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AGU: Journal highlights 17 Dec., 2012

Public release date: 17-Dec-2012
[ | E-mail |

Share ]

Contact: Kate Ramsayer
kramsayer@agu.org
202-777-7524
American Geophysical Union

Highlights, including authors and their institutions
The following highlights summarize research papers that have been recently published in Geophysical Research Letters (GRL).
In this release:
1. First satellite detection of volcanogenic carbon monoxide
2. Antarctic sea ice thickness affects algae populations
3. Central European Summer Temperature Variability to Increase
4. Global ocean salinity changing due to anthropogenic climate change
5. Chamber measurements find plants potentially important methane sink
6. Low-frequency radio emissions from high-altitude sprite discharge
Anyone may read the scientific abstract for any already-published paper by clicking on the link provided at the end of each Highlight. You can also read the abstract by going to http://www.agu.org/pubs/search_options.shtml and inserting into the search engine the full doi (digital object identifier), e.g. 10.1029/2012GL053275. The doi is found at the end of each Highlight below.
Journalists and public information officers (PIOs) at educational or scientific institutions who are registered with AGU also may download papers cited in this release by clicking on the links below. Instructions for members of the news media, PIOs, and the public for downloading or ordering the full text of any research paper summarized below are available at http://www.agu.org/news/press/papers.shtml.
1. First satellite detection of volcanogenic carbon monoxide
Measuring and tracking the gases that vent from an erupting volcano is a project wrought with potential dangers and difficulties. On the ground measurements place researchers in harm's way, as do airborne sampling surveys. These approaches may also suffer from issues around accurately representing the spatial and temporal shifts in gas emissions rates. As such, satellite-based remote sensing techniques are becoming a favorite way to assess the dispersion and concentrations of various volcanic gases. Devising a functional remote sensing scheme, however, depends on identifying a satellite sensor that can reliably identify the chemical species in question and pick the volcanic emissions out from the background concentrations. Such efforts have so far been successful for only a few volcanic gases: sulfuric acid, hydrochloric acid, and hydrogen sulfide.
Working from satellite observational records from the 2010 Eyjafjallajkull and 2011 Grmsvtn eruptions, Martnez-Alonso et al. find that the Measurements of Pollution in the Troposphere sensor aboard NASA's Terra satellite and the Infrared Atmospheric Sounding Interferometer on the European Space Agency's Meteorological Operational satellite MetOp-A could be used to remotely detect volcanic carbon monoxide emissions. The two sensors measured atmospheric carbon monoxide in different ways and hence could be used to support the other's observations. The authors find that the remotely sensed volcanogenic carbon monoxide is not a misdiagnosis of atmospheric water vapor or aerosols. Further, their concentration measurements aligned with airborne surveys.
Based on their detections, the authors estimate that the global emission of volcanic carbon monoxide is approximately 5.5 teragrams per year, a small but not insignificant fraction of total annual emissions.
Source: Geophysical Research Letters, doi:10.1029/2012GL053275, 2012
http://dx.doi.org/10.1029/2012GL053275
Title: First satellite identification of volcanic carbon monoxide
Authors: Sara Martnez-Alonso, Merritt N. Deeter, Helen M. Worden, Debbie Mao, and John C. Gille: Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, Colorado, USA;
Cathy Clerbaux: LATMOS, IPSL, CNRS/INSU, UPMC Universit Paris 06, Universit Versailles St.-Quentin, Paris, France.
2. Antarctic sea ice thickness affects algae populations
In the waters off Antarctica, algae grow and live in the sea ice that surrounds the southern continent-a floating habitat sure to change as the planet warms. As with most aquatic ecosystems, microscopic algae form the base of the Southern Ocean food web. Distinct algae populations reside in the sea ice surface layers, on the ice's underside, and within the floating ice itself. The algae that reside on the floating ice's underside are particularly important for the region's krill population, while those on the interior or surface layers are less accessible. How changing sea ice properties will affect the regional biology, then, depends on understanding how algae populations interact with the ice.
Drawing together samples collected by previous researchers, and through their own efforts, Meiners et al. developed the Antarctic Sea Ice Processes and Climate-Biology database, a collection of 1,300 Antarctic sea ice core samples collected from 1983 to 2008. By melting core samples and measuring the concentration of chlorophyll a, researchers can estimate the amount of algae living in the ice, with vertical profiles indicating where ice algal biomass peaks.
Using their database, the authors find that algae populations vary seasonally, peaking in the spring and late summer. They find that though algal biomass is distributed evenly among surface, interior, and underside populations, there is a distinct relationship between sea ice thickness and the likelihood of biomass maxima in different layers. They find that on thin ice, less than 0.4 meters (1.3 feet) thick, algae live on both the surface and the underside. For ice from 0.4 to 1 m (1.3 to 3.3 feet) thick, however, the majority of the algae were on the ice's underside. Thick ice, often formed by rafting of ice floes, showed a more homogeneous distribution of ice algal biomass.
Source: Geophysical Research Letters, doi: 10.1029/2012GL053478, 2012
http://dx.doi.org/10.1029/2012GL053478
Title: Chlorophyll a in Antarctic sea ice from historical ice core data
Authors: K. M. Meiners and B. Raymond: Australian Antarctic Division, Department of Sustainability, Environment, Water, Population and Communities, Kingston, Tasmania, Australia, and Antarctic Climate and Ecosystems Cooperative Research Centre, University of Tasmania, Hobart, Tasmania, Australia;
M. Vancoppenolle: Laboratoire d'Ocanographie et du Climat (CNRS/UPMC/IRD/MNHN), IPSL, Paris, France;
S. Thanassekos: Commission for the Conservation of Antarctic Marine Living Resources, Hobart, Tasmania, Australia;
G. S. Dieckmann: Alfred Wegener Institute for Polar and Marine Science, Bremerhaven, Germany;
D. N. Thomas: School of Ocean Sciences, Bangor University, Anglesey, UK, and Finnish Environment Institute, Helsinki, Finland and Arctic Centre, Aarhus University, Aarhus, Denmark;
J.-L. Tison: Laboratoire de Glaciologie, Universit Libre de Bruxelles, Brussels, Belgium;
K. R. Arrigo: Department of Environmental Earth System Science, Stanford University, Stanford, California, USA;
D. L. Garrison: Biological Oceanography Program, Division of Ocean Sciences, National Science Foundation, Arlington, Virginia, USA;
