Remote GPS Networks: Rationale Carol A. Raymond, Erik R. Ivins JPL/Caltech

Rationale for Antarctic Continuous GPS stations and Constraints on Station Architecture Continuous GPS measurements contribute to understanding the interaction between ice sheet history and dynamics, and earth rheology. Support time-varying gravity measurements of ice mass change. Rationale for Continuous Measurements: Vertical rates are low (typically few cm?) and need for accuracy is high to resolve gentle gradients Incomplete noise characterization (phase center drifts, biases, seasonal tropospheric variations, ionosphere, reference frame issues)for data lengths of < 30 days? Constraints: If rheology is stiff, and loads are ancient, uplift gradients are small If loads are young, uplift gradients might be large. Likely there will be a spectrum of uplift scales that must be deconvolved to understand their origin in lateral heterogeneity of earth rheology, and/or glacial loading histories of individual drainage basins

High precision vertical components are critical for distinguishing competing models Current results favor recent ice mass change - indicating smaller scale gradients are expected

Proposed TAM CGPS Network continues decadal-length times series at 4 sites WAGN occupations W13 Network proposed in 2004 (Raymond et al.) is designed to measure glacioisostatic deformation in region most sensitive to testing models Donnellan and Luyendyk (1997-2001) Raymond et al. (1996-2001) TAMDEF Air Force Seismic Stations (new)

Proposed Next-Generation Station Architecture

Picosat and UAV System Engineering (PAUSE) Li-SoCl2 batteries Magnetometer package is undergoing lab thermal testing (30 C to -60C) Stratospheric balloon tests in October 2004 Components, software and architecture can be reused for GPS stations Freewave modem magnetometer single board computer

Tumbleweed Polar Rover