NOHRSC PRODUCT IDENTIFIERS, DESCRIPTIONS, and DISTRIBUTION ========================================================== Author: Bill Sites Telephone: (952) 361-6610 ex 236 Email: bill.sites@noaa.gov Last update: 2002 March 25 The NWS National Operational Hydrologic Remote Sensing Center (NOHRSC) in Chanhassen, Minnesota, generates and distributes snow information products to end-users in various formats via several different communications mechanisms. The purpose of this document is to summarize the NOHRSC product types, their identifiers, their formats, their resolutions, and their various distribution methods. A. SHEF PRODUCTS NOHRSC alphanumeric text products (in Standard Hydrologic Exchange Format - SHEF) are distributed on the NWS Advanced Weather Interactive Processing System (AWIPS) and posted to the NOHRSC web page. AWIPS ID AND WMO HEADER PRODUCT IDENTIFIERS AWIPS ID WMO HEADER DESCRIPTION ================================================================ MSPRRMASB SRUS43 KMSR Airborne Soil Moisture by Basin MSPRRMASF SRUS43 KMSR Airborne Soil Moisture by Flight Line MSPRRMASP SRUS43 KMSR Airborne Snow Water Eq by Flight Line MSPRRMASW SRUS43 KMSR Airborne Estimated Snow Water Eq by Basin ---------------------------------------------------------------------- MSPSCVACR SRUS43 KMSR Satellite Areal Extent of SCV for APRFC MSPSCVALR SRUS43 KMSR Satellite Areal Extent of SCV for SERFC MSPSCVFWR SRUS43 KMSR Satellite Areal Extent of SCV for WGRFC MSPSCVKRF SRUS43 KMSR Satellite Areal Extent of SCV for MBRFC MSPSCVMSR SRUS43 KMSR Satellite Areal Extent of SCV for NCRFC MSPSCVORN SRUS43 KMSR Satellite Areal Extent of SCV for LMRFC MSPSCVPTR SRUS43 KMSR Satellite Areal Extent of SCV for NWRFC MSPSCVRHA SRUS43 KMSR Satellite Areal Extent of SCV for MARFC MSPSCVRSA SRUS43 KMSR Satellite Areal Extent of SCV for CNRFC MSPSCVSTR SRUS43 KMSR Satellite Areal Extent of SCV for CBRFC MSPSCVTAR SRUS43 KMSR Satellite Areal Extent of SCV for NERFC MSPSCVTIR SRUS43 KMSR Satellite Areal Extent of SCV for OHRFC MSPSCVTUA SRUS43 KMSR Satellite Areal Extent of SCV for ABRFC ---------------------------------------------------------------------- MSPSWEACR SRUS43 KMSR Estimated SWE by Basin for APRFC MSPSWEALR SRUS43 KMSR Estimated SWE by Basin for SERFC MSPSWEFWR SRUS43 KMSR Estimated SWE by Basin for WGRFC MSPSWEKRF SRUS43 KMSR Estimated SWE by Basin for MBRFC MSPSWEMSR SRUS43 KMSR Estimated SWE by Basin for NCRFC MSPSWEORN SRUS43 KMSR Estimated SWE by Basin for LMRFC MSPSWEPTR SRUS43 KMSR Estimated SWE by Basin for NWRFC MSPSWERHA SRUS43 KMSR Estimated SWE by Basin for MARFC MSPSWERSA SRUS43 KMSR Estimated SWE by Basin for CNRFC MSPSWESTR SRUS43 KMSR Estimated SWE by Basin for CBRFC MSPSWETAR SRUS43 KMSR Estimated SWE by Basin for NERFC MSPSWETIR SRUS43 KMSR Estimated SWE by Basin for OHRFC MSPSWETUA SRUS43 KMSR Estimated SWE by Basin for ABRFC ================================================================== In the above headers: * RRM is used for NOHRSC airborne survey gamma products which are generated for the surveyed area and released only during airborne survey operations. * SCV is used for Satellite Areal Extent of Snow Cover products which are generated for each RFC and released daily at approximately 15z. * SWE is used for Estimated Snow Water Equivalent by Basin products which are generated for each RFC and released daily at approximately 15z. The NOHRSC SHEF products are ftp'd to the NWS Telecommunications Gateway (NWSTG) where they are routed across the High Speed Interface (HSI) to the Network Control Facility (NCF) for broadcasting on the Satellite Broadcast Network (SBN). NOAAPORT data and product delivery service are provided over the SBN. The NOHRSC SHEF products are also posted to the NOHRSC web page (www.nohrsc.nws.gov under Operational Products Search Engine). B. GRIB-IMAGE PRODUCTS FOR AWIPS NOHRSC generates and distributes GRIB-image products to AWIPS and to the National Centers for Environmental Prediction (NCEP) Environmental Modeling Center (EMC). The NOHRSC GRIB-image products are ftp'd to the NWSTG which routes them across the HSI to the NCF for broadcast on SBN/NOAAPORT for display on AWIPS. The GRIB-image products are generated and released once per day at approximately 15z, except for weekends and holidays. The NOHRSC GRIB-image files were made available on the AWIPS D2D pulldown menus in October 2001 with the installation of Build 5.1.1. Click on Surface, click on Precip & Stability, click on Snow Images, to display the NOHRSC menu. The GRIB-images are stored locally (at the NCRFC) in the AWIPS directory: /data/fxa/Grid/SBN/Snow. WMO HEADERS AND DESCRIPTIONS FOR THE GRIB-IMAGE PRODUCTS WMO HEADER DESCRIPTION =========================================================== YSQA88 KMSR CONUS Areal Extent of Snow Cover YEQA88 KMSR CONUS Snow Water Equivalent ZSQA88 KMSR CONUS Areal Extent of Snow Cover by Elevation ZEQA88 KMSR CONUS Deviation from Normal Snow Water Equivalent ============================================================ B.1. GRIB-IMAGE RESOLUTION INFORMATION The original, full-resolution NOHRSC GRIB-gridded products ranged in file size from 3 megabytes to 9 