P1.28 ACCESS TO REAL-TIME AND RETROSPECTIVE NUMERICAL WEATHER PREDICTION MODELS AT THE NATIONAL CLIMATIC DATA CENTER AND THE NATIONAL CENTERS FOR ENVIRONMENTAL PREDICTION Glenn K. Rutledge * National Climatic Data Center Scientific Services Division Asheville, NC 28801 Jordan Alpert National Centers for Environmental Prediction Environmental Modeling Center Camp Springs, MD 20736 William Ted Smith National Climatic Data Center STG, Inc Asheville, NC 28801 1. BACKGROUND go to the NCDC Home Page, Climate, and then Model Resources . Numerical Weather Prediction (NWP) models are available in real-time through a number of different 2. PARTNERSHIPS FOR DISTRIBUTED DATA channels . However, historical model input and output ACCESS which are needed for research, model improvement, publications, training, and collaboration, are more NOMADS adopted and actively supports the difficult to obtain. Local piecemeal approaches at growing use and agreements necessary for format government laboratories, data centers, and universities independent distributed access. Leveraging off of many fall short of filling the need for access to retrospective distributed data access projects from many cooperating models and associated data. Even with increases in sources (see the NOMADS Home Page for list of available bandwidth and technological advances in collaborators), NOMADS uses the OPeNDAP (formerly distribution and access systems, access to retrospective DODS), binary data transport protocol, and an XML models has been very limited. In fact, until now a U.S. based protocol, to provide data over the internet. The National digital archive of operational weather models servers at NCEP and NCDC include the GrADS-DODS has simply not existed. Server (GDS), and traditional Web based services. The A new historical model archive at the National distributed data access features with is the core of the Climatic Data Center (NCDC) and a new real-time data NOMADS data access philosophy for temporal and access service at the National Centers for spatial sub-setting is provided by the GDS, and a local Environmental Prediction (NCEP) under a collaborative web based access interface was developed jointly by project called the NOAA Operational Model Archive and NCDC and NCEP. All of the access capabilities for Distribution System (NOMADS) is now operational. Both NOMADS are detailed at the NCDC model resources systems are considered pilot projects with plans for site using the “Model Data Access Guide” at future expansion. nomads.ncdc.noaa.gov/user-guide.html. The data that are available include both real-time One of the major successes of NOMADS is the and retrospective NWP initialization and restart files , development of partnerships between many of the NWP output, reanalysis, limited ocean data and climate leading weather and climate science groups, both General Circulation Models . Access to these data in a research and operational, into the ocean community. distributed open and format neutral manner is provided The OPeNDAP partnership is now stronger due to the to promote improvements to operational models by NOMADS collaborators, and a global vision for open, providing a feedback mechanism from the research and interoperable approach to data access, is several steps Regional modeling communities to the operational closer toward a reality. communities , and promote model intercomparison NOMADS is actively partnering with and supported efforts. by the University Corporation for Atmospheric Research The NOMADS site at NCDC can be found at (UCAR), Unidata Program Center’s Thematic Real-time www.ncdc.noaa.gov/oa/model/model-resources.html or Environmental Distributed Data Services (THREDDS), as well as the Digital Library for Earth System Education ____________________________________________ (DLESE), and the National Science Digital Library * Corresponding author address: Glenn Rutledge, (NSDL). Alignment with these activities, OPeNDAP, and National Climatic Data Center, 151 Patton Avenue, other NOMADS partners such as new developments Asheville, NC 28801; e-mail: [email protected]. within PMEL’s Live Access Server and the Center for Ocean-Land-Atmosphere Studies’ (COLA) GDS, (NCEP) ensures that NOAA can play a lead role in the national 3) Reanalysis (at NCEP and NCDC): Global and multi-organization efforts to provide users with coherent Regional access to the vast array of environmental data stored in 4) Ocean models, weather and climate (Spring data collections around the country and the world. 