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Project Summary

Difficulty	7  –  9
Time required	Average (About one week)
Prerequisites	Familiarity with computers and web browser is helpful for this project.
Material Availability	Readily available
Cost	Very Low (under $20)
Safety	No issues

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Abstract

Objective

The goal of this project is to test the hypothesis that warmer seas make stronger hurricanes. You will collect historical data on hurricane strength and sea surface temperature to see if these two variables are correlated.

Introduction

In this project you will use your web browser to collect data on hurricane strength and sea surface temperature. The goal is to see if there is a consistent relationship between water temperature and hurricane strength. Each hurricane will be one data point on your graph, so you will need to collect data from many, many hurricanes to make a reliable graph.

In this project you will be analyzing two kinds of archived data:

1. hurricane track data, and
2. meterological data from monitoring buoys.

A typical hurricane lasts for many days, and its strength usually fluctuates during its lifetime. You have to start somewhere, though, so the method you will use is to look for the peak intensity of the hurricane, and take all of the measurements there.

Before you start collecting data, you should do background research on how hurricanes form and grow. The next two sections will help you get started with your background research.

Terms, Concepts and Questions to Start Background Research

To do this project, you should do research that enables you to understand the following terms and concepts:

• air pressure,
• air density,
• Hadley cells,
• Saffir-Simpson scale for hurricane strength.

Questions

• How do hurricanes form?
• In what part of the hurricane is the air pressure lowest?
• Why are warm water temperatures important for hurricane formation?

Bibliography

• There are many websites where you can find background information on hurricanes. You'll want to learn about how hurricanes form, which means learning about global wind patterns, and areas of high and low air pressure, among other things. The following web sites are good places to start:
  • DAS, 1999. "Hurricanes: Online Meterology Guide," Department of Atmospheric Sciences, University of Illinois at Urbana-Champaign [accessed May 17, 2006] http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/home.rxml.
  • O'Connor, N.F., date unknown. "Weather Talk: Hurricanes," Naval Meteorology and Oceanography Command [accessed May 17, 2006] http://pao.cnmoc.navy.mil/pao/Educate/WeatherTalk2/indexnew.htm.
  • Keiner, L. and C. Gilman, date unkown. "Physical Oceanography Animations: Hadley Cells and Global Atmospheric Circulation," Department of Marine Science, Coastal Carolina University [accessed May 17, 2006] http://kingfish.coastal.edu/marine/Animations/Hadley/hadley.html.
  • UCAR, 2001. "Pressure: Surface Highs and Lows," University Corporation for Atmospheric Research [accessed May 17, 2006] http://meted.ucar.edu/hazwx/2_2_4.htm.
• Test your knowledge of hurricane formation with this interactive applet (requires Java). You can drag a hurricane around to areas with different water temperature and see what happens to it!
  Whittaker, T. and S. Ackerman, 2005. "Hurricane Applet," Weatherwise, University of Wisconsin [accessed May 17, 2006] http://profhorn.aos.wisc.edu/wxwise/hurr/hurr.html.
• This is one of many online sources of historical hurricane data. We chose this website because the track maps include index information at selected data points so that you can easily correlate position and date (the one drawback is that the background color of the maps is black):
  Unisys, 2004. "Atlantic Tropical Storm Tracking by Year," Unisys Weather [accessed May 17, 2006] http://weather.unisys.com/hurricane/atlantic/.
• The National Data Buoy Center has current and historical meterological data from a network of continuous monitoring buoys:
  NDBC, 2006. "National Data Buoy Center," NDBC, National Oceanic and Atmospheric Administration [accessed May 17, 2006] http://www.ndbc.noaa.gov/.
• For calculating distances on your hurricane track map, try this longitude and latitude distance calculator:
  CSGNetwork.com, 2006. "Length of a Degree of Latitude and Longitude," CSGNetwork.com [accessed May 17, 2006] http://www.csgnetwork.com/degreelenllavcalc.html.

Materials and Equipment

To do this experiment you will need the following materials and equipment:

• computer with Internet access and printer.

Experimental Procedure

1. Do your background research so that you are knowledgeable about the terms, concepts, and questions above.
2. To illustrate the steps involved in the analysis, we will work through a single example. You will need to repeat the data collection (steps 3 and 4, below) for many more hurricanes in order to test the hypothesis. You should collect data for no less than 40 hurricanes (even more is better). Not every storm will have a data buoy nearby. To see how close the buoy is, you can use an online calculator to convert degrees of latitude and longitude to other distance scales (CSGNetwork.com, 2004). If reliable sea surface temperature data is not available for a particular storm, don't use it in your data set.

