Geology topics

T. A. Scambos

Publications and source records attributed to T. A. Scambos.

4 recordsLinked to original sources

USGS2014

Landsat-8: Science and product vision for terrestrial global change research

Landsat 8, a NASA and USGS collaboration, acquires global moderate-resolution measurements of the Earth's terrestrial and polar regions in the visible, near-infrared, short wave, and thermal infrared. Landsat 8 extends the remarkable 40 year Landsat record and has enhanced capabilities including new spectral bands in the blue and cirrus cloud-detection portion of the spectrum, two thermal bands, improved sensor signal-to-noise performance and associated improvements in radiometric resolution, and an improved duty cycle that allows collection of a significantly greater number of images per day. This paper introduces the current (2012–2017) Landsat Science Team's efforts to establish an initial understanding of Landsat 8 capabilities and the steps ahead in support of priorities identified by the team. Preliminary evaluation of Landsat 8 capabilities and identification of new science and applications opportunities are described with respect to calibration and radiometric characterization; surface reflectance; surface albedo; surface temperature, evapotranspiration and drought; agriculture; land cover, condition, disturbance and change; fresh and coastal water; and snow and ice. Insights into the development of derived ‘higher-level’ Landsat products are provided in recognition of the growing need for consistently processed, moderate spatial resolution, large area, long-term terrestrial data records for resource management and for climate and global change studies. The paper concludes with future prospects, emphasizing the opportunities for land imaging constellations by combining Landsat data with data collected from other international sensing systems, and consideration of successor Landsat mission requirements.

Remote Sensing of Environment↗

USGS2011

Recent surface temperature trends in the interior of East Antarctica from borehole firn temperature measurements and geophysical inverse methods

We use measured firn temperatures down to depths of 80 to 90 m at four locations in the interior of Dronning Maud Land, East Antarctica to derive surface temperature histories spanning the past few decades using two different inverse methods. We find that the mean surface temperatures near the ice divide (the highest‐elevation ridge of East Antarctic Ice Sheet) have increased approximately 1 to 1.5 K within the past ∼50 years, although the onset and rate of this warming vary by site. Histories at two locations, NUS07‐5 (78.65°S, 35.64°E) and NUS07‐7 (82.07°S, 54.89°E), suggest that the majority of this warming took place in the past one or two decades. Slight cooling to no change was indicated at one location, NUS08‐5 (82.63°S, 17.87°E), off the divide near the Recovery Lakes region. In the most recent decade, inversion results indicate both cooler and warmer periods at different sites due to high interannual variability and relatively high resolution of the inverted surface temperature histories. The overall results of our analysis fit a pattern of recent climate trends emerging from several sources of the Antarctic temperature reconstructions: there is a contrast in surface temperature trends possibly related to altitude in this part of East Antarctica.

Geophysical Research Letters↗

USGS1998

Influence of subglacial geology on the onset of a West Antarctic ice stream from aerogeophysical observations

Marine ice-sheet collapse can contribute to rapid sea-level rise . Today, the West Antarctic Ice Sheet contains an amount of ice equivalent to approximately six metres of sea-level rise, but most of the ice is in the slowly moving interior reservoir. A relatively small fraction of the ice sheet comprises several rapidly flowing ice streams which drain the ice to the sea. The evolution of this drainage system almost certainly governs the process of ice-sheet collapse . The thick and slow-moving interior ice reservoir is generally fixed to the underlying bedrock while the ice streams glide over lubricated beds at velocities of up to several hundred metres per year. The source of the basal lubricant — a water-saturated till overlain by a water system — may be linked to the underlying geology. The West Antarctic Ice Sheet rests over a geologically complex region characterized by thin crust, high heat flows, active volcanism and sedimentary basins . Here we use aerogeophysical measurements to constrain the geological setting of the onset of an active West Antarctic ice stream. The onset coincides with a sediment-filled basin incised by a steep-sided valley. This observation supports the suggestion that ice-stream dynamics — and therefore the response of the West Antarctice Ice Sheet to changes in climate — are strongly modulated by the underlying geology.

Nature↗

USGS1986

The Center Pond pluton: The restite of the story (phase separation and melt evolution in granitoid genesis)

The Center Pond pluton is a calc-alkaline post-tectonic Acadian body intruding chlorite grade Silurian metasediments of E-central Maine. Mapping and petrographic work reveal that the pluton contains 5 igneous rock types; quartz diorite, hornblende-biotite granodiorite, biotite granite, porphyritic granite, and aplitic granite. The linearity of major and trace element trends and Rb-Sr isotope systematics indicate that partial melting and unmixing of a single mafic or intermediate metaigneous rock to restite (residual phases in equilibrium with the melting event at depth) and near-eutectic minimum melt may account for much of the observed geochemical variation within the Center Pond pluton. Major and trace element trends rule out fractional crystallization as a model for Center Pond. -from Authors

Maine↗