Data in Table 1 below are from drifter buoys in the North Pacific Ocean. Released into the ocean, the buoys float with the currents and take measurements of the water with built-in instruments. They are tracked by satellites in orbits far above Earth and transmit data several times a day. Ships and airplanes can drop these low cost (~$4500) and durable buoys into the sea. When released by ships, they have a 98% survival rate; from the air, survival drops to 78%. About half of the drifters lose their ability to communicate with the satellite, for one reason or another, after 440 days. Other buoys last longer and transmit their information for several years. Click on the world map to see the global buoys in the ocean in June 1995.
The floater at the top of the buoy sits at the surface of the water and holds an antenna for sending data to a satellite above. Drogues well below the surface cause the ocean currents to take the buoy along instead of the surface wind (Figure 1 below). The buoy also holds electronic instruments for measuring sea surface temperatures (SST), submergence, irradiance (for sunlight) and barometric pressure. At the top is another device for measuring temperature and conductivity (used to calculate salinity).
Figure 1. An example of freely drifting surface buoys. Two different types of drogues, used to move with the surface currents and reduce the effects of the wind, are shown. The two types of drogues are the parachute drogue and the window shade drogue.
1. (a.) Plot the 1995 data from 3 buoys in the North Pacific (Table 1) on the Pacific Ocean Map (print a hard copy using your local printer). Use longitude and latitude data to plot the position of each buoy location during the year; then connect the locations with lines and draw an arrow to show the direction of motion.
NOTE: Longitudes 80-180 degrees on the left (west) side of the diagram are East Longitudes (positive numbers); longitudes 180 to 80 on the right (east) side of the diagram are West Longitudes (negative numbers). North Latitudes are in the upper half of the map and South Latitudes are in the lower half of the map.
Label the numbers on the map as N and S latitudes and E and W longitudes.
| TABLE 1. NORTH PACIFIC BUOY DATA | |||
| Buoy no | Position day | Latitude | Longitude |
| 12410 | 27 Feb 95 | 30.1 | -123.7 |
| 12410 | 28 Mar 95 | 27.5 | -121.8 |
| 12410 | 22 Apr 95 | 25 | -124.6 |
| 12410 | 22 May 95 | 23.6 | -128 |
| 12410 | 24 June 95 | 22.5 | -133.9 |
| 12410 | 24 July 95 | 23.1 | -138.4 |
| 12410 | 26 Aug 95 | 20.5 | -145.4 |
| 12410 | 25 Sept 95 | 20 | -147.6 |
| 12410 | 20 Nov 95 | 17.9 | -155.3 |
| 12410 | 18 Dec 95 | 21.4 | -159.5 |
| 15022 | 25 Feb 95 | 10.7 | 162 |
| 15022 | 27 Mar 95 | 10.5 | 152.1 |
| 15022 | 23 Apr 95 | 11.6 | 145.5 |
| 15022 | 20 May 95 | 12.4 | 137.6 |
| 15022 | 25 June 95 | 17 | 131.1 |
| 15022 | 22 July 95 | 21.7 | 127.8 |
| 15022 | 27 Aug 95 | 33 | 141.6 |
| 15022 | 23 Sept 95 | 37 | 147.8 |
| 15022 | 23 Oct 95 | 39.3 | 152 |
| 15022 | 25 Nov 95 | 40.1 | 154.5 |
| 15022 | 31 Dec 95 | 37.6 | 160.4 |
| 22217 | 27 Feb 95 | 51.2 | -162.7 |
| 22217 | 27 Mar 95 | 50.4 | -165.3 |
| 22217 | 24 Apr 95 | 48.7 | -159.5 |
| 22217 | 29 May 95 | 50.7 | -155.1 |
| 22217 | 26 June 95 | 50.4 | -151.7 |
| 22217 | 24 July 95 | 51.5 | -149.3 |
| 22217 | 28 Aug 95 | 51 | -145 |
| 22217 | 25 Sept 95 | 53.1 | -143.8 |
| 22217 | 23 Oct 95 | 55.2 | -139.1 |
| 22217 | 27 Nov 95 | 57.1 | -141.4 |
| 22217 | 18 Dec 95 | 56.9 | -141.7 |
(b.) Refer to the Map of Surface Currents.
What are the names of the surface currents that moved the buoys whose courses you plotted?
Buoy 12410:
Buoy 15022:
Buoy 22217:
To check your plotting, see Map of Plotted Buoy Data.
(c.) The currents plotted in a.) are all part of the North Pacific gyre, a clockwise-moving current that redistributes heat in the North Pacific.
What is the name of the current that moves water past the coast of California?
Do you think it carries warm or cold water past the coast of California?