HR: 14:25h
AN: G43D-04 INVITED    [Abstracts]
TI: Kinematic GPS positioning of an aircraft and the vertical structure of atmospheric refractivity
AU: * Bevis, M
EM: mbevis@osu.edu
AF: Ohio State University, 275 Mendenhall Laboratory 125 South Oval Mall, Columbus, OH 43210, United States
AU: Mader, G
EM: gerry20882@yahoo.com
AF: National Geodetic Survey, 1315 East-West Highway, Silver Springs, MD 20910, United States
AU: Shan, S
EM: shan.19@osu.edu
AF: Ohio State University, 275 Mendenhall Laboratory 125 South Oval Mall, Columbus, OH 43210, United States
AB: During the B4 LIDAR survey each flight of the NCALM aircraft was positioned using many different base stations: instantaneous baseline lengths ranged from less than 1 km to more than 200 km. When we used our kinematic GPS processing software (KARS) in its default mode, the individual trajectory solutions were usually mutually biased in the vertical, particularly when the base stations were located in areas with significant topography. In these cases, relative height biases as large as 20 cm were observed. We found that these biases were caused by errors in atmospheric delay modeling which were systematically organized according to the elevation of the base station (or aircraft). We previously demonstrated how static geodetic analysis of the network of base stations could be used to estimate how zenith delay [ZD] varied with station elevation, and that when the KGPS software was forced to use a ZD(h) model that was consistent with these external measurements, the height biases in the various trajectory solutions almost completely disappeared. This 'external calibration' technique was extremely useful in diagnosing the problem we had encountered, but it is not a good general purpose solution for the problem because (i) it works only in areas with significant topography, and (ii) it involves a rather cumbersome interaction between the static and kinematic GPS analyses. In this talk we present an alternative approach based on direct estimation of zenith delay parameters in the context of the kinematic analysis. We are using this approach to reprocess the entire set of B4 flight trajectories.
DE: 1241 Satellite geodesy: technical issues (6994, 7969)
DE: 1243 Space geodetic surveys
SC: Geodesy [G]
MN: 2007 Fall Meeting