GLASS Panel Meeting
1/13

October 2-4, 2002
Calverton MD, USA

People Present:
Polcher, Jan Chair
Bastidas, Luis
Best, Martin
Dirmeyer, PaulHouser, Paul
Koster, Randy
Oki, Taikan
Pitman, Andy
Viterbo, Pedro
Invited experts :Ken MitchellAron Boone
Tom Philipps
Rick Lawford
Jared Entin
Antonio Busalacchi

The PILPS-San Pedro and GLACÉ experiments will be posted on the GLASS web assoon as possible.

GLASS Panel Meeting
2/13

October 2-4, 2002
Calverton MD, USA

Meeting with CLIVAR
In this first half day of the panel meeting a number of representatives from CLIVAR
and funding agencies were present to discuss possible collaborations. A number ofareas were identified in which GLASS could contribute to CLIVAR projects byproviding it's expertise on land-surface processes.
From the presentations of the funding agencies and the CLIVAR projects it became
apparent that there is a strong interest in the global coupled action. GLASS was also
encouraged to expand on the inter-comparison of LSMs at the processes level.
Off-line experiments
The planed San-Pedro experiment goes well with the NAME initiative and a close
collaboration should be encouraged.
Proposal on data mining
Randy Koster is proposing a study on soil moisture memory, mining the data from theAMIP-II experiment. According to Tom Philips, it may be some sort of diagnostic
subproject within AMIP and promises to expedite the data acquisition.
It was recommended:
The study would quantify soil moisture memory in the different AMIP models.
Differences in memory between models would be related (through an establisheddiagnostic framework) to differences in climatic forcing and land surface modelcharacteristics.
to check for the possible spatial autocorrelations and the possible correlations withthe forcing
to carry out the experiment within the auspices of the GMPP (GEWEX Model
Prediction Panel), the GLASS panel is part of it.
to use several models for the experiment.
General discussion
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•
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Land-surface scheme have not been sufficiently evaluated over South America.
Work is required on the routing on the big rivers of South America for instance.
There is no parameterization for the routing over the flood plains.
There is a need to demonstrate that the models can track the evaporation rates
during the dry seasons. Some work is being carried out in South America on the
topic, mainly using the Sib 2 and the RAMS. However is not clear whether they
are working on modeling or rather on vulnerability issues.
The ECMWF is working on the low level jet. They are putting some transects totrack it.
There are problems with the availability of data for model evaluation, particularly
with river gauges. No measurements of soil moisture are available. GLASS
should encourage new observations and help define the needs.
Experiments beyond GLACÉ are needed to asses the importance of the landsurface in climate variability

GLASS Panel Meeting
3/13

October 2-4, 2002
Calverton MD, USA

GLACE
The GLACÉ project was well received and the panel encouraged that it be launchedvery soon. During the discussion a number of suggestions were made.
It was recommended:• To use the Kolmogorov-Smirnov test to check the similarity of the parameter
distributions.
• Because the daily average temperature does not tell you much, information on
Tmax and Tmin is requested. This would allow to evaluate the impact on thediurnal cycle.
• The experiment should start in November 2002, with the distribution of theexperiment plan.
• The period to be used in for the simulations should be June, July and August
1994. The analysis could focus skip the early part of the period where somescheme might still be spinning-up.
Ensemble simulations
The question of how to set up the initial conditions for the ensemble simulation arose.
Especially with regard to some critical surface processes like the deep soil
temperature was discussed. Snow or frozen soil is only an issue for very small regions
as the period is chosen to be northern summer. The issue is thus left to the participantgroups.
A list, in order of preference by the panel, of possible ways to initialize theatmosphere was proposed. The preferred solution is to take restarts from June 1, 1994
form archived from an ensemble of AMIP simulations. But it was realized that not allgroups will be have such a set of initial conditions and thus alternatives need to beprovided. No method is a priori excluded but we strongly discourage some of them.
The panel proposed to extend the list of requested output which was in the original
project. The following variables are to be required from the participants:• Daily total precipitation• Daily total evaporation• Daily averaged air temperature in GCM layer closest to the surface• Soil wetness index (as defined by ALMA)• Dew point temperature• Outgoing longwave
The slow component relaxation experiment lead to some debate as it was not clear
how comparable they would be between difference land-surface schemes. It is notpossible to impose a method for choosing the slow variables to be relaxed which willproduce similar results in all schemes. It was judged not to be a critical problem as
there is the full relaxation experiment to which it can be compared.
The data should be provided in netCDF format, if that cannot be done the data need to
be provided in a rectangular grid. Groups not familiar with netCDF should get inGLASS Panel Meeting
4/13