2004) Never before has the U.S. maintained a digital 5) AOGCM climate models at GFDL library for gridded model output. In the past NCEP 6) Reference observational data sets (CARDS, maintained a short term collection for its own use, ERSST’s, GHCN, etc.) however the need for a publicly available historical model input and output archive was not justifiable. Models and associated data will be stored at NCDC Within the last half decade or less however, the need for and retrieved by NOMADS from a 5 year rotating historical model data, and model initialization and archive. Analysis products will be archived for the longer boundary conditions for NWP has never been greater. term however. Other data such as observational and With the increasing power of desktop computers and the reference data sets such as the Smith-Reynolds availability of Regional models , a new paradigm for Extended Reconstructed Sea Surface Temperature’s distributed and local model development is emerging. are currently available under the NOMADS framework These regional modeling centers and other research at NCDC. However, the focus of this paper is model centers are a vast NOAA resource and will continue to data availability. grow. A two-way feedback mechanism needs to be developed and fostered at all levels of the geo-sciences 3.1 Model Output Archive community. NOMADS allows these activities to grow since both computer and research scientists are actively The model output data currently available at NCDC engaged in solving these issues from a bottom-up for the period beginning May 2002 to the present approach based upon what uses use and need most. include: There is a good deal of work remaining however. Interoperable data access requires metadata Eta Model management, and communications between Data are available four times a day (00Z, 06Z, 12Z, collaborators and many of these pilot projects, including 18Z), out to 48 hour forecasts at 3-hour intervals on NOMADS require testing for operational demands . various resolutions from 12km to 40Km on various Conversion issues (e.g., grib to NetCDF), on some grids and projections . complex climate grids also remain but are slowly being addressed. Finally, the entire climate, weather and Global Forecast System ocean communities need to develop an overarching Data will be available four times a day (00Z, 06Z, plan, forge agreements, and a methodology to support 12Z, 18Z), out to 7 day forecasts at 3-hour intervals distributed processing across organizational boundaries . on a 1x1 degree global and regional grids from Organizations and/or Programs such as CLIVAR, 60km to 200km (grids 201-213), and from 8 – 16 WCRP, USWRP, and the Climate Change Science day forecasts on a 2.5x2.5 degree global grid in Program could be used to provide this leadership. compressed GRIB grid #2. 3. NWP AVAILABILITY AND ACCESS Rapid Update Cycle (RUC) System RUC fields as received on the NOAAPort system Traditional data access methods such as ftp, http, are available hourly out to 12hour forecasts in 3hrly and wget are available under the NOMADS umbrella. forecast cycles. (FSL soon to provide a full suite of The browse and plot capability on the NOMADS server RUC model data on a NOMADS (DODS) Server at is called “Web Plotter” developed by NCEP, and FSL.) modified for use under NOMADS by NCDC. A data selection capability was added to the front end of Web 3.2 Model Input Archive Plotter for user selection of data for historical archive requests . These requests can span the on-line disks Under NOMADS and for the first time, the regional (currently up to 2 years), or reach into the NCDC modeling community will have direct access to NCEP’s archive for longer term access and manipulation. The real-time and historical model assimilation fields . As Web plotter allows time series plots, lat/long vs. time NCEP runs a series of computer analyses and forecasts (Hovmoller diagrams), and other host side data operationally. One of the primary operational systems is manipulation services . the Global Data Assimilation System (GDAS) Under NOMADS six primary categories of data are (Kanamitsu, 1989), which uses the spectral Medium available at NCDC: Range Forecast model (MRF) for the forecast (Sela, 1980). In simple terms, for each run, unequally spaced 1) NWP Model Output (NCDC’s NOAAPort conventional and remote sensed observations are ingest, and NCEP’s Hi-Res fields) assimilated with "first guess" data fields (forecasts from 1a) FSL RUC model as provided by the the previous model run), and dynamic imbalances in the NOAAPort Broadcast data are reduced, resulting in "analyzed" data fields . 2) NWP Model Input Then the forecast is made. The analyzed data provides an optim al representation of the real atmosphere on a data set. The data set consists of conventional and grid or spectral coefficients of spherical harmonics . remote sensed observations made ready to start NCEP These can be compared to observations which have cycling analysis system. Other NCEP operational limitations due to measurement error or other instrument models in addition to the GSM, such as the Eta and problems, and non-uniform spatial and temporal WRF regional models are coming soon. Additional data dis tributions of the observations. sets consisting of model run history in GRIB pressure Publicly available on the NOMADS servers at vertical coordinate on a longitude/latitude grid will be NCEP and NCDC is the GDAS dataset. GDAS consists present as determined by NOMADS panel. of the minimum set necessary to re-generate NCEP “Post” is a FORTRAN program available from analysis and forecast products (model re-start and NCEP that will convert spectral coefficients to gaussian initialization files).