Martinson, D. G. and D. C. McKee, 2012: Transport of warm Upper Circumpolar Deep Water onto the western Antarctic Peninsula continental shelf. Ocean Science, 8(4): 433-442.
Five thermistor moorings were placed on the continental shelf of the western Antarctic Peninsula (between 2007 and 2010) in an effort to identify the mechanism(s) responsible for delivering warm Upper Circumpolar Deep Water (UCDW) onto the broad continental shelf from the Antarctic Circumpolar Current (ACC) flowing over the adjacent continental slope. Historically, four mechanisms have been suggested: (1) eddies shed from the ACC, (2) flow into the cross-shelf-cutting canyons with overflow onto the nominal shelf, (3) general upwelling, and (4) episodic advective diversions of the ACC onto the shelf. The mooring array showed that for the years of deployment, the dominant mechanism is eddies; upwelling may also contribute but to an unknown extent. Mechanism 2 played no role, though the canyons have been shown previously to channel UCDW across the shelf into Marguerite Bay. Mechanism 4 played no role independently, though eddies may be advected within a greater intrusion of the background flow.
Martinson, D. G., 2012: Antarctic circumpolar current's role in the Antarctic ice system: An overview. Palaeogeography Palaeoclimatology Palaeoecology, 335: 71-74.
The Antarctic Circumpolar Current (ACC) provides fundamental control on the Antarctic ice system. The tilt of the isopycnals of the ACC, in response to strong westerlies, serves to thermally isolate the Antarctic continent from directly receiving the overwhelming subtropical ocean surface heat. This same tilt provides the northern boundary of the polar seas; as such it "contains" the statically stable cold fresh surface polar waters required for sea ice formation. In this manner it effectively sets the northern limit for seasonal sea ice formation. The isopycnal tilt also allows warm deep water to upwell to the surface near the continental margin in western Antarctica where the ACC skirts the continental shelf, leading to excessive ocean heat flux to the atmosphere in winter, and providing heat to melt the underside of the glacial ice. (c) 2011 Elsevier B.V. All rights reserved.
Ruiz, D., D. G. Martinson and W. Vergara, 2012: Trends, stability and stress in the Colombian Central Andes. Climatic Change, 112(3-4): 717-732.
Mountain ecosystems have been projected to experience faster rates of warming than surrounding lowlands. These changes in climatic conditions could have significant impacts on high-altitude Andean environments, affecting the quality and magnitude of their economic and environmental services. Even though long-term data in these regions are limited, it is important to identify any discernible long-term trends in local climatic conditions. Time series of several variables were analyzed to detect statistically significant long-term linear trends that occurred over recent years in a ecosystem of the Colombian Central Andes. Records included cloud characteristics, sunshine, rainfall, minimum and maximum temperatures, diurnal temperature range, and relative humidity. Conditions of atmospheric stability were also explored. Total sunshine exhibited decreasing trends ranging from -3.7 to -8.5% per decade at altitudes around the pluviometric optimum. The strongest changes in sunshine occurred during the December-January-February season. Mean relative humidity observed at altitudes around and below this threshold showed increasing trends of +0.6 to +0.7% per decade. Annual rainfall and mean relative humidity above the optimum showed decreasing trends ranging from -7 to -11% per decade and from -1.5 to -3.6% per decade, respectively. Minimum temperatures on the coldest days and maximum temperatures on the warmest days exhibited increasing trends at all altitudes ranging from +0.1 to +0.6, and from +0.2 to +1.1A degrees C per decade, respectively. Increases in minimum and maximum temperatures at higher altitudes were significantly greater than those observed in average at lower altitudes. The strongest changes in minimum temperatures, particularly, occurred during the December-January-February and June-July-August dry seasons. All these changes suggest that atmospheric conditions in the area are shifting from statically unstable conditions to conditionally unstable or statically stable conditions. Observed historical trends indicate that climate impacts and other human activities have stressed these unique and fragile environments.
Steinberg, D. K., D. G. Martinson and D. P. Costa, 2012: Two Decades of Pelagic Ecology of the Western Antarctic Peninsula. Oceanography, 25(3): 56-67.
Significant strides in our understanding of the marine pelagic ecosystem of the Western Antarctic Peninsula (WAP) region have been made over the past two decades, resulting from research conducted aboard ARSV Laurence M. Gould and RVIB Nathaniel B. Palmer. These advances range from an understanding of the physical forcing on biology, to food web ecology (from microbes to top predators), to biogeochemical cycling, often in the larger context of rapid climate warming in the region. The proximity of the WAP to the Antarctic Circumpolar Current and WAP continental shelf bathymetry affects the hydrography and helps structure the biological community. Seasonal, spatial, and interannual variability at all levels of the food web, as well as the mechanisms supporting their production, are now more clearly understood. New tools and technologies employed in the region were critical for making this research possible. As a result, our knowledge of the WAP pelagic ecosystem during a time of rapid climate change has vastly improved.
The database was updated today.