   Accessing Archived Hurricane Data

3. The Unisys weather website is a good source for historical hurricane data. You can obtain the data in both map and tabular formats. In this example, we will be looking at data from Hurricane Katrina in 2005.
   1. Go to Atlantic Tropical Storm Tracking by Year (Unisys, 2004), and click on the year of interest.
   2. At the top of the page you will see a map with all of the hurricane and tropical storm tracks for the selected year. These maps have overlapping storm tracks and no date information, so we won't be using them for the analysis. They do give you a visual impression of the number of storms that occurred during a given a year.
   3. Scroll down the page to the "Individual Storm Summary" section (illustration below). You will see a summary table showing the number and name of each storm, along with a line of data about the maximum strength of each storm. From this table you can quickly see how many hurricanes occurred during the selected year.

   4. Scroll down further to the "Saffir-Simpson Scale" section (illustration below). This section describes the Saffir-Simspon hurricane strength scale, and also explains the color code used for showing hurricane strength in the maps.

   5. Scroll down further to the "Individual Storm Details" section. For each storm there is a thumbnail map of the storm's path, and a link to the the tabular data for the storm (illustration for Hurricane Katrina below).

   6. Click on the map for an enlarged view of the hurricane track. Print the map. The data points are numbered sequentially. Each advance of the index represents six hours of elapsed time. In the next step, you'll print a data table that matches up with these index numbers.

   7. Use your browser's "back" button to return to the individual storm details. Click on the "Details" button or the "Tracking Information" link for a table of tracking data for the storm (see below). Print the data table. Add a column at the right for "sea surface temperature." In step 4, you'll fill in this value for the time point when the storm was at its maximum strength.

   8. Here is an explanation of each of the data columns in the table:
      • ADV: the numbers on the map correspond to the "ADV" column in the data table. This number is a count of the 6-hour intervals at which the measurements were recorded.
      • LAT: latitude of the hurricane center.
      • LON: longitude of the hurricane center (negative numbers correspond to degrees west of 0°).
      • TIME: date and time of the measurements, in the format "mm/dd/hhZ". The "Z" stands for "Zulu," which is one of many ways to refer to Coordinated Universal Time or UTC (also known as Greenwich Mean Time, or GMT). The hours are in 24-hour format, so "00" means midnight.
      • WIND: in knots (nautical miles per hour; 1 nautical mile equals 1.15 miles).
      • PR: air pressure at hurricane center, in millibars (mb).
      • STAT: status of the storm on Saffir-Simpson scale.
   9. Scan down the WIND and PR columns to find the entry where the hurricane was at its maximum strength. In this example, Katrina reached its maximum strength (lowest pressure, highest wind) at row 21. The wind speed was 150 kt, and the pressure was 902 mb, on August 28 at 18 hours UTC. Find this position on the map.

   Accessing Archived Meteorological Data from Buoys

4. The next step is to find the sea surface temperature at the location where the storm reached its peak. The National Oceanic and Atmospheric Administration (NOAA) maintains a network of moored buoys with sensors that continuously monitor ocean conditions. The data records, with hourly readings, are archived and available online at the National Data Buoy Center (NDBC, 2006). For this project, you will be accessing sea surface temperature data from the buoys. The monitoring buoys also collect other interesting information (wind speed and direction, barometric pressure, and wave height information) which you may also wish to analyze (see the Variations section, below, for some ideas to get you started). Here are detailed instructions for locating buoys near the hurricane track and accessing archived data from them. (You'll find it's much easier to do it than it is to describe it!)
   1. With your hurricane track map handy, go to National Data Buoy Center. You'll see a map like the one below. Each of the rectangles links to a higher-resolution map of the indicated area, showing data buoy locations. Since this project is focused on Atlantic hurricanes, you will be using data buoys from the regions highlighted by the red oval.

   2. Click on the rectangle over the northwestern portion of the Gulf of Mexico. You'll see a map like the one below. The legend (lower left) identifies the types of the data buoys. Not all of the buoys will have sea surface temperature information. To start with, look for the blue squares, which indicate NDBC moored buoys.

   3. Just like your hurricane track map, the data buoy regional maps are marked with latitude and longitude grid squares at 5-degree intervals. Using the grid squares as a reference, locate the data buoy that is closest to the hurricane track. In the map above, buoy 42001 is close to Hurricane Katrina's location on August 21, 2005. Click on the symbol for buoy 42001, which will connect you to the webpage for that buoy.
   4. At the top of the page, you'll find information about the data buoy, including the owner, the type of buoy, the instrumentation onboard ("payload") and the buoy's latitude and longitude (see below). Use the latitude and longitude data to mark the buoy location on your hurricane track map. (For your display board, you can mark the data buoy locations with pushpins and labels.)

   5. Scroll down to the bottom of the data buoy page and find the link for "Historical Data & Climatic Summaries" (see screenshot below). [Note: there are two additional links that you may find useful. "Description of Measurements" tells you what the measurements the data buoy takes and the units that the data are reported in. "Data Inventory" tells you what data is available for past time periods.]

   6. Click on the link for Historical & Climatic Summaries. Under "Standard meterological data," (see below) click on the year of interest (2005, in our case). (The "data descriptions" link takes you to the "Description of Measurements" page, mentioned above in step 4e.)

