Abstract
Analysis of the mean wind, equivalent potential temperature and virtual potential temperature profiles observed by the National Center for Atmospheric Research (NCAR) Electra aircraft and obtained from dropwindsondes and ship-launched radiosondes were made in conjunction with synoptic observations to study the structure of the monsoon boundary layer over the Arabian Sea during MONEX 79. Comparison of mean profiles indicates the monsoon boundary layer to be much different from the trade wind boundary layer. Results confirm the existence of a boundary-layer jet known as East African or Somali Jet. Regions of multiple cloud layers at roughly the height of the capping inversion layer were associated with the jet. Regions in which a more well-mixed layer was observed showed a jet structure depressed in height. A free-jet surface-layer model appears to describe the mean wind structure of this jet observed during the present study and by others. An approximate balance of forces was found in the monsoon boundary layer between friction, advective acceleration, Coriolis and pressure gradient forces. Friction and advective acceleration terms were significant in the lower levels of the boundary layer. Forces in a typical trade wind boundary layer were found to be approximately one order of magnitude smaller than those observed in the monsoon boundary layer.
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Bannon, P. R.: 1982, ‘On the dynamics of the East African Jet. III: Arabian Sea Branch’, J. Atmos Sci. 39. 2267–2278.
Brummer, B.: 1976, ‘The Kinematics, Dynamics and Kinetic Energy Budget of the Trade Wind Flow over the Atlantic Ocean’, Meteor.-Forsch.-Ergeb. B11, 1–24.
Businger, J. A., Wyngaard, J. C., Izumi, Y., and Bradley, E. F.: 1971, ‘Flux Profile Relationships in the Atmospheric Surface Layer’, J. Atmos. Sci. 18, 181–189.
Findlater, J.: 1969, ‘A Major Low Level Air Current near the Indian Ocean During the Northern Summer. Quart. J. Roy. Meteorol. Soc. 95, 362–380.
Findlater, J.: 1977a, ‘A Numerical Index to Monitor the Afro-Asian Monsoon During the Northern Summers’, Meteorol. Mag. 106, 170–180.
Findlater, J.: 1977b, Observational Aspects of the Low Level Cross Equatorial Jet Stream, T. N. Krishnamurti (ed.), in Monsoon Dynamics, Birkhauser Verlag, Basel, Stuttgart, pp. 1251–1262.
Grossman, R. L. and Durran, D. R.: 1984, ‘Interaction of Low-level Flow with the Western Ghat Mountains and Offshore Convection in the Summer Monsoon’, Mon. Wea. Rev. 112, 652–672.
Hasler, A. F., Skillman, W. C., Shenk, W. E., and Steranka, J.: 1979, ‘In situ Aircraft Verification of the Quality of Satellite Cloud Winds over Oceanic Regions’, J. Appl. Meteorol. 18, 1481–1489.
Holland, J. Z. and Rasmusson, E. M.: 1973, ‘Measurements of the Atmospheric Mass, Energy and Momentum Budgets over a 500 km Square of the Tropical Ocean’, Mon. Wea. Rev. 101, 44–55.
Holton, J. R.: 1979, An Introduction to Dynamic Meteorology, Academic Press, N.Y., 319 pp.
Krishnamurti, T. N., Molinari, J., and Pan, H. L.: 1976, ‘Numerical Simulation of the Somali Jet’, J. Atmos. Sci. 33, 2350–2362.
Krishnamurti, T. N., Wong, V., Hua-Lu, Pan, Pasch, R., Molinari, J., and Ardanuy, P.: 1983, ‘A Three-Dimensional Planetary Boundary Layer Model for the Somali Jet’, J. Atmos. Sci. 40, 894–908.
Large, W. G. and Pond, S.: 1981, ‘Open Ocean Momentum Flux Measurements in Moderate to Strong Winds’, J. Phys. Oceanogr. 11, 324–336.
LeMone, M. A.: 1980, The Marine Boundary Layer, Workshop on the Planetary Boundary Layer, American Meteorological Society, Boston, MA. pp. 182–246.
Long, C. S.: 1980. ‘Analysis of Aircraft Measurements of Boundary Layer Turbulence in Monsoonal Flow’. Master's Thesis submitted to the University of Wisconsin-Madison, 93 pp.
Rao, G. V. and Haney, J. L.: 1982, ‘Kinematic and Thermal Structures of Two Surges of Flow in the Northern Mozambique Channel Area’, Quart. J. Roy. Meteorol. Soc. 108, 957–974.
Reverdin, G. and Sommeria, G.: 1983, ‘The Dynamical Structure of the Planetary Boundary Layer over the Arabian Sea, as Deduced from Constant-Level Balloon Trajectories’, J. Atmos. Sci. 40, 1435–1452.
Schlicting, H.: 1979, Boundary-Layer Theory, McGraw-Hill, 817 pp.
Sikka, D. R. and Grossman, B.: 1980, Summer MONEX Chronological Weather Summary, International MONEX Management Centre, New Delhi, India, December 1980 (first edition), pp.49.
Stout, J. E. and Young, J. A.: 1983, ‘Low-level Monsoon Dynamics Derived from Satellite Winds’, Mon. Wea. Rev. 111, 774–798.
Van de Boogaard, H.: 1977, ‘The Mean Circulation of the Tropical and Subtropical Atmosphere — July. NCAR Tech. Note NCAR/TN-118, 48 pp.
WMO: 1981, The Summer MONEX Field Phase Report, FGGE Operations Report, Vol. 8, World Meteorological Organization, Geneva.
Young, J. A., Virji, H., Wylie, D. P., and Lo, C.: 1980. Summer Monsoon Wind sets from Geostationary Data. Summer MONEX: 1 May – 31 July, 1979. NSF Report, Space Science and Engineering Center and Dept. Meteor., University of Winconsin-Madison, 127 pp.
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Holt, T., Sethuraman, S. Aircraft and ship observations of the mean structure of the marine boundary layer over the Arabian Sea during MONEX 79. Boundary-Layer Meteorol 33, 259–282 (1985). https://doi.org/10.1007/BF00052059
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DOI: https://doi.org/10.1007/BF00052059