Recent Climatology of Kinematic Variables in the TOGA-COARE Region

Dayton G. Vincent Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana

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Jon M. Schrage Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana

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L. David Sliwinski Department of Earth and Atmospheric Sciences, Purdue University, West Lafayette, Indiana

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Abstract

The importance of the “warm pool” region of the western Pacific on in situ and global-scale circulations has gained wide recognition in the last decade with the advent of TOGA and, more recently, with the field experiment TOGA-COARE. The objectives of this study are two fold: 1)to provide a climatology of the kinematic properties of the atmosphere over the tropical western Pacific and adjacent areas, based on 1985–90 analyses., and 2) to focus on a detailed diagnosis of the four-month period, November–February, since the intensive observing period of TOGA-COARE occurred during those months. The dataset used in this study is the WCRP/TOGA archive II analyses produced by ECMWF. The analyses contain uninitialized gridpoint values of several variables at 2.5° lat/long and at 14 mandatory pressure levels. The dataset also includes a full surface package at the same horizontal resolution. The variables examined are mean sea level pressure, zonal and meridional wind components, vertical velocity, and relative vorticity. Many well-known features of the circulation are reproduced by the analyses. In particular, there is a good documentation of the differences between the El Niño event of 1986–1987 and the La Niña event of 1988–1989. During the four-month period, the circulation features across the large-scale array of TOGA-COARE, as well as those associated with the Australian monsoon and SPCZ, show well-defined patterns, both temporally and spatially.

Abstract

The importance of the “warm pool” region of the western Pacific on in situ and global-scale circulations has gained wide recognition in the last decade with the advent of TOGA and, more recently, with the field experiment TOGA-COARE. The objectives of this study are two fold: 1)to provide a climatology of the kinematic properties of the atmosphere over the tropical western Pacific and adjacent areas, based on 1985–90 analyses., and 2) to focus on a detailed diagnosis of the four-month period, November–February, since the intensive observing period of TOGA-COARE occurred during those months. The dataset used in this study is the WCRP/TOGA archive II analyses produced by ECMWF. The analyses contain uninitialized gridpoint values of several variables at 2.5° lat/long and at 14 mandatory pressure levels. The dataset also includes a full surface package at the same horizontal resolution. The variables examined are mean sea level pressure, zonal and meridional wind components, vertical velocity, and relative vorticity. Many well-known features of the circulation are reproduced by the analyses. In particular, there is a good documentation of the differences between the El Niño event of 1986–1987 and the La Niña event of 1988–1989. During the four-month period, the circulation features across the large-scale array of TOGA-COARE, as well as those associated with the Australian monsoon and SPCZ, show well-defined patterns, both temporally and spatially.

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