4. Programmatic Contributions

4.1. Contribution to EOS Program/Panel Activities

The principal investigator and co-investigators have participated in the Investigator Working Group meetings, and meetings associated with the Precision Orbit Determination/Mission Design Panel, Oceans Panel, Solid Earth Panel, Atmosphere Panel, EOSDIS Panel, Calibration and Data Product Validation Panel, PO-DAAC User Group, and the Payload Advisory Panel. The investigators are contributing to the draft of the EOS Science Plan and other relevant EOS documents.

In addition, the principal investigator served as a member of the EOS Science Executive Committee (SEC) and chaired the SEC Payload Advisory Panel. He also chaired the SEC-formed EOS Altimeter Study Group, charged with assessing the applicability of the NASA/CNES TPFO mission and the NASA/Navy GFO mission to the requirements of the EOS ALT-R mission [Tapley et al., 1994]. The output of this study provided the basis for the NASA decision to recommend in a joint NASA/Navy congressionally mandated report that the EOS ALT-R requirements be met by the NASA/CNES TPFO mission. In addition, the principal investigator has been charged with conducting a collaborative study with European counterparts to define the mission requirements for a gravity mapping mission to improve the global marine geoid. This mission is required for altimeter-based studies of the general ocean circulation.

4.2. Data Product Requirements

We have compiled input/output data product size, schedule, data types, and proposed data transfer mechanism for our EOS IDS investigation. The information was submitted in response to a request from Bruce Barstrom, Chair, the Ad Hoc Working Group on Production (AHWGP). The specific higher level data products we require include: (1) Earth orientation time series (Universal Time and polar motion), (2) time-varying gravitational effects, (3) sea level variations, (4) atmospheric and oceanic motion (winds/currents) and mass field, (5) surface stress torques from scatterometer-measured vector winds, (6) ice sheet variations, (7) sea and land surface temperatures, and (8) fields of water vapor distribution and transport. The highly accurate determination of the Earth orientation parameters can be measured by modern space-based techniques of satellite laser ranging, very long baseline interferometry, and the Global Positioning System. Time-varying gravitational effects resulting from complicated interactions between the solid Earth-atmosphere-ocean-cryosphere components can be measured by analysis of SLR measurements to geodetic satellites, and by analyzing model outputs from GCMs for each of the components, or coupled models. Global mean sea level variations can be measured by long-term altimeter measurements. These measurements and stress torques from satellite scatterometry can be used to establish angular momentum and torque budgets for the Earth system dynamics. Mass balance of global ice sheets can be measured by EOS laser altimeter (GLAS). Other measurements include output from atmospheric, hydrological and oceanic GCMs (e.g., GEOS), and pre-EOS and EOS atmospheric, wind, and sea level measurements.

4.3. Data Products and Deliverables

The data products we are currently producing from pre-EOS sensors and will produce using EOS and other space geodetic measurements include (1) three Earth orientation excitation time series from IERS Earth Orientation Parameters which are free from the effect of Earth and ocean tides, (2) two complex orbital excitation time series for each spherically-shaped SLR satellite which are free from the effects of Earth and ocean tides and, to the extent possible, from non-gravitational perturbations, (3) synthesized excitations of predicted orbital and Earth orientation excitations due to atmospheric mass redistribution and angular momentum from analysis of available wind, pressure, and hydrologic fields, such as GEOS, NMC and ECMWF, or from a combination of such results (coupled-model outputs), with and without apply inverted barometric corrections, (4) predicted orbital and Earth orientation excitations due to ocean bottom pressure fields from the output of ocean circulation models, and from coupled-atmosphere-ocean-land models, predicted orbital and Earth orientation excitations from ground water variations, and ice sheet volume changes. Lower level data products from our investigation include (1) dynamic ocean topography, mesoscale variabilities, and mean sea level variations, from radar altimeter missions, and from the combined altimeter measurements, (2) SLR-derived Earth orientation parameters and station coordinates and orbital excitations, (3) accurate ephemerides for altimetric and geodetic satellites (Lageos, Starlette, Ajisai, Seasat, ERS-1, ERS-2, Geosat, TOPEX/Poseidon, GFO-1, and Envisat), (4) global ocean tide and tidal-loading models, (5) atmospheric angular momentum time series, (6) oceanic angular momentum time series, and (7) time series for atmosphere-land-ocean torques.

Results of our investigation lead directly to the broad distribution of the atmospheric angular momentum time series and related data products to the international geodetic, astronomical, geophysical, and meteorological scientific communities through the International Earth Rotation Service. The TOPEX/Poseidon (T/P) observed oceanic dynamic topography maps are being computed with unprecedented accuracy, and in near-real time. We have been contributing monthly computed T/P sea level maps to NOAA's Climate Diagnostic Bulletin. The center has established and will update a WWW homepage to support educational outreach resources, promote and discuss EOS related projects and analyses, provide a forum for scientific results and interchange, and facilitate access to current and future analysis products.