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The first meeting of the GEWEX Global Land-Atmosphere System Study (GLASS) Science Panel (GSP) was held from 19 to 21 July 2000 at the Australian Nuclear Science Technology Organization (ANSTO) in Lucas Heights, New South Wales, Australia. Dr Jan Polcher, the Chair of GLASS, chaired the meeting. The arrangements for holding the meeting at the ANSTO facility were made by Dr A. Henderson-Sellers’ Office.
GLASS has been organized under the GEWEX Modeling and Prediction Panel (GMPP) to coordinate land-surface scheme development activities. The work of GLASS will be done in association with the Working Group on Numerical Experimentation (WGNE) and in collaboration with the International Geosphere-Biosphere Program (IGBP) core project on the Biospheric Aspects of the Hydrological Cycle (BAHC). The goal is to achieve improvements in land-surface schemes for the benefit of numerical weather prediction and climate models such that confidence in the simulated land-surface quantities will be enhanced. This goal will be pursued with schemes decoupled from the atmosphere at the local and global scale, as well as schemes coupled to single atmospheric column models and general circulation models (GCMs). The parallel and coordinated off-line and on-line validations of land-surface schemes has become a necessity with the progress made in planetary-boundary layer and cloud models as well as the requirement to include land-surface processes in operational data assimilation.
GLASS has been organized to achieve these goals, by providing a structure to facilitate the promotion, implementation and coordination of land-surface scheme intercomparisons. Four complementary science actions form the framework within which GLASS will structure land-surface scheme validation and development activities. The inter-actions of these components can be visualized in the form of a matrix, which pairs off-line (uncoupled) and on-line (coupled) modeling activities with local (point/plot/catchment) and large (continental/global) spatial scales ( Table 1 ). A fifth element of GLASS is provided to aid participants involved in meeting the technical and scientific goals of the overall effort. This infrastructure action will coordinate the logistics related to the work of the other parts of GLASS. The overall project is depicted in Figure 1.
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Local Scales |
Continental Scales |
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Off-line |
PILPS |
GSWP |
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Coupled |
Assimilation Action |
Coupled Action |
Table 1: GLASS Matrix Structure
The GEWEX Scientific Steering Group (SSG) at its January 2000 meeting endorsed these plans and the structure of GLASS. The SSG gave the action to Dr Polcher to finalize the Draft Science and Implementation Plan and to form the GSP from the points of contact for each element of the GLASS plus other interested researchers by mid-2000. It was recommended that a meeting of the GSP be convened to address any remaining issues associated with completing the Science and Implementation Plan and having it published by the end of 2000 and to be prepared to report progress on all aspects of GLASS at the 2001 session of the SSG. The goals of this first GSP meeting are associated with the efforts to act on these actions and recommendations.
The current activity within the GLASS has been undertaken within the following framework:
Local Off-Line Action Group (PILPS) A. Henderson-Sellers, A. Pitman
Global Off-Line Action Group (GSWP) P. Dirmeyer, T. Oki
Coupled Off-Line Action Group H. Gupta, P. Houser, P. Viterbo
Coupled On-Line Action Group P. Cox, R. Koster
Infrastructure Action Group (ALMA) J. Polcher, T. Oki
The Panel agreed that emphasis should be given to experiments associated with an improved understanding of how CO2 is being represented in the current generation of LSS’s. Han Dolman has been asked to be the point of contact for all actions on this topic. A PILPS C1 (carbon) intercomparison project was, therefore, to be given a high priority in the GLASS Science and Implementation Plan. A PILPS project under preparation (PILPS 2f, An instrumented site in South Ontario) will also be expanded to include CO2 as a component of the experiment providing the basis for a GLASS C-2 type effort. Improved descriptions of these initiatives are required from the Local Off-Line Action Group leaders with support from the Chairman of the GLASS Science Panel. The GLASS Infrastructure architecture (ALMA) must be utilized in all GLASS initiatives and its application included in documentation for use in the Science and Implementation Plan, which addresses the designs of the various Action Group experiments. A data set from the Rhone Valley in Europe will be prepared for a “regional” experiment under the Global Off-Line Action Group (GSWP) and a satellite data validation component will be developed in that Action Group. Documentation on these changes is required from the Global Off-Line Action Group leaders to note these changes in the Science and Implementation Plan. The PILPS-like ARM/CART-based (PILPS 2g) experiment will now be developed as part of the parameter estimation and Coupled Off-Line Action Group. The Coupled Off-Line Action Group will also develop a data assimilation initiative. Documentation reflecting these changes is required from the Coupled Off-Line Action Group leaders for inclusion in the Science and Implementation Plan. A condensed version of the Land-surface Data Assimilation Scheme (C-LDAS) will be adapted for use in the initial effort undertaken by the Coupled On-Line Action Group. A write up on this initiative and the development of a longer term “land use” focused experiment is required from the Coupled On-Line Action Group Leaders to add to the Science and Implementation Plan. The Science and Implementation Plan will also reflect a change in emphasis toward tropical and arid and semi-arid data sets and regional initiatives. Evaluations of various validation data sets to be used in follow-on experiments related to such regions are required for inclusion in the Science and Implementation Plan. Various individuals have been assigned these evaluation tasks. All actions for additional documentation are due to the GSP Chairman by 15 October 2000. A visual representation of these changes with their associated timelines and milestones is given in Figure 2. Details of these and other related actions and recommendations are contained below.
