ECMWF WMO Daily Data

ECMWF ERA-15 Missing Days and Comments on Data Quality

Summary of data deficiencies in the ERA-15 archive

This section summarizes all known data deficiencies (suspect or missing data) of the ERA-15 Data Sets from December 1978 to February 1994.

Date	Time	Step	Parameter	Level	Notes
17 November 1981	12	+00	specific humidity	model level22	missing data*
01 December 1982	00	+12h	convective precipitation	sfc	treat with care
01 December 1982	00	+24h	convective precipitation	sfc	corrupted
05 February 1982	06		relative humidity	all pressure levels	missing *
23 December 1983	12	+00	cloud water	all model levels	missing *
24 December 1983	00/06	+00	cloud water	all model levels	missing *
27 December 1983	00	+00	cloud water	all model levels	missing *
31 December 1983	06	+00	cloud water	all model levels	missing *

* Due to technical problems a few GRIB-fields in ERA-15 were never, or incompletely, archived. The root cause was a ftp-problem when transferring GRIB data from the super-computer used for the data assimilation to the server used for the archiving The missing data known to us are listed above. Should any other missing field be encountered, please report to era@ecmwf.int

Other comments

The ERA-15 production system generated re-analyses from December 1978 to February 1994. The following observations were used:

FGGE Level II-B data for 1978/79;
COADS ship and buoy observations;
ALPEX Level II-B data;
ECMWF archive of observations received via the WMO GTS;
additional TEMP and AIREP data from the Japan Meteorological Agency (JMA);
Australian PAOB surface pressure pseudo-observations from Bureau of Meteorology (BoM), Melbourne;
TOGA COARE data;
TOVS Cloud Cleared Radiance data;
Hadley Centre GISST and NCEP SST analyses.

The data assimilation system used for ERA-15 had the following characteristics:

Spectral T106 resolution with 31 vertical hybrid levels.
Intermittent statistical (optimum interpolation) analysis with 6 hour cycling and noFGAT.
One dimensional variational (1D-VAR) physical retrieval of TOVS cloud cleared radiances below 100hPa, and NESDIS operational retrievals above. No TOVS data were used above 100hPa between 20°N and 20°S.
Diabatic, non-linear normal mode initialisation, five vertical modes.
The Integrated Forecast System (IFS) version of the ECMWF forecast model with 3-dimensional semi-Lagrangian advection.
Mean orography with a compatible parametrization of the effects of sub-grid scale orography.
Prognostic soil temperature and soil moisture, with nudging of the moisture from boundary layer atmospheric humidity analyses.
Prognostic equations for cloud water and ice content and the cloud cover.
ECMWF operational radiation parametrization with prescribed concentrations of aerosols, CO2 and O3, with O3 varying geographically and seasonally, the aerosols varying geographically and vertically and the CO2 held constant.
ECMWF operational planetary boundary layer parametrization.

The externally prescribed forcing of the re-analyses, in addition to the observations, came from the ocean surface temperature (SST) analyses and the ocean ice cover, determined from SMMR and SSM/I data.