GEO Task DA-09-02d: Atmospheric Model Evaluation Network
< GEO AQ CoP < HTAP Data Network Pilot
The HTAP Data Network Pilot is a demonstration of a service-oriented, loosely coupled air quality data sharing network. It is implemented using international [standards and conventions for publishing, finding and accessing distributed holdings of atmospheric model outputs and observations. The portable WCS data server software and the tools developed and used in this HTAP Pilot are contributions to GEOSS through GEO Task DA-09-02d: Atmospheric Model Evaluation Network.
The purpose of this task is to demonstrate the use of web services to compare global and regional atmospheric models (including atmospheric chemistry/air quality models), combine models with Earth observations and to contribute toward improved performance of these models. Through this initial network, the variety of Earth Observations (EO) and models are brought together as a network. This GEO Task builds upon the work of the Task Force on Hemispheric Transport of Air Pollutants (www.htap.org). This initial phase created a pilot data network that connected the HTAP modeling server at Forschungszentrum Jülich (FZJ), Germany, the HTAP-EBAS data system at the Norwegian Institute of Air Research (NILU) and the federated data system, DataFed (datafed.net), at the Center for Air Pollution Impact and Trend Analysis (CAPITA) at Washington University, St. Louis, USA. In an earlier NASA-supported project a direct connection was developed between the FZ Jülich data server and the Giovanni data system at Goddard Space Flight Center (Giovanni HTAP).
The contribution of this task is toward improving the infrastructure of GEOSS by developing, demonstrating and then applying interoperability of distributed data systems using Service Oriented Architecture (SOA). The specific functionality is to facilitate publishing data access services by the providers, finding services and accessing the data through formal, standard protocols.
The application software for model evaluation will be developed and implemented using the connectivity infrastructure described in this pilot project. The specific software components and the operating procedures will be deterrmined during the next phases of this GEO task.
Initial Activities for Task DA 0902d
The first and most significant sub-task is the implementation of web services for accessing data through the Internet. Through web services, software applications can request clearly specified subsets of data from the offerings of a given server. This means that the software that uses the data, i.e. the client, can be separate from the data server, and connected only through a protocol-based, service interface. Implementing a standard-based data access protocol that is universally applicable for all models and observations constitutes the most challenging task while turning static data into dynamically accessible web services. For atmospheric and oceanic observations and models the OGC protocols for Web Map Services (WMS), Web Coverage Service (WCS), Web Feature Service (WFS) constitute the suite of protocols for formally describing and accessing data.
The next significant sub-task is to develop and implement the facilities for publishing and finding web services. While the OGC data access protocols do facilitate the unambiguous access to the data, these protocols are inadequate for finding services. Service oriented architecture requires additional domain specific-conventions, i.e. standards-based metadata, for publishing and finding suitable services. Such metadata standards for atmospheric observations and models are not yet fully developed. However, CF Conventions constitute significant advance in that direction. Service orientation, i.e. loose-coupling between servers and clients, is facilitated by the service broker. Metadata standards for finding observations and models are used by the service broker. Through the broker, providers can publish their data offerings and users can find desired services by the catalog and search facilities.
The implementation of service oriented architecture allows for the loose-coupling between the data server and the client. Such loose-coupling allows a client, say Earth, to access the content of any of the data servers in the distributed, interoperable network. More importantly, additional client-side data processing or analysis can be performed using data from multiple servers. For instance, model outputs may be provided by a "model server" while corresponding observations may be delivered by a "data server". The significant benefit of this loose coupling is that the servers can retain custody of their respective holdings.
Initiatives Supported by GEO Task DA-09-02d
The intent of the network is to support the connectivity of providers and clients in order to maximize the productivity of model/data evaluation and integration. Hence, GEO Task DA-09-02d follows the strategic goal of connecting and enabling specific projects and evaluation initiatives illustrated below. Following this strategic, enabling approach, this GEO task explicitly avoids competing with on-going, integrating initiatives. Rather, it focuses on building the infrastructure that will make existing initiatives more effective.
The outcome of this task is most directly applicable to the community and programs that develop air quality models. These models are typically used for air quality forecasts, estimating source impacts on human health and welfare (visibility, terrestrial, aquatic effects), and for developing AQ control strategies to evaluate their long-term effectivness. A small subset of AQ modeling initiatives that can benefit from this task are listed below.
IGACO (Integrated Global Atmospheric Chemistry Observations) is a strategy for bringing together ground-based, aircraft and satellite observations of 13 chemical species in the atmosphere. IGACO will be implemented as a strategic element of the Global Atmospheric Watch (GAW) programme of the World Meteorological Organization (WMO).
MACC (Monitoring Atmospheric Composition and Climate) is the current pre-operational atmospheric service of the European GMES programme. MACC provides data records on atmospheric composition for recent years, data for monitoring present conditions and forecasts of the distribution of key constituents for a few days ahead. MACC combines state-of-the-art atmospheric modelling with Earth observation data to provide information services covering European Air Quality, Global Atmospheric Composition, Climate, and UV and Solar Energy.
AQMEII (Air Quality Model Evaluation International Initiative.) An initiative for international coordination on the evaluation of regional air quality modelling AQMEII aims at promoting research on regional air quality model evaluation across the European and North American atmospheric modelling communities, through the exchange of information on practices, the realization of inter-community activities and the identification of research priorities, keeping in focus policy needs.
Additional model evaluation projects and initiatives will be added here by the community of stakeholders.
Relationship to GEOSS
There is an outstanding opportunity to develop a mutually beneficial and supportive relationship between the activities of the HTAP Task Force and that of the Group of Earth Observations (GEO). The national and organizational members of GEO have adapted a general architectural framework for turning Earth observations into societal benefits. The three main components of this architecture are models, and observations, which feed into decision support systems for a variety of societal decision making processes.
The FT HTAP activities and the Global Observing System of Systems (GEOSS) share common characteristics: (1) their stakeholders are autonomous organizations, managers and scientists; (2) participation is largely voluntary and (3) information integration is key to success. Furthermore, FT HTAP and GEOSS have symbiotic relationship : GEOSS is a good (system of systems) model for HTAP. Conversely, HTAP is a suitable use case for the emerging GEOSS. This symbiotic relationship between FT HTAP and GEOSS offered opportunities to co-develop both programs. The HTAP Model Data Server Project is an outcome of that relationship. Connecting FZ Jülich server to Washington University DataFed client has
This pilot is a contribution to several components of GEOSS including the GEOSS Common Infrastructure (GCI) and the fostering of User Engagement. An important product of this subtask is the development of a robust WCS 'wrapper' code that can be re-used for standardized CF-netCDF formatted data files. The code is open, portable to Windows/Linux and has been implemented at four servers. The primary end users of the outputs of this sub-task are regional and global air quality modelers involved in air quality research and management. By working through existing international cooperative air quality modeling activities (TF HTAP, AC&C, AQMEII), this sub-task will engage the user community throughout the development. Feedback will be sought through the HTAP Wiki and through workshops associated with these existing activities.
