Summary
In this paper, interseasonal characteristics of the Asian summer monsoon in the years of 1987 and 1988 are studied as 1987 is characterized by a large deficiency of monsoon rainfall (drought) and that of 1988 by a large excess monsoon rainfall (flood) over India. In order to compare the similarities and differences seen in the large scale dynamics and energetics of the Asian summer monsoon during the years of extreme monsoon activity, uninitialized analyses (12 Z) of the European Centre for Medium Range Weather Forecasts (ECMWF), U.K. are utilized in this study for the summer monsoon seasons of 1987 and 1988.
It is found that the excess rainfall season (1988) is characterized by much stronger tropical easterly jet (TEJ) associated with the upper tropospheric easterlies and the East African low level jet (Somali Jet) associated with lower tropospheric westerlies. Such a feature mainly determines the strength of the reverse Hadley circulation which normally covers the South Asian continent during the northern summer. Further, the energetics of the TEJ show that the monsoon of 1988 has comparatively stronger zones of kinetic energy flux divergence (convergence) at its entrance (exit) regions. These zones of kinetic energy flux divergence are largely maintained by the adiabatic processes over the strong kinetic energy flux divergence zones over the Bay of Bengal and east central Arabian Sea as compared to that of 1987. Apart from this, both the zonal and meridional components of the ageostrophic flows are found to be stronger during 1988 monsoon season. Analysis of the vertically integrated thermodynamical features of the monsoon indicate that the monsoon of 1988 was characterized by an excess import of heat and moisture into the monsoon atmosphere as compared to that of 1987. Further, from the quantitative estimation of certain significant heat and moisture budget parameters during the contrasting monsoon seasons of 1987 and 1988, it becomes evident that considerable differences exist in the quantities of adiabatic production of heat energy, diabatic heating and the moisture source/sink.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Ananthakrishnan, R., Keshavamurty, R. N., 1973: A preliminary study on the adiabatic generation and dissipation of kinetic energy by meridional and zonal winds over India and neighbourhood during the winter season.Ind. J. Met. & Geop.,24, 235–244.
Anjaneyulu, T. S. S., 1971: Estimates of kinetic energy over the Indian monsoon trough zone.Quart. J. Roy. Meteor. Soc.,97, 103–109.
Das, P. K., 1984:MONSOONS, WMO Monograph (Fifth IMO Lectures), 155pp.
Joseph, P. V., 1975: A triennial oscillation of upper tropospheric westerlies and the Indian summer monsoon. Rep. No. 223, India Met. Dept., New Delhi, 1–15.
Julian, P. R., 1984: Some comparisons of ECMWF IIIb and GFDL IIIb analyses in the tropics. GWE News Letter No. 3 USC-GARP, 20–22.
Kanamitsu, M., Krishnamurti, T. N., 1978: Northern summer tropical circulations during drought and normal rainfall months.Mon. Wea. Rev.,10, 331–347.
Kanamitsu, M., 1981: Some climatological and energy budget calculations using the FGGE level-IIIb analyses during January 1979. Dynamic Meteorology-Data Assimilation Methods. New York: Springer.
Keshavamurty, R. N., 1968: On the maintenance of the mean zonal motion in the Indian summer monsoon.Mon. Wea. Rev.,96, 23–31.
Keshavamurty, R. N., Awade, S. T., 1970: On the mean monsoon trough over north India.Mon. Wea Rev.,98 (4), 315–320.
Krishnamurti, T. N., Bedi, H. S., Subramaniam, M., 1989: The summer monsoon of 1987.J. Climate,2 (4), 321–340.
Krishnamurti, T. N., Bedi, H. S., Subramaniam, M., 1990: The summer monsoon of 1988.Meteorol. Atmos. Phys.,42, 19–37.
Krueger, A. F., Winston, J. S., 1975: Large scale circulation anomalies over the tropics during 1971–72.Mon. Wea. Rev.,103, 465–473.
Kung, E. C., Smith, P. J., 1974: Problems of large scale kinetic energy balance—A diagnostic analysis in GARP.Bull. Amer. Meteor. Soc.,55, 768–777.
Mohanty, U. C., Dube, S. K., Singh, M. P., 1983: A study of heat and moisture budgets over the Arabian Sea and their role in the onset and maintenance of summer monsoon.J. Meteor. Soc. Japan,61, 208–221.
Mohanty, U. C., Ramesh, K. J., Dash, S. K., 1989: Energy transformations in the tropical circulation during the FGGE winter.J. Meteor. Soc. Japan,67 (5), 691–704.
Mohanty, U. C., Ramesh, K. J., 1994: A study on the dynamics and energetics of the Indian summer monsoon.Proc. Ind. Natn. Sci. Acad.,60, A, 1, 23–55.
O'Brien, J. J., 1970: Alternative solutions to classical vertical velocity problem.J. Appl. Meteor.,9, 197–203.
Pearce, R. P., 1978: On the concept of available potential energy,Quart. J. Roy. Meteor. Soc.,104, 737–755.
Rao, Y. P., 1976:South-West Monsoon. Met Monograph,1/1976, Indian Met. Dept, India.
Author information
Authors and Affiliations
Additional information
With 13 Figures
Rights and permissions
About this article
Cite this article
Ramesh, K.J., Mohanty, U.C. & Rao, P.L.S. A study on the distinct features of the Asian summer monsoon during the years of extreme monsoon activity over India. Meteorl. Atmos. Phys. 59, 173–183 (1996). https://doi.org/10.1007/BF01030142
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF01030142