   7. Almost there! Now use "Method 2" to access the data. The instructions are self-explanatory (see screenshot below).

   8. At last, here it is: a year's worth of hourly records, 365×24=8,760 lines! (It may take awhile to load. If it takes too long, you may want to try downloading the compressed files (Method 1). You'll need to uncompress the files on your computer to access the data.) The illustration below shows only the first 25 hours of data, to make a few points about what you'll find.

   9. The top line is a "header" identifying the data in each column. For detailed information on the data, use one of the "descriptions" links (see step 4e or 4f, above). In addition to the date and time information, you'll be using the "WTMP" column (third column from the right), which reports the water temperature in °C. The date information is in the first three columns (self-explanatory). The time information is in 24-hour format, and like the hurricane tracking data, is in Coordinated Universal Time (UTC, columns four and five, highlighted in red). Any data field that is "9-filled" (e.g., the right-most columns highlighted in blue) is invalid. In this case, it means that the data buoy is not equipped to collect this information. In other cases, it can indicate that a sensor is not functioning properly.
   10. Scroll down and find the date and time of interest, in this case, August 28, 18:00 (see illustration, below). Read the water temperature (third column from the right, 25.4°C) and copy the value to your printed data table for the hurricane.

   Graphing and Analyzing the Data

5. Once you have collected the hurricane and sea surface tempeature data, it's time to put it all together. Make two separate graphs of sea surface temperature (y-axis) vs. hurricane strength (x-axis). For one graph, use either wind speed or pressure as the measure of hurricane strength. For the other graph, use the Saffir-Simpson intensity (1–5) as the measure of hurricane strength.
6. Do you find a consistent relationship between sea surface temperature and hurricane strength? Do both graphs show the relationship? Does the graph support the hypothesis that warmer ocean temperatures increase hurricane strength? Explain why or why not. [Note: it is important to remember that correlation between two variables does not imply causality. In other words, finding a correlation shows that there is a relationship between the variables, but does not show that warmer seas cause stronger hurricanes. Finding a correlation between two variables is often the first step in explaining a causal relationship, but correlation alone is not proof of a causal relationship.]
7. More advanced students should perform a linear regression analysis to quantify the correlation between sea surface temperature and hurricane strength. See Variation 1, below.

Variations

• More advanced students can do further analysis to examine the statistical significance of the correlation using the linear regression technique. For comparison, you might want to also look at the correlation between central pressure and wind speed (should be strongly correlated). See the Science Buddies project Which Team Batting Statistic Predicts Run Production Best? for an example of statistical correlation analysis using a spreadsheet program.
• The hurricane data in your table was collected every six hours, or four times in each 24-hour period. Does the peak intensity of each hurricane tend to occur at different times of day or at the same time of day? What does this tell you? The buoy data also includes air temperature. What is the correlation between hurricane strength and air temperature?
• In addition to water temperature, the data buoys also collect information on wave height, air pressure, wind direction, and wind speed. Many other projects are possible using this data. For example: how far away from the hurricane center is wave height affected? How does this vary with the strength of the storm (minimum pressure at the center)? How does the wind direction change as the hurricane passes through?
• One problem with the buoy data used in this project is that there are relatively few buoys. This means that the temperature data is often collected at a point distant from the hurricane. You may want to measure the distance More advanced students can use high-resolution satellite data for sea surface temperature measurement. The data set begins in 2002, and is available from http://oceancolor.gsfc.nasa.gov/. You will have to learn how to access the data from the instructions on the page.
• How does the amount of time a hurricane spends over warm water affect its strength? Do hurricanes with longer tracks over warm water grow stronger than hurricanes with shorter tracks over warm water?

• For more science project ideas in this area of science, see Ocean Sciences Project Ideas.

Credits

Andrew Olson, Ph.D., Science Buddies

Sources

• Background references on hurricane formation selected from the an NSDL/NSTA web seminar on hurricanes:
  Van Gundy, S. and R. Payo, 2006. "NSDL/NSTA Web Seminars: Hurricanes," National Science Digital Library/National Science Teacher's Association [accessed May 17, 2006] http://ia.usu.edu/viewproject.php?project=ia:2582.

Last edit date: 2006-08-15 17:12:35

Career Focus

If you like this project, you might enjoy exploring careers in Ocean Sciences.

	Diver Thousands of structures, like bridge supports, ocean oil rigs, and marine research equipment lie underwater and it is the job of commercial divers to maintain those structures. Using scuba gear, commercial divers do a wide variety of underwater tasks, including installing equipment and structures, conducting tests or experiments, rigging explosives, and photographing structures or marine life.			Ship and Boat Captain Ship and boat captains have the important job of commanding ships and boats through domestic and deep-sea waterways, so that passengers and cargo arrive safely. To do this, they need knowledge of the mechanical and electrical workings of ships, navigation, signaling, national and international legal rules in waterways, as well as strong leadership skills, since they supervise the work of all other crew members.

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