THE SOUTH PACIFIC CONVERGENCE ZONE AND ENERGY BALANCE OF THE SOUTHERN HEMISPHERE (METEOROLOGY, SPCZ, ENERGY BALANCE)
Abstract
This thesis presents a diagnostic analysis of the general circulation and energy balance of the Southern Hemisphere (0-60(DEGREES)S) during part of FGGE SOP-1, 10-27 January, 1979. A modified set of Level III-b grid point analyses produced by the European Centre for Medium-range Weather Forecasts and satellite-derived estimates of outgoing longwave radiation are used. One of the dominant features during this period is the South Pacific Convergence Zone (SPCZ), which consists of a semi-permanent, convectively-active, slowly-meandering cloud band over the South Pacific Ocean. The present study focuses on the relationship between the SPCZ and the Southern Hemisphere atmospheric circulation. A zonal Fourier analysis is applied to partition atmospheric variables into their zonal average and wave components for wave numbers (n) 1-15. A portion of the energy cycle which includes energy contents and conversions, is presented in space domain, mixed space-time domain and wave number domain. The major findings are: (1) the SPCZ is located between the surface pressure trough and upper tropospheric ridge during 10-24 January, in a region characterized by moist, rising air, with maximum cyclonic (anticyclonic) vorticity along the surface pressure trough (upper tropospheric ridge); (2) during the last few days, when the SPCZ is decaying, drastic changes are evident in all of the variables and energy fields; (3) long waves (n = 1-4) dominate the eddy processes in the tropics and a thermally-direct circulation from zonal available potential (AZ) to zonal kinetic (KZ) energy is found there; (4) in particular, wave number 4 is closely associated with the SPCZ and plays an important role in the energy conversion from eddy available potential (AE) to eddy kinetic (KE) energy in the Southern Hemisphere tropics, especially in the vicinity of the SPCZ; and (5) medium (synoptic)-scale waves (n = 5-8) are significant in middle latitudes and result in a conversion of AZ to AE, AE to KE and KE to KZ, together with an indirect mean meridional circulation.
Degree
Ph.D.
Subject Area
Atmosphere
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