Ramesh Govind

University of Cape Town | UCT · Division of Geomatics

Tide gauge data is important for determining global or local sea level rise with respect to a global geocentric reference frame. Data from repeated precise levelling connections between the tide gauges and a series of coastal and inland benchmarks, including Continuous GPS (CGPS) benchmarks, are used to determine the stability of tide gauges at 12...

In 2012, the International Earth Rotation and Reference Systems Service (IERS) released a call for space geodetic solutions corrected for non-tidal atmospheric loading at the observation level. The main objective of this analysis campaign is to evaluate the impact of non-tidal atmospheric loading corrections on Terrestrial Reference Frame (TRF), ge...

For the preparation of ITRF2008, the IDS processed data from 1993 to 2008, including data from TOPEX/Poseidon, the SPOT satellites and Envisat in the weekly solutions. Since the development of ITRF2008, the IDS has been engaged in a number of efforts to try and improve the reference frame solutions. These efforts include (i) assessing the contribut...

In a collaborative effort with the regional sub-commissions within IAG sub-commission 1.3 "Regional Reference Frames", the IAG Working Group (WG) on "Regional Dense Velocity Fields" (see http://epncb.oma.be/IAG) has made a first attempt to create a dense global velocity field. GNSS-based velocity solutions for more than 6,000 continuous and episodi...

For the preparation of ITRF2008, the IDS processed data from 1993 to 2008, including data from TOPEX/Poseidon, the SPOT satellites and Envisat in the weekly solutions. Since the development of ITRF2008, the IDS has been engaged in a number of efforts to try and improve the reference frame solutions. These efforts include assessing the contribution...

Geoscience Australia contributed a multi-satellite, multi-year weekly time series to the International DORIS Service combined submission for the construction of International Terrestrial Reference Frame 2008 (ITRF2008). This contributing solution was extended to a study of the capability of DORIS to dynamically estimate the variation in the geocent...

Updated absolute calibration results from Bass Strait, Australia, are presented for the TOPEX/Poseidon (T/P) and Jason-1 altimeter missions. Data from an oceanographic mooring array and coastal tide gauge have been used in addition to the previously described episodic GPS buoy deployments. The results represent a significant improvement in absolute...

An absolute calibration of the TOPEX/Poseidon (T/P) and Jason-1 altimeters has been undertaken during the dedicated calibration phase of the Jason-1 mission, in Bass Strait, Australia. The present study incorporates several improvements to the earlier calibration methodology used for Bass Strait, namely the use of GPS buoys and the determination of...

The Lambert–Amery System is the largest glacier–ice shelf system in East Antarctica, draining a significant portion of the ice sheet. Variation in ice sheet discharge from Antarctica or Greenland has an impact on the rate of change in global mean sea level; which is a manifestation of climate change. In conjunction with a measure of ice thickness c...

The International DORIS Service (IDS), in operation since 2003, submitted three sets of solutions to ITRF2005 from the IGN/JPL, LEGOS/CLS, and INASAN analysis centers, but no DORIS technique combination. Since that time new analysis centers have become operational including the Geodetic Observatory Pecny (GOP), the European Space Operations Center...

The International DORIS Service (IDS), in operation since 2003, submitted three sets of solutions to ITRF2005 from the IGN/JPL, LEGOS/CLS, and INASAN analysis centers, but no DORIS technique combination. Since that time new analysis centers, have become operational, including the Geodetic Observatory Pecny (GOP), and the European Space Operations C...

The Working Group “Regional Dense Velocity Fields” was created at the IUGG meeting in Perugia in 2007. It is part of IAG Sub-Commission 1.3 ’Regional Reference Frames’ which is imbedded in IAG Commission 1 on Reference Frames. The Working Group aims at using the large amount of available GNSS CORS and campaign data to produce dense velocity fields....

The IAG Working Group (WG) on "Regional Dense Velocity Fields" was created within IAG sub-commission 1.3 "Regional Reference Frames" at the IUGG General Assembly in Perugia in 2007. The goal of the Working Group is to densify the latest realization of the ITRS and provide regional dense velocity information in a common global reference frame. For t...

