Book contents
- Frontmatter
- Contents
- Contributors
- Editors' preface
- Keynote address to the 1977 Symposium SIR JAMES LIGHTHILL
- Part I The large-scale climatology of the tropical atmosphere
- Part II The summer monsoon over the Indian subcontinent and East Africa
- 12 The monsoon as reflected in the behaviour of the tropical high-pressure belt
- 13 On the onset of the Indian southwest monsoon and the monsoon general circulation
- 14 Medium-range forecasting of monsoon rains
- 15 Sea-surface temperature and the monsoon
- 16 The effect of elevation on monsoon rainfall distribution in the central Himalayas
- 17 Use of the equation of continuity of water vapour for computation of average precipitation over peninsular India during the summer monsoon
- 18 Determination of cloud cluster properties from MONSOON-77 data
- 19 Analysis of superpressure balloon trajectories and conventional observations over the Indian Ocean during different phases of the 1975 southwest monsoon
- 20 An experiment in monitoring cross-equatorial airflow at low level over Kenya and rainfall of western India during the northern summers
- 21 Structure of the Somali Jet deduced from aerial observations taken during June–July, 1977
- 22 Certain aspects of monsoonal precipitation dynamics over Lake Victoria
- 23 A numerical model of the monsoon trough
- 24 On the monsoonal midtropospheric cyclogenesis over western India
- 25 Downstream development of baroclinic waves in the uppertropospheric monsoon easterlies suggested by a simple model experiment
- 26 The stability of the monsoon zonal flow with a superposed stationary monsoon wave
- 27 Growth of monsoon disturbances over western India
- 28 Topographic Rossby waves in the summer monsoon
- Part III The physics and dynamics of the Indian Ocean during the summer monsoon
- Part IV Some important mathematical modelling techniques
- Part V Storm surges and flood forecasting
- Index
23 - A numerical model of the monsoon trough
Published online by Cambridge University Press: 05 November 2011
Book contents
- Frontmatter
- Contents
- Contributors
- Editors' preface
- Keynote address to the 1977 Symposium SIR JAMES LIGHTHILL
- Part I The large-scale climatology of the tropical atmosphere
- Part II The summer monsoon over the Indian subcontinent and East Africa
- 12 The monsoon as reflected in the behaviour of the tropical high-pressure belt
- 13 On the onset of the Indian southwest monsoon and the monsoon general circulation
- 14 Medium-range forecasting of monsoon rains
- 15 Sea-surface temperature and the monsoon
- 16 The effect of elevation on monsoon rainfall distribution in the central Himalayas
- 17 Use of the equation of continuity of water vapour for computation of average precipitation over peninsular India during the summer monsoon
- 18 Determination of cloud cluster properties from MONSOON-77 data
- 19 Analysis of superpressure balloon trajectories and conventional observations over the Indian Ocean during different phases of the 1975 southwest monsoon
- 20 An experiment in monitoring cross-equatorial airflow at low level over Kenya and rainfall of western India during the northern summers
- 21 Structure of the Somali Jet deduced from aerial observations taken during June–July, 1977
- 22 Certain aspects of monsoonal precipitation dynamics over Lake Victoria
- 23 A numerical model of the monsoon trough
- 24 On the monsoonal midtropospheric cyclogenesis over western India
- 25 Downstream development of baroclinic waves in the uppertropospheric monsoon easterlies suggested by a simple model experiment
- 26 The stability of the monsoon zonal flow with a superposed stationary monsoon wave
- 27 Growth of monsoon disturbances over western India
- 28 Topographic Rossby waves in the summer monsoon
- Part III The physics and dynamics of the Indian Ocean during the summer monsoon
- Part IV Some important mathematical modelling techniques
- Part V Storm surges and flood forecasting
- Index
Summary
A regional primitive equation model is used to simulate the monsoon trough. The model has three layers and a boundary layer adjacent to the Earth's surface. It has smooth profiles for the Himalayas, Western Ghats, and the Burma mountains and includes radiative heating at the surface, but no precipitation.
The model has been integrated up to 8 days starting with an idealised wind and temperature field with meridional and vertical shear. It was observed that the monsoon trough could not be generated by topographic features alone, but the inclusion of radiative heating at the surface led to patterns resembling the monsoon trough. On decreasing the surface albedo near northwest India the monsoon trough was intensified. A Bowen ratio was used to estimate the flux of latent heat due to evaporation of soil moisture. Results suggest that a high rate of evaporation over northeast India leads to a southward extension of the monsoon trough.
Introduction
An elongated trough, running parallel to the southern periphery of the Himalayas, is an important feature of the monsoon. It is known as the monsoon trough, and its normal position in June is shown in Fig. 23.1. The line of symmetry, shown by a dashed line on the figure, is the axis of the trough. The trough is most marked at sea level, and rarely extends above 700 mb.
Short-period variations in monsoon rain are closely associated with the position of the trough.
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- Monsoon Dynamics , pp. 351 - 364Publisher: Cambridge University PressPrint publication year: 1981
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