PNNL

Abstract

The PNNL Nexrad Wind Retrieval System (PNWRS) was developed to enable real-time retrieval of spatially resolved wind fields from level II Nexrad data. Horizontal velocity fields are retrieved from radial velocity measurements using an algorithm developed at NOAA/NSSL (Xu et al. 2006; Xu and Gong 2003). This algorithm compared favorably to winds measured by wind profiling radars and to an alternate retrieval algorithm (Fast and Newsom, 20XX). The retrieval technique, which is referred to as 2DVar, is based on statistical interpolation and can be regarded as regarded as an extension of the traditional Velocity Azimuth Display (VAD) technique (Browning and Wexler 1968). In addition to its ability to process wind fields in real-time, the PNWRS can be used to process level II Nexrad data obtained from the NOAA/NCDC archive. This document describes how to install and run the PNWRS and associated software components. The PNWRS was developed on an x86_64 Linux workstation running RedHat Linux 5. Software components that should be installed on the host machine include the following: 1. PNWRS 2. IDL 6.2 or higher 3. netCDF libraries 4. Unidata Local Data Manager (LDM) 5. Intel Fortran Compiler We note that LDM is only required in order to process a real-time data-feed. The PNWRS can be used to process archived data without LDM. Also, if the PNWRS is installed on an x86_64 Linux workstation, compilation of the Fortran executables may not be necessary, since the executables are already included in the distribution. In that case, the Intel Fortran Compiler is not be needed. A number of routines are written in IDL. The IDL routines are used for data ingest and decoding, image file generation and processing hourly averaged wind fields. Thus, the PNWRS will not run without an IDL license (or run-time license).