I blogged earlier about the sensor web that is taking shape.  It involves satellites and ground sensors.  I blogged about very inexpensive nanosatellites, typicaly 10 cm x 10 cm x 10 cm,  that are dramatically reducing the cost of sateliite imagery.

Drifting buoys are less than 22 feet long, weigh no more than 100 pounds, and typically survive on the open seas for an average of 450 days. Each drifter consists of a surface buoy and an underwater drogue attached by a tether. The thermometer, pressure sensors, batteries and other electronics reside in the buoy.  There are about 1,000 drifting buoys on the world’s oceans. The modern drifter weighs about 44 pounds with 16-foot drogues and cost around $1,700 each.

Roughly every hour, the drifter uploads data to a satellite passing overhead which in turn relays the observations back to an Earth receiving station.   Drifters measure sea-surface temperature and ocean current data as well as their location. For example, their observations help in tracking the impact of El Niño and La Niña on global ocean currents. In addition NOAA will sometimes deploy drifters in front of hurricanes to improve forecasts and investigate how the ocean and atmosphere interact within and around the storm.

The 1,000 or so drifters in the oceans collect about 30,000 observations per day, which are processed by NOAA’s Drifter Data Assembly Center in Miami and archived for research and placed on the Global Telecommunications System, where the National Weather Service and other forecasters can use them for weather prediction.

The map shows the location of all drifters as of April 26, 2013. (Credit: NOAA Climate.gov, based on drifter data from the Atlantic Oceanographic & Meteorological Laboratory.)