October 2-4, 2002
Calverton MD, USA

touch with Randy Koster to see if their format can be handled. The best solution
would be for participants to use their ftp servers to distribute results.
The results of these simulations should be returned to Randy Koster by mid 2003.
This requires that the participants be identified in early 2003.
During the discussion of GLACÉ the C4MIP was also covered. The outcome was thatthe panel would like to see a closer link between C4MIP and the C20C experiment.
Both cover the same period and have the same scientific objective : improve ourunderstanding of the variability of the climate of the 20th century. C4MIP would
contribute the carbon cycle and help understand the link between the variability ofclimate and the carbon cycle.

GLASS Panel Meeting
5/13

October 2-4, 2002
Calverton MD, USA

PILPS C1
The PILPS-C1 experiment is running well. The time line has slipped slightly. Thisconsidered to be a minor problem by the panel in view of the fact that many carbon
scheme in land-surface schemes are under development. Still it was judged important
not to let the workshop slip beyond spring 2003.
A number of recommendations were made to the PILPS-C1 experiment :• The list of participating models is short and is missing some major groups such as
MOSES, LPJ and CLM
o Paul Houser will take care of CLM
o Martin Best will ask somebody for MOSES participation• To encourage the link with the C4MIP experiment (Coupled Carbon Cycle
Climate Simulations)• Nicolas Viovy needs funds for workshop which should be held in spring 2003. JanPolcher will help with finding the funds required in France.
PILPS San Pedro
The PILPS San Pedro proposal was presented by L. Bastidas and accepted by thepanel. This will be the first local off-line experiment to address the following issues :An evaluation of the schemes in a semi-arid region.
It will encourage all schemes to perform some kind of parameter optimization.
Having 3 sites with similar conditions allows to test the transferability of theschemes and their parameters.
To ensure a large participation, this project should be presented as starting with anormal PILPS inter-comparison on which the parameter optimization will build. Thisshould take out some fear of the work associated with the optimization infrastructure.
The discussion by the panel lead to some suggestions and recommendations for theorganization of the project :• To use longwave forcing from model outputs, e.g. Reanalysis or LDAS. LDAS
especially should be able to provide a better estimate of this parameter.
• To provide with 'observable' parameters, i.e. albedo, LAI, roughness, vegetation
height, as was done in previous PILPS experiments.
• The data handling procedure should take more strongly into account the ALMA
infrastructure. Especially for the output of variables and their description.
• The data available for the end of the year 1996 should be used, together with the 8
first month of 97 for the spin-up of the schemes.
• The data available for the New Mexico site is a little short but should be enoughin the context of this 3 site approach.
• The time-line is to be redefined to fit with the calendar of activities for 2003. It
was suggested that before the schemes are asked to optimize their parameters astandard PILPS experiment be conducted (See table at the end for details). The
workshop should combine the evaluation of the first model output and setting up
the optimization procedures for the parameters.
• Optimization codes should also be provided in Fortran 90.

