It has been known for nearly a decade that the outstanding problems in global change are those at the intersection of the various disciplines of physics, chemistry, dynamics, biology and human intervention. However, it has been very difficult to translate this awareness into action, in part because we lack observations of such interdisciplinary phenomena. The urgency and the great impetus for studying these arise from several recent developments which demonstrate their significance to global climate and chemistry. Increases in sulfate aerosols can lead to a radiative cooling directly by enhancing clear sky albedo and indirectly through modification of the shortwave cloud forcing. Potential anthropogenic radiative forcing of climate.
Direct effect refers to the increase in clear-sky albedo.
The indirect effect is the increase in cloud albedo. The radiative effects of these background aerosols is an important factor for simulating the present day climate. In this regard, a fundamental issue concerns the inter-hemispheric mixing of continental air. The rapid vertical transport within the deep convective-cirrus cloud systems of the ITCZ and subsequent horizontal distribution by fast zonal upper air flows provide a fundamental link between regional emissions and global distributions of radiatively active species. Our current understanding of the role of the ITCZ in the transport of trace gases and aerosols is largely based on model studies.