A listing of the specific Action Group recommendations and actions, particularly associated with items which have an impact on the finalization of Science and Implementation Plan, that were taken at the first session of the GLASS Science Panel in Lucas Heights, NSW, Australia during the period from 19-21 July, follows.
It was agreed that the priority issues for the leaders of the Local Off-Line Action Group, which had impact on the Science and Implementation strategy were:
To support the initial phase of an experiment that will study the, well instrumented, Torne/Kalix Rivers Basin, in Sweden. The lead PI for the first stage of this experiment (PILPS-2e), which has already been launched, will be Dr Dennis P. Lettenmaier from the University of Washington. Dr Lettenmaier will organize the experimental procedure, as well as the comparison and ultimate dissemination of model results. This effort is also being designed to establish an initial process for conforming to the GLASS infrastructure scheme, designated the Assistance for Land-surface Modelling Activities (ALMA). Dr Lettenmaier will be contacted to ensure that the development work related to using the standard data exchange procedure will be packaged for use by other GLASS experiments. Work on this experiment should be completed by the end of 2000. Other areas under consideration for additional study in the context of this high latitude experiment are the Mackenzie River in Canada and the Lena River in Russia. Priority within GLASS for these subsequent phases will be assessed in due course.
To encourage all development and testing schemes to include simulation of CO2 fluxes and, thereby, to define and support an experiment (PILPS C1), which can evaluate the newly gained ability of land-surface schemes to simulate CO2 fluxes, as the next highest priority scientific issue for consideration by the GLASS community. Dr H. Dolman is preparing a gap filled, quality controlled data set, for this initial experimental effort that covers a four-year study of a temperate coniferous forest (Loobos, The Netherlands). The goal is to address the performance of the models to reproduce the observed inter-annual variability of CO2 fluxes. The GLASS Chairman will provide a contact point at the Institut Pierre Simon Laplace (IPSL) to work with Dr Dolman to assist with development of a precise definition of the experiment and its organization, implementation and reporting of results. This experiment should begin by mid-2001 and be completed by early 2002.
To begin planning for follow-on experiments in the evaluation of LSS handling of CO2 fluxes in different climate regimes. As an initial effort in this arena, support should be provided to the work being carried out by Dr D. Verseghy, AES, Canada, and Dr Battista, University of Arizona, which utilizing data from FLUXNET sites with data from the Centre for Atmospheric Research Experiments (CARE). An effort is required to insure that the work on this experiment, nominally designated PILPS-CARE, utilizes the GLASS infrastructure (ALMA) and is broadened to encompass the goals of a GLASS PILPS-C2 initiative. This work should begin as soon after the results of PILPS C1 are known and a viable PILPS-CARE data set has been prepared. An expected time line for a PILPS 2f/C2 experiment is from mid-2002 to early 2003.
