Using Space-Based Radar to Derive Fully Integrated, Real-Time Weather Information

Article excerpt

Editorial Abstract:

Generally, space-based radars (SBR) used in weather and other military/civilian aviation operations have been designed and fielded separately. This practice has prevented the integration of time-sensitive, mission-critical, radar-derived meteorological information with other key radar-derived data. Major Fionno argues that the collection of weather data from future SBR platforms would significantly benefit operational- and tactical-level war fighters. Toward that end, he proposes techniques for integrating weather data within the SBR platform.

In any combat operation or any conflict, weather's probably your number one concern.

-Gen Richard B. Myers

Chairman, Joint Chiefs of Staff

CURRENT PLANS FOR the fielding of a space-based radar (SBR) capability in 2010 include developing and testing a space platform that can provide a ground moving target indicator (GMTI); precision geolocating; single-pass, digital, terrain-elevation data collection; electronic protection; single-pass, synthetic aperture radar (SAR) imaging; and high-data-rate, secure communications. The plans, presentations, and news releases concerning SBR, however, do not specifically address the collection of meteorological data. The history of radar development suggests that despite many hardware similarities, radars for weather and other military/ civilian aviation operations have generally been designed and fielded separately, probably due to the human-intensive analysis required to process the distinctive radar data generated by each function. Thus, the integration of time-sensitive, mission-critical, radar-derived meteorological information with other key radar-derived parameters has historically suffered from a cumbersome manual-fusing process, often involving different equipment and different organizations.

This article hypothesizes that modern communications and electronic signal-processing capabilities would allow the derivation of fully integrated meteorological information from the proposed SBR constellation without significant additional costs or program delays. It presents previously proven techniques for obtaining weather information from this constellation, along with evidence that minor additions of equipment could greatly enhance SBR's "see-through" capability in weather-clutter areas. One could expect the integration of real-time weather information into the SBR data stream to benefit operational- and tactical-level war fighters significantly. Collection of weather data from SBR would also provide a vast source of observational information about global weather, thus improving numerical weather forecasts for military and civilian endeavors alike.

Uses of Modern Weather and Tracking Radars

Active surface microwave sensors (ground radars) have monitored precipitation for research and operational purposes for decades-and one space-based version has operated since 1997. Radars that employ the Doppler principle in their signal processing first emerged during World War II to better detect aircraft and other moving objects in the presence of "cluttering" background echoes created by the radar beam's sidelobe emissions. The earliest Doppler (moving target indicator [MTI]) radars detected only relative motions of objects rather than quantifying velocities, as do modern pulsed-Doppler radars. The MTI designation has persisted to the present day, as is apparent in the GMTI radar equipment used aboard Joint Surveillance Target Attack Radar System (JSTARS) aircraft. The rapid development of pulsed-Doppler radar was impeded by the formidable amount of signal processing required to extract quantitative estimates of the Doppler shift at each of the thousands of range locations a radar can survey. Not until the late 1960s and early 1970s did solid-state devices make the implementation of Doppler measurements practical at all resolvable ranges.1 Thus, the first 25 years of operational radar were dominated by manual signal processing of fleeting cathode-ray-tube images. …