Weather Forecasting Gets Better
February 9, 2000
The best weather forecasts today will usually give you accurate predictions 24 to 48 hours in advance, but there's a steep drop in accuracy when you go out three, four or five days.
Aerospace giant Lockheed Martin has been working on something that may change all that. The company has developed a new sensor that can measure Earth's air temperatures from space with great precision.
The Atmospheric Infrared Sounder (AIRS) is the result of nearly ten years of research and development by Sanders' Infrared Imaging Systems in Lexington, MA, under contract to NASA's Jet Propulsion Laboratory. The 390-pound instrument is scheduled for launch in December 2000 aboard NASA's AQUA spacecraft, which is an essential element of its Earth Observing System (EOS) mission.
A major advance in satellite remote sensing technology, AIRS promises to provide NASA and the world's scientific community with new and highly accurate data about the atmosphere, land, and oceans for use in climate studies and improved weather predictions.
"The AIRS instrument will have a profound impact on weather forecasting for everyone. For example, with accurate seasonal rain prediction, we can predict and manage our water resources better, even before the rain actually hits the ground," said Dr. Moustafa Chahine, AIRS science team leader and chief scientist at NASA's Jet Propulsion Laboratory.
"AIRS will be able to read atmospheric temperatures to within one degree centigrade in one kilometer layers of altitude in the Earth's lower atmosphere. That degree of accuracy will allow weather forecasters to significantly improve and extend their weather predictions to seven-day forecasts."
AIRS' high resolution spectrometer will precisely sample the Earth's atmosphere from the ground up to as high as 30 miles. The system determines air temperatures and moisture profiles by observing the infrared signatures of carbon dioxide and water vapor. Because gases such as
carbon dioxide, water vapor, ozone, and methane absorb most strongly within specific wavelengths of infrared energy, and because this absorption increases as one looks deeper into the atmosphere from space, AIRS can "see" exact environmental conditions at different levels of the atmosphere.
The very high spectral resolution -- with data collected in many very narrow wavelength bands -- not only allows scientists to determine the temperature and humidity at specific altitudes, but also derives an accurate vertical profile of the state of the lower atmosphere on a global scale.
From these measurements, climate experts will be able to study variations in the Earth's water and energy cycles. AIRS will provide new information about cloud types and cloud cover, and show how they are affected by changes in temperature, evaporation and condensation rates, and atmospheric circulation patterns. The information will also shed more light on how greenhouse gases such as carbon dioxide, water vapor, industrial pollutants and aerosols are trapped in Earth's atmosphere.