To promote the development of data sets for subsequent GLASS experiments, which carry forward as a high priority the evaluation of the hydrological cycle and of CO2 fluxes in different climate regimes. There is a need to work in Tropical and Semi-Arid regions as opposed to high latitude regions, where a number of experiments have already been successfully planned and completed. Specific actions were given to review and evaluate existing and planned data collection procedures and candidate data sets for their potential application to the highest priority GLASS-Local Off-Line experimental requirements and to report the findings to the Chair of GLASS by the end of 2000.
To note that the GLASS community sees value in work that is not directly contributing to understanding CO2 flux issues nor, which is in Tropical or Semi-Arid regions but, which is funded and, which agrees to adopt the use of the GLASS standard data exchange format (ALMA). In this context reference will be maintained in the GLASS Science and Implementation plan to an local off-line experiment which may follow on from earlier work over high latitude vegetation types (PILPS 2d) but which expands to cover steppe (growing and mature forest processes) vegetation types. This inter-comparison is proposed by Alan Robock has nominally been labeled PILPS-2f and is scheduled for 2002..
In the subsequent discussion, the Chair of GLASS agreed to fashion a statement which can be added to the introduction of the Science and Implementation Plan that addresses the specific criteria for the endorsement of experiments and data sets for consideration by GLASS. The criterion is to note the shift in experimental emphasis toward Tropical and Arid/Semi-Arid regimes and toward evaluation, in all cases, of CO2 flux results. For data, the goal is to encourage development of better data sets that meet important technical (distinguish between Short and Long wave Radiation) and spatial and temporal characteristics. This statement should clarify what GLASS needs and at what precision it must be provided and accomplished in order for GLASS to meet the scientific objectives contained in the Science and Implementation Plan.
It was agreed that the priority issues for the leaders of the Global Off-Line Action Group, which had impact on the Science and Implementation strategy were:
To move forward with the planning and implementation of GSWP 1.5, whereby, studies will be undertaken over the period covered by the data sets available from the International Satellite Land-Surface Climatology Project (ISLSCP) Initiative I data set. Many of these studies will be re-runs of the original GSWP Pilot Phase, which used only the atmospheric forcing data for the years 1987 and 1988 available on the ISLSCP Initiative I CD-ROM. In GSWP 1.5, however, updated versions of many of the original data sets will be used. Improved estimates of many variables will insure enhanced results and allow for a better understanding of unresolved issues, which occurred during the GSWP Pilot Phase. The Panel endorsed this activity as a precursor to GSWP-2 and concurred with the timeline for setting up the available forcing data using the ALMA tools before the end of 2000 and delivering results before the end of 2001. It was felt to be very important that the local off-line PILPS-2e activity and the global off-line GSWP 1.5 effort both be running concurrently using the ALMA infrastructure to test and evaluate it. This would ensure that the ALMA concept is robust and will be able to serve all GLASS projects.
To plan for a GSWP-2 effort triggered by the availability and preparation of ISLSCP Initiative II data sets in GLASS/ALMA standardized configuration (early 2002). The data set will cover a 10-year period (1986-1995) and allow for improvements in specifying LSS parameters, validating results, running sensitivity studies and assessing inter-annual variability. The plan to have results available beginning in early to mid-2003 was endorsed by the Panel.
To define and initiate a Regional/Aggregation exercise, as soon as possible, that will overlap the period just prior to the end of GSWP-1.5 and the early initiation of GSWP-2 (approximately 3rd quarter 2001 to 3rd quarter 2002). This effort is to be based on one or possibly two data sets. First priority is to be given to a 8 km resolution data set from the Rhone River Valley in Europe and second priority is to be placed on a USA-Based Land Data Assimilation (LDAS) data set. A write-up of this effort emphasizing the need for this work and defining the specific approach is required for inclusion in the Science and Implementation Plan. The Chairman has determined that resources are available from INSU for preparation of the “Rhone” data set for this exercise and Dr Houser has agreed to investigate the availability of resources to prepare the LDAS data set for application to this initiative.
The best hope for validation of land-surface schemes at the global scale reside in remote sensed data. To encourage the community to move in this direction GLASS will help participants in the Global Off-Line Action Group to diagnose from their schemes variables which could be compared to remote sensed data. Dr Houser agreed to contribute to this work with the Dr Dirmeyer. Software will be provided which will compute for instance the snow cover, near surface soil moisture or surface temperature as seen by satellites.