Due to its accuracy, low cost of receivers, versatility and the ability to provide results in a global reference frame, Global Navigation Satellite Systems (GNSS) are presently the main sensor of the Earth’s surface deformation. Consequently, GNSS networks have been installed all over the world and repeated GNSS campaigns are conducted to monitor g...

The International DORIS Service is in operation since 2003. Over the last four years, five instruments on the SPOT 2-4-5, ENVISAT and the JASON-1 satellites have provided DORIS Doppler data collected from a global network of about 50 stations. The number of Analysis Centers (AC) who have processed the data and have high level experience has progres...

The Lageos-1 (L1) and Lageos-2 (L2) satellites have formed the basis of the ILRS contribution to the ITRF2005. These geodetic cannonball satellites, launched in 1976, and 1992 respectively are well suited for this purpose, by virtue of their high altitude, and lack of sensitivity to either high degree gravity terms or the deleterious effects of atm...

Absolute gravity measurements have been carried out in Perth and Canberra, Australia, and at Syowa Station, Antarctica, as a part of activities of the 45th Japanese Antarctic Research Expedition during 2003–2004. Using a FG-5 (#210), the measurements in Perth were conducted at the Perth Observatory on November 25 and 26, 2003, and those in Canberra...

An absolute calibration of the TOPEX/Poseidon (T/P) and Jason-1 altimeters has been undertaken during the dedicated calibration phase of the Jason-1 mission, in Bass Strait, Australia. The present study incorporates several improvements to the earlier calibration methodology used for Bass Strait, namely the use of GPS buoys and the determination of...

The Asia Pacific Regional Geodetic Project 1997 (APRGP97) was undertaken under the auspices of the Working Group on Asia and the Pacific Regional Geodetic Networks, Permanent Committee on GIS Infrastructure for Asia and the Pacific, UN Regional Cartographic Conference for Asia and the Pacific. The planned major outcomes of the project, which includ...

The history of both local and geocentric geoid evaluation for Australia is reviewed and the present status of detailed geoid computation given. As of December, 1990 all of Australia has been evaluated at a resolution of 0.1° by the Geodetic Services Section of AUSLIG, using OSU89A as the reference model, and detailed gravity from a modified version...

All geoids in this category are relative to the Australian Geodetic Datum — the AGD, defined by the Australian National Spheroid (ANS), a = 6378160, f−1 = 298.25, and the position of Johnstone Origin which was defined by φ = −25° 57’, λ= 133° 12’, h = 571.2 m.

In mid 1987 the Division of National Mapping (now amalgamated into the Australian Survey and Land Information Group (AUSLIG) of the Department of Administrative Services), and the School of Surveying of the University of New South Wales (UNSW) jointly initiated and embarked upon an Australian GPS Orbit Determination Pilot Project (Rizos et al., 198...

The Australian Surveying and Land Information Group's Online GPS Processing Service (AUSPOS) provides users with the facility to submit via the Internet, dual frequency geodetic quality GPS RINEX data observed in a 'static' mode and receive rapid turn-around precise coordinates. The service is free and provides ITRF coordinates worldwide, it is ava...

In order to monitor changes in absolute sea level, the vertical motion of the crust at the tide gauge location must also be monitored in an accurate, global terrestrial reference frame. During the last week of May 1995, five days of GPS data was observed at over 30 inland and coastal sites related to the tide gauge array. In addition, the data set...

The Asia Pacific Regional Geodetic Project 1997 (APRGP97) includes GPS observations from 73 GPS receivers throughout the Asia Pacific region. Nine days of APRGP97 GPS data, observed GPS week 927 (days 0 – 6) and 928 (days 0 -1), has been processed and analysed at AUSLIG. The data set, processing strategy (measurement, orbit and reference frame mode...

Thesis (Ph. D.)--University of Colorado, 1994. Includes bibliographical references (leaves 208-214).