NESOB 1997 ABRFC WSR-88D Stage III Precipitation Imagery 1.0 General Description The Arkansas-Red Basin River Forecast Center (ABRFC) Stage III Precipitation composite product is one of several image datasets provided in the GEWEX Continental-Scale International Project (GCIP) Near Surface Observation Dataset (NESOB) 1997. The ABRFC imagery covers a sector (approx. 31 to 40 degrees N latitude by 91 to 107 degrees W longitude box) over the Central United States. The ABRFC imagery contains daily composites of radar derived precipitation for a 24-hour period for the NESOB 1997 time period (01 April 1997 through 31 March 1998). 2.0 Detailed Data Description The ABRFC routinely ingests WSR-88D precipitation derived products (Level III) from each of the radar sites with coverage in the Arkansas-Red River Basin domain (15 radars). In addition, the ABRFC ingests real-time precipitation data from a total of approximately 500 gages. These data are used to support real-time operations (i.e., hydrological modeling) as well as the production of various radar "Stage Products" used by the River Forecast Center. The ABRFC produces a number of derived or "Stage" products using all the available radars and precipitation gage data in the Arkansas- Red River Basin. A Stage II product is produced by merging radar precipitation estimates (Stage I) with ground truth data provided by the precipitation gages. The Stage II estimates are then composited into a Stage III precipitation 4 x 4 km resolution area averaged mosaic for the Arkansas-Red River Basin. Daily Stage III 24-hour total precipitation estimates were then produced and saved as Graphical Interchange Format (GIF) imagery by the ABRFC. These GIF images can be viewed using any standard GIF display software package. However, any additional detailed information from the original files (i.e., pixel digital values, navigation, etc.) are not retrievable from the GIF image, but can be obtained from the actual data available from the University Corporation for Atmospheric Research/Joint Office for Science Support (UCAR/JOSS). The WSR-88D radars have difficulty detecting precipitation when the rain drops are very small or when the precipitation is in the form of snow. Under these conditions precipitation estimates tend to be under estimated. Large Hail within a storm causes the radar to over estimate precipitation amounts. 2.1 Detailed Format Description General information on GIF files, structure and format are provided in the References. 2.2 Data Remarks The GIF Imagery were produced directly from the screens of workstations at the ABRFC. As part of producing the imagery, the scroll bars and some program buttons from the workstation screen were "captured" in the GIF imagery. The user must be aware that any scroll bars or program buttons are NOT functional and executing any of the control-type key sequences indicated by these buttons and bars might produce unwanted results depending on the type of GIF viewer used. Imagery was unavailable for the following dates: 3.0 Quality Control Processing No additional quality control or re-navigation was performed on the imagery by the UCAR/JOSS. 4.0 References Kay: Graphics File Formats, 2/E. ISBN: 0-07-034025-0, McGraw Hill. Luse, M: Bitmapped Graphics Programming in C++. ISBN: 0-201- 63209-8, Addison-Wesley.