Publikationsdatum:
2013-04-23
Beschreibung:
[1] In this study, MODIS fine mode fraction and MISR non-spherical 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 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.
Print ISSN:
0148-0227
Thema:
Geologie und Paläontologie
,
Physik
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