GLASS Panel Meeting
6/13

October 2-4, 2002
Calverton MD, USA

GSWP 2The GSWP-2 proposal and the outcome of the workshop was evaluated and discussed
by the panel. The panel was very happy with the progress made by this proposal since
it was last discussed at the 2001 panel meeting and it is looking forward to the start ofthe project in January 2003.
GSWP-2 is considered by the GLASS panel as the best attempt by the land-surface
modeling community to estimate land-surface fluxes at the global scale. The diversityof models and the chosen set of sensitivity experiments should provide a good
estimate of the uncertainties associated to these estimations. For this effort the work
done for ocean fluxes should serve as an example(http://www.soc.soton.ac.uk/JRD/MET/WGASF/get_report.html).
The general discussion of GSWP-2 lead to some recommendations which should betaken up in the final version of the proposal :• Procedures for redistributing the data to the community once the experiment isfinished are to be written in the experimental plan. The recommendation is that
Paul Dirmeyer and Taikan Oki manage this process and that the GLASS panel
serves as a mediator in case of conflict.
• All model outputs should be available to other models. For the diagnostic groups
it is important to preserve their priority on their topic until results are published.
• For the validation exerciseso As there might be error compensations between the land-surface schemeand the routing model it was recommend that more than one routing
model be used :e.g. Jay Famiglietti, C. Vorosmarty encourage them to participate
o Regional hydrological experts should be sought for the validations of
GSWP 2 outputs. Through GEWEX at least some experts from the GHP
continental scale experiments should be solicited.
o Station validation is needed to check the forcing and evaluate in somesense the simulated fluxes. But it has to be said clearly that there is a big
scale issue with this type of validation.
o To use satellite information for soil moisture evaluation and skintemperature is aimed at encouraging the community to move in thisdirection.
Satellite information (soil moisture) is not entirely reliable
therefore the comparison is only another source for comparison forthe moment.
Satellite information has to be used because it is the only global
data for surface conditions and it potential for future applications.
It suggests research activities post-GSWP 2.
This validation will show under which conditions remote sensed
data can discriminate between various models and it will thus
reveal some of it's information content.
Soil moisture retrievals from microwave : Manfred Holtz asked forsupportEleanor Burke only to produce values that will make people used
to output of observable variables from the models

GLASS Panel Meeting
7/13

October 2-4, 2002
Calverton MD, USA

o Satellite information on vegetation could also be validated, although insome schemes this variable is prescribed.
Use only LAINDVI dismissed as it was considered a thing of the past in view of
the new sensors.
o Snow validation should use more than one product out of the following listof data sources :USAF 95 onwards
USSR up to 91
NSIDC Canada for the whole periodo The contact with Alan Robock should be reestablished for the comparison
with his soil moisture database.
o On some large basins with a good observational networks, the atmosphericwater convergence can be derived from the NCEP and ECWMF reanalysis
and serve as an extra validation of the regional water balance. It cancomplement well the river discharge validation with routing models.
In the presentation of these validation exercises there should be a clear distinction
between those which directly contribute a validation to the overarching objective of
producing a global climatology and those which are more of exploratory nature.
•••

Initializationo The spin up until 82 can be chosen by the modeler. The only requirement
is that the scheme is in equilibrium. The period 82-85 should be done withthe data provided so that the model goes into the right variability.
The preparation of the forcing for control run was discussed.
o The CRU data could be used with the gauge correction. The CRU did not
do this correction because no reasonable procedure could be found for theentire period 1900-2000. This does not apply for the GSWP-2 period.
o GPCC is also a good option and should be considered. This climatology
offers the advantage of building on data from more countries
o All atmospheric variables should be provided at the same level. To change
the height of the wind the same code as for Rhône-AGG could be used.
o SRB product needs correction for altitude. The common altitude will be
provided by the CRU as it provides the 2m temperature.
o Paul Dirmeyer will look more in detail into the products to make a final
recommendationo Surface pressure needs to be adapted to the orography and it needs to beensured that it is consistent for all variables.
Sensitivity runs
o Run without gauge correction for precipitation.
o Run with dataset constructed with the ECMWF reanalysis.
o Use the reanalysis without any correctiono Using different vegetation land cover classificationso Models with tiling scheme turned off
o The data size for the forcing is around 2.5 Gb/year. This is a strong
limitation for the number of sensitivity experiments which can be done. It
should be left to the interest of the modelers to decide which one should be
done.

