Footprint of the dynamical amplifier of global warmings at the TOA
Christelle Castet, Florida State University, Tallahassee, FL; and M. Cai
The largest warmings over the last several decades were observed in high latitudes. Cai (2004) proposed that part of the large amplitude climate warmings in high latitudes can be explained by the so-called “dynamical amplifier” mechanism. The dynamical amplifier feedback results from a net increase of poleward heat transport due to an increase of greenhouse gases. This paper provides observational and modeling evidences to validate the dynamical amplifier mechanism. We have analyzed the radiation budget at the top of the atmosphere (TOA) using the ERA40 and NCEP/NCAR reanalysis and climate model simulations with anthropogenic radiative forcings made at various centers (e.g., NCAR, GFDL, NASA/GISS, CCCMA). Our diagnostics using the two independent reanalyses indicate that both the radiation energy surplus in low latitudes and deficit in high latitudes at the TOA have been strengthened over the last several decades. Such an intensification of radiation energy imbalance at the TOA is also confirmed by some of the climate model simulations we have examined. These results strongly suggest that the dynamical amplifier mechanism indeed has taken place in nature and is captured by the climate models.
Joint Poster Session 2, Formal Poster Viewing - High Latitude Climate Variability and Change (Joint with the Eight Conference on Polar Meteorology and the 16th symposium on Global Change & Climate Variations)
Thursday, 13 January 2005, 9:45 AM-11:00 AM
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