Per Knudsen

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The Greenland GPS Network (GNET) uses the Global Positioning System (GPS) to measure the displacement of bedrock exposed near the margins of the Greenland ice sheet. The entire network is uplifting in response to past and present-day changes in ice mass. Crustal displacement is largely accounted for by an annual oscillation superimposed on a sustained(More)
HPLC utilizing a high efficiency anion-exchange column provides a rapid and easily automated technique for the qualitative and quantitative analysis of subnanogram to microgram amounts of DNA fragments generated by the PCR. The accuracy, precision and linearity of this method exceed those attainable with electrophoretic techniques. In addition, because of(More)
Accurate quantification of the millennial-scale mass balance of the Greenland ice sheet (GrIS) and its contribution to global sea-level rise remain challenging because of sparse in situ observations in key regions. Glacial isostatic adjustment (GIA) is the ongoing response of the solid Earth to ice and ocean load changes occurring since the Last Glacial(More)
We review the procedures and challenges that must be considered when using geoid data derived from the Gravity and steady-state Ocean Circulation Explorer (GOCE) mission in order to constrain the circulation and water mass representation in an ocean general circulation model. It covers the combination of the geoid information with time-mean sea level(More)
This report is a quantitative study of gravity field and geoid, mean sea surface, mean ocean dynamic topography and tides for the Arctic Ocean, for a large range of existing and new models. The report gives quantitative assessments of errors and error covariances of the different fields, mainly for use of understanding total errors in the mean sea surface(More)
This paper describes the design of a simple low cost GNSS sampler with integrated storage. The sampler is built from low cost, off-the-shelf components. The proposed design stores digital IF samples from two separate front ends and record the data to a SD card for post-mission processing. The GNSS sampler currently supports GPS and GLONASS signals, but(More)
A procedure of making membranes of amphiphilic materials at the bottom of a U-shaped flexible plastic tube within an aqueous medium is described. The membranes were made sufficiently large in order for the annulus area to be neglected. Consequently the hydrophobic thickness of the membrane could be measured by a capacitance technique assuming the relative(More)
From a transdisciplinary approach in the town of Thyboron, Denmark, we investigate couplings between sea state (i.e., mean and extreme) and flooding hazards today and ahead. This includes analyses of change and variability in the groundwater table, precipitation, land motion, geotechnical ground properties, sewerage systems and other infrastructure to(More)
NASA’s Space Environment Simulation Laboratory’s (SESL) Chamber A, located at the Johnson Space Center in Houston Texas has recently implemented major enhancements of its cryogenic and vacuum systems. The new liquid nitrogen (LN) thermo-siphon system was successfully commissioned in August of 2012. Chamber A, which has 20 K helium cryo-panels (or “shrouds”)(More)
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