FIGURE 2-10 Velocity potential for the lower troposphere (850 hPa or about 1.5 km) in the lower panel and for the upper troposphere (200 hPa) in the upper panel. The solar heating by absorbing aerosols, mainly due to black carbon, is concentrated over South Asia and the North Indian Ocean (i.e., over the red shaded regions in the lower panel). The red region in the lower panel shows areas of convergence of air or alternately rising motions in response to the solar heating of the lower atmosphere by black carbon. The convergence at the lower levels is followed by divergence (air flowing out of the region) at the upper levels (the blue shaded region in the upper troposphere) over the source region. SOURCE: Adapted from Chung and Ramanathan (2003).