HR: 0800h
AN: GC51D-1080    [Abstracts]
TI: Spatiotemporal Analysis on the Long-term Climate Trend in the Twentieth Century
AU: * Chen, J
EM: jchen@giss.nasa.gov
AF: NASA/Goddard Institute for Space Studies, NASA, 2880 Broadway, New York, NY 10025 United States
AU: * Chen, J
EM: jchen@giss.nasa.gov
AF: Department of Earth and Environmental Sciences, Columbia University, Lamont-Doherty Earth Observatory, Palisades, NY 10964 United States
AU: Del Genio, A D
EM: adelgenio@giss.nasa.gov
AF: NASA/Goddard Institute for Space Studies, NASA, 2880 Broadway, New York, NY 10025 United States
AU: Carlson, B E
EM: bcarlson@giss.nasa.gov
AF: NASA/Goddard Institute for Space Studies, NASA, 2880 Broadway, New York, NY 10025 United States
AB: The spatiotemporal signal of the twentieth century long-term climate trend is obtained from the global surface temperature datasets by applying ENSO-removed EOF analysis. The trend mode principle component time series match with the global mean temperature time series. The relative uniform global warming shown in the EOF spatial patterns implies that the global long-term trend should be attributed to relative evenly distributed radiative forcing. And the feature of that stronger warming happens in middle-high latitude land region is consistent with previous linear trend analyses and anthropogenic greenhouse gases model simulations. Several embedded cooling spots that have been related to the anthropogenic sulfate aerosol forcing are also detected in our analysis. Except above previously discovered characters of the 20th century long-term trend, we addressed other characters of the global long-term trend. The most significant one is the mild warming happened in the Pacific basin, comparing to the stronger temperature increase along and beyond the west and east coast of the Pacific Ocean. The changes in the atmospheric parameter fields associated with the long-term trend are also been isolated from the NCEP/NCAR reanalysis dataset. Consistent with the surface temperature zonal contrast caused by the weakened warming in the Pacific Ocean, the main feature of the atmosphere circulation change appears to be a large scale anomalous zonal overturning circulation over the Pacific basin and the surround region, with two ascending wet branches located over the Maritime Continent region and the east Pacific-Amazon region, and one descending dry branch located over the middle Pacific region. This anomalous zonal overturning circulation manifests itself clearer in the middle and upper troposphere than in the lower troposphere, because the atmosphere change in the lower troposphere is affected more by the regional characteristic of the underlying surface. We will also discuss the possible mechanisms behind the weakened warming in the Pacific Ocean and the meaning of this newly disclosed character of the long-term climate change.
DE: 4215 Climate and interannual variability (3309)
DE: 3319 General circulation
DE: 1610 Atmosphere (0315, 0325)
DE: 1620 Climate dynamics (3309)
DE: 1635 Oceans (4203)
SC: Global Climate Change [GC]
MN: 2004 AGU Fall Meeting