Variability in background stratospheric aerosols over the tropics and its association with atmospheric dynamics

摘要: [1] Spatiotemporal variability of background stratospheric aerosols over the tropics (30°S–30°N) and its association with atmospheric dynamics are studied using zonal-averaged Stratospheric Aerosol Gas Experiment II (SAGE-II) derived aerosol extinction at 525 nm along lidar data 532 from Gadanki (13.5°N, 79.2°E) during period 1998–2005. In general, a pronounced increase in loading is observed spatial distribution equatorial region compared to off-equatorial regions. The particulate optical depth (τP) lower showed an increasing trend particularly after 2002 both these This could partly be attributed corresponding number feeble/minor volcanic eruptions. Over above this steady increase, τP also significant periodic variations. addition prominent short-period variations, biennial variation (with ∼30 months) quasi-biennial oscillation zonal wind (QBOU). During westerly phase QBOU, mean decreases rapidly latitude on either side equator hemispheres, while it remains fairly around up 15° small bite-out easterly phase, very quiet 1998–2002. latter half (after 2002), when stratosphere was mildly disturbed, latitudinal similar phases QBOU higher value near phase. QBO signal 25 km found opposite that upper regime (28–32 km) (18–22 km), depicting influence secondary meridional circulation produced owing vertical shear region.