Trial of the French Transportable Laser Ranging System (FTLRS)

Jason Zhang¹ Chris Watson², Francis Pierron³, Richard Coleman^2,4,5, Paul Tregoning¹

1 Research School of Earth Sciences, Australian National University, Canberra, ACT
2 University of Tasmania, Hobart, Tasmania
3 Observatoire de la Côte d'Azur, Grasse, France
4 Centre for Australian Weather and Climate Research (CAWCR), Hobart, Tasmania
5Antarctic Climate and Ecosystems Cooperative Research Centre, Hobart, Tasmania

Figure 1. FTLRS in night operation

The Bass Strait in-situ calibration site has been used in the calibration and validation of satellite altimeter data since the launch of TOPEX/Poseidon in 1992. The primary focus at the site has been the estimation of absolute bias in altimeter derived sea surface height (SSH) using a combination of oceanographic moorings, GPS buoy deployments, coastal tide gauge and land based GPS data. As the sole site of its kind in the Southern Hemisphere, the Bass Strait site provides important input into understanding various error sources in satellite altimetery.

With an objective of improving our understanding of any geographically correlated orbit errors present in altimeter orbits, the Bass Strait site was selected as part of a collaborative French/Australian project to trial the French Transportable Laser Ranging System (FTLRS). The FTLRS was operated in Tasmania over a five month period between 1 December 2007 to 17 April 2008 jointly by French and Australian staff. The FTLRS and temporary GPS were located within the city of Burnie beneath Jason-1 descending pass 088, several kilometers from the Burnie tide gauge/CGPS and inland CGPS sites.

During the Tasmanian FTLRS campaign, a total of 673overflights from 12 different satellites were observed and a total of 9200 normal points have been computed In this poster, we present initial results from our analysis of FTLRS data. Whilst building SLR capacity in Australia, we seek to highlight the influence of an additional tracking station in this area of the Southern Hemisphere. Our FTLRS based orbits will assist in quantifying regional or geographically correlated orbit errors present in satellite altimeter data, allowing any bias in altimetry derived SSH in this region to be estimated.

Figure 2. Sketch of the Bass Straite In-Situ Calibration Site.