WORLD METEOROLOGICAL ORGANIZATION________________________COMMISSION FOR ATMOSPHERIC SCIENCES
THORPEX ICSCEXECUTIVE BOARD
Second Meeting

CAS/THORPEX ICSC EB-2/
Doc 3.5(1)(04.IV.2006)__________
Item: 3.5

Geneva, Switzerland
15-16 May 2005

Original: ENGLISHREPORT ON THE SECOND MEETING OF THE GIFS-TIGGE WORKING GROUP
University of Reading
22 March 2006
(Prepared by Philippe Bougeault)
1.

Introduction

The Second Meeting of the GIFS-TIGGE WG took place at the University of Reading on
20 March 2006. This was a short meeting, with a few of observers, which was held in thecontext of the THORPEX kick-off workshop. The meeting was preceded and followed byplenary sessions which included participants from all THORPEX Working Groups.
The meeting started with a short talk by Baudouin Raoult explaining the technical status ofthe project. GRIB2 samples of all parameters have been prepared at ECMWF and await
validation by other partners. The TIGGE Internet site is nearly ready. A precise descriptionof all parameters is being prepared, and this will be updated as appropriate. There will be afacility for all partners to provide comments and questions on the details of the database,through the Internet site. Trial exchanges of data have been conducted with CMA andNCAR. The LDM data exchange software has been tested favourably and is now thepreferred solution for Phase 1. It has been decided that data exchange will involve individual
GRIB files, not structured files as previously announced.
2.

Data base content

The following decisions were made on the remaining open issues.
1. The accumulation will be from the start of the forecasts for all fluxes and precipitations.
The Units will be those of time-integrated fluxes (detailed specifications will be available
on the Internet site soon). The SST field will contain the skin temperature for both seaand land.
2. The soil moisture field was discussed in some detail, and it was agreed on the following
definition: Averaged soil moisture content on the top 20cm of the soil layer - Units will be
kg/m3. To allow the interpretation of this quantity, the min and max value of the same
quantity for each grid point (proxy of wilting point and field capacity) will be provided onlyCAS/THORPEX ICSC EB-2/Doc. 3.5(1), p. 2
for the control member of the each forecast (as decided for orography and the land seamask).
3. The CIN was discussed. In view of both serious requirements and difficulty of production,
it was agreed to retain this parameter, but with the understanding that many partners will
not be able to produce it at the beginning. Software to compute CIN was provided byZoltan Toth and will be made available.
4. The group gave full consideration to the new requirements expressed by the PDP WG in
the first plenary (22 March 2006). It was decided to accept to this request and to tradeoff one pressure level fields to keep the total volume of the data base constant - the 600
hPa level will not be provided therefore. Based on the PDP WG request, the newparameters are:Geopotential at 50 hPa
Theta, u and v on the PV=2 surface
PV on the theta=320K surface
5. It was agreed that TCW will contain the total atmospheric column water under the threephases (vapour, liquid, ice)
6. The flux sign convention will be positive downward.
7. There may be difficulty in the lack of homogeneity for the CAPE computation. It wasdecided to exchange our CAPE algorithms to assess the extent of the problem.
8. It was further clarified that the initial state (t=0) is an integral part of all forecasts, allmembers,etc.This means that for all accumulations, all values should be zero for t=0.
9. We confirmed that all partners are encouraged to provide also their deterministic forecast(as an additional control) projected on the same horizontal grid and resolution as theensemble members.
10. Each partner will need to provide (via the Internet site) a logical description of its
ensemble (how many members and controls, etc..) so that the ECMWF team can checkif the metadata system allows proper description of the whole dataset without anyambiguity. As recommended by Zoltan Toth (by phone) it was agreed to coordinate thisaction with the ET-EPS group of the CBS which has initiated a similar survey.
Partners were reminded to provide names of technical points of contact (if not yet done).
3.

Discussion on TIGGE-LAMs

According to the 2005 workshop and to the TIP, LAM EPS should be an integral part ofTIGGE. This is also very important for the development the Global Interactive Forecasting
Systems generally. The WG has decided to devote attention to this in 2006 and we had afirst discussion on the best way to initiate a TIGGE-LAM component.

