ERA-40 Global Observational Feedback Record Reports

DSS presents a comprehensive set of global, 3 hourly feedback record reports used in the ECMWF 45-year reanalysis (ERA-40) covering the period from September 1957 to August 2002. This data set contains the full collection of observations, from many data sources, which were assimilated into an ECMWF model and produced ERA-40. The metadata generated during the ERA-40 quality control/data assimilation (QC/DA) process were appended to the input observations. The final combination of input observations and feedback metadata are called feedback record reports. Feedback record reports include a set of input observation variables, analyzed variables, and associated metadata information. Input variables include pressure, mean sea level pressure, three hour pressure change, characteristic of pressure tendency, temperature, dew point temperature, relative humidity, wind speed, and wind direction. Analyzed variables are derived from input variables, and were used in the model assimilation. These variables include pressure, height, relative humidity, u- and v- wind speed components. The feedback metadata available includes QC flags for entire reports and individual variables, and differences between individual variables and interpolated six-hour forecasts and final model analyses. Further, in the case of QC report or variable rejection, some details why rejection occurred are given in the codes provided.

The ERA-Interim data from ECMWF is an update to the ERA-40 project. The ERA-Interim data starts in 1989 and has a higher horizontal resolution (T255, N128 nominally 0.703125 degrees) than the ERA-40 data (T159, N80 nominally 1.125 degrees). ERA-Interim is based on a more current model than ERA-40 and uses 4DVAR (as opposed to 3DVAR in ERA-40). ECMWF will continue to run the ERA-Interim model in near real time through at least 2010, and possibly longer.