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
- Part III The physics and dynamics of the Indian Ocean during the summer monsoon
- 29 Observations of the Somali Current and its relationship to the monsoon winds
- 30 Structure of currents and hydrographic conditions in the western equatorial Indian Ocean during the summer monsoon
- 31 Recent observations in the equatorial Indian Ocean
- 32 Sea temperature variations in the northeastern Arabian Sea in relation to the southwest monsoon
- 33 Heat budget of the north Indian oceanic surface during MONSOON-77
- 34 The energy budget at selected stations over the north Indian Ocean during MONSOON-77
- 35 Observations of coastal-water upwelling around India
- 36 A numerical study of surface cooling processes during summer in the Arabian Sea
- 37 Maximum simplification of nonlinear Somali Current dynamics
- 38 Laboratory modelling of the oceanic response to monsoonal winds
- Part IV Some important mathematical modelling techniques
- Part V Storm surges and flood forecasting
- Index
36 - A numerical study of surface cooling processes during summer in the Arabian Sea
Published online by Cambridge University Press: 05 November 2011
- 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
- Part III The physics and dynamics of the Indian Ocean during the summer monsoon
- 29 Observations of the Somali Current and its relationship to the monsoon winds
- 30 Structure of currents and hydrographic conditions in the western equatorial Indian Ocean during the summer monsoon
- 31 Recent observations in the equatorial Indian Ocean
- 32 Sea temperature variations in the northeastern Arabian Sea in relation to the southwest monsoon
- 33 Heat budget of the north Indian oceanic surface during MONSOON-77
- 34 The energy budget at selected stations over the north Indian Ocean during MONSOON-77
- 35 Observations of coastal-water upwelling around India
- 36 A numerical study of surface cooling processes during summer in the Arabian Sea
- 37 Maximum simplification of nonlinear Somali Current dynamics
- 38 Laboratory modelling of the oceanic response to monsoonal winds
- Part IV Some important mathematical modelling techniques
- Part V Storm surges and flood forecasting
- Index
Summary
One of the primary causes of surface cooling in the Arabian Sea during late spring and early summer is upwelling along the Somali and Arabian coasts. Along the Somali coast, upwelling apparently occurs as rather intense mesoscale phenomena associated with variations in the Somali Current. A three-dimensional numerical model of an equatorial ocean indicates that the formation and behaviour of these upwelling areas is sensitive to the orientation of the western boundary. Analysis of the local vorticity sources and sinks in the model solution indicates that the movement of the systems along the coast is caused by an imbalance between advective effects, producing northeastward motion, vortex stretching and the beta-effect producing southwestward motion, and the curl of the wind stress which is capable of producing either. These results suggest that surface cooling may be very sensitive to wind scales of the order of the baroclinic radius of deformation of the ocean near the coast.
Introduction
The effect of the sea-surface temperature (SST) of the Arabian Sea on rainfall over India has recently been studied by several investigators. While cause and effect is difficult to determine from observational data, Shukla (1975) has found, using a numerical atmospheric model, that SST anomalies of 1 to 3 °C during the Arabian Sea summer monsoon strongly affect the rainfall downstream. Fieux and Stommel (1976) have analysed data from heavily used shipping lanes in the Arabian Sea and found that such anomalies in the mean monthly SST do occur from year to year.
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- Monsoon Dynamics , pp. 529 - 540Publisher: Cambridge University PressPrint publication year: 1981
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