The table below (VVV) shows a time series of data. In this case, the data "series" has 12 hours of observations from the "Gulf of Maine" buoy.

• NOTE that many buoys DO NOT record all of these different types of data!

Hours are shown in the third column as "Zulu time," which is also known as Greenwich Mean Time (GMT).

• Greenwich, England is globally accepted as a reference standard for both time and longitude (its location marks zero degrees longitude). "Zulu" time is based on a 24-hour clock.
• Click here to check out how U.S. time zones compare to GMT.

The "Previous 12 observations" may be posted each hour for these measurements:

• WIND DIRECTION (WDIR)
  • Average wind direction (degrees clockwise from north) over an eight-minute sampling time.
    • Winds blow FROM the direction listed.
• WIND SPEED (WSPD)
  • Average wind speed (knots) over an eight-minute sampling time.
• WIND GUST (GST)
  • Peak 5 second gust speed (knots) measured during an eight-minute sampling time.
• WAVE HEIGHT (WVHT)
  • Significant wave height (feet) is calculated as the highest one-third of all of the wave heights during a 20-minute sampling time.
• DOMINANT WAVE PERIOD (DPD)
  • Dominant wave period (seconds) is the period with the maximum wave energy.
    • Click here to learn about wave periods.
    • Click here to see the relationship between wave energy and wave period.
• AVERAGE WAVE PERIOD (APD)
  • Average wave period (seconds) of all waves during a 20-minute sampling time.
• ATMOSPHERIC PRESSURE (PRES)
  • Sea level pressure (millibars)
• AIR TEMPERATURE (ATMP)
  • Air temperature (degrees Fahrenheit)
• WATER TEMPEATURE (WTMP)
  • Sea surface temperature (degrees Fahrenheit)
• PRESSURE TENDENCY (PTDY)
  • How barometric pressure (millibars) is changing over time (steady, rising, or falling)

[Learn more about these measurements at http://seaboard.ndbc.noaa.gov/measdes.shtml]

1. Look at wind data in the table above (WDIR, WSPD, GST).
   • Which measurement showed the most variability (or tendency to change)?
   • During any of these 12 observations, were the wind gusts very different from the average wind speed?
     • Can you guess why or why not?
   • How do these data compare to the latest data for the "Gulf of Maine" buoy?
     • Or you can compare these data to wind conditions at buoys located closer to you by accessing the "clickable map" at the National Data Buoy Center Station Information page.
   • How do you explain the differences between the data above (from August 5, 1998) and the latest data?
     • Seasonal changes? Storm activity?
   • How do the latest 12 hours of wind condition observations at the "Gulf of Maine" (or any other) buoy compare with those from:
     • the "Portland" buoy?
     • the "Georges Bank" buoy?
2. Look at the wave data in the table above (WVHT, DPD, APD).
   • Which measurement showed the most variability (or tendency to change)?
   • During any of these 12 observations, was the Dominant Wave Period (DPD) very different from the Average Wave Period (APD)?
     • Can you guess why or why not?
   • How do these data compare to the latest data for the "Gulf of Maine" buoy?
     • Or you can compare these data to wave conditions at buoys located closer to you by accessing the "clickable map" at the National Data Buoy Center Station Information page.
   • How do you explain the differences between the data above (from August 5, 1998) and the latest data?
     • Seasonal changes? Storm activity?
   • How do the latest 12 hours of wave observations at the "Gulf of Maine" (or any other) buoy compare with those from:
     • the "Portland" buoy?
     • the "Georges Bank" buoy?
3. In the table above, the last four columns with data are related to atmospheric conditions (PRES, ATMP, PTDY) and water temperature (WTMP).
   • Consider the barometric pressure-related data (PRES, PTDY).
     • Earth's average sea level pressure is 29.92 inches of mercury.
       • Is pressure at the "Gulf of Maine" buoy on August 5, 1998 higher or lower than Earth's average?
       • How do the latest readings from the following stations compare with Earth's average pressure for :
         • the "Gulf of Maine" buoy?
         • the "Portland" buoy?
         • the "Georges Bank" buoy?
         • a buoy located closer to you?
           • How are these pressure readings relate to current weather at the buoy(s) site(s)r? (Click here to access the "Weather" section)
     • Look at the "Pressure Tendency" (PTDY) over the 12-hour observation period in the table above.
       • Was pressure generally steady, rising, falling, or a combination of these?
       • How do the latest Pressure Tendency readings compare with:
         • the "Gulf of Maine" buoy?
         • the "Portland" buoy?
         • the "Georges Bank" buoy?
         • a buoy located closer to you?
   • Compare the air temperature (ATMP) and water temperature (WTMP) readings in the table above.
     • Which was generally warmer?
       • Can you guess why?
     • Would you expect air temperature to ALWAYS be warmer than water temperature?
       • Why or why not?
   • Look at the latest air and water temperature readings for:
     • the "Gulf of Maine" buoy
     • the "Portland" buoy
     • the "Georges Bank" buoy
     • Or at a buoy located closer to you.
       • At each station, how do the air and water temperature readings compare?
       • How do they compare from station-to-station?
         • Are the results what you expected?
4. Changes in our weather are usually tied to shifts in low and high pressure systems. Because the U.S. is in the northern hemisphere:
   • High-pressure systems (H) = Winds circulate clockwise
   • Low-pressure systems (L) = Winds circulate counterclockwise
     • Look at the latest "12 observations" of wind direction (WDIR) for either the "Gulf of Maine" buoy or the "Georges Bank" buoy or a buoy located nearer to you. Draw a series of arrows that show how winds shifted over the previous 12-hour period (recall that "WDIR" shows the direction from which the winds were blowing).
       • Were winds generally circulating clockwise, counterclockwise, or neither?
       • Is the wind circulation pattern consistent with the pressure data for this buoy?
     • Repeat this process for the "Portland" buoy.
       • Are these wind data consistent with those at the other buoy you chose?
         • If not, can you explain the differences?
           • Think about the location of the "Portland" buoy (#44007).
             • What factors other than high- and low-pressure systems might strongly affect winds at the "Portland" buoy?
             • HINT: Click here to see an image representing one possible factor.
   • How might these readings relate to near-future weather? (Click here to access a "hands on" activity that will help you forecast weather based on atmosheric pressure and wind readings.)