Released on 2011Categories

Spatial and Temporal Dynamics of Primary Production in Antarctic Sea Ice

Spatial and Temporal Dynamics of Primary Production in Antarctic Sea Ice

Author:

Publisher: Stanford University

ISBN: STANFORD:pr685xp6352

Category:

Page:

View: 685

Sea ice is an important driver of climate patterns and polar marine ecosystem dynamics. In particular, primary production by microalgae in sea ice has been postulated as a sink for anthropogenic CO2, and as a critical resource in the life cycle of Antarctic krill Euphausia superba, a keystone species. Study of the sea ice ecosystem is difficult at regional and global scales, however, because of the expense and logistical difficulties in accessing such a remote and hostile environment. Consequently, models remain valuable tools for investigations of the spatial and temporal dynamics of sea ice and associated ecology and biogeochemistry. Recent advances in model representations of sea ice have called into question the accuracy of previous studies, and allow the creation of new tools to perform mechanistic simulations of sea ice physics and biogeochemistry. To address spatial and temporal variability in Antarctic sea ice algal production, and to establish the bounds and sensitivities of the sea ice ecosystem, a new, coupled sea ice ecosystem model was developed. In the vertical dimension, the model resolves incorporated saline brine, macronutrients concentrations, spectral shortwave radiation, and the sea ice algae community at high resolution. A novel method for thermodynamics, desalination, and fluid transfer in slushy, high-brine fraction sea ice was developed to simulate regions of high algal productivity. The processes of desalination, fluid transfer, snow-ice creation, and superimposed ice formation allowed the evolution of realistic vertical profiles of sea ice salinity and algal growth. The model replicated time series observations of ice temperature, salinity, algal biomass, and estimated fluid flux from the Ice Station Weddell experiment. In the horizontal dimension, sub-grid scale parameterizations of snow and ice thickness allow more realistic simulation of the ice thickness distribution, and consequently, sea ice algal habitat. The model is forced from above by atmospheric reanalysis climatologies, and from below by climatological ocean heat flux and deep-water ocean characteristics. Areal sea ice concentration and motion are specified according to SSM/I passive microwave satellite estimates of these parameters. Sensitivity testing of different snow and ice parameterizations showed that without a sub-grid scale ice thickness distribution, mean ice and snow thickness is lower and bottom sea ice algal production is elevated. Atmospheric forcing from different reanalysis data sets cause mean and regional shifts in sea ice production and associated ecology, even when sea ice extent and motion is controlled. Snow cover represents a first-order control over ice algal production by limiting the light available to bottom ice algal communities, and changes to the regional, rather than mean, snow thickness due to the use of different ice and snow representations are responsible for large differences in the magnitude and distribution of sea ice algal production. Improved convective nutrient exchange in high-brine fraction (slush) sea ice is responsible for up to 18% of total sea ice algal production. A continuous 10-year model run using climatological years 1996-2005 produced a time series of sea ice algal primary production that varied between 15.5 and 18.0 Tg C yr-1. This study represents the first interannual estimate of Antarctic sea ice algal production that dynamically considers the light, temperature, salinity, and nutrient conditions that control algal growth. On average, 64% of algal production occurred in the bottom 0.2 m of the ice pack. Production was spatially heterogeneous, with little consistency between years when examined at regional scales; however, at basin or hemispheric scales, annual production was fairly consistent in magnitude. At a mean of 0.9 g C m-2 yr-1, the magnitude of carbon uptake by sea ice algae will not significantly affect the Southern Ocean carbon cycle. Light availability was the dominant
Released on 2011Categories

Spatial and Temporal Dynamics of Primary Production in Antarctic Sea Ice

Spatial and Temporal Dynamics of Primary Production in Antarctic Sea Ice

Author: Benjamin Lundquist Saenz

Publisher:

ISBN: OCLC:744526142

Category:

Page:

