Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) Station Position Product for Precise Orbit Determination from the NASA Crustal Dynamics Data Information System (CDDIS). DORIS is a dual-frequency Doppler system consisting of a receiver flying aboard a satellite and a globally distributed network of ground beacons. The DORIS receiver on-board the orbiting satellite tracks the dual-frequency radio signals transmitted by the network of ground beacons and generates the DORIS data. A measurement is made of either the Doppler shift or absolute phase as the satellite’s orbit moves over the ground-based beacon. DORIS data records contain a time-tagged range-rate measurement with associated ancillary information. DORIS observations from a global network can be utilized for a variety of products. Analysis Centers (ACs) of the International DORIS Service (IDS) retrieve DORIS data on a regular basis to compute station position solutions for the DORIS beacons supporting the IDS network. The IDS Analysis Center Coordinator combines these solutions to produce an official IDS product. This DPOD (DORIS extension of the ITRF for Precise Orbit Determination) solution is a set of coordinates and velocities of all the DORIS tracking stations for Precise Orbit Determination (POD) applications. The combined solution is generated in conjunction with official determination of the International Terrestrial Reference Frame. DPOD solutions are available in SINEX format.

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CDDIS Short Name: CDDIS_DORIS_IDSdpod_product Version ID: 1 Unique ID: C1602788193-CDDIS

Doppler Orbitography by Radiopositioning Integrated on Satellite (DORIS) Data (multi-day files) from the NASA Crustal Dynamics Data Information System (CDDIS). DORIS is a dual-frequency Doppler system consisting of a receiver flying aboard a satellite and a globally distributed network of ground beacons. The DORIS receiver on-board the orbiting satellite tracks the dual-frequency radio signals transmitted by the network of ground beacons and generates the DORIS data. A measurement is made of either the Doppler shift or absolute phase as the satellite’s orbit moves over the ground-based beacon. DORIS data records contain a time-tagged range-rate measurement with associated ancillary information. The data records also contain information about any corrections that may have been applied during the processing phase, such as for the ionosphere, troposphere, and satellite center of mass, among others. Furthermore, meteorological measurements (e.g., temperature, relative humidity, ground pressure) recorded by instruments co-located with the ground-based beacons are included with the DORIS data and can be used to determine the tropospheric correction. DORIS data in the original format are also supplied to the data center in multi-day files, corresponding to the mission’s data processing arc, and are forwarded approximately 20 days after the end of the last observation day contained in the file. More information about these data is available on the CDDIS website at https://cddis.nasa.gov/Data_and_Derived_Products/DORIS/DORIS_data_holdings.html.

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CDDIS Short Name: CDDIS_DORIS_data_multiday Version ID: 1 Unique ID: C1538790162-CDDIS

Doppler Orbitography by Radiopositioning Integrated on Satellite (DORIS) Station Position Time Series Product from the NASA Crustal Dynamics Data Information System (CDDIS). DORIS is a dual-frequency Doppler system consisting of a receiver flying aboard a satellite and a globally distributed network of ground beacons. The DORIS receiver on-board the orbiting satellite tracks the dual-frequency radio signals transmitted by the network of ground beacons and generates the DORIS data. A measurement is made of either the Doppler shift or absolute phase as the satellite’s orbit moves over the ground-based beacon. DORIS data records contain a time-tagged range-rate measurement with associated ancillary information. DORIS observations from a global network can be utilized for a variety of products. Analysis Centers (ACs) of the International DORIS Service (IDS) retrieve DORIS data on a regular basis and after producing the weekly SINEX files using the current ITRF, compute station position time series solutions for the DORIS beacons supporting the IDS network. The IDS Analysis Center Coordinator combines these individual AC solutions to generate the official IDS DORIS network time series solution in the IDS STCD (Station Coordinates Difference) format.

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CDDIS Short Name: CDDIS_DORIS_IDStimeseriesPositions_product Version ID: 1 Unique ID: C1544926730-CDDIS

