HR: 09:30h
AN: A51F-07    [Abstracts]
TI: An Approach for Retrieving Marine Boundary Layer Refractivity From GPS Occultation Data
AU: * XIE, F
EM: xie@atmo.arizona.edu
AF: Department of Atmospheric Sciences, Institute of Atmospheric Physics, University of Arizona, 1118 East Fouth Street, P.O. BOX 210081, TUCSON, AZ 85721 United States
AU: Syndergaard, S
EM: ssy@ucar.edu
AF: COSMIC Project Office, UCAR, P.O. Box 3000, Boulder, CO 80307 United States
AU: Kursinski, R E
EM: kursinski@atmo.arizona.edu
AF: Department of Atmospheric Sciences, Institute of Atmospheric Physics, University of Arizona, 1118 East Fouth Street, P.O. BOX 210081, TUCSON, AZ 85721 United States
AU: Ao, C O
EM: chi.o.ao@jpl.nasa.gov
AF: Ionospheric and Atmospheric Remote Sensing Group, Jet Propulsion Laboratory M/S 238-600, 4800 Oak Grove Drive, Pasadena, CA 91109 United States
AU: Herman, B M
EM: herman@atmo.arizona.edu
AF: Department of Atmospheric Sciences, Institute of Atmospheric Physics, University of Arizona, 1118 East Fouth Street, P.O. BOX 210081, TUCSON, AZ 85721 United States
AB: The Marine Boundary Layer (MBL) is the lowest layer of the atmosphere over the ocean extending from the surface to about 1~3km. Information about this layer is very important for global weather forecasting and climate modeling, since the boundary layer is the interval where energy, momentum and mass are exchanged between the surface and the free atmosphere. However, the limited vertical extent of the MBL makes observations difficult in remote marine areas. Several features of GPS occultation technique provide a potential for MBL sensing from space. These features include global coverage, high vertical resolution, and cloud penetration capability. Over moist marine areas, a sharp increase in temperature and decrease in moisture are often observed at the top of the MBL. These sharp temperature and moisture gradients give rise to large refractivity gradients that cause a large bending of GPS occultation signal paths. This can cause super refraction (SR), i.e., the curvature radius of the signal ray path in principle becomes less than that of the Earth surface. Previous research shows that in the case of super refraction, the standard retrieved refractivity profile will be negatively biased inside and below the SR layer. Our studies indicate that beside the standard retrieved refractivity profile, a given bending angle profile from the observation can yield an infinite number of refractivity profiles. We have developed an approach to deal with such an ill-posed inverse problem. Based on some simple parameterizations, we are able to reconstruct the refractivity structure within and below the SR layer that is closest to the truth. In addition, a series of radiosonde datasets over oceans are analyzed for verification of our simple parameterizations. And the errors due to the key parameters used in the reconstruction method are evaluated. This reconstruction approach should greatly enhance our ability to measure the MBL structure globally using GPS observations, and would greatly improve the weather forecasting and climate modeling especially over remote ocean areas.
DE: 0350 Pressure, density, and temperature
DE: 1217 Time variable gravity (7223, 7230)
DE: 1220 Atmosphere monitoring with geodetic techniques (6952)
DE: 1225 Global change from geodesy (1222, 1622, 1630, 1641, 1645, 4556)
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005