North Atlantic Oscillation

Observed data . Reanalysis . Satellite data . Model  results NAO

NAO signal

Climate variability

NCAR/NCEP

Data Analysis

Climate variability

Climate predictability

  • The ECMWF Re-analysis (ERA) Archive contains global analyses and short range forecasts of all relevant weather parameters obtained with an invariant and consistent data assimilation system which is kept unchanged over the interval 1979-1993. The full model resolution for ERA is Spectral T106, Gaussian N80 (approximately equivalent to latitude/longitude 1.125 degrees), with 31 hybrid model levels in the vertical , six of them below 850 hPa.

  • As in the NCEP reanalysis experiment, the data base has been enhanced with data not available when operational analyses were made (satellite data, ship and buoy observations , data from special observation periods FGGE, Alpex ). A comprehensive description is given in Gibson et. al. (1997).

  • Some questionable trends of increasing precipitation over tropical ocean are visible in ERA. Another problem it was identified beginning around 1986-87 when it was discovered that the African ITCZ precipitation maximum shifts from north of the equator to a position just to the south. Kalberg (1997) describes a discrepancy in the precipitation and soil temperature and moisture in a limited area in the western equatorial Amazonia affecting the first 8 year of ERA data and stresses that detailed conclusions on the behaviour of the tropical convergence, particularly over America, and its associated precipitation patterns should be carefully drawn.

 

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