Coupling Climate and Hydrological Models Interoperability Through Web Services

Outline Project Objective Motivation System Description – Components – Frameworks – System Driver Logical Workflow Data Flow Architecture Future Directions

Project Objective The development of an end-to-end workflow that executes, in a loosely coupled mode, a distributed modeling system comprised of an atmospheric climate model using ESMF and a hydrological model using OpenMI

Motivation Hydrological impact studies can be improved when forced with data from climate models [Zeng et al., 2003; Yong et al., 2009] A technology gap exists: – Many hydrological models run on personal computers – Most climate models run on high performance supercomputers The leveraging of ESMF and OpenMI can mitigate the communication difficulties between these modeling types – ESMF contains web services interfaces that can be used to communicate across a distributed network – Both ESMF and OpenMI are widely used within their respective communities

System Description High Performance Computer ESMF Web Services ESMF CAM Component ESMF CAM Component SWAT OpenMI CAM OpenMI Wrapper Driver Personal Computer SWAT (hydrology model) runs on PC CAM (climate model) runs on HPC Wrappers for both SWAT and CAM provide OpenMI interface to each model Driver (OpenMI Configuration Editor) uses OpenMI interface to timestep through models via wrappers Access to CAM across the network provided by ESMF Web Services CAM output data streamed to CAM wrapper via ESMF Web Services

Components: SWAT The hydrological model chosen for this project is the Soil Water Assessment Tool (SWAT) It is a river basin scale model developed to quantify the impact of land management practices in large, complex watersheds It was chosen for this project because it is widely used, is open source, and runs on a Windows platform

Components: CAM The atmospheric model chosen for this system is the Community Atmospheric Model (CAM5), part of the Community Climate System Model (CESM1.0.3) It was chosen because: Has ESMF Component Interfaces Our group has an ongoing collaboration with CESM It is Open Source

Frameworks: Earth System Modeling Framework Is a high-performance, flexible software infrastructure that increases the ease of use, performance portability, interoperability, and reuse of Earth science applications Provides an architecture for composing complex, coupled modeling systems and includes array-based, multi- dimensional data structures Has utilities for developing individual models including utilities to make models self-describing Web services included in the ESMF distribution allow any networked ESMF component to be available as a web service.

Frameworks: OpenMI The OpenMI Software Development Kit (SDK) is a software library that provides a standardized interface that focuses on time dependent data transfer Primarily designed to work with systems that run simultaneously, but in a single-threaded environment [Gregerson et al., 2007] The primary data structure in OpenMI is the ExchangeItem, which comes in the form of an InputExchangeItem and an OutputExchangeItem (single point, single timestep)

The system driver Controls the application flow Implemented using OpenMI’s Configuration Editor Convenient tool for the testing of the OpenMI implementations and model interactions

Hardware Architecture Personal Computer (Windows) High Performance Computer Virtual Linux Server Login Nodes (kraken) Compute Nodes (kraken) The Client contains the OpenMI and SWAT software, which run on a Windows platform. The Atmospheric Model runs on a HPC platform Access to the HPC Compute Nodes must be through the Login Nodes Access to the Login Nodes is through the Virtual Server (Web Svcs)

Software Achitecture Client Personal Computer (Windows) OpenMI Configuration Editor CAM OpenMI Wrapper SWAT 2005 OpenMI … to Web Services Configuration Editor is the driver… it is used to link the models and trigger the start of the run. Hydrological model (SWAT 2005) is a modified version to work with OpenMI Access to Atmospheric model (CAM) is done through “wrapper” code that accesses ESMF Web Services via an OpenMI interface

Software Architecture Server Linux Server (Web Svr) Tomcat/Axis2 SOAP Svcs HPC Login Nodes HPC Compute Nodes Job Scheduler Comp Svc Comp Svc Comp Svc CAM Process Controller Registrar In some HPC systems, access to nodes can be restrictive. In XSEDE, only the Login Nodes can communicate with the Compute Nodes. Access to/from external systems can be controlled via “gateway” systems using Web Services. Running applications (such as CAM Component Svc) on Compute Nodes must be handled by a Job Scheduler.

Logical Workflow One-Way Coupling DriverSWAT/OpenMIATM/OpenMI WrapperESMF Web ServicesESMF Component Initialize Prepare GetValues Finish Dispose NewClient Initialize RunTimestep Finalize GetData EndClient GetValues ESMF_GridCompInitialize ESMF_GridCompRun ESMF_GridCompFinalize ValueSet

Logical Workflow Two-Way Coupling DriverSWAT/OpenMIATM/OpenMI WrapperESMF Web ServicesESMF Component Initialize Prepare GetValues Finish Dispose NewClient Initialize RunTimestep Finalize GetData EndClient GetValues ESMF_GridCompInitialize ESMF_GridCompRun ESMF_GridCompFinalize GetValues Extrapolate ValueSet

Data Flow One-Way Coupling ESMF Component/CAM ESMF State CAM/OpenMI Wrapper Output Exchange Item Output Exchange Item SWAT/OpenMI Input Exchange Item Input Exchange Item GetValues Personal ComputerHigh Performance Computer GetDataValues The data is pulled from the CAM Component to SWAT via the wrapper, initiated by the OpenMI GetValues call; this call is made once per timestep. Data is exchanged between CAM and SWAT using the OpenMI Exchange Item structures that handle the translation from grid to point values

Data Flow Two-Way Coupling ESMF Component/CAM ESMF Export State CAM/OpenMI Wrapper Output Exchange Item Output Exchange Item Import SWAT/OpenMI Input Exchange Item Input Exchange Item GetValues Personal ComputerHigh Performance Computer GetDataValues Output Exchange Item Output Exchange Item Input Exchange Item Input Exchange Item GetValues SetInputData ESMF Import State In two-way coupling, each model pulls the data from the other model using the OpenMI GetValues method. Extrapolation is used on the first timestep to break the deadlock between the two model requests. OpenMI Input and Output Exchanges items are again used to exchange and translate the data.

