ERA-Interim and ASR Data Management at NCAR
Steven Worley
Dave Stepaniak
Chi-Fan Shih
February 17, 2009
ERA-Interim
Time Period, 1989-current T255L60 4DVAR global, spectral or reduced Gaussian Products
high resolution reg. gaussian (512x256) 37 press. lvls. (10001) 15 isentropic surf. 30 ocn. wave anal. fields 47 surface anal. fields
Total size 84 TB (tapes)≅ Network Access 18 TB ≅
Detailshttp://www.ecmwf.int/research/era/do/get/era-interimhttp://dss.ucar.edu/datasets/ds627.0/ (to be here)
Information sources / documentation
Web pageshttp://dss.ucar.edu/datasets/ds627.0/docs/
IFS @ ECMWF
Chapter 14 – Data Flow• difference between analysis (an), 4D-Var analysis (4v), 4D-
increment analysis (4i) files• variables coming out of the analysis• variables coming out of the forecasts – with reference times
Model levels and layers
Documented accurate method to determine model level and layer coefficients. Tables and codes that provide
them netCDF file with values
Tricky matter GRIB files have model layer
interfaces defined, not the level
Contrast of ERA-15 (red) versus ERA-40 and ERA-Interim (blue)
High Resolution Model Level Data
Two forms combined define atmosphere T255 spectral coefficients, Model Level Fields
Z, geopotential height of level 1 T, temperature, 60 levels W, vertical velocity, 60 levels VO, relative vorticity, 60 levels LNSP, log. of surface pressure D, divergence, 60 levels
N128 reduced Gaussian, Model Level Fields Q, specific humidity, 60 levels O3, ozone mass mixing ratio, 60 levels CLWC, cloud liquid water content, 60 levels CIWC, cloud ice water content, 60 levels CC, cloud cover, 60 levels
dss.ucar.edu/datasets/ds627.0/docs/era_interim_grib_table.oper_an_ml.html
Horizontal GridsNCAR will compute Regular Gaussian (512x256)
N128 512x256
Regular Gaussian (512x256)
Transform to aid usersN128 Reduced Gaussian Regular GaussianT255 Spectral Regular GaussianU and V winds are computed from VO and D
Products to be transformed Analyses on model levels (ml), surface (sfc),
pressure levels (pl), isentropic levels (pt), and potential vorticity levels (pv).
Note: Important fields are in the forecast files Transform only selected fields and forecast
intervals
Surface Forecast Grids – Model resolution
Initialization every 12 hours Generally, out to 240 hours
3,6,9,12,15,18,21,24,30,36,42,48,60,72,84,96,108,120,132,144,156,168,180,192,204,216,228,240
http://dss.ucar.edu/datasets/ds627.0/docs/era_interim_grib_table.oper_fc_sfc.html
Regular Gaussian (512x256), continued
What high resolution data will ASR use?N128 and T255 spectral model level or regular
Gaussian model level data created at NCAR?
If regular Gaussian, then:We expect ASR to use the analysis (an) files.We will extract some fields from the forecast (fc) files.Are there any fields in the ‘fc’ files that you need?Planning just one pass on the ‘fc’ files to create
regular Gaussian
Let’s get coordinated soon!
Regular Gaussian (512x256), continued
Surface and Single level analysis (N128)47 fieldshttp://dss.ucar.edu/datasets/ds627.0/docs/
era_interim_grib_table.oper_an_sfc.html
Status @ NCAR
All products for January 1989 High resolution transformations (reg. gaussian)
Decision still to be made on fields coming from the forecasts
ASR Product Size (GB/mn)
✔ an.ml 21
an.pl 16
an.pt 4
✔ an.sfc 2
an.pv .2
Status @ NCAR Within a product there are 6-hourly synoptic files
Our recommendation – if you plan to work with regular Gaussian model level fieldsASAP begin working with the January 1989 data
Examine the model level and surface level analyses. Examine forecasts for additional fields that ASR might need.
Documents, metadata tables, test data (on NCAR/MSS)
http://dss.ucar.edu/datasets/ds627.0/docs/ /DSS/DS627.0/ei.oper.an.ml/198901/ei.oper.an.ml.regn128sc.1989010100
/DSS/DS627.0/ei.oper.an.ml/198901/ei.oper.an.ml.regn128uv.1989010100
/DSS/DS627.0/ei.oper.an.sfc/198901/ei.oper.an.sfc.regn128sc.1989010100
/DSS/DS627.0/ei.oper.fc.sfc/198901/ei.oper.fc.sfc.regn128sc.1989010100
/DSS/DS627.0/ei.oper.fc.sfc/198901/ei.oper.fc.sfc.regn128sc.1989010112
Status
FutureDecember 2007 data will arrive next
Delivery – probably, mid-March, 2009
Receive and process 1989 – 2007Receive 2008, about August, 20092009 updates by network transfer
Lagging about 3 months behind real time @ ECMWF
Establish the RDA online service. Product suite TBDAll data will be on the NCAR MSSHow will ASR get a copy of ERA-Interim?
ASR Data Management at NCAR
Managed a component in the NCAR/CISL Research Data Archive (RDA)http://dss.ucar.edu/index.html
Planning for about 55 TB total (?) Duplicate copies on the NCAR MSS All data available to the public (?)
usage restriction?
5-7 TB online, network access (TBD) Follow template used for JRA-25
http://dss.ucar.edu/datasets/ds625.0/
What we need to know
Was there a proposed data management plan? Is a product model like ERA-Interim suitable
e.g. ml, pl, sfc, forecasts, etc. ?
Will the netCDF file metadata be CF compliant?Good idea, enables tool compatibility
How will the data files be structured?Synoptic 3-hourlySingle variable time series
What we need to know
How to deal with the 2x horizontal resolution and polar projection?What interpolations from model coordinates will be
done?
Will pressure level data be computed? Will time averages be computed
e.g. monthly means
Will model assimilation feedback be added to the observations used, should that data be archived? In what format?
What we need to know
What other organization will host ASR data? We must not duplicate efforts
How will we get the data to NCAR?Tapes, TB disks, network?
Who will provide other organization bulk data delivery?
How do we handle re-runs and fixes?
ContactsSteven Worley [email protected]
Dave Stepaniak [email protected]
Chi-Fan Shih [email protected]
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