East Asia and Western Pacific METEOROLOGY AND CLIMATE

of the orography, establishing a narrow belt of cold air.During the
passage of air, the exciting effect of Plateau's boundary brings
about in the rear of the cold front an extremely high wind center
that moves along the fringe of the topography, at first down to the
south along its east side till it crosses 2Q°N and then turns westward
on its south side to the Indian. Such waves are found of the
character of Kelvin waves;
(3) Our simulation with and without the orography indicates that
in the frontal edge of a cold surge the northerly wind enforcement
is roughly 12 hr ahead of temperature drop, a result that may be
due to the southward propagation of fast-travelling gravity waves
produced by the cold front excitation;
(4) The surge goes southward under the Hadley cell, operating to
intensify the cell and to move it further southward.
REFERENCES
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over the tropics and midlatitudes during northern winter, Part
I:Contrast between active and inactive periods", Mon.Vea.Rev.,
110,938-946 (1982).
2 Chang, C»P. and Erickson, J.E., "Northeasterly cold surge and
near-equatorial disturbance over the winter MONEX area during
December 1974 f Part Ii Synoptic aspects and conclusions", Mon.
Wea.Rev., K)J,8l3-829 (1979).
3 Chang, C.P. and Lau, K. M», "Northeasterly cold surge and nearequatorial
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1974* Part IIi planetary scale aspects", Mon.Wea.Rev.,
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4 Chang, C.P. and Millard, J.E. "Gravitational characters of cold
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2377-2392 (1981).
6 Murakami,T« and Nakamura, H., "Orographic effect on cold surge
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Part 1$ Transient aspects'*»J.Meteor.Soc.Japan,61,547-567(1983).
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