Model Configurations SWAT – Hydrology science information provided by Jon Goodall of University of S. Carolina – Lake Fork Watershed (TX) – Watershed Area: km2 – Model run: 2 years, 1977 – 1978 – Timestep = 1 day – Weather Stations: wea62 (33.03 N, W) wea43 (33.25 N, W) CAM – Global Atmospheric Model – Model run: 1 day – Timestep: 1800 sec – Dynamical Core: finite volume – Horizontal Grid: 10x15 – Export data variables: surface air temperature precipitation wind speed relative humidity solar radiation

Scaling Analysis 4 areas of increasing size 3 variations of CAM resolution (.25,.5, and 1 degree) CAM almost always gating factor in run times Data transfer rates minimal – 5 data values CAM to SWAT – 1 data value SWAT to CAM

Future Tasks Additional SWAT configurations for larger scales Possible integration with other models – Currently working on replacement of CAM with WRF Abstraction of data exchange within the ESMF wrapper code to accommodate configuration of different variables for different model implementations

Logical Flow - Startup Personal Computer (Windows) Config Editor CAM Wrapper SWAT 2005 OpenMI Linux Server Web Svcs HPC Login Nodes Job Scheduler Process Controller Registrar HPC Compute Nodes HPC Compute Nodes Comp Svc CAM Initialize 2.New Client 3.New Client 4.Submit Job 5.Status = SUBMITTED 6.Instantiate Job (Comp Svc) 7.Status = READY When loading models into the Configuration Editor, each model is initialized. For CAM, this involves starting a “New Client” in the Process Controller, which submits a new CAM Component Service using the Job Scheduler.

Logical Flow - Status Personal Computer (Windows) Config Editor CAM Wrapper SWAT 2005 OpenMI Linux Server Web Svcs HPC Login Nodes Job Scheduler Process Controller Registrar HPC Compute Nodes HPC Compute Nodes Comp Svc CAM Get Status 2.Get Status 3.Get State The status of the CAM Component Service is checked often throughout the workflow. The status is stored in the Registrar, so it can be retrieved via the Process Controller.

Logical Flow - Initialize Personal Computer (Windows) Config Editor CAM Wrapper SWAT 2005 OpenMI Linux Server Web Svcs HPC Login Nodes Job Scheduler Process Controller Registrar HPC Compute Nodes HPC Compute Nodes Comp Svc CAM Prepare 2.Initialize 3.Initialize 4.Initialize 5.Status = INITIALIZING 6.Status = INIT_DONE Before the models can be run, they need to be initialized. For CAM, the Initialize call is sent to the CAM Component Service via Web Services and the Process Controller. The CAM Component Svc updates it’s status in the Registrar prior to and after Initialization.

Logical Flow – Timestep (Run) Personal Computer (Windows) Config Editor CAM Wrapper SWAT 2005 OpenMI Linux Server Web Svcs HPC Login Nodes Job Scheduler Process Controller Registrar HPC Compute Nodes HPC Compute Nodes Comp Svc CAM Get Values 2.Get Values 3.Run Timestep 4.Run Timestep 5.Run Timestep 6.Status = RUNNING 7.Set Output Data 8.Status = TIMESTEP_DONE For each Timestep in SWAT, the trigger to run a timestep in CAM is a Get Values request in the OpenMI Interface. The Run Timestep request is passed to the CAM Component Service and the Component Service sets the output data making it available for later retrieval (see Get Data).

Logical Flow – Timestep (Get Data) Personal Computer (Windows) Config Editor CAM Wrapper SWAT 2005 OpenMI Linux Server Web Svcs HPC Login Nodes Job Scheduler Process Controller Registrar HPC Compute Nodes HPC Compute Nodes Comp Svc CAM Get Data Desc* 2.Get Data Desc* 3.Get Data Desc* 4.Get Data 5.Get Data 6.Get Data * one time only After each Timestep Run, the output data is then fetched from the CAM Component Service via the Web Services and Process Controller. The first time fetching data, a description of the data structure is requested. This description is then used for the remaining Timesteps.

Logical Flow - Finalize Personal Computer (Windows) Config Editor CAM Wrapper SWAT 2005 OpenMI Linux Server Web Svcs HPC Login Nodes Job Scheduler Process Controller Registrar HPC Compute Nodes HPC Compute Nodes Comp Svc CAM Finish 2.Finalize 3.Finalize 4.Finalize 5.Status = FINALIZING 6.Status = FINAL_DONE End Client (Next Slide) After all timesteps have completed, the models need to be finalized. For CAM, the Finalize call is sent to the CAM Component Service via Web Services and the Process Controller. The CAM Component Svc updates it’s status in the Registrar prior to and after finalization.

Logical Flow – End Client Personal Computer (Windows) Config Editor CAM Wrapper SWAT 2005 OpenMI Linux Server Web Svcs HPC Login Nodes Job Scheduler Process Controller Registrar HPC Compute Nodes HPC Compute Nodes Comp Svc CAM End Client 2.End Client 3.Kill Server 4.Exit Service Loop After the Finalize call, the CAM Component Service is done, so the CAM Wrapper closes it out by calling End Client. This call results in the CAM Component Service completing it’s loop and exiting as well as the Process Controller removing all references to the client. 5.Status = COMPLETED 5 5