Publication Abstracts

Fu 1991

Fu, R., 1991: Deep Convection and its Relation to the Large-Circulation in the Tropical Pacific. Ph.D. thesis. Columbia University.

Behavior of deep convection and its relation to sea surface temperature (SST), surface wind divergence and convective instability are analyzed by using ISCCP cloud data, conventional SST and surface wind data and rawinsonde data in the tropical Pacific for July 1983-July 1985. The intensive deep convective clouds (DCC) and surface wind convergence areas shift latitudinally in phase with the maximum solar radiation. The warm SST area lags them one to three months in equinox seasons in the central Pacific. SST has major impact on atmospheric conditional instability. When SST ≥ 28°C, surface wind divergence only affect the planetary boundary layer (PBL) instability. When SST < 27°C, strong surface wind convergence destabilizes inversion layer and moisten PBL so that atmosphere becomes convectively neutral stable. DCC is enhanced only in the area of warm SST without strong surface wind divergence when the fractional area of warm SST exceed 10% of a region. When the fractional area of warm SST is smaller than 10% in a region, DCC is enhanced in cold SST (<27°C) when strong surface wind convergence occurs. This is consistent with the distribution of convective instability. DCC areas are latitudinally narrower than warm SST area in the western Pacific due to lower relative humidity in PBL or inversion capped on the top of trade cumulus boundary layer (TCBL). The area with dry PBL that separates north and south branches of DCC area may be caused by subsidence and easterly advection of dry air. In warm SST area, DCC occurs more frequently, and DCC top rises due to increase of PBL. The mean cirrus/anvil clouds (CAC) over the western and central Pacific are colder and optically thinner in El Nino months. This behavior of CAC introduces an anomally warming effect on atmosphere-ocean system during El Nino events. The EOF analysis suggests that the vertical temperature and humidity variations are dominated by variations of large-scale vertical motion and shallow convections associated with easterly waves and pertubations of Walker and Hadley circulations. The occurrence of deep convection is mainly regulated by temperature change in the trade inversion layer on short time scales.

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BibTeX Citation

  author={Fu, R.},
  title={Deep Convection and its Relation to the Large-Circulation in the Tropical Pacific},
  school={Columbia University},
  address={New York, N.Y.},

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RIS Citation

ID  - fu05100g
AU  - Fu, R.
PY  - 1991
BT  - Deep Convection and its Relation to the Large-Circulation in the Tropical Pacific
PB  - Columbia University
CY  - New York, N.Y.
ER  -

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