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On 8 March 2016, ECMWF upgraded the horizontal resolution of its analyses and forecasts.The upgrade has a horizontal resolution that translates to about 9 km for HRES and the data assimilation (the outer loop of the 4D-Var) and to about 18 km for the ENS up to day 15. The resolution of the ENS extended (day 16 up to day 46)  is about 36 km.

A new cycle of the IFS has been introduced to implement the horizontal resolution upgrade. This cycle is labelled 41r2 and includes a number of enhancements to the model and data assimilation listed herein. The detailed specification of the resolution upgrades included in IFS cycle 41r2 are:

  • Introduction of a new form of the reduced Gaussian grid, the octahedral grid, for HRES, ENS and ENS Extended;
  • Horizontal resolution of the HRES increased from TL1279 / N640 to TCO1279 / O1280, where subscript C stands for cubic and O for octahedral, with a model time step of 450s;
  • Horizontal resolution of the ENS increased from TL639 / N320 to TCO639 / O640 for ENS (Days 0 - 15) with a model time step of 720s and from TL319 / N160 to TCO319 / O320  for ENS Extended (Days 16 - 46) with a model time step of 1200s;
  • For the medium-range ENS there will no longer be a decrease of resolution at day 10: the ENS Days 11 - 15 will be run at the same TCO639 / O640 resolution as ENS Days 0 - 10;
  • Increase of the HRES-WAM resolution from 0.25 to 0.125 degrees and the ENS-WAM Days 0 - 15 from  0.5 to 0.25 degrees;
  • Horizontal resolution of the EDA outer loop is increased from TL399 to TCO639 with its two inner loops increased from TL159 / TL159 to TL191 / TL191, respectively;
  • Horizontal resolution of the three 4DVar inner loops is increased from TL255 / TL255 / TL255 to TL255 / TL319 / TL399, respectively.

These upgrades

  • do not include any increase in the vertical resolution;
  • do not apply to the ECMWF seasonal forecasting system;
  • do not apply to the standalone wave model (HRES-SAW);
  • do apply to products from the Boundary Condition Optional Programme.

During the Release Candidate test phase forecast data will be made available close to real time via

 


The page will be updated as required. It was last changed on 8 April 2016.

For a record of changes made to this page please refer to Document versions.

Further information and advice regarding the upgrade can be obtained from User Support. 


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Table of Contents
maxLevel2
excludeDescription of upgrade

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Old:  N640 original reduced Gaussian grid (~16 km resolution)New: O1280 octahedral reduced Gaussian grid (~9 km resolution)
N640 original reduced Gaussian grid
O1280 octahedral reduced Gaussian grid

 


ENS

Old Day 0 - 10: N320 original reduced Gaussian grid (~32 km resolution)New Day 0 - 15: O640 octahedral reduced Gaussian grid (~18 km resolution)
N320 original reduced Gaussian grid
O640 octahedral reduced Gaussian grid
Old Day 11 - 46 : N160 original reduced Gaussian grid (~64 km resolution)New Day 16 - 46: O320 octahedral reduced Gaussian grid (~36 km resolution)
N160 original reduced Gaussian grid
O320 octahedral reduced Gaussian grid

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GRIB 1
Section 2
Octets
GRIB 2
Section 3
Octets
grib_api keyHRESENSENS Extended

 OldNewOld (Day 0 - 10)New (Day 0 - 15)Old (Day 11 - 46)New (Day 16 - 46)
9-1035-38Nj128025606401280320640
11-1347-50latitudeOfFirstGridPointInDegrees89.89289.94689.78489.89289.57089.784
18-2056-59latitudeOfLastGridPointInDegrees-89.892-89.946-89.784-89.892-89.570-89.784
21-2360-63longitudeOfLastGridPointInDegrees359.859359.929359.718359.860359.437359.722
26-276-7N6401280320640160320
33-nn35-nnplN640O1280N320O640N160O320

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paramIdshortNamenameunitsGRIB editionComponentTest data availableDisseminationProposed for Catalogue
228216fzraAccumulated freezing rainm1HRES / ENS(tick)
(tick)Image Removed(tick)Image Added
TBC
228044capesConvective available potential energy shearm2/s21HRES / ENS(error)TBCTBC
140120sh10Significant wave height of all waves with period larger than 10sm1HRES-WAM / ENS-WAM / HRES-SAW(tick)TBCTBC

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Not all grid names and grid number combinations are supported. MARS requests specifying an unsupported grid will failCurrently, the Gaussian grid names and numbers supported for MARS retrievals are:

Octahedral reduced Gaussian (O grids)O1280O640O512O400O320O256O200O160O128O96O64O48O32
Original reduced Gaussian  (N grids) N640N512N400N320N256N200N160N128N96N64N48N32
Regular (Full) Gaussian (F grids)F1280F640F512F400F320F256F200F160F128F96F64F48F32

For example, a retrieval request with GRID=N1280 or GRID=O124 will return an error. 

 

See Gaussian Grids supported by MARS and Dissemination for a list of the  Gaussian grid names and numbers supported for MARS retrievals.

In addition, the MARS post-processing keywords GAUSSIAN=REDUCED and GAUSSIAN=REGULAR are deprecated.

