Remote Sensing of the Oceans and Atmosphere Tom Collow December 10 2009 Aura was launched on July 15 2004 from Vandenburg Air Force Base California Aura is the last satellite in line on the A train The Aura Mission studies the Earth s ozone air quality and climate It conducts research on the composition chemistry and dynamics of the Earth s atmosphere More Facts Sun synchronous polar orbit 98 inclination retrograde orbit Altitude is 705 km Design life is 5 years with an operational goal of 6 years Remember it was launched in 2004 so the satellite is probably nearing the end of its usage The Aura satellite uses four different instruments to collect data HIRDLS High Resolution Dynamics Limb Sounder MLS Microwave Limb Sounder OMI Ozone Monitoring Instrument TES Tropospheric Emission Spectrometer Is the ozone layer recovering as expected What are the sources and processes that control atmospheric pollutants What is the quantitative impact of these constituents on climate change Ozone hole progress September 16 2009 Limb infrared filter radiometer 21 channels ranging from 6 2 to 17 76 m Vertical resolution of 1 2 km A good vertical resolution is important because most physical processes of interest to Aura occur on short vertical scales 5 km Measures variables in the upper troposphere stratosphere and mesosphere A blockage on the instrument caused the aperture to only be able to see 20 of the Earth s surface Attempts to remove the blockage have failed but even so the instrument can still make measurements at a high vertical resolution How it Works First radiance calibration is done by having the instrument view cold space just above the limb of the atmosphere and then an internal blackbody target of known temperature Four channels measure the emission of CO2 which has a known mixing ratio Using that data transmittance is then calculated The equation of radiative transfer is inverted to determine the vertical distribution of the Plank black body function from which temperature is a function of pressure Using the temperature profile the Planck function profiles of the other constituents can be obtained These profiles are then used to calculate the transmittance of these compounds as well as the corresponding mixing ratios What does it Measure O3 H2O CH4 N2 O NO2 N2 O HNO3 N2 O5 CFC11 CFC12 CIONO2 Aerosols It can also determine the locations of cloud tops subvisible cirrus clouds and polar stratospheric clouds using the H2O data Sub visible cirrus over eastern Africa and Saudi Arabia HIRDLS measurement of temperature over the Northern Hemisphere Source http www eos ucar edu hirdls science gallery HirdlsTe mp20050129 jpg Mountain Waves as seen through temperature fluctuations Mountain waves reaching the mesosphere have been theorized but this is the first time they are actually being observed Source http aura gsfc nasa gov science feature 030907 html Microwave Limb Sounder Five frequency bands ranging from 118 GHz to 2500 GHz 1 GHz 1 000 000 000 s 1 1 5 3 0 km vertical resolution Measures atmospheric composition temperature humidity and cloud ice in the upper troposphere stratosphere and mesosphere Unlike the HIRDLS which can see clouds the MLS can see cloud ice The data is used to track the stability of the stratospheric ozone layer help improve predictions of climate change and variability and help improve understanding of global air quality Variables Measured H2O O3 CIO BrO HCl OH HNO2 HNO3 HCN N2O CO HOCl CH3CN Cloud Ice Temperature ClO chlorine monoxide is the primary form of chlorine that destroys ozone BrO bromine monoxide is the primary form of bromine that destroys ozone It is also the primary form of bromine in the stratosphere Measurements of H2O water vapor and cloud ice allows for a better understanding of climate change H2O HNO3 nitric acid and temperature provide information on processes that can lead to ozone loss in the antarctic and arctic Measurements in the upper troposphere of O3 and CO are important for air quality research as these pollutants can be transported upwards from the boundary layer by convective processes and then transported great distances due to stronger winds there The upper troposphere is highly significant in the transport of pollutants from Asia to North America 2006 Antarctic ozone hole as seen by the Microwave Limb Sounder Source http aura gsfc nasa gov science feature 022207 html Cloud ice measured by MLS upper left and compared to computer model simulations There is a noticeable discrepancy over South America between the observation and the models Source http aura gsfc nasa gov science top10 cloudice html References Goddard Space Flight Center 2009 Aura atmospheric chemistry Retrieved from http aura gsfc nasa gov index html Goddard Space Flight Center 2007 Double record breaker 2006 anarctic ozone hole seen by MLS Retrieved from http aura gsfc nasa gov science feature 022207 html Goddard Space Flight Center 2006 First global measurement of cloud ice in upper troposphere Retrieved from http aura gsfc nasa gov science top10 cloudice html Goddard Space Flight Center 2007 Spectacular mountain wave events observed by HIRDLS Retrieved from http aura gsfc nasa gov science feature 030907 html Jet Propulsion Laboratory 2009 Microwave limb sounder Retrieved from http mls jpl nasa gov NASA 2009 Aura understanding and protecting the air we breathe Retrieved from http www nasa gov mission pages aura main index html Schoeberl M R Douglass A R Hilsenrath E Bhartia P K Barnett J Gille J Beer R Gunson M Waters J Levelt P F DeCola P 2004 Earth observing systems missions benefit atmospheric research Electronic version EOS Transactions American Geophysical Union 85 18 177 184 UCAR 2008 High resolution dynamics limb sounder Retrieved from http www eos ucar edu hirdls