One robotic plane, called an Aerosonde, can fly at altitudes lower than 500 feet in the hurricane boundary layer, reach an altitude range of 20,000 feet, and has a flight range of 1800 miles. The first Aersonde reconnaissance flight was flown into Tropical Storm Ophelia on September 16, 2005. More flights are anticipated in 2006.
Historically, satellites have served as the most crucial tool for monitoring tropical cyclones. Recent advances include the Advanced Microwave Sounding Unit (AMSU) instrument, which can measure the warm core of a hurricane, and the NASA Aqua satellite, which can retrieve profiles via MODIS retrieval algorithms and the AIRS. However, all have trouble with cloudy regions or with heavy precipitation.
Recently (April 14 2006), a new constellation of satellites was successfully launched. These low-orbitting satellites will provide real-time data over thousands of points throughout the globe. Called the Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC), these satellites will provide temperature and moisture profiles (Anthes, Ricken, and Kuo 2000; Cucurull et al. 2006). COSMIC relies on a technology known as radio occultation. As radio signals from GPS satellites pass through the atmosphere, the paths of the signals are bent and their progress slowed. The rate of these changes depends on atmospheric density along the signal path. COSMIC's low-Earth-orbiting (LEO) satellites take advantage of this effect by intercepting the GPS radio signals just above Earth's horizon and precisely measuring the bend and signal delay along the signal path. These parameters can then be used to compute temperature and moisture information. Because radio signals can pass through thick cloud cover and precipitation, weather conditions will not interfere with data gathering, as often occurs with remote sensing platforms. Therefore, this technology could be very useful to the monitoring of tropical cyclones. More information is available at: http://www.cosmic.ucar.edu.
This study will investigate Aerosonde and COSMIC capabilities in studying hurricanes. Analysis of these data, along with NASA satellite data, will be performed on a 2006 hurricane. In consultation with the Hurricane Research Division, we will assess what new information is obtained compared to the reconnaissance, in-situ observations, and other available satellites. In particular, the ability of the UAS and COSMIC to observe critical regions inaccessible to other platforms will be assessed. This analysis will also provide observation error characteristics critical to future data assimilation work.