On the development of a weather radar data assimilation system for the US Navy

The Marine Meteorology Division of the Naval Research Laboratory (NRL-Monterey) is developing a weather radar data assimilation system that will take advantage of Navy vessels in the battle fleet having weather radar capability. The Hazardous Weather Detection and Display Capability system, installed onboard a selected number of aircraft carriers and large-deck amphibious ships, is a weather radar processor and web-display server that converts the volumetric returns from the ships' SPS-48E radar into spectral moment data, which are then archived into files following the so-called universal format (UF). NRL-Monterey is working with Space and Naval Warfare Systems Center and Basic Commerce and Industries to implement a system to transmit the UF files to NRL-Monterey. The ship-based UF radar data will be assimilated along with ground-based NOAA radar data and a variety of other conventional atmospheric and oceanic data into the Navy's Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS) at Fleet Numerical Meteorology and Oceanography Center in Monterey. COAMPS forecast products (0-24 hour range) are made available to the US Armed Forces through the net-centric information system.

To minimize the load on the operational bandwidth, the UF files have to be significantly compressed before transmission off the ships to a shore location. A novel UF file compression algorithm has been developed which achieves a typical UF file compression ratio of 40:1. Furthermore, progress has been made in addressing quality control issues, unique to the platform and ocean environment, such as ship mast reflection artifacts, sea clutter, anomalous propagation due to surface and evaporation ducts, and assimilation of data from a moving platform. Results and examples from an archived UF data set obtained from an at-sea experiment onboard the USS PELELIU (LHA5) in February 2006 will be presented.