P2.20
Does the Madden-Julian Oscillation Influence Aerosol Variability?
Baijun Tian, UCLA, Pasadena, CA; and D. E. Waliser, R. A. Kahn, Q. Li, Y. Yung, T. Tyranowski, I. Geogdzhayev, M. I. Mishchenko, and O. Torres
We investigate the modulation of aerosols by the Madden-Julian Oscillation (MJO) using satellite-based global aerosol products, including aerosol index (AI) from the Total Ozone Mapping Spectrometer (TOMS) on Nimbus-7, and aerosol optical thickness (AOT) from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua and the Advanced Very High Resolution Radiometer (AVHRR) on NOAA satellites. A composite analysis is performed for boreal winter, and the global pentad rainfall data from the NOAA Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) are used to identify MJO events. The MJO composites exhibit large variations in the TOMS AI and MODIS/AVHRR AOT over the equatorial Indian and western Pacific Oceans where MJO convection is active, as well as the tropical Africa and Atlantic Ocean where MJO convection is relatively weak but the background aerosol level is relatively high. A strong inverse linear relationship between the TOMS AI and rainfall anomalies was found, but a weaker, less coherent positive correlation between the MODIS/AVHRR AOT and rainfall anomalies. The Aerosol Robotic Network AOT pattern at Kaashidoo (73.5šE, 4.9šN) and Nauru (167šE, 0.5šS) is more consistent with MODIS and AVHRR. These results indicate a connection between the MJO, its associated rainfall and circulation variability, and the observed aerosol variations. Aerosol humidification effect, wet deposition, surface wind, and phytoplankton, different sensor sensitivity (absorbing versus non-absorbing aerosols and upper versus lower tropospheric aerosols), sampling issue, and cloud contamination are discussed. However, a clear causal explanation for the observed patterns remains elusive. Further investigation is needed to unravel this complex rainfall and aerosol relationship.
Poster Session 2, General Climate Studies: Poster Session
Monday, 21 January 2008, 2:30 PM-4:00 PM, Exhibit Hall B
Previous paper Next paper