December 1, 2007 Electrical engineers are providing meteorologists with better information for their forecasts with Tropospheric Airborne Meteorological Data Reports. Sensors are placed on regional airliners cruising at around 25,000 feet, where they gather information on a variety of weather variables, then sends it to satellites that route it to weather centers. The sensors increase the amount of weather-gathering devices in the air, providing more data on which meteorologists can base their forecasts.
Our sky is filled with all types of weather, it's also filled with airplanes -- some facing rough weather head-on. Now, some weather forecasters are using these planes to make better weather predictions.
"One of the big jumbo jets which flies, can cruise around 30, 35-thousand feet, that altitude way up there is way above the weather," Taumi Daniels, Aerospace Engineer at NASA Langley Research Center said.
But smaller, low flying aircrafts come face-to-face with bad weather daily. Now, forecasters are taking advantage of the weather these planes experience, with a new tiny on-board device, called TAMDAR.
"TAMDAR is important because it is mounted on these smaller aircraft. These aircraft don't fly up above the weather," Daniels said.
Most weather information above ground level is collected from satellites and weather balloons. The new device detects moisture at level as the plane flies, which is an important ingredient in forecasting severe weather.
"For a complete understanding of the atmosphere in order to improve weather forecasts, you need to know where the moisture is and where it's moving," Daniels said.
Developed by aerospace engineers at NASA, the device measures humidity, temperature, winds, ice and turbulence. Satellites collect the information and send it remotely to weather centers on the ground, providing better, more up-to-date local forecasts.
"It does it all in one small compact package that can be installed easily onto any airplane," Daniels said. It's being installed on over 400 planes flying shorter, daily routes, providing meteorologists more weather information, more often.
BACKGROUND: Weather forecasters in the middle of the U.S. are making better local predictions for pilots and others thanks to an airborne sensor being tested by NASA's Aviation Safety Program. Dozens of commuter aircraft have been equipped with the Tropospheric Airborne Meteorological Data Report (TAMDAR) instrument. The information collected benefits weather models and forecasts because it increases the number of observations in the lower atmosphere. Larger airplanes fly above most weather and collect less data from the atmosphere.
HOW IT WORKS: TAMDAR is a tiny sensor that allows aircraft to automatically sense and report conditions in the atmosphere. Observations are sent by satellite to a data center on the ground that processes and distributes up-to-date weather information to forecasters and pilots. Initial research shows that the airborne sensor makes a forecast model that's 10 to 20 percent more accurate, with just the temperature being taken into account. It also measures humidity, pressure, winds, icing, and turbulence with the help of the Global Positioning System (GPS), which adds information on location, time and altitude into the mix. Meteorologists at the National Weather Service have found tat TAMDAR is useful in forecasting severe thunderstorms, dense fog, winter storms, and low-level wind shear.
ABOUT GPS: The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. GPS was originally intended for military applications, but in the 1980s, the government made the system available for civilian use. GPS works in any weather conditions, anywhere in the world, 24 hours a day. GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. GPS receivers take this information and use a combination of signals to calculate the user's exact location. Essentially, the GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. Now, with distance measurements from a few more satellites, the receiver can determine the user's position and display it on the unit's electronic map.
HOW MANY POINTS? A GPS receiver must be locked on to the signal of at least three satellites to calculate a 2D position (latitude and longitude) and to track movement. With four or more satellites in view, the receiver can determine the user's 3D position (latitude, longitude and altitude). Once the user's position has been determined, the GPS unit can calculate other information, such as speed, bearing, track, trip distance, distance to destination, sunrise and sunset time.