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(A)
80°N
60°
40°
20°
0°
0°
90°E
180°
Longitude
90°W
0°
(B)
80°N
0
0
0
40°
-5
-10
-15
-20
5
5
20°
-5
0
0
0°
0°
90°E
180°
Longitude
90°W
0°
(C)
30°N
H
10°N
Ocean
Land
Figure 7.21
Schematic illustrations of suggested processes that form/maintain the northern subtropical
anticylones in summer. A: Boxes where summer heat sources are imposed in the atmospheric model. B:
Pattern of resultant stationary planetary waves (solid/dashed lines denote positive/negative height
anomalies (Chen et al., 2001). C: Schematic of the circulation elements proposed by Hoskins (1996);
monsoon heating over the continents with descent west and poleward where there is interaction with
the westerlies. The descent leads to enhanced radiative cooling acting as a positive feedback and to
equatorward motion; the latter drives Ekman ocean drift and upwelling.
Sources: From Chen et al. (2001, J. Atmos. Sci. 58, p. 1832, fig. 8(a)), and from Hoskins (1996, Bull. Amer. Met. Soc. 11, p. 1291,
fig.5). Courtesy of the American Meteorological Society.
