Bathymetry in 3D

NOAA Portsmouth Harbor Bathymetry

Using depth data collected from sonar measurements, oceanographers create bathymetric charts showing physical features of the ocean floor. During our physical oceanography studies, students create both two-dimensional and three-dimensional bathymetric charts using depth data collected from "mystery boxes" containing models of various ocean features. During the lab activity, students complete the following tasks:

• Collect depth data in rectangular grid patterns across the mystery boxes
• Draw and colorize isobaths (lines of equal depth) to delineate areas of similar depth
• Identify names of the ocean features found inside the mystery boxes
• Create 3D surface charts from the data to finally "see" what's inside the mystery boxes

At the beginning of the lesson, students are rather daunted when I tell them they will be creating a 3D bathymetric chart. By the end of the lesson, they are quite proud of their accomplishments.

To create the final 3D bathymetric chart, students enter their data into Microsoft Excel and use the surface chart option to visualize a realistic model of their original mystery box. Just as we cannot lift the ocean to see the features below, students may never open the mystery boxes to see what's inside—they are reliant upon their data and 3D models to "see" the ocean floor.

The process for creating a 3D surface chart in Microsoft Excel (2007 and 2010 versions) is outlined as follows:

1. Type in all of the bathymetry data (including grid numbers) and select it
2. Go to Insert tab on the ribbon
3. Click "Other Charts" and select "3D Surface Chart"
4. Move Chart to "New Sheet"
5. Right-click the vertical (value) axis and choose "Format Axis"
• Change Maximum to "Fixed" and enter the maximum data value
• Change Minimum to 0 (sea level)
• Change Major Unit to "Fixed" and enter a value of 5.0 (the isobath interval)
• Check the "Values in Reverse Order" box
• Close
6. Right-click the horizontal (category) axis and choose "Format Axis"
• Check the "Categories in Reverse Order" box
• Close
7. Right-click the chart and choose "3-D Rotation"
• Use the arrows and options to adjust the chart to a nice view
• Close
8. Click the entire legend ONCE to select it. Then click ONCE on an individual color in the legend to select it by itself.
• Right-click that color and choose "Format Band"
• Experiment with either the Solid Fill or the Gradient Fill to create a nice blend of colors from deep to shallow
• Close
9. Format the rest of the chart as necessary to include items such as a descriptive title, axis labels, and a well-written caption
10. Add clip art and images to create a unique, eye-catching final style for the 3D chart

See the results below...

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Science Data Exploration

Earth as a system,
from Investigating Earth Systems

Learning about the Earth as a system provides a wide range of opportunities for students to explore various sets of data to better understand the individual components — the atmosphere, the hydrosphere, the geosphere, the biosphere — and how they are interconnected. Throughout our study of Earth science, I give students multiple occasions to interpret, analyze, and evaluate various Earth system data. Over the years, I've built up a collection of simple, useful datasets for students to manipulate using graphing software such as Microsoft Excel, Create A Graph, or Google Spreadsheet. Here is a sampling of some of these data.

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The Atmosphere

Each year, we begin our study of the Earth system within the atmosphere—the gaseous envelope surrounding our planet which has evolved from and interacts with the other "spheres" of the Earth system. Investigating the composition of Earth's atmosphere is thus a logical first step in our data exploration.

Composition of Earth's Atmosphere

Data source: Wallace, J.M. and Hobbs, P.V., 1977, Atmospheric Science—An Introductory Survey

Compound	Percent
Nitrogen	78.08
Oxygen	20.95
Argon	0.93
Trace Gases	0.04

It is useful to refer back to this set of data often during our climate studies, reminding students that the tiny fraction of trace gases are responsible for the greenhouse effect and instrumental in maintaining the balance in Earth's energy budget.

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The Hydrosphere 

As we move from the atmosphere to the hydrosphere, students explore how water is distributed across our planet as well as examine the composition of ocean water. When examining global water distribution, it is useful to have students consider how much of this water is readily available for daily human use. Additionally, this set of data provides an opportunity for students to learn how to create "pie-of-pie" graphs to best show data that has a large range of values.

Global Water Distribution

Data source: Gleick, P. H., 1996, Water resources. In Encyclopedia of Climate and Weather, ed. by S. H. Schneider, Oxford University Press, New York, vol. 2, pp. 817-823

Water Source	Percent
Oceans, Seas, and Bays	96.5
Ice Caps, Glaciers, and Permanent Snow	1.74
Groundwater (fresh)	0.76
Groundwater (saline)	0.94
Soil Moisture	0.001
Ground Ice and Permafrost	0.022
Lakes (fresh)	0.007
Lakes (saline)	0.006
Atmosphere	0.001
Swamp Water	0.0008
Rivers	0.0002
Biological Water	0.0001

"Have you ever had a mouthful of ocean water?" is a great question to ask students when introducing the next set of data. It elicits an immediate "Ewww!" response and primes students to think about the compounds contained in that mouthful of water and how they got there.

Composition of Ocean Water

Data source: National Science Teachers Association, 1992, Project Earth Science, Physical Oceanography

Element	Percent
Oxygen	85.7
Hydrogen	10.8
Chlorine	1.9
Sodium	1.05
Magnesium	0.135
Sulfur	0.0885
Calcium	0.04
Potassium	0.038
Bromine	0.0065
Carbon	0.0028
Other	0.001

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The Geosphere 

When we transition to our studies of the geosphere, students take a look at data comprising the Earth's crust. The composition of Earth's crust shows many commonalities with the composition of ocean water data above. It is useful to have students compare and contrast the two sets of data. It is quite a challenging discussion when students are asked to explain how the Earth's crust can be nearly 50% oxygen; it helps reinforce the meaning of "compound."

Composition of Earth's Crust

Data source: Glencoe Earth Science, 1999

Element	Percent
Oxygen	46.6
Silicon	27.7
Aluminum	8.1
Iron	5.0
Calcium	3.6
Sodium	2.8
Potassium	2.6
Magnesium	2.1
Other	1.5

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The Solar System 

Finally, as we move from the safety of our home planet and journey into the rest of the solar system, it is interesting to ponder the composition of the solar system itself. Once again, it is useful to compare and contrast the similarities and differences among the various sets of data ("What's up with all that hydrogen?"). It is also interesting to ponder how knowledge of Earth's composition can help scientists understand and make sense of the compositions of other objects in our solar system.

Composition of the Solar System

Data source: Mineral Information Institute, Golden CO, 2002, http://www.mii.org

Element	Percent
Hydrogen	91.04
Helium	8.81
Oxygen	0.08
Carbon	0.03
Neon	0.01
Nitrogen	0.01
Magnesium	0.004
Silicon	0.003
Iron	0.003

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With an endless variety of Earth system data available, students have many opportunities to deeply engage in scientific analysis and interpretation as well as develop an appreciation for the Earth as an interconnected system. If you use other interesting datasets, please feel free to share them in the comments...