megabytes. The maximum file size that can be successfully processed by the NWSTG is 330 kilobytes. That's a problem. The original, full-resolution NOHRSC GRIB-gridded products range in size from 756 columns x 736 rows to 3467 columns x 1671 rows. The maximum size gridded product that AWIPS can contour and display in a reasonable amount of time is approximately 300 x 300. That's another problem. Fortunately, the maximum size GRIB-image product that AWIPS can display in a reasonable amount of time is approximately 3000 x 3000. As a result of the above NWSTG and AWIPS limitations, we have opted to create and ship our products to AWIPS in GRIB-image format. To accommodate the NWSTG and AWIPS limitations, we have made several modifications to the GRIB products: 1. We converted the GRIB-gridded products to GRIB-image products. GRIB-image files are smaller than GRIB-gridded files and they do not require contouring. Both factors can enhance display performance, and the smaller file size allows the file to flow without obstruction through the AWIPS communications network. This approach was agreed upon by representatives of the Forecast Systems Laboratory, the AWIPS Program Office, the NWSTG, and NOHRSC. 2. The spectral resolution for some of the products was degraded when converted from a GRIB-gridded product to a GRIB-image product. In the GRIB-image product, the data are represented by only 255 integer values. In a GRIB-gridded product, the data are floating-point and, consequently, the files are much larger. The fixed-point, GRIB-image files are smaller but have degraded spectral resolution. 3. The spatial resolution was degraded. The conversion from a GRIB-gridded product to a GRIB-image product alone did not render a file size sufficiently small to accommodate the limited NWSTG bandwidth. Therefore, the spatial resolution was degraded for all products and is given in the table below. The spatial resolution was degraded until a file size of less than 330 kilobytes could be generated on a routine basis. These sacrifices are required to distribute the NOHRSC products over AWIPS given the limitations of AWIPS and the NWSTG. Information on how to obtain the NOHRSC full-resolution, gridded raster products is provided in Section C. NOHRSC GRIB-IMAGE PRODUCT RESOLUTION GRIB-GRIDDED GRIB-IMAGE GRIB-GRIDDED GRIB-IMAGE PROD. SPATIAL SPATIAL SPECTRAL SPECTRAL TYPE RESOLUTION RESOLUTION RESOLUTION RESOLUT. ==================================================================== SC 1km x 1km 8km x 8km dna dna SCE 1km x 1km 8km x 8km 1m 100m SWE 3km x 3km 9km x 9km 1mm 2cm SWEPN 3km x 3km 9km x 9km < 1% 1% ==================================================================== where SC = areal extent of snow cover, SCE = areal extent of snow cover by elevation, SWE = snow water equivalent, SWEPN = deviation from normal snow water equivalent. B.2. GRIB PRODUCT DEFINITION SECTION The product definition section (PDS) of the GRIB-image files includes a description of the data contained in the files (data type and themes/units): For the NOHRSC GRIB-image products, the originating center code is set to 9, the sub-center code is set to 163, the generating process is set to 185, and the parameters are set as follows: 207 = Snow cover (snow=250, clouds=100, no-snow/no-clouds=50), abbreviation set to SC, non-dimensional units. 208 = Snow cover by elevation (snow=0 to 252, no-snow/no-cloud =253, clouds=254), abbreviation is set to SCE, units are in 100s of meters. 209 = Snow water equivalent; units set to increments of 2 cm, abbreviation is set to SWE. 210 = Snow water equivalent percent of normal, units set to percent of normal, abbreviation is set to SWEPN. C. GRIDDED RASTER PRODUCTS NOHRSC generates and distributes full-resolution, gridded raster products in GIS compatible format to the following end-users: * NOHRSC web page. * RFCs: CNRFC, CBRFC, MARFC, NCRFC, NWRFC. * NASA GSFC, NASA Hydrologic Services Branch, NESDIS IMS. These full-resolution, gridded raster products have a spatial resolution that varies from 1km x 1km to 3km x 3km depending on the product type. The areal extent of snow cover products have a spatial resolution of 1km x 1km. The SWE products have a spatial resolution of 3km x 3km. The numerical resolution for gridded SWE products is 1mm. The full- resolution, gridded raster products are released once per day at approximately 15z, except for weekends and holidays. D. IMAGE PRODUCTS NOHRSC generates and distributes image products, in GIF and gunzipped PostScript format (to facilitate hardcopy map printout), to the NOHRSC web page and to MARFC. The NOHRSC image products are generated and released once per day at approximately 15z, except for weekends and holidays. NOTE: The PostScript files are retained on the NOHRSC web page for only 5 days due to their large file size and storage limitations. This document is intended to clarify the NOHRSC product specifications and the AWIPS and web distribution process. If you have any questions, require any additional information, or have any suggestions for improving this document, please contact Bill Sites at the NOHRSC: (952) 361-6610 ex 236 or bill.sites@noaa.gov.