980816.fig.004a
(a)  Divergence
980816.fig.004b
(b) RWS
980816.fig.004c
(c) VS
980816.fig.004d
(d) AV
Figure 4: Anomaly for strong HC cases at 200 hPa in JJA for: (a) divergence, (b) Rossby wave source (RWS), (c) vortex stretching term (VS), (d) advection of absolute vorticity by divergent flow term (AV). The shaded areas represent positive values. The divergence contour plot has a contour interval of  s−1. RWS and its terms contour plots have contour interval of  s−2. The symbols C and CS are described in the text.