Herbert Landau

Determination of instantaneous sea surface, wave heights, and ocean currents using satellite observations of the global positioning system

Abstract Using GPS phase observations in the kinematic mode, we are able to achieve centimeter accuracy in relative three‐dimensional coordinates. This could be verified even for fast‐moving sensors in aircraft, such as airborne photogrammetric cameras, at the time of exposure. Sophisticated kinematic software has been developed resolving cycle slips and carrier‐phase ambiguities during motion. To determine the instantaneous sea surface, the GPS receiver is placed in a free‐drifting buoy with the antenna on top. Differencing the 1‐Hz observations, wave heights can be determined as well as velocity and direction of ocean (tidal) currents. This article deals with the experiences from a test for the practical realization of this proposal. Hardware installation, software, and data analysis are described. Plans to use such an observational scenario of a GPS buoy array in the North Sea for the calibration of the radar altimeter of the European satellite ERS‐1 are presented.

An Integrated Precise Airborne Navigation and Gravity Recovery System

In July / August 1989 a series of test-flights was carried out to investigate the possibility of integrating different sensors for precise position determination and gravity recovery. The tests were flown with a Dornier DO 128 fixed-wing research aircraft over the North Sea and also over a test area in the northern part of Germany.

GPS Derived Displacements in the Azores Triple Junction Region

The Global Positioning System (GPS) has been used to establish a high precision network in the Azores Archipelago for detection of relative displacements between the different islands.