View: 318

Sea ice is an important driver of climate patterns and polar marine ecosystem dynamics. In particular, primary production by microalgae in sea ice has been postulated as a sink for anthropogenic CO2, and as a critical resource in the life cycle of Antarctic krill Euphausia superba, a keystone species. Study of the sea ice ecosystem is difficult at regional and global scales, however, because of the expense and logistical difficulties in accessing such a remote and hostile environment. Consequently, models remain valuable tools for investigations of the spatial and temporal dynamics of sea ice and associated ecology and biogeochemistry. Recent advances in model representations of sea ice have called into question the accuracy of previous studies, and allow the creation of new tools to perform mechanistic simulations of sea ice physics and biogeochemistry. To address spatial and temporal variability in Antarctic sea ice algal production, and to establish the bounds and sensitivities of the sea ice ecosystem, a new, coupled sea ice ecosystem model was developed. In the vertical dimension, the model resolves incorporated saline brine, macronutrients concentrations, spectral shortwave radiation, and the sea ice algae community at high resolution. A novel method for thermodynamics, desalination, and fluid transfer in slushy, high-brine fraction sea ice was developed to simulate regions of high algal productivity. The processes of desalination, fluid transfer, snow-ice creation, and superimposed ice formation allowed the evolution of realistic vertical profiles of sea ice salinity and algal growth. The model replicated time series observations of ice temperature, salinity, algal biomass, and estimated fluid flux from the Ice Station Weddell experiment. In the horizontal dimension, sub-grid scale parameterizations of snow and ice thickness allow more realistic simulation of the ice thickness distribution, and consequently, sea ice algal habitat. The model is forced from above by atmospheric reanalysis climatologies, and from below by climatological ocean heat flux and deep-water ocean characteristics. Areal sea ice concentration and motion are specified according to SSM/I passive microwave satellite estimates of these parameters. Sensitivity testing of different snow and ice parameterizations showed that without a sub-grid scale ice thickness distribution, mean ice and snow thickness is lower and bottom sea ice algal production is elevated. Atmospheric forcing from different reanalysis data sets cause mean and regional shifts in sea ice production and associated ecology, even when sea ice extent and motion is controlled. Snow cover represents a first-order control over ice algal production by limiting the light available to bottom ice algal communities, and changes to the regional, rather than mean, snow thickness due to the use of different ice and snow representations are responsible for large differences in the magnitude and distribution of sea ice algal production. Improved convective nutrient exchange in high-brine fraction (slush) sea ice is responsible for up to 18% of total sea ice algal production. A continuous 10-year model run using climatological years 1996-2005 produced a time series of sea ice algal primary production that varied between 15.5 and 18.0 Tg C yr-1. This study represents the first interannual estimate of Antarctic sea ice algal production that dynamically considers the light, temperature, salinity, and nutrient conditions that control algal growth. On average, 64% of algal production occurred in the bottom 0.2 m of the ice pack. Production was spatially heterogeneous, with little consistency between years when examined at regional scales; however, at basin or hemispheric scales, annual production was fairly consistent in magnitude. At a mean of 0.9 g C m-2 yr-1, the magnitude of carbon uptake by sea ice algae will not significantly affect the Southern Ocean carbon cycle. Light availability was the dominant control on sea ice algae growth over the majority of the year; however, severe nutrient limitation that occurred annually during late spring and summer proved to be the largest control over sea ice algal productivity.
Released on 2012-12-06Categories Science

Ross Sea Ecology

Ross Sea Ecology

Author: F.M. Faranda

Publisher: Springer Science & Business Media

ISBN: 9783642596070

Category: Science

Page: 604

View: 689

The Antarctic represents the last of the world's still unexplored continents. Since 1985, Italy has sent 10 expeditions to this region, three of those have been exclusively devoted to research on the marine ecology of the Ross Sea region. This volume presents a global picture of this research. It includes contributions on water mass characteristics, particulate organic matter and nutrient utilization, and physiological aspects of primary production. Further topics are zooplankton, krill and top predator interactions in relation to physical and biological parameters, ecological features of coastal fish communities and the spatio-temporal variability of benthic biocenoses.
Released on 2012-12-06Categories Science

