleton-like creature, known as a phyllosome. As it develops, it can
drift for months in the ocean currents. Once it becomes a juvenile,
looking much more like the adult version; it settles to the sea floor
and begins its journey into adulthood. In South Florida spiny lobster
are commercially fished in some areas and protected in others, like the
Florida Keys National Marine Sanctuary. Scientists are studying currents
in an attempt to determine where Florida lobsters originate, thereby
providing answers to questions such as: is there a local source of
lobster larvae and do circular currents, called eddies, keep them within
the area, or do larvae come from a distant upstream source somewhere in
the Caribbean ?

Using data from YOTO Drifters, you might be able to help answer this
important question.

If a lobster were to spawn just south of Jamaica in the Caribbean Sea,
and small phyllosomes began their journey as plankton, where would they
drift? In three months where would the closest land and reef habitat be
on which they might settle ?

**The answer to this depends on whether the larvae get caught in small
scale eddies or meanders, drift landward, or remain in the flow of large
scale current systems. The phyllosome could end up settling near Jamaica
or as far away as the Florida Keys.**

5\. An oil tanker in the Gulf of Mexico collides with a pleasure yacht
just north of the western tip of Cuba in the Gulf of Mexico. If oil
starts seeping from the tanker where would the ocean currents carry it?
If the oil cannot be cleaned up while at sea or a big storm makes it
impossible to contain the spill, use Drifter data to predict which
coastal communities should make preparations to prevent damage to their
local environment.

**The answer to this is dependent on when the spill occurs as current
patterns in the Gulf of Mexico change throughout the year. Base the
answer on the latest drifter patterns and discuss previous tracks and
possibilities.**

6\. Scientists use data from satellites to obtain a view of the oceans
which would otherwise be impossible. With remotely sensed data
(satellite imagery), we can see large sections of the ocean at one time.
But how do we know that these images are accurate? Scientists do
something called ground-truthing. Ground-truthing is when ocean data are
collected at the same time and in the same location as the image.
Drifter data can be used to ground-truth satellite images of sea surface
temperature and ocean color. Look at YOTO Drifter temperature data and
compare these results to the images of sea surface temperature at the
sites provided. Would the date of comparison make a difference?

**Sometimes, 1) it depends on where you are making comparisons, 2)
slight seasonal changes do occur in large scale sea surface
temperatures, and 3) eddies, meanders, river inflows, and storms could
effect the data.**

7\. Predictability, Choose 1 or 2 Drifters and try to predict where they
will be 1 week later. Compare your prediction with the real Drifter
position, were you right ? If not why?