This study identifies the typical synoptic patterns associated with the occurrence of tropical cyclones (TCs) with a particular size. The sizes of the TCs occurring between 1991 and 1996 are estimated using the European Remote Sensing satellite 1 and 2 (ERS-1 and ERS-2) scatterometer data based on the definition of TC size proposed by Liu and Chan (1997). For each case, the synoptic pattern associated with the TC is identified from the operational 850 and 500 hPa analyses of the UK Meteorological Office. The patterns are then classified into different categories according to the synoptic classification of Carr and Elsberry (1994). Preliminary results show that TCs tend to be smaller when embedded in the easterlies equatorward of the subtropical ridge and larger when entering the vicinity of the break of the ridge and the westerly poleward of the ridge. Small TCs also form in the peripheral cloud band of a monsoon gyre. An investigation of the physical processes governing the sizes and the size changes of TCs are currently underway and the results will be presented at the Conference.
References:
Carr, L. E., III, and R. L. Elsberry, 1994: Systematic and integrated approach to tropical cyclone track forecasting. Part I. Approach overview and description of meteorological basis. Tech. Rep. NPS-MR-94-002, Naval Postgraduate School, Monterey, CA 93943-5114, 273 pp.
Liu K. S. and J. C. L. Chan, 1997: Size changes of tropical cyclones as inferred from ERS-1 and ERS-2 data. Preprints, 22nd Conference on Hurricanes and Tropical Meteorology. American Meteorological Society, Boston, MA, 39-40.