Huo-Jin Huang

Significance of the South Pacific Convergence Zone in energy conversions of the Southern Hemisphere during FGGE, 10-27 January 1979

Abstract A modified set of Level III-b grid point analyses, originally produced by ECMWF, is used to diagnose the circulation features and energy conversions in the Southern Hemisphere during the FGGE SOP-1 period of 10–27 January 1979. One of the dominant features during the period was the South Pacific Convergence Zone (SPCZ), a large-scale, quasi-stationary, convectively-active cloud band over the South Pacific Ocean. The study focuses on the significance of the SPCZ on Southern Hemisphere energy conversions by partitioning the conversions into zonal and eddy (transient and standing) components. The mean state is examined for a 15-day period, 10–24 January, when the SPCZ was most active. After 24 January it dissipated. In addition, daily variations are examined for the entire period and a zonal wavenumber analysis fox. wavenumbers 1–15 is performed. The major findings are that 1) the baroclinic conversion of eddy potential to eddy kinetic energy (CE) is the dominant conversion term in the tropics (0–30...

Major Changes in Circulation Features over the South Pacific During FGGE, 10–27 January 1979

Abstract An analysis of the large-scale atmospheric circulation patterns over the South Pacific during part of FGGE SOP-1, 10–27 January 1979, is presented. Results, which are derived from Level III-b analyses produced at ECMWF, are composited for three time periods, based on changing characteristics of the South Pacific Convergence Zone (SPCZ): 0000 GMT 10 January–1200 GMT 18 January, when the SPCZ was a quasistationary persistent feature of the circulation; 0000 GMT 19 January–0000 GMT 24 January, when the SPCZ propagated westward and began to weaken; and 1200 GMT 24 January–1200 GMT 27 January, when it disappeared. The major findings include 1) the buildup of high pressure in the eastern Pacific coincident with the westward movement of the SPCZ, followed by a rapid buildup of high pressure over the central Pacific and demise of the SPCZ; 2) a trend from middle and upper tropospheric wavelike patterns in wind, temperature and height to more zonally-oriented patterns when the SPCZ disappears; and 3) stro...