85th AMS Annual Meeting

Thursday, 13 January 2005: 2:00 PM
Hydrometeorology of the Amazon from ERA-40
Alan K. Betts, Atmospheric Research, Pittsford, VT; and J. H. Ball, P. Viterbo, A. Dai, and J. A. Marengo
We first compare the hydrometeorology of the Amazon basin using data from ERA-40 for 1958-2001 with observations of precipitation, temperature and streamflow. There is a large upward drift in the early years (1958-1972) in reanalysis precipitation and runoff associated with an upward drift in the atmospheric water vapor analysis in the pre-satellite data period, and a somewhat smaller (downward) drift of temperature as precipitation increases. Approximate bias corrections can be made on an annual basis, but this also removes interannual variability. We then discuss the coupling of different physical processes over the Amazon in ERA-40. Soilwater is coupled to mean lifting condensation level, low cloud cover and surface net longwave radiation. Precipitation, total column precipitable water and total cloud cover are coupled to the mid-tropospheric vertical motion on daily timescales, and interrelated on the seasonal timescale.

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