Understanding the operations of a large \u27net-centric system-of-systems requires in-depth knowledge of the interfaces among the various systems, sub-systems and components. Architectural modeling can help in reducing the complexity involved in designing such large networked systems. An example of such a complex system is the Global Earth Observation System of Systems (GEOSS) - a system for monitoring and collecting information related to Earth\u27s resources. This paper demonstrates the use of Systems Modeling Language (SysML), which supports specification, analysis, design, verification and validation of a broad range of complex systems, to model some aspects of the GEOSS. The paper discusses issues related to architecture description, development, presentation, and integration for the chosen domain. The paper discusses issues related to model evaluation and how architectures can be simulated to better understand their efficacy