Linked to this record are a report providing further details about the project, as well as the data from the project. Public Summary Regions of Antarctica are undergoing significant change in response to the Earth's changing climate. This project will provide a state of the art contemporary insight into the changing behaviour of the Totten drainage basin in East Antarctica - an area of vital importance in understanding ice/ocean/atmosphere and climate interactions in the Australian region of Antarctica. We will estimate the contribution of the Totten Glacier drainage basin to present-day sea level rise and simultaneously provide a critical validation of the European Space Agency (ESA) CryoSat-2 satellite mission over this region. Project #3121 investigated the mass balance of the Totten basin and provided an Australian contribution to the validation of CryoSat-2 data over Law Dome and the Totten Glacier. With field seasons in 2010/11 and 2011/12, the project gathered a range of in situ data using field and airborne data collection techniques. These data include geodetic quality GPS observations from up to 6 quasi-permanent GPS sites from which ice velocity, tropospheric water vapour and in some cases, tidal motion are derived. These sites were equipped with temperature and atmospheric pressure sensors, and in some cases, acoustic snow accumulation sensors. GPS equipped skidoo surveys were undertaken over the survey region on Law Dome to facilitate the generation of a validation surface to compare against airborne LiDAR and ASIRAS based DEMs. In the 2011/12 season, AWI collaborators achieved 4 days of survey flights in Polar-6, obtaining LiDAR and ASIRAS data over specific flight lines spanning Law Dome and the Totten Glacier. Project objectives: This project will provide a state-of-the-art contemporary insight into the most recent changes in the surface elevation of the Totten drainage basin in East Antarctica, whilst simultaneously providing a critical and unique contribution to the calibration and validation of the new European Space Agency (ESA) CryoSat-2 satellite mission and the Australian Antarctic Division (AAD) LiDAR/RADAR system. The present-day mass balance change of Antarctica plays a key role in understanding the effects of global warming on the Earth system, in particular the contribution of melting Antarctic ice to present-day sea level rise. The Totten Glacier is known to be undergoing significant surface lowering and is perhaps the most significant basin in the East Antarctic (e.g., Shepherd and Wingham, 2007). The basin itself drains approximately 1/8th of the East Antarctic Ice Sheet (EAIS) and, as a marine-based system, is analogous to the West Antarctic Ice Sheet (WAIS) whose changing mass balance dominates the Antarctic contribution to global sea level rise(Lemke et al., 2007). The TOT-Cal project will independently lead Australian research in understanding the contribution of Antarctic ice to changing sea-levels by focusing new data on this key drainage basin of international scientific interest. Importantly, this region can be reached with relative ease by AAD logistics - it is located literally at the doorstep of the Australian Casey station, in close proximity to the Wilkins intercontinental airstrip. With international interest focused on this region, this project provides a showcase of AAD short-stay logistics in support of vital time-critical research and a major new ESA satellite mission that will undoubtedly play a major role in cryospheric science into the future. The TOT-Cal project will draw upon key resources and personnel within the University of Tasmania (UTAS), Australian National University (ANU), Laboratoire d'Etudes en Geophysique et Oceanographie Spatiales (LEGOS, France), Scripps Institution of Oceanography (SIO, USA) and the AAD, requiring the collection and analysis of field based, airborne and satellite data over a multi-season campaign. It builds upon and extends related past, existing and planned Australian Antarctic Science (AAS), Australian Research Council (ARC) and International Polar Year (IPY) projects, addressing three specific questions: 1) What is the present-day mass balance of the Totten drainage basin and what is its contribution to global sea level change? This will be assessed through a combination of airborne LiDAR/RADAR observations, satellite altimetry observations including Seasat (1978), Geosat (1985-1989), ERS-1 (1992-1996), ERS-2 (1995-2005), Envisat-RA2 (2002 to present), ICESat (2003-present) and CryoSat-2 (expected launch 2009), space gravity observations (GRACE), along with ground-based validation experiments. 2) What are the accuracies and uncertainty characteristics of the altimetry measurement systems? (In other words, what is the expected accuracy of the altimetry-derived mass balance estimates?) With an emphasis on the new CryoSat-2 and AAD LiDAR/RADAR systems, this will be assessed through repeated ground and airborne experiments, providing direct contribution to the CryoSat-2 international Calibration, Validation and Retrieval Team (CVRT), whilst also providing an important cross-calibration of synchronous ICESat, Envisat and CryoSat-2 data. Of particular focus will be the understanding of the different surface interactions between the incident radar and laser waveforms (both satellite and airborne) with the surface snow/ice characteristics (topography, firn, seasonal changes, etc). 3) What is the magnitude of the present-day Glacial Isostatic Adjustment (GIA) in the region that needs to be removed from the space-based geodetic observations in order to estimate mass balance using a space geodetic approach? Present uncertainty in the magnitude of GIA is a dominant error source in the mass balance error budget and requires an analysis of recent models and in-situ geodetic evidence in order to fully understand and minimise this error contribution. Each of the objectives set out above will be assessed with data acquired over the coming three summer seasons, leading into participating in the larger period of logistics support around the Totten Glacier in 2011/12. This also enables this project to provide state-of-the-art estimates of surface lowering to the Australian AAD/ACECRC modelling team (R.Warner et al) for integration into dynamic ice models in the subsequent years of this project. These estimates will be fundamental in improving conventional forward ice models which to date, are not able to predict the observed changes in the Totten Glacier (van der Veen et al. 2008). The timing of the work outlined in this proposal is critical given the CryoSat-2 launch (expected late 2009) and the impending conclusion of the GRACE mission, this research needs to be undertaken now for the field seasons indicated in order to maximise the scientific impact and provide the necessary complement to other planned AAS projects that will operate over the same future field seasons. Public summary of the season progress: 2010/11 was the first field season for this project. Valuable GPS field data were acquired in the Law Dome and Totten Glacier regions to assist with providing an Australian contribution to the validation of the CryoSat-2 ice monitoring satellite mission, and to further understand ice shelf/ocean interactions and climate change in this region. Planned airborne surveys by the German AWI Polar-5 aircraft were unable to be completed due to poor weather. Collaboration with the 'Investigating the Cryospheric Evolution of the Central Antarctic Plate' project (ICECAP - UTexas) yielded important airborne scanning laser altimeter elevation data over the Law Dome site.

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AU_AADC Short Name: AAS_3121 Version ID: 1 Unique ID: C1214311635-AU_AADC

This ITS_LIVE data set, part of the Making Earth System Data Records for Use in Research Environments (MEaSUREs) Program, includes quarterly estimates of Antarctic ice shelf surface elevation, thickness, basal melt rate, surface mass balance, firn air content, and associated errors, from 17 March 1992 through 16 December 2017 at 1920 m resolution. The data were generated from four European Space Agency (ESA) satellite radar altimetry missions—ERS-1, ERS-2, Envisat, and CryoSat-2—using a novel data fusion approach and the Glacier Energy and Mass Balance model (GEMB).

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NSIDC_ECS Short Name: NSIDC-0792 Version ID: 1 Unique ID: C3178054062-NSIDC_ECS