NOAA Teacher at Sea
Onboard NOAA Ship Ronald H. Brown
July 4 – 23, 2004
Mission: New England Air Quality Study (NEAQS)
Geographical Area: Northwest Atlantic Ocean
Date: July 6, 2004
If you are standing on the ground, or in our case floating on the ocean, looking up into clear skies how could you tell the speed and direction of the wind a mile or two above you?
I spent the morning with Dan and Michelle who are from NOAA’s Environmental Technology Lab in Boulder, Colorado. Dan spent most of the morning showing me how the wind profiler he designed, can determine the wind speed and direction at any point above the ship, up to 6 kilometers in altitude. Dan was the chief engineer in designing NOAA’s wind profiler network, which has facilities strategically located across the United States. One of the phased-array radar wind-profilers is also installed on the BROWN. The profiler uses radar to remotely detect wind speed and direction in the column of air above our location. Five radar beams are aimed upwards from the ship, one looks straight up and the other four look upwards but at a slight angle. The radar signals bounce off turbulence in the air (kind of like air bubbles in a flowing river) and are then picked up by an antenna back at the profiler. The instrument then combines the signals from the five beams and determines the wind speed and direction at any point above the ship, up to about 6 kilometers (km). The computer monitor on the profiler gives a constant readout of the air’s movement. The chart this morning is showing that the air from the surface to about 3 km has shifted considerably both in speed and direction during the past 24 hours as a weak cold front passed through. However, the air above 3 km did not change its speed and direction much at all.
Dan and Michelle will also be launching radiosondes (commonly called weather balloons) four times a day. The radiosonde is attached to a large helium balloon. As it is rises through the atmosphere it measures relative humidity, air temperature, air pressure, wind speed and wind direction. Normally the sonde will rise to a height of 50,000 – 60,000 feet before the balloon burst and the radiosonde falls back to Earth. So this afternoon we went to the aft (back) of the ship. There Dan filled the balloon with helium until the balloon was about four feet in diameter. He then attached the radiosonde, which is smaller than a paperback novel, so that it was hanging from the bottom of the balloon. Once the computer had a good signal from the radiosonde’s Global Positioning System (GPS) he released the balloon. We all went back inside to the computer monitor that was graphing the relative humidity, air temperature, air pressure, wind speed and wind direction as the balloon ascended.
In the evenings after dinner the scientists have show and tell time. Different research groups showed some of the data that was collected today and gave a status report of how their equipment is working.
Questions of the Day
Why would the helium balloon burst as it reaches high altitudes?
How many MILES high can Dan and Michelle’s wind profiler determine wind speed and direction?
What is a GPS used for?