Ecological Studies in the Antarctic Sea Ice Zone

Ecological Studies in the Antarctic Sea Ice Zone

Author: Wolf E. Arntz

Publisher: Springer Science & Business Media

ISBN: 9783642594199

Category: Science

Page: 277

View: 128

Ten years ago Polar Biology published the book, Weddell Sea Ecology, containing the European "Polarstern" study EPOS in the Weddell Sea and Peninsula waters 1988/89. In certain respects, the present collection of papers, first published in Polar Biology in 2001, is a follow-up as it combines papers partly based on three "Polarstern" expeditions to the same region. Further articles relate to both land-based and shipborne studies, again primarily in the Atlantic sector and around the Antarctic Peninsula. The SCAR programme, "Ecology of the Antarctic Sea Ice Zone" (EASIZ), served as an umbrella for a truly international cooperation. Although funding came exclusively from national sources, 40% of the scientists on board "Polarstern" were foreigners. Out of the 35 papers of the present volume not less than 14 papers have multinational authorship. The scope of EASIZ is wider ilian the Southern Ocean Studies in JGOFS and GLOBEC. The Contents reflect emphasis on the study of benthos, which hitherto had not received the necessary attention in the attempt to understand key questions of evolution and zoogeography of fauna from the Southern Hemisphere. The information collected under EASIZ enhanced greatly our recognition of the rather high biodiversity of ilie Antarctic shelf benthos. In order to extend these studies to ilie deeper continental slopes and the deep sea, "Polarstern" is presently on her way for ilie first international survey of deep-sea benthos in the Atlantic sector of ilie Southern Ocean.
Released on 2007-07-09Categories Science

Polynyas: Windows to the World

Polynyas: Windows to the World

Author: Walker O. Smith, Jr.

Publisher: Elsevier

ISBN: 0080522939

Category: Science

Page: 474

View: 384

Polynyas are relatively ice-free regions when compared to the areas around them, and have been suggested as being foci for energy transfer between the atmosphere and ocean, ice “factories , and critical areas with respect to polar ecosystems and biogeochemical cycles. This volume presents an integrated, multidisciplinary review of polynyas in both the Arctic and Antarctic. It emphasizes the meteorology, ice dynamics, oceanography, biological components, chemistry, and modeling of these systems, particularly with respect to their roles in polar processes and distributions. The various interactions within polynyas, particularly between the physical forcing and biological responses, is emphasized, as are the potential changes in polynyas that might occur under a climate regime that is rapidly changing. The authors of the reviews are leaders among their respective countries in polynya research, and all are internationally recognized. * Addresses the findings from actively researched polynyas and reports on the new understandings of polar systems that have evolved from these studies * Includes topics from meteorology to physics to biology and chemistry, and seeks to integrate them into a synthetic assessment * Provides material from both the Arctic and Antarctic, which is highly unusual in books of this type
Released on 2021-10-12Categories Science

Chemistry In The Cryosphere (In 2 Parts)

Chemistry In The Cryosphere (In 2 Parts)

Author: Paul Shepson

Publisher: World Scientific

ISBN: 9789811230141

Category: Science

Page: 924

View: 841

Ice and snow on Earth modulate and modify the climate, chemistry and fate of air and water pollutants. Climate change is drastically impacting Nature and extent of the cryosphere, with attendant feedbacks on atmospheric composition and climate. These changes are happening at a rate that outpaces the development of fundamental knowledge of processes that occur within/on the surfaces of ice and snow, confounding our ability to develop a predictive capability for future states of the Earth environment.This set, comprising 17 chapters, written by world experts on these topics, are thus intended to document the current state of understanding of the structure, physical properties, abundance, and chemical and microbiological processes that occur within/on ice and snow in all Earth environments in which it exists, and to express needs for improvement of that understanding. This, only comprehensive treatise/collection that covers environmentally relevant chemistry and related physical aspects of snow and ice in the Earth system, and the connections to climate change, will be accessible to those with introductory college-level understanding of chemistry and physics.