Observed 3-D Structure of Atmospheric Temperature and Moisture Associated with the Madden-Julian Oscillation

The Atmospheric InfraRed Sounder (AIRS) is the first of a new generation of high spectral resolution infrared sounder with 2378 channels measuring outgoing radiance between 650 cm-1 and 2675 cm-1. The fine vertical resolving power of AIRS provides us with an opportunity to examine the 3-dimensional structure of atmospheric temperature and moisture with improved accuracy. In NOAA/NESDIS, these AIRS-based high quality atmospheric temperature and moisture products have been produced operationally on a near real-time basis since August 2002.

Variations in atmospheric temperature and moisture associated with the Madden-Julian Oscillation (MJO) over the global tropics are investigated using the 2-year AIRS retrievals. First, mean seasonal variations of 3-dimensional temperature and moisture are computed to document the mean atmospheric structure over the global tropics. Band pass filtering is then implemented to the original time series of the AIRS-observed temperature and moisture data to extract the components associated with variations of intraseasonal time scale (20 – 80 days). Composite analysis and Extended EOF analysis are then performed to these bandpassed intra-seasonal components to construct mean spatial distribution and its temporal evolution patterns of 3-D temperature and moisture associated with the MJO. The results of these analyses provide quantitative description of the MJO with improved quality and spatial resolution compared to those based on previous satellite observations.

Furthermore, the quantitative description achieved above will be compared to those derived from the numerical models including the NCEP GFS weather forecast model and CFS climate forecast model to check to what extent the 3-D atmospheric structure associated with the MJO is reproduced by these operational models. Detailed results will be reported at the conference.