In the ensuing discussion, the point was made that it will be necessary to show linkage of the GLASS Carbon Cycle work to the relevant Core Projects in the International Geosphere/Biosphere Programme (IGBP), especially the Global Carbon and Terrestrial Eco-system (GCTE) and the Global … (GAIM) studies. Drs Dolman, Polcher and Pitman have agreed to insure the appropriate connections are made between the GLASS effort and the IGBP carbon initiatives. For the time being GLASS is expected to be focused on the generation of carbon fluxes related to the up-take “evolution” of carbon by plants that is currently of greatest importance to the global modeling community. Later work will move more toward an understanding of the more subtle carbon cycle issues related to vegetation dynamics/phenology. In addition, Dr R. Avissar, Rutgers University, has agreed to be the representative of the IGBP Core Project on the Biospheric Aspects of the Hydrological Cycle (BAHC), to GLASS. This connection will relate to hydrological routing, carbon and vegetation issues. Other interactions with IGBP will be appropriately adjusted as GLASS evolves.
Similarly Dr K. Puri, Chairman of WGNE, encouraged an appropriate interface with the Working Group on Numerical Experimentation (WGNE). This interaction will be realized by way of the conjoint meetings held between GMPP and WGNE at which GLASS is well represented. The issues of importance, which must be addressed, are the level of complexity currently being reached in the handling of land-surface factors in NWP/GCM models. Bucket land-surface schemes are no longer applied in NWP models and work is being done to converge on exactly what level of complexity is necessary in the LSS components of these models to achieve the “best” results (e.g. 10 forecast). The higher level of complexity also leades to a greater need for improved parameter sets to describe the surface and assimilation schemes to determine initial conditions. The off-line studies and simpler coupled exercises being defined by GLASS should help in further understanding the sensitivity of these larger-scale models to land-surface parameters such as soil moisture which are used to initialize the models. On the longer term GLASS assimilation, in situ and remote sensing studies should provide the basis for an even stronger connection between GLASS and WGNE as well as to the Working Group on Coupled Models (WGCM) in WCRP.
It was agreed that the priority issues for the leaders of the Local Coupled Action Group, which had impact on the Science and Implementation strategy were:
To define and launch a simplified coupled system as a test-bed for assimilation methods and LSS intercomparisons. In this context, work will be undertaken to advance knowledge and gain expertise in three distinct but inter-related components of research leading to (a) further development of the parameterization estimation techniques now underway, (b) an understanding of the steps necessary to successfully perform coupled intercomparison exercises in a GLASS-ALMA configuration, and (c) a process for direct assimilation of in-situ observations and remotely sensed Land-Surface parameters.
To develop expertise in applying a simplified (local)-coupled methodology through an intercomparison exercise, which uses an ARM/CART site data set. The initial action, by early 2001, will be to set-up a local off-line ("PILPS like") inter-comparison and utilize the ALMA environment. Dr P. Wetzel at, NASA GSFC was proposed as a coordinator for this action item. The aim of this inter-comparison would be to prepare the community to the following steps which will lead to the fully coupled experiment on this site.
To begin work, in parallel with the ARM/CART PILPS-like and PE action, on the choice of a Single Column Model (SCM) suitable for the purpose of GLASS. The action is to adapt an available SCM to this use and have the interface to the surface modified by the end of 2001 so that it conforms with the PILPS-4c coupler. The GLASS adapted SCM would be introduced and distributed in early 2002.
To continue work up to mid-2002 when an appropriate GLASS-ALMA configured, simplified-coupled “environment” should be introduced and placed “in service” and the GLASS Local Coupled “ARM/CART-based” initiative started. This effort would extend through the end of 2003.
To begin experimentation associated with the assimilation of observed (in situ and remotely sensed) land-surface variables. This activity, which will be led by Dr P. Viterbo, should be initiated by the start of 2003, in parallel with the Coupled ARM-CART exercise. It should begin with in situ data exercises validated with satellite data and later result in direct assimilation of satellite data itself. This activity should continue to evolve for an indefinite period, as a major GLASS pursuit.
