DIAGNOSIS OF THE IMPACT OF DEEP DEPRESSIONAL ACTIVITY IN NORTHERN ARABIAN SEA OVER KARACHI DURING MONSOON

Muhammad Hasan Ali Baig, Ghulam Rasul

Abstract


The burgeoning usage of Numerical weather prediction techniques provide numerous dimensions to forecasting in modern days. As reliance on these models is increasing, hectic involvements to address the shortcomings of their applications is also in full swing. In this study an attempt has been made to diagnose the devastating dust/wind
storm accompanied by torrential pre-monsoon rain which lashed Karachi and smashed the city’s infrastructure. Sudden and rapid development of supercell Cumulo nimbus (Cb) clouds over Karachi in the outskirts of strong Deep Depression over Arabian Sea followed by severe wind storm (whole gale) which deceived the forecasters has been analyzed here. High Resolution Regional Model (HRM) has been utilizing by PMD for
forecasting purposes. In this study simulations based upon the U.S. National Centre for Environmental Prediction (NCEP) and Albany data under the scope of conventional techniques have been analyzed and compared with HRM simulations to diagnose the causes of this disastrous activity and to address the discrepancies/limitations of the
HRM. Model successfully predicted the pressure fall, and upper tmospheric conditions at 1200 GMT. Little deviation has been observed in HRM’s simulations for humidity and temperature to the actual data recorded at different meteorological stations of PMD. Almost complete deviation is observed in simulations for predicting wind,
cloudiness and precipitation from actual record. This event has forced the modelers to review its physical processes, parameterization and numerical schemes for capturing wind, cloud cover and precipitation to realistic limits.


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References


Black T.M, 1994. NMC’s ETA model: Description and Examples. Weather and Forecasting, 9, 265-278.

Chaudhry, Q.Z., G. Rasul., 2007. Development of a mesoscale convective system over the foothills of Himalaya into a severe storm. Mountains witnesses of Global Changes, ELSEVIER, Ch.33, pp 301-311.

Das, S., 2002. Real Time Mesoscale Weather Forecasting over Indian region using MM5 modelling system. NCMRWF R.No. NMRF/RR/3/2002, NCMRWF, Noida, UP, India.

Kalnay et al., 1996. The NCEP/NCAR 40-year reanalysis project, Bull. Amer. Meteor. Soc., 77, 437-470,. Kato, Y., 1997. Hydrostatic and Non-hydrostatic Simulations of Moist Convection: Review and Further Study. Meteorology and Atmospheric Physics, 63. Springer-Verlag, Austria. pp 39-51.

Khan, J.A., 1993. The Climate of Pakistan. Rehbar Publishers, Karachi, Pakistan.

Lutgens, F.K., E.J. Tarbuck,, 2004. The Atmosphere: an introduction to meteorology.Pearson Education, Inc. Upper Saddle River, New Jersey, USA.Majewski, D., 2007. HRM User’s Guide. DWD, Germany.

NCAR, 2002. PSU/NCAR Mesoscale Modelling System (MM5 version 3), tutorial class, notes and user guide, Available from the National Centre for Atmospheric Research Boulder, Colorado, USA.

Pielke, R.A., W. R. Cotton1, R. L. Walko1, C. J. Tremback1, W. A. Lyons1, L. D. Grasso1, M. E. Nicholls1, M. D. Moran1, D. A. Wesley1, T. J. Lee1 and J. H. Copeland1, 1992. A Comparison of Meteorological Modelling System-RAMS.

Meteorological and Atmospheric Physics. 49, pp 69-91.

Rasul, G., Q. Z. Chaudhry, Z. Sixiong, Z. Qingcum, QI. Linlin, and Z. Gaoying, 2005. A Diagnostic Study of Heavy rainfall in Karachi Due to Merging of a Mesoscale Low and a Diffused Tropical depression during South Asian Summer Monsoon.

Advances in Atmospheric Sciences, Vol. 22, No. 3, 2005, 375-391.

Shamshad, K.M., 1988. The Meteorology of Pakistan. Royal Book Company, Karachi, Pakistan, pp 167-169.


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