GLASS Panel Meeting
8/13

October 2-4, 2002
Calverton MD, USA

The table of variables and associated meta-data provided on the ALMA web-pageneeds to be updated for GSWP-2.
• Outputs
o Extrema on the period over which the variables are needed in some cases :Surface temperature
Longwave up
Radiative surface temperatureo Runoff :Distinguish between lateral and vertical groundwater flowo Potential evaporation :make it recommended not required• A table for the ancillary data needed by LSMs needs to be build for AMMA in thesimilar way as was done for the forcing and the output.
As with any project of this scale there are concerns in other communities about
GSWP-2 moving into their turfs. Concerns were raised for the following topics :• BAHC (or IGBP/iLEAPs now) with regards to the carbon cycle.
• IAHS program on modeling un-gauged basins and a focus on land surface
parameterizations• GSWP-2, and LDAS even more, are competing with flood forecasting
agencies.
In all these cases it is for GSWP-2 and GLASS to approach these organizations andsolicit their participation.
It was recommended that the following actions be taken :• Be cautious !
• Taikan Oki will write a letter to IAHS to point to the potential use of the GSWP-2
for water resource evaluation and validation of models which attempt to predictthese resources. In the meantime GSWP-2 should not get into water resources.
• State that GSWP is research, and does not produce operational products.
• Results are 10 years old.
• Involve those other groups in regional validation. Help is especially needed for
runoff validation.
EXPECTATIONS FROM ISLSCP-III
Following the GSWP-2 review, the panel discussed what we would expect from afuture ISLSCP project. As GSWP is the biggest user of the atmospheric forcing data
which is distributed by ISLSCP, GLASS should express it's needs early on.
We believe that the true added value ISLSCP can bring to the data it collects anddistributes is to the perform a more critical evaluation. This is especially true for thevariables describing the state of the surface. This will set ISLSCP apart from theInternet which provides the same data but without any critical review.
Clearly the production of the atmospheric forcing should be reorganized. We suggestthat it be done in collaboration with the GLDAS project. GLDAS could, for each
ISLSCP phase, produce a re-analysis of it's operational products which would then be
distributed by ISLSCP and used for GSWP experiments. One of the main advantages

GLASS Panel Meeting
9/13

October 2-4, 2002
Calverton MD, USA

would be that the forcing data would benefit from the expertise gained in the Land
Data Assimilation Systems to improve the forcing data.
This recommendation sets GLDAS apart from the other LDAS's within GLASS. It
means that GLASS will promote GLDAS and encourage the entire community tocontribute. This positioning of GLDAS within the community was agreeable to
LDAS (Ken Mitchell) and ELDAS (Pedro Viterbo).
Within GEWEX we need to promote the evaluation by other groups of GLDAS's
forcing and simulated fluxes. This is already the case for CEOP period but should be
expanded to previous GHP and GRP activities. Compared to GSWP, GLDAS offers
the advantage of being closer to present and thus better suited for a comparison withdata from the various continental scale experiments which were underway in thesecond half of the 90's. This evaluation will then be beneficial for a future GSWP
experiment.

GLASS Panel Meeting
10/13

October 2-4, 2002
Calverton MD, USA

DISCUSSION WITH KEN MITCHELL
The issue of land memory and the model initialization was brought up because it
affects:
Weather and seasonal time scales
Impact of land anomalies in changes of large scale moisture convergence
Soil moisture anomalies, soil heat anomaly affect wind patterns
Mean fluxes dominant – eddy fluxes small
Effect on surface recycling
Soil moisture anomaly -> soil temperature anomaly -> air temp anomaly
Anomaly in soil moisture -> anomaly in precipitation recycling.
••

Modelingo Land modeling and land initialization (Global, North American,
European LDAS)o Coupled and uncoupled reanalysis
o Seasonal predictabilityo Transferability
o Embedded regional climate models, e.g.
www.atmos.umd.edu/~berbery/etasam
Initialization issues
o How similar are soil moisture fields from different LDAS LSMs?
Answer: not too similaro Can the soil moisture from one LSM be used to initialize another?
Not good to transplant, always problems
Models do not recover from wrong initialization even after 20
years of spin up (Gao et al, JGR 96).
o How long should the model spin-up period be?
The idea is to make sure that the initialization is properly done
and to define how long the spin-up has to be. Optimizations
allow for shorter spin-ups.
Do we need a soil moisture transplant experiment? UK Met
Office is doing some transplant for soil initialization. A
function has been identified to transform the input into theoperational model.
The problem is difficult and requires a consistent solution
because intermediate solutions are not optimal.
o The problem is similar and parallel to that of C4MIPGLASS Panel Meeting
11/13