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It was agreed that the priority to realise the GIFS is to facilitate exchange of initial andboundary conditions between ALL global ensembles and ALL LAM ensembles by defining
standard formats for this operation. However, we should not ignore the scientific issues.
With regard to the scientific aspects, several assessments are needed:
1. Assessment of the impact of mismatch between the physical parameterizations ofglobal and regional models
2. Assessment of the need to define bias corrections
3. Assessment of the impact of large mismatch in horizontal resolution
4. Determination of the best way of generating perturbations for LAM EPS
The whole THORPEX community is urged to explore these issues.
Regarding technical aspects, it was mentioned that the concept of data concentration(Phase 1 of global TIGGE) does not work for the LAM component because of the volume ofdata and the real-time needs. Rather, the group advocated a concept whereby global model
providers would make their global products available on their Internet Site for a limited time,
together with tools to prepare initial and boundary conditions on any limited area domain on
request. This should be completed by a common internet site to exchange meta-data on theglobal models and LAMs specifications (ie, we more or less anticipate on Phase 2).
The urgency for the BeiJing08 project was stressed.
The group also recognized a number of technical issues (some of them with science
impacts).
Will GRIB2 support the variety of projection and grid systems used by LAMs? Maintenanceof software to interpolate from any global grid to any LAM grid would have a high cost for thecommunity. Perhaps it is preferable to have a common lat-lon intermediary? There is aneed to agree a standard list of all necessary initial and boundary fields to drive a LAM, andagree on units, formats, etc.. Also agree the content of a common database for Lam EPS
outputs.
The agreed way forward was:
1. To gather material on the data exchanged on current projects (ie WRF, BeiJing08,MAP D-Phase) as a starting point
2. To set up a TIGGE-LAM group composed of specialists and scientists involved in thedemo projects, to discuss and agree the above issues.
3. To appoint a leader for this group (perhaps from the WRF community, or among oneof the many European multi-model LAM projects)

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4. To start discussions by email, then provoke a meeting in 2007 - to keep good liaison
between GIFS-TIGGE WG and the new group
Other actions agreed by the group:
1. Deliver TIGGE presentations at the Landshut conference
2. Organize an evening meeting of the GIFS-TIGGE WG at the Landshut Symposium
3. Prepare a common paper to advertise the TIGGE approach and opportunities for thescience community at large (for BAMS?) as soon as accumulation of data in the database has started (October 2006?)
4. Organize a TIGGE User workshop at the end 2007 or 2008, venue and frameworktbd. In the plenary, the SERA WG commented that they want to be associated to thisevent.
4.

Membership of the GIFS-TIGGE WG

We were reminded by the IPO Director the general policy for THORPEX WG membership:
the mandate is for three years, any member can be renewed only once, and every year
(from year 4) one third of the WG should be renewed.
We discussed how this would be implemented in the GIFS-TIGGE WG. There was ageneral feeling that members might rotate in a natural way just because they take newduties in their organization or for personal reasons. Another specific constraint for GIFSTIGGE is that most members are in fact representing NWP centres, so the choice should beleft to these centres do designate their representatives. The group agreed that this issue isnot urgent, and that as a first approximation the co-chairs should be trusted to organize therotation in the best interest of the project.
5.

Next meeting of the GIFS-TIGGE WG

Next GIFS-TIGGE full session should be organized in March 2007 (an invitation from China
was received after the end of the WG meeting).
6.

Additional comments from Warren Tenant

I would just like to clarify my proposal for extracting LAM input from the TIGGE database as I
see some concern being noted here
You have a web interface to select your region, dates (e.g. drop down menu of currentdates), output frequency (e.g. a drop down menu of hourly, 3-hourly etc), format type (GRIB2
or other if needed/available), ensemble members (e.g. all, only controls, specify only onecentre). The drop-down menus would prevent unrealistic demands being placed on thesystem.

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The request then contacts the centres and produces a temporary directory of data on aregular lat-lon frame at the global ensemble model resolution. It could well be a block withzero's in the middle as GRIB2 will compress these zero's extremely effectively. This would
also help to have all outputs the same including an initial field (for which you would probably
want the full domain anyway). We could also add a warning popup window thatrecommends a minimum resolution for your LAM based on the global ensemble resolution
plus any other foremost issues.
It would then be up to the users to create their own LAM configuration input etc. I do notthink it is fair to expect global providers to be able to configure data for any shape and size
LAM, although as suggested we could perhaps provide some standard output for known
experiments
It is up to providers of course how much resources they have to do this additional work. We
could also provide various tools to do some of these conversions, but I think it is fair toassume that if someone has the ability to run a LAM, they can surely construct their own
LBCs and initial conditions without too much difficulty.
A more general point that I would like to make is that our WG should be careful not to place
restrictions on users based on our own feelings or possible misunderstanding of the users
needs. We can certainly suggest or recommend "good usage" of the system, but we should
not block experiments (crazy as they may sound) for reasons other than that of a physicalconstraint like bandwidth, storage capacity etc.
7.

Progress since the Working Group meeting

Since the second meeting I have been discussing the membership of the TIGGE-LAM groupwith various organizations, and a draft membership will be circulated soon. We would
welcome advice from the EB regarding this membership.
The TIGGE Internet site at ECMWF (http://tigge.ecmwf.int) has been constructed and willsoon be opened to TIGGE data providers for final definition and agreement on the global
data exchange.