A contact must be made with an appropriate individual/group/Center(s) to assist in the development of the required SCM interface for the GLASS Coupled ARM-CART exercise. Possible candidates to be contacted to work on this effort, suggested at the meeting, included Dr R. Atlas at GSFC/DAO (Code 912) and Dr D. Randall at CSU. It was felt that adapting an existing SCM to this purpose would be possible in the time period allotted leading up to distribution through ALMA of a GLASS “adapted” SCM by the end of 2001.
In the ensuing discussion, the Panel agreed that the assimilation of observed (particularly remotely sensed) land-surface variables into GCM and NWP processes represented an especially important “deliverable” of GLASS to the scientific and operational/applications communities. Dr Polcher, agreed to develop an introductory paragraph for the Science and Implementation Plan, which more specifically emphasized this particular goal of GLASS.
It was agreed that the priority issues for the Global Coupled Action were (i) an inter-comparison project that would quantify the impact of surface processes on the predictability of the hydrological cycle and (ii) an inter-comparison project that would quantify the impact of land-use and climate change on surface processes and climate.
Regarding the first issue, a proposal was put forward to run GCMs with and without a flux correction applied to precipitation as it is passed to the land-surface scheme. The idea is to determine if updating the model's surface reservoirs with realistic precipitation leads to more realistic surface fluxes that in turn lead to more realistic simulated precipitation. In short, the experiment should determine whether an accurate initialization of surface moisture enhances precipitation predictability. A preliminary analysis shows promising results.
It was proposed that upon completion (by R. Koster of NASA/GSFC) of the "proof of concept" of this experimental design, it will be turned into an international project involving long integrations performed by a large number of models. Dr R. Avissar, Rutgers University, has agreed to contribute to the feasibility study by providing resources (personnel and computing time) to configure and run this experiment using the Goddard Institute of Space Studies (GISS). The proof of concept would result in an experimental design that would be released during the 2nd quarter of 2001. Data collection would start by the end of 2001.
Also regarding the first issue, a secondary (and more idealized) experiment was described that is especially well-suited for intercomparison studies. The experiment tests the robustness of a GCM's precipitation response to prescribed time series of surface conditions. The experiment is computationally cheap and has already been performed by three groups, the main result (so far) being a high intermodel variation in the strength of land-atmosphere coupling. This can serve as a backup experiment in case the computational requirements of the above predictability experiment preclude its use in a full intercomparison study.
Regarding the second issue, an experimental design concept built around land use and uncertainty linked to surface processes in a changed climate will be developed. Funding support has been sought for this activity in early 2000 from the European Union's Framework IV without success. Drs. Cox and Polcher will continue the development/funding process for this aspect of the Global Coupled Action Group theme. It is expected that such a project would start after the above predictability activity.
This action will keep in close contact with two AMIP diagnostic subprojects (sub-projects #11 by A. Robock and #12 by A. Henderson-Sellers) related to surface processes. It is expected that the results of these subprojects could be used to design specific experiments within the framwork of the Global Coupled action.
In the ensuing discussion, it was agreed that the "coupled" aspects of GLASS (and especially the longer-term elements of the Global Coupled Action group) need to provide an experimental basis for better understanding the role of the land-surface in the generation of monsoonal weather patterns. By making the coupled work relevant to monsoonal flow analyses and the prediction of monsoon on-set, breaks and related characteristics, the experiments of the global coupled action will provide an important "tool" to the climate research community with direct application to GCM and NWP development. An action for the global coupled action is to consider the scientific background for this potential "application" and to address this issue in the planning of experimental designs.
It was agreed that the priority issues for the leaders of the Infrastructure Action Group (ALMA), which had impact on the Science and Implementation strategy were:
To ensure that the PILPS-2e experiment is undertaken in the ALMA configuration and that the necessary tools for conforming to the ALMA standard are provided as a “deliverable” from the inter-comparisons using this standard. (See local off-line action)
To evaluate the degree of acceptance of the ALMA data exchange procedure and adapt it as required. The aim is to make the process as user friendly as possible.
To ensure that the PILPS-C1 (Dolman) and GSWP 1.5 (Oki/Dirmeyer), at a minimum, are running simultaneously under the ALMA configuration and that, if possible, the PILPS-CARE (Verseghy) experiment is also initiated using ALMA. The goal is to provide the support necessary to ensure that all GLASS experiments, which are scheduled to begin in 2001, are able to run under the ALMA configuration.
