Summary
The dynamical characteristics of Asian summer monsoon are examined with a global spectral model. In addition to the seasonal circulation features, the large scale budgets of kinetic energy, vorticity and angular momentum are examined making use of mean analysis and forecast fields (upto day 5) for summer season comprising June, July and August, (JJA) 1994. Apart from elucidating the systematic errors over the monsoon region, the study expounded the influence of these errors on associated dynamics.
The significant errors in the low level flow (850 hPa) evince (i) weakening of south easterly trades and cross equatorial flow into the Northern Hemisphere and (ii) weakening of westerly flow over the North Indian Ocean. Similarly, in the upper level flow (200 hPa) they indicate (i) weakening of Tibetan anti-cyclone and (ii) reduction of return flow into the Southern Hemisphere.
The balance requirements in the mean analysis as well as forecast fields are fairly in agreement with the observed over the summer monsoon. The monsoon domain is discerned as the source region of kinetic energy and vorticity. Both are produced in the monsoon region and transported horizontally across. The model forecasts fail to retain the analyzed atmospheric variability in terms of mean as well as transient circulations which is revealed by kinetic energy budget. This is further corroborated by vorticity and angular momentum budgets. It is noticed that the forecasts in all ranges produce feeble monsoon circulation which weakens considerably with increase in the forecast period.
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Alpert, J. C., Kanamitsu, M., Caplan, P. M., Sela, J. G., White, G. H., Kalney, E., 1988: Mountain induced wave drag parametrization in the NMC medium-range model, 8th Conference on Numerical Weather Prediction, Baltimore, Md., Feb. 22–26, 1988, American Meteorological Society, 252–259.
Chu, J. H., Yanai, M., Sui, C. H., 1981: Effects of cumulus convection on the vorticity field in the tropics. Part-I The large scale budget.J. Meteor. Soc. Japan,59(4), 535–546.
Fein, J. S., 1977: Global vorticity budget over the tropics and subtropics at 200 mb during the northern hemisphere summer.PAGEOPH,115, 1493–1500.
Haltiner, G. J., Williams, R. T., 1980:Numerical Prediction and Dynamic Meteorology, 2nd ed. New York: John Wiley & Sons.
Heckley, W. A., 1985a: Systematic errors of the ECMWF operational forecasting model in tropical regions.Quart. J. Roy. Meteor. Soc.,111, 709–738.
Heckley, W. A., 1985b: The performance and systematic errors of the ECMWF tropical forecasts (1982–1984). ECMWF Technical Report No: 53.
Holopainen, E. O., Oort, A. H., 1981: Mean surface stress curl over the oceans as determined from the vorticity budget of the atmosphere.J. Atoms. Sci.,33, 773–792.
Holopainen, E. O., Eerola, K. 1979: A diagnostic study of the long term balance of kinetic energy of atmospheric large scale motion over the British Isles.Quart. J. Roy. Meteor. Soc.,105, 849–858.
Holton, J. R., Colton, D. F., 1972: A diagnostic study of the vorticity balance at 200 mb in the tropics during the northern summer.J. Atmos. Sci.,29, 1124–1128.
Holton, J. R., 1992:An Introduction to Dynamic Meteorology, 3rd ed. Academic Press, (International Geophysics Series, vol. 48).
Kanamitsu, M., 1985: A study of the predictability of the ECMWF operational forecast model in the tropics.J. Meteor. Soc. Japan,63(5), 779–804.
Kanamitsu, M., 1989: Description of the NMC global data assimilation and forecast system.Wea. Forecasting,4, 335–342.
Krishnamurti, T. N., Ardanuy, P., Ramanathan, Y., Pasch, R., 1981: On the onset vortex of the summer monsoon.Mon. Wea. Rev.,109, 344–363.
Kung, E. C., 1966: Large scale balance of kinetic energy in the atmosphere.Mon. Wea. Rev.,94, 627–640.
Kung, E. C., 1971: A diagnosis of adiabatic production and destruction of kinetic energy by the meridional and zonal motions of the atmosphere.Quart. J. Roy. Meteor. Soc.,97, 61–74.
