About the Mission The Atmospheric Infrared Sounder, AIRS, advances climate research and weather prediction into the 21st century. AIRS is one of six instruments onboard Aqua, a satellite that is part of NASA’s Earth Observing System. AIRS, along with two partner microwave sounding instruments, represents the most advanced atmospheric sounding system ever deployed in space. Together these instruments observe the global water and energy cycles, climate variation and trends, and the response of the climate system to increased greenhouse gases. The AIRS instrument measures the amount of infrared energy emitted from the atmosphere. On the ground, computer programs trans- form these measurements into temperature, humidity, cloud prop- erties, and the amounts of green- house gases. AIRS data even reveals land and sea surface temperatures. To date, weather balloons have provided the most accurate infor- mation for weather forecasting. But these land-launched balloons leave large areas over the ocean unob- served. From the vantage point of space, the AIRS and microwave instruments provide global cover- age every day with accuracy com- parable to weather balloons. This highly accurate data, gathered over land and sea, ushers in a new era of atmospheric monitoring on a truly global scale. Monitoring Earth’s Atmosphere Establish the connection between severe weather and climate change Improve weather forecasting Determine if the global water cycle is accelerating Detect the effects of increased greenhouse gases The AIRS Instrument: Electronics Module IR Spectrometer & Visible Light Imager Radiative Cooler & Earth Shield Cooler/Dewar Assembly Scan Mirror AIRS will:
Transcript
About the Mission
The Atmospheric Infrared Sounder,AIRS, advances climate researchand weather prediction into the21st century. AIRS is one of sixinstruments onboard Aqua, a satellite that is part of NASA’sEarth Observing System. AIRS,along with two partner microwavesounding instruments, representsthe most advanced atmosphericsounding system ever deployed inspace. Together these instrumentsobserve the global water and energy cycles, climate variation and trends, and the response of the climate system to increasedgreenhouse gases.
The AIRS instrument measures theamount of infrared energy emittedfrom the atmosphere. On the
ground, computer programs trans-form these measurements intotemperature, humidity, cloud prop-erties, and the amounts of green-house gases. AIRS data evenreveals land and sea surface temperatures.
To date, weather balloons haveprovided the most accurate infor-mation for weather forecasting. Butthese land-launched balloons leavelarge areas over the ocean unob-served. From the vantage point ofspace, the AIRS and microwaveinstruments provide global cover-age every day with accuracy com-parable to weather balloons. Thishighly accurate data, gathered overland and sea, ushers in a new eraof atmospheric monitoring on atruly global scale.
Monitoring Earth’s Atmosphere
Establish the connectionbetween severe weatherand climate change
Improve weatherforecasting
Determine if the global water cycle is accelerating
Detect the effectsof increasedgreenhouse gases
The AIRS Instrument:
ElectronicsModule
IR Spectrometer& Visible LightImager
Radiative Cooler& Earth Shield
Cooler/DewarAssembly
Scan Mirror
AIRS will:
Infrared Sounding
When ancient mariners needed toknow the depth of the water theywere sailing in, they would use aweighted line to plumb the depths.They called this practice “sounding.”From space, AIRS will “plumb” theatmosphere at multiple depths fortemperature and humidity.
The AIRS instrument looks down atthe Earth and measures the infraredbrightness in many wavelengths.Each infrared wavelength is sensitiveto a particular height in the atmos-phere. By having multiple infrareddetectors, each sensing a particularwavelength, a temperature profile, orsounding of the atmosphere, can bemade. While prior space instrumentshad only 15 detectors, AIRS has2378. This greatly improves the accu-racy, making it comparable to meas-urements made by weather balloons.
Thick clouds act like a wall to theinfrared energy measured by AIRS.However, the microwave instruments
onboard Aqua can see through theclouds with limited accuracy. Usinga special computer algorithm, datafrom AIRS and the microwave instru-ments will be combined to providehighly accurate measurements in allcloud conditions resulting in a dailyglobal snapshot of the state of theatmosphere.
Instrument Operation
AIRS, built by BAE SYSTEMS forNASA/JPL, is a cross-track scanninginstrument. Its scan mirror rotatesaround an axis along the line offlight and directs infrared energyfrom the Earth into the instrument.As the spacecraft moves along, thismirror sweeps the ground creatinga scan “swath” that extends rough-ly 800 km on either side of theground track. Within the AIRSinstrument, the infrared energy isseparated into wavelengths. Thisinformation is sent from AIRS to theAqua spacecraft, which relays it tothe ground.
ImprovingWeather Prediction
Today’s weather forecasts rely onsophisticated computer models of theatmosphere. These models use wind,temperature, moisture and pressuremeasurements to make predictionsabout the weather. The accuracy ofthese forecasts is limited by the accu-racy of the data they use. In currentforecasting models, error in the datadoubles every two or three days andthe data quickly loses any informa-tive value. AIRS data improves theaccuracy by a factor of 2, increasingthe useful range of weather forecastsby two to three days.
AIRS Data
The data collected by AIRS and thecompanion microwave sounders willbe used by scientists around theworld to better understand weatherand climate, and by the United StatesNational Weather Service and otherinternational forecasting agencies toimprove weather prediction.
AIRS data is publicly available andcan be accessed through the EarthObserving System Data Gateway athttp://eos.nasa.gov/imswelcome.
AIRS Sounding System Contractors:BAE SYSTEMS, TRW,MATRA MARCONI SPACE, AEROJET
http://www.jpl.nasa.gov/airs
Data are collected within the scan swath.JPL 400-1008B 3/02
