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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 . (1000  1)

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Era interim and asr data management at ncar

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. (10001)

    • 15 isentropic surf.

    • 30 ocn. wave anal. fields

    • 47 surface anal. fields

  • Total size ≅ 84 TB (tapes)

  • Network Access ≅ 18 TB

  • Details


    • (to be here)

Information sources documentation
Information sources / documentation

  • Web pages


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
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
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

  • Horizontal grids ncar will compute regular gaussian 512x256
    Horizontal GridsNCAR will compute Regular Gaussian (512x256)



    Regular Gaussian (512x256)

    Transform to aid users

    • N128 Reduced Gaussian  Regular Gaussian

    • T255 Spectral  Regular Gaussian

    • U 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
    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

    Regular gaussian 512x256 continued
    Regular Gaussian (512x256), continued

    What high resolution data will ASR use?

    • N128 and T255 spectral model level orregular 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 continued1
    Regular Gaussian (512x256), continued

    • Surface and Single level analysis (N128)

      • 47 fields


    Status @ ncar
    Status @ NCAR

    • All products for January 1989

      • High resolution transformations (reg. gaussian)

    • Decision still to be made on fields coming from the forecasts

    Status @ ncar1
    Status @ NCAR

    • Within a product there are 6-hourly synoptic files

    • Our recommendation – if you plan to work with regular Gaussian model level fields

      ASAP 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)








    • December 2007 data will arrive next

      • Delivery – probably, mid-March, 2009

    • Receive and process 1989 – 2007

    • Receive 2008, about August, 2009

    • 2009 updates by network transfer

      • Lagging about 3 months behind real time @ ECMWF

    • Establish the RDA online service. Product suite TBD

    • All data will be on the NCAR MSS

    • How will ASR get a copy of ERA-Interim?

    Asr data management at ncar
    ASR Data Management at NCAR

    • Managed a component in the NCAR/CISL Research Data Archive (RDA)


    • 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


    What we need to know
    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-hourly

      • Single variable time series

    What we need to know1
    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 know2
    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?