  • If the GAUSSIAN keyword is used along with, e.g. GRID=O640, GRID=N640 or GRID=F640 then it is ignored. 
  • A MARS request with GRID=640, GAUSSIAN=REDUCED returns the original reduced Gaussian grid with 640 latitude lines between pole and equator (equivalent to GRID=N640).
  • Similarly, a MARS request with GRID=640, GAUSSIAN=REGULAR returns the full (regular) Gaussian grid with 640 latitude lines between pole and equator (equivalent to GRID=F640).
  • A MARS request with GRID=640 only (no GAUSSIAN keyword) returns the full (regular) Gaussian grid with 640 latitude lines between pole and equator (equivalent to GRID=F640).

MARS requests specifying GRID=AV will return the model grid.  After the implementation of IFS cycle 41r2, this will be O1280 for HRES, O640 for ENS (Day 0 - 15) and O320 for ENS Extended (Day 16 - 46).

The MARS keyword RESOL=N128 was used to truncate products from ENS Day 0 - 10 to the N=128 original reduced Gaussian grid of ENS Day 11 - 15 prior to interpolation to regular latitude-longitude grids. Following the horizontal resolution upgrade, anyone using this intermediate interpolation method should use RESOL=O320 to truncate O640 ENS Days 0 -15 products to the O320 octahedral grid of ENS Extended (Days 16 - 46).

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Note

A bug has been fixed which will change results for interpolations from global grid point fields to regular lat-lon or regular Gaussian grids.  The problem and the specific cases where differences can occur are described in  Bug fix implemented in EMOSLIB 4.3.x.

We are happy that these changes are correct but further evaluation by ECMWF is ongoing. If further issues are found then these will be addressed and an updated version of EMOSLIB released.  Therefore we ask users to test and evaluate EMOSLIB 4.3.7 carefully before using it operationally.

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Magics versions from 2.26.0 provide support for visualisation of products on the octahedral reduced Gaussian grid. Users are recommended to upgrade to Magics 2.26.2 which is the default version in use on ECMWF systems since 9 February 2016 and can be downloaded from the Magics Releases page.

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technical_dissemination
technical_dissemination
Dissemination

The MARS language changes described above apply also to the web based dissemination requirements tool.  In particular, the specification of Gaussian grid products has changed in the MARS language

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New octahedral grid based products can be requested by specifying GRID=O1280, etc.The following grid numbers are supported for all Gaussian grid names - full (F-grids), original reduced (N-grids) and octahedral reduced (O-grids) :

 
HRES1280640400 
256200160128804832
ENS (Days 0 - 15)
640 
320 
200160128804832
ENS-Extended (Days 16 - 46)   


320 
200160128804832

As before, any sub-area of the global field is supported

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Member State users of the  "Simple time-critical jobs" framework can test that their scripts will work with the IFS cycle 41r2 test data by using the special 'events' set up for this purpose:

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Note

Users with scripts subscribed to the fc00hmetgram or fc12hmetgram events for the HRES "classic" meteogram should note that the product is discontinued with the introduction of IFS cycle 41r2.  See ENS meteograms above for details. Jobs subscribed to this event will not be triggered following the implementation of IFS cycle 41r2.  Anyone using this event to trigger scripts that undertake processing other than the plotting of the HRES meteograms are advised to use instead the fc00h240 and fc12h240 events.

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Option 2 or 3 time-critical applications can be tested with the  IFS cycle 41r2 test data retrieved from MARS or received in Dissemination.

Availability of IFS cycle 41r2 test data

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Warning

The data are intended for testing technical aspects only and should not be used for operational forecasting.

Only data from 12 UTC on 9 November 2015 have been produced with the corrected land-sea mask and other climatological fields.

An error in the precipitation type diagnostic (ptype, 260015) in the test data was corrected for the 12 UTC run on 8 Dec 2015. Cold phase precipitation types were missing or misrepresented. The precipitation type diagnostic should therefore only be used after this date.

All registered users of ECMWF computing systems will be able to access the test data sets in MARS. Users of our operational real time forecasts without access to our systems can contact our Data Services to obtain test data.

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Since 8 December 2015, IFS cycle 41r2 test Dissemination data is available through the test dissemination system, close to real time. Up to 14 January 2016, IFS cycle 41r2 dissemination products were based on users' operational dissemination requirements, backwards compatible with the IFS cycle 41r1.

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IFS cycle 41r2 test data is accessible via the ecCharts layers menu, identified by the label "esuite 0069" as shown in the screenshot on the left. They can be displayed as any other layers of ecCharts, and they can be saved in the Dashboard, as seen in the screenshot on the right. 


Column

ecCharts - forecaster view


Column


 ecCharts - dashboard view

The point probe and time series tools will be also available for the 41r2 test data.

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DateReason for update
4 November 2015
  • Initial version
8 December 2015
  • Release Candidate test phase
  • Test data available in dissemination and ecCharts
  • ENS Days 11 - 15 will be run at the same resolution as ENS Days 0 - 10
14 January 2016
10 February 2016
10 March 2016
8 April 2016
  • Information about model time step for HRES, ENS and ENS-extended added.

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