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.
Kung, E. C., Beaker, W. E., 1975: Energy transformations in mid-latitude disturbances.Quart. J. Roy. Meteor. Soc.,101, 793–815.
Lorenz, E. N., 1967: The nature and theory of the general circulation of the atmosphere, First IMO lecture, WMO Tech Rep # 218, 161pp.
Mohanty, U. C., Dube, S. K., Singh, M. P., 1983: A study of heat and moisture budgets over the Arbian sea and their role in the onset and maintenance of summer monsoon.J. Meteor. Soc. Japan,61, 208–211.
Mohanty, U. C., Ramesh, K. J., 1994: A study on the dynamics and energetics of the Indian summer monsoon.Proceedings of the Indian National Science Academy,60(A,1), 23–55.
Mohanty, U. C., Heckley, W. A., Ramesh, K. J., 1995a: A study on the systematic errors of the tropical forecasts. Influence of Physical processes.Meteorol. Atmos. Phys.,55, 151–166.
Mohanty, U. C., Das, S., Saseendran, S. A., et al. 1995b: Medium range prediction of Atmospheric system over Indian region by NCMRWF forecasting system. Proceedings of Fifth regional workshop on Asian/African monsoon emphasizing training aspects (WMO Tropical Meteorology Research Programme series Report No: 52, WMO/TD-NO: 698), 51–62.
O'Brien, J. J., 1970: Alternative solutions to classical vertical velocity problem.J. Appl. Meteor.,9, 197–203.
Parrish, D. F., Derber, J. C., 1992: The National Meteorological Centre's spectral statistical interpolation analysis system.Mon. Wea. Rev.,120, 1747–1763.
Pearce, R. P., 1979: On the concept of available potential energy.Quart. J. Roy. Meteor. Soc.,104, 737–755.
Pearce, R. P., Mohanty, U. C., 1984: Onsets of the Asian summer monsoon 1979–82.J. Atmos. Sci.,41(9), 1622–1639.
Rabier, F., Klinker, E., Courtier, P., Hollingsworth, A., 1996: Sensitivity of the forecast errors to initial conditions.Quart. J. Roy. Meteor. Soc.,122, 529, Part-A, 121–150.
Reed, R. J., Johnson, R. H., 1974: The vorticity budget of the synoptic-scale wave disturbances in the tropical western Pacific.J. Atmos. Sci.,31, 1784–1790.
Savijarvi, H., 1980: Energy budget calculations and diabatic effects for limited areas computed from ECMWF analyses and forecasts, Proceedings of the workshop: Diagnostics of diabatic processes, ECMWF, 115–134.
Savijarvi, H., 1981: The energy budgets in North America, North Atlantic and Europe based on ECMWF analyses and forecasts, ECMWF Tech Report No: 27.
Slingo, J. M., Mohanty, U. C., Tiedke, M., Pearce, R. P., 1988: Prediction of the 1979 summer monsoon onset with modified parameterization schemes.Mon. Wea. Rev.,116, 328–346.
Tiedke, M., Heckley, W. A., Slingo, J., 1988: Tropical forecasting at ECMWF: The influence of physical parametrization on the mean structure of forecasts and analyses.Quart. J. Roy. Meteor. Soc.,114, 639–664.
White, G. H., 1988a: On the performance of the NMC medium range forecast model in mid latitudes. Palmen Memorial Symposium on Extratropical Cyclones, Helsinki, Finland, 1988, American Met. Society, 305–308.
White, G. H., 1988b: The NMC model systematic errors in medium and extended range forecasts, Workshop on systematic errors in models in the atmosphere Toronto, Canada, 19–23 September 1988, 12, WMO/TD No. 273.
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Rao, P.L.S., Mohanty, U.C. & Ramesh, K.J. Mean dynamical characteristics of the Asian summer monsoon with a global analysis — Forecast system. Meteorl. Atmos. Phys. 68, 57–77 (1998). https://doi.org/10.1007/BF01025385
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DOI: https://doi.org/10.1007/BF01025385