October 2-4, 2002
Calverton MD, USA

SOIL MOISTURE INITIALIZATION
Following the discussion with Ken Mitchell it was felt that the GLASS panel needs totake action on this issue. The aim is to raise the awareness on problems associated toland-surface initialization in models and express the panel's opinion on the best
method available. The typical audience for such a message would be the atmosphericmodeling community which uses land-surface models without being fully aware of
the issues of initialization.
Such a paper would start with illustrating the problem using some NWP cases (Martin
Best and Pedro Viterbo volunteered) . It would then include a description of thefundamental reason for this problems which lies in longer scales involved in surface
processes and the conceptual nature of the land-surface schemes (Jan Polcher
volunteered).
The paper would then proceed with a ranked list of preferred solutions to initialize
surface conditions. The most satisfactory solution is to spin-up the land-surface
scheme decoupled from the atmosphere over a longer period using the best possible
estimation of the atmospheric conditions. In case such a forcing is not available itwould be preferable to spin up the coupled (land/atmosphere) system. After that, thesolutions left are all based on linear proxies of the land-surface schemes as proposedby Koster and Milly. The latter method can only be justified by the minimization of
the spin-up of some fluxes and they do not solve the general problem.
In all cases, the externalization of the land-surface surface scheme, from theatmospheric model, according to the PILPS-4c proposal, will greatly facilitate thegeneration of proper initial conditions. This should be one of the recommendation of
the paper so that atmospheric models move into this direction.
Randy Koster volunteered to take the general leadership for this paper.
Related event : Jan Polcher presented informally this project during the
WGNE/GMPP. The atmospheric modeling community present at this meeting,expressed a great interest in such information. Especially the group preparing thetransposed AMIP experiment, in which climate models are intended to be evaluated ina NWP environment would like to have advice. For this experiment they are still
pondering the best way to initialize the land-surface conditions of the climate models
in accordance with what is provided by the NWP models.

GLASS Panel Meeting
12/13

October 2-4, 2002
Calverton MD, USA

ILEAP
A short part of the meeting was dedicated to prepare the meeting of iLEAP/IGBP
which was to take place mid October. The panel asked Andy Pitman and Jan Polcher
to carry to the meeting the following message :GLASS has been launched with the support of BACH and has always benefited
from this close collaboration.
BACH was key in making ISLSCP and GSWP happen.
GLASS represents essentially the community of large scale land-surface modelers
and is thus complementary to BACH.
GLASS has a privileged link to the NWP centers through it's participation in the
WGNE/GMPP panel.
GLASS is open to experiments proposed by iLEAP/IGBP. Such experiments would
either be coordinated by the local off-line, local coupled or global off-line actions of
GLASS together with iLEAP.
LOCAL COUPLED
The panel shared the conclusions of the workshop organized by Bart van den Hurkand Paul Houser in de Bilt in April 2002. The conclusion of the workshop are
published in GEWEX News, May 2002.
Paul Houser and Luis Bastidas need to put together a proposal to make progressbeyond the ideas expressed during the workshop. The suggestion was made to look at
Y. Sud's single column model which seems to work well over the ARM site.
COMMON LAND SURFACE MODEL ISSUE
Following the discussions last year in Toulouse Chris Milly was contacted on thepossible distribution of his model by GLASS.
The LaD (Land Dynamics) model is distributed under the GNU license license
and Chris would welcome it's distribution by GLASS as an acceptable minimalland-surface scheme. Chris would be happy to offer a scientific support for his
model.
This model does not yet use the PILPS4c interface. For the moment it is not known
who could implement this interface or who could fund such work.
The interest for such a model is rising within GMPP. GABLS would also needsuch a model for it's PBL studies.
Martin Best presented an update of the PILPS 4c coupler which can handle an
implicit coupling with a tiling scheme and a more complex parametrization of the
turbulent diffusion.
Within the European PRISM project an approach similar to the PILPS4c is being
examined by the sea-ice community and the oceanographers.

TIME LINESThe schedule of experiments for 2003 is very busy but should be manageable.

GLASS Panel Meeting
13/13

October 2-4, 2002
Calverton MD, USA

PILPS-C1 is already underway and a large part of the work is already done. But itneeds to conclude during the spring 2003.
GSWP-2 will take the entire year but we expect models to be run before thesummer vacations of the Northern Hemisphere.
GLACÉ will solicit a slightly different group of modelers than the otherexperiments. Thus a return of results at about the same time as GSWP-2 seams
feasible
PILPS San Pedro will start to generate work, the off-line simulation in early
autumn 2003. The work associated to the parameter estimation will come after theworkshop in 2003.
The next GLASS panel meeting should take place in October 2003 in Tucson justafter or just before the PILPS San Pedro experiment. This will be the 4th and last
meeting of the panel in it's current form. It will thus be an important issue on theagenda to select the next membership of the panel. The panel also needs to find a newhead to take over from Jan Polcher on the 1st of January 2004.