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Tropical Atlantic dust and smoke aerosol variations related to the Madden‐Julian Oscillation in MODIS and MISR observations
Author(s) -
Guo Yanjuan,
Tian Baijun,
Kahn Ralph A.,
Kalashnikova Olga,
Wong Sun,
Waliser Duane E.
Publication year - 2013
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/jgrd.50409
Subject(s) - aerosol , climatology , smoke , environmental science , madden–julian oscillation , atmospheric sciences , tropical atlantic , meteorology , geography , geology , sea surface temperature , convection
In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) fine mode fraction and Multi‐angle Imaging SpectroRadiometer (MISR) nonspherical fraction data are used to derive dust and smoke aerosol optical thickness (τ dust and τ smoke ) over the tropical Atlantic in a complementary way: due to its wider swath, MODIS has 3–4 times greater sampling than MISR, but MISR dust discrimination is based on particle shape retrievals, whereas an empirical scheme is used for MODIS. MODIS and MISR show very similar dust and smoke winter climatologies. τ dust is the dominant aerosol component over the tropical Atlantic, accounting for 40–70% of the total aerosol optical thickness (AOT), whereas τ smoke is significantly smaller than τ dust . The consistency and high correlation between these climatologies and their daily variations lends confidence to their use for investigating the relative dust and smoke contributions to the total AOT variation associated with the Madden‐Julian Oscillation (MJO). The temporal evolution and spatial patterns of the τ dus anomalies associated with the MJO are consistent between MODIS and MISR: the magnitude of MJO‐realted τ dust anomalies is comparable to or even larger than that of the total τ, while the τ smoke anomaly represents about 15% compared to the total, which is quite different from their relative magnitudes to the total τ on the climatological time scale. This suggests that dust and smoke are not influenced by the MJO in the same way. Based on correlation analysis, dust is strongly influenced by the MJO‐modulated trade wind and precipitation anomalies, and can last as long as one MJO phase, whereas smoke is less affected.