ERA-Interim and ASR Data Management at NCAR

Steven WorleyDave Stepaniak

Chi-Fan ShihFebruary 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 GaussianLet’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, 2009Receive and process 1989 – 2007Receive 2008, about August, 20092009 updates by network transfer

Lagging about 3 months behind real time @ ECMWFEstablish 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 worley@ucar.eduDave Stepaniak davestep@ucar.eduChi-Fan Shih chifan@ucar.edu