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ERA40 T85 Monthly Mean Surface Analysis and Surface Forecast Fields, created at NCAR

Entry ID: NCAR_DS126.0

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Summary

Abstract: DS126.0 represents a dataset implemented and computed by NCAR's Data Support Section, and forms an essential part of efforts undertaken in late 2004, early 2005, to produce an archive of selected segments of ERA-40 on a standard transformation grid. In this case, forty seven ERA-40 monthly mean (designated as "MODA" or "moda" below) ... surface and single level analysis variables were transformed from a reduced N80 Gaussian grid to a 256x128 regular Gaussian grid. (These are further designated as "SURFACE", or "SURFACE/SINGLE LEVEL", or "SFC/sfc", variables below.) All fields were transformed using routines from the ECMWF EMOS library, including 10 meter winds which were treated as scalars because of a lack of 10 meter spectral vorticity and divergence. A missing value of 9.999e+20 occurs in the sea surface temperature and sea ice (SSTK and CI) fields to mask grid points occurring over land. Fields formerly archived as whole integers, such as vegetation indices and cloud cover, occur as integers plus a fractional part in the T85 version due to interpolation. Twenty seven ERA-40 monthly mean (designated as "MODA" or "moda" below) surface and single level 6-hour forecast variables were transformed from a reduced N80 Gaussian grid to a 256x128 regular Gaussian grid. (These are further designated as "OTHER", or "othr", variables below.) Four of the variables are "instantaneous" variables, and the remaining twenty three variables are "accumulated" over the 6-hour forecast time. Divide the accumulated variables by 21600 seconds to obtain instantaneous values. (Multiplication by minus one may also be necessary to match the sign convention one is accustomed to.) All fields were transformed using routines from the ECMWF EMOS library, including three pairs of stresses which were treated as scalars because of a lack of spectral precursors. In addition, all corresponding 00Z, 06Z, 12Z, and 18Z monthly mean surface and single level analysis variables and 6-hour forecast variables were also transformed to a T85 Gaussian grid (designated as "MNLY", "mnly", or "mnth" below) All forecast variables are valid 6 hours after the forecast was initiated. Thus, 00Z 6-hour forecast evaporation is valid at 06Z. Divide the accumulated variables by 21600 seconds to obtain instantaneous values. (Multiplication by minus one may also be necessary to match the sign convention one is to.) The choice of a T85 Gaussian grid was based on considerations of limiting the volume of new data generated to a moderate level, and to match the horizontal resolution of the Community Atmosphere Model (CAM) [http://www.ccsm.ucar.edu/models/atm-cam/] component of NCAR's Community Climate System Model (CCSM). 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 4-D VAR (as apposed to 3-D VAR in ERA-40). ECMWF will continue to run the ERA-Interim model in near real time thru at least 2010, and possibly longer. This data is available in ds627.0 [http://rda.ucar.edu/datasets/ds627.0].

Related URL

Link: VIEW RELATED INFORMATION

Description: ECMWF's ERA40 web site

Data Set Citation

Dataset Originator/Creator: UCAR/NCAR/CISL/DSS > Data Support Section, Computational and Information Systems Laboratory, National Center for Atmospheric Research, University Corporation for Atmospheric Research

Dataset Title: ERA40 T85 Monthly Mean Surface Analysis and Surface Forecast Fields, created at NCAR

Dataset Publisher: UCAR/NCAR/CISL/DSS > Data Support Section, Computational and Information Systems Laboratory, National Center for Atmospheric Research, University Corporation for Atmospheric Research

Online Resource: http://rda.ucar.edu/datasets/ds126.0/

Temporal Coverage

Start Date: 1957-09-01

Stop Date: 2002-08-31

Data Resolution

Latitude Resolution: 1.375 degrees
Longitude Resolution: 1.4 degrees
Horizontal Resolution Range: 100 km - < 250 km or approximately 1 degree - < 2.5 degrees

Science Keywords

ATMOSPHERE > AIR QUALITY > TROPOSPHERIC OZONE

ATMOSPHERE > ALTITUDE > PLANETARY BOUNDARY LAYER HEIGHT

ISO Topic Category

BIOTA

ENVIRONMENT

GEOSCIENTIFIC INFORMATION

INLAND WATERS

Quality Although there is a very strong relationship between diatom composition and
salinity this dataset is considered too small to use for a local transfer
function and so samples are only used in the larger combined Salinity transfer
function.

Access Constraints None

Use Constraints None

Ancillary Keywords

The European Diatom Database

surface-sediment diatom assemblages

Data Set Progress

COMPLETE

Data Center

European Diatom Database, University of Newcastle, UK

Data Center URL: http://craticula.ncl.ac.uk/Eddi/jsp/
Dataset ID: Caspian

Data Center Personnel
Name: STEPHEN JUGGINS Phone: 44 191 222 8799 Fax: 44 191 222 5421 Email: Stephen.Juggins at ncl.ac.uk Contact Address: University of Newcastle Department of Geography Newcastle upon Tyne NEI 7RU Country: UNITED KINGDOM