It was agreed that other priority issues for the leaders of the GLASS Action Groups, which had impact on the Science and Implementation strategy or which should be reported on in subsequent GSP meetings were:
To become aware of opportunities for National funding of GLASS relevant research topics and especially to be proactive in moving GLASS related goals and objectives forward in the Climate Research Plans of the National and International funding agencies.
In this context, each Action Group Leader reported on recent developments in funding of Climate Research initiatives of relevance to GLASS, at their National level :
Japan may decide to close the funding line associated with the first (Observational) phase of the regional GEWEX Asian Monsoon Experiment (GAME) effective in March 2002. A new funding line may be created at that time to accommodate a second (Analysis) phase of GAME. This line may provide some support for near term GLASS activities. Longer-term support for this work may also be available under the theme of Information Technology (IT) knowledge base development that will support the WCRP/GEWEX Coordinated Enhanced Observing Period (CEOP) and related experimental initiatives that interconnect with GLASS.
Although there is no independent funding source for a PILPS “Central” team to support the Local Off-Line Action Group work, the Principal Investigator (PI) on each of the proposed experiments under this GLASS component are providing the resources sufficient to organize the experimental procedure, perform the comparisons and disseminate and analyze the results. This arrangement should be sufficient to ensure the GLASS objectives under this Action Group are met.
NASA is planning a call for proposals (normally restricted to national researchers) which will be released under a Global Water and Energy Cycle (GWEC) theme. The call is expected to set aside US$5M in “new” as opposed to “re-programmed” money the first year and US$10M in new money the second year. This source of funds should support the C-LDAS effort under the Global Coupled Action Group activity plans. The global off-line action will be seeking funding from GWEC as well for GSWP2. The NOAA Office of Global Programs (OGP), by way of support to the GEWEX Continental-Scale International Project (GCIP) and its extension to the GEWEX America Prediction Project (GAPP) should provide sources of funding for the development of the PE and SCM development activities and support for the SALSA (and related arid/semi-arid) data set(s) preparation for work in various GLASS Action areas. Department of Energy (DOE) money will also be sought to support the preparation of the ARM/CART data set for work in the Local Coupled Action Group. Multi-Agency funding should also be made available to support the “two-stage” workshops being planned by the Local Coupled Action Group, to assist in the development/introduction and application of the GLASS SCM and PE configurations/actions.
European Union (EU) money will be sought to support the longer-term land use initiative planned under the Global Coupled Action list. An interest in climate variability may also provide the basis for support of various European Groups in the C-LDAS initiative. Dr Polcher has already found funding at INSU to support the preparation of the Rhone Valley data at Meteo-France (Dr. Noilhan) set in support of the GSWP aggregation exercise.
Funds will be sought, at the international level, through the initiative of the GLASS Chairman with support of the other Action Group leaders for an “at large” GLASS, research assistant.The aim is to allow a PostDoc to contribute to the various projects with GLASS, establish contacts within the community and gain expertise in the field of land-surface modelling.
To take action to update and finalize elements of the Science and Implementation Plan in order to support the production of a final draft of the Plan before the end of October and publication and distribution of the Plan before the end of 2000. The International GEWEX Project Office (IGPO) has agreed to support the publication and distribution effort.
To develop an article based on the content of the Science and Implementation plan, which describes the scientific background and specific plans, and milestones of GLASS, that can be submitted for publication in the Bulletin of the American Meteorological Society (BAMS) or similar publication/journal. Production of this article will be led by the Chair of GLASS with support from the Action Group leaders and should be ready for submittal in early 2001.
To further refine and update the GLASS web page currently being designed and implemented by Dr Oki. Other Action Group leaders were asked to contribute relevant information on meetings, conferences and workshops that can be placed on the Web page. The IGPO will link the GEWEX web page to the GLASS web page.
To design a GLASS Logo. IGPO has agreed to act as a point of contact for ideas relative to the design of the logo and Dr Gupta has agreed to support development of an initial sketch to be done at NASA GSFC.
It is planed to hold the next meeting of the Panel in Europe during June 2001.
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