Improving Weather and Climate Prediction with the AIRS on Aqua

The Atmospheric Infrared Sounder (AIRS) is a hyperspectral infrared instrument on the EOS Aqua Spacecraft, launched on May 4, 2002. AIRS has 2378 infrared channels ranging from 3.7 um to 15.4 um and a 13.5 km footprint. The AIRS is a “facility” instrument developed by NASA as an experimental demonstration of advanced technology for remote sensing and the benefits of high resolution infrared spectra to science investigations. As such, it is a pre-curser to the NPOESS CrIS instrument.

AIRS radiances are routinely assimilated by National Weather Prediction Centers worldwide. AIRS radiances and data products are widely used to study weather and climate processes involving temperature, water vapor, surface temperature and clouds. AIRS also measures several anthropogenic and naturally produced trace gases enabling studies of global transport and circulation.

AIRS radiance data are produced and distributed in near real time by NOAA and have been assimilated into operational weather prediction models at NWP centers worldwide since 2003. A 5 hour improvement has been demonstrated operationally on the 6 day forecast. Additional improvement has been identified by assimilation of more spectral channels and footprints or by using cloud cleared radiances (LeMarshall 2008). In other studies, assimilation of temperature profiles from the AIRS greatly improved the prediction of position and intensity of tropical cyclones (Reale, 2008). This paper will highlight the accomplishments and challenges posed in assimilation of AIRS data for forecast improvement.

Scientists have found the AIRS water vapor data particularly useful for validation of climate model humidity fields. AIRS data have identified significant biases in water vapor annual climatology in 17 major climate models (Pierce, 2006). More recently, scientists have measured “water vapor feedback” using AIRS data in response to seasonal changes in surface temperature (Gettleman, 2008) and changes in annual temperatures (warm minus cool years), (Dessler 2008). In both cases the findings conclude that the water vapor feedback is positive and is correctly handled in the models.

AIRS global daily Carbon Monoxide maps can see global plumes of this gas due to anthropogenic biomass burning in South America and Africa as well as regional sources such as the California Wildfires in the Central Valley in 2008. AIRS Ozone data provide sufficient vertical information to identify stratospheric-tropospheric exchange and observe the annual Brewer-Dobson circulation. AIRS SO2 has been used for understanding transport of this gas for alerts to the aviation industry. AIRS maps of mid-tropospheric Carbon Dioxide are being used by scientists to validate CO2 inversion models and for understanding the global transport of this gas. Animations of all these gases will be presented.