| |
University of Hawai'i |
(808) 956-8856 Telephone |
For Immediate Release: |
August 26, 1999 |
Contact: Donnë Florence, PIO, 808-956-7522, donne@hawaii.edu Steven Businger, 808-956-2569, businger@soest.hawaii.edu |
UH Meteorologist to address Chapman Conference on Water Vapor Steven Businger, professor of meteorology at the University of Hawai'i Manoa, has been invited to address the American Geophysical Union's Chapman Conference on Water Vapor in the Climate System, October 12-15 at the William F. Bolger Center for Leadership Development in Potomac, Maryland. Businger will discuss progress in GPS (global positioning system) meteorology-the use of satellite-gathered data to analyze and predict weather phenomena. Businger's presentation is scheduled for 1:50 p.m., Wednesday, Oct. 13. Summary and background information follows this page. Steven Businger is one of four UH researchers included in a directory of global change experts published recently by the National Aeronautics and Space Administration. The directory profiles about 240 scientists around the world who are using NASA's Earth Observing System to study and forecast global changes. Businger's expertise is in the areas of atmospheric sciences, synoptic and mesoscale meteorology, hurricane energetics and water vapor using GPS. His presentation at the Chapman conference will explore recent GPS research results, opportunities, and some of the challenges facing this fast developing field. -UH- How water vapor affects the weather Water plays a pivotal role in atmospheric processes that act over a wide range of space and time. Latent energy is associated with water's phase changes (for example, from liquid to vapor). The transfer of this energy when water changes form affects the vertical stability of the atmosphere, the structure and evolution of storm systems, and the energy balance of the atmosphere from Equator to Pole. Water vapor-the most variable and inhomogeneous of the major constituents of the atmosphere-also contributes more than any other component to the greenhouse effect. Conversely, because liquid water in the form of clouds reflects light, it limits the solar radiation available to heat the Earth and its atmosphere. In both of these ways, the distribution of water vapor plays a crucial role in weather and global climate. How GPS helps quantify data on water vapor The ionosphere and the neutral atmosphere induce delays as GPS signals pass through the atmosphere. These delays can be precisely measured along a dozen or so GPS ray paths in the field of view of an Earth-based GPS receiver. Along each ray path the delays can be converted to a measurement of total water vapor, if surface pressure data are available. Using GPS to evaluate the distribution of humidity in the atmosphere A second approach for monitoring the Earth's atmosphere using GPS signals is to measure the delay of GPS signals that reach a Low Earth Orbit (LEO) satellite, as the LEO sets relative to the GPS satellite. Pressure and temperature assessments can be recovered from the resulting refractivity profile. The refractivity profiles can also yield information on the atmospheric humidity distribution if temperature and pressure distributions are known. Using GPS to improve weather forecasting Short-range precipitation forecasts might be improved with better resolution of the variability of water vapor. For example, simulations have shown that when water vapor data from GPS are included, the precipitation forecasts improve. |
-UH-
