Abstract
The study delineates the vorticity and angular momentum balances of Asian summer monsoon during the evolution and established phases. It also elucidates the differences between these balances in the National Centre for Environmental Prediction/National Centre for Atmospheric Research (NCEP/NCAR) reanalysis and the National Centre for Medium Range Weather Forecasts (NCMRWF) analysis fields. The NCEP/NCAR reanalysis for a 40 year period (1958-97) and the NCMRWF analysis for a three year (1994-96) period are made use of for the purpose. The time mean summer monsoon circulation is bifurcated into stable mean and transient eddy components and the mean component is elucidated.
The generation of vorticity due to stretching of isobars balances most of the vorticity transported out of the monsoon domain during the evolution period. However, during the established period, the transportation by the relative and planetary vorticity components exceeds the generation due to stretching. The effective balancing mechanism is provided by vorticity generation due to sub-grid scale processes. The flux convergence of omega and relative momenta over the monsoon domain is effectively balanced by pressure torque during the evolution and established phases. Nevertheless, the balance is stronger during the established period due to the increase in the strength of circulation.
Both the NCMRWF and NCEP fields indicate the mean features related to vorticity and angular momentum budgets realistically. Apart from the oceanic bias (strong circulation over oceans rather than continents), the summer monsoon circulation indicated by the NCEP is feeble compared to NCMRWF. The significant terms in the large-scale budgets of vorticity and angular momentum enunciate this aspect
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References
Anthes R A 1977 A cumulus parameterization scheme utilizing a one-dimensional cloud model;Mon. Weather Rev. 105 270–286
Campana K A, Hou Y T, Mitchell Yang S K and Cullather R 1994 Improved diagnostic cloud parameterization in NMC’s global model. Preprints 10th Conf. on Numerical Weather Prediction, Portland, OR;Amer. Meteor. Soc. 324–325
Chen S C, Norris C L and Roads J O 1996 Balancing the atmospheric hydrologic budget;J. Geophys. Res. 101 7341–7358
Chu J H, Yanai M and Sui C H 1981 Effects of cumulus convection on the vorticity field in the tropics Part-I: The large scale budget;J. Met.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
Holopainen E O and Oort A H 1981 Mean surface stress curl over the oceans as determined from the vorticity budget of the atmosphere;J. Atmos. Sci 33 773–792
Kalnay E and Co-authors 1996 The NCEP/NCAR 40-year reanalysis project;Bulletin of American Met. Society,77 3 437–471
Kanamitsu M 1989 Description of the NMC global data assimilation and forecast system;Weather Forecasting 4 335–342
Mo K C and Higgins R W 1996 Large scale atmospheric moisture transport as evaluated in the NCEP/NCAR and the NASA/DAO reanalyses;J. Climate 9 1531–1545
Mohanty U C and 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
O’Brien J J 1970 Alternative solutions to classical vertical velocity problem;J. Appl. Met 9 197–203
Oort A H and Chan P H 1977 On the role of the Asian monsoon in the angular momentum and kinetic energy balances of the tropics;Pageoph,115 1167–1186
Oort A H and Peixoto J P 1983 Global angular momentum and energy balance requirements from observations;Adv. Geophys 25 355–490
Pan H L and Mahrt L 1987 Interaction between soil hydrology and boundary layer development;Bound. Layer Meteor. 38, 185–220
Pan H L and Wan-Shu Wu 1994 Implementing a mass flux convective parameterization package for the NMC medium-range forecast model. Preprints 10th Conf. on Numerical Weather Prediction, Portland, OR;Amer. Meteor. Soc. 96–98
Parrish D F and Derber J C 1992 The National Meteorological Center’s spectral statistical interpolation analysis system;Mon. Weather Rev. 120 1747–1763
Rao PLS 2001 The energetics of Asian summer monsoon;Pageoph 158 5-6 965–988
Reed R J and Johnson R H 1974 The vorticity budget of the synoptic-scale wave disturbances in the tropical western Pacific;J. Atmos. Sci. 31 1784–1790
Sardeshmukh P D and Held I M 1984 The vorticity balance in the tropical upper troposphere of a general circulation model;J. Atmos. Sci. 41 5 768–778
Schmitz J T and Mullen S L 1996 Water vapor transport associated with the summertime north American Monsoon as depicted by ECMWF Analyses;J Climate 9 1621–1634
Slingo J M1987 The development and verification of a cloud prediction scheme for the ECMWF model;Q.J.R. Meteorol. Soc. 113 899–927
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Rao, P.L.S., Mohanty, U.C., Raju, P.V.S. et al. The vorticity and angular momentum budgets of Asian summer monsoon. J Earth Syst Sci 113, 281–298 (2004). https://doi.org/10.1007/BF02716726
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DOI: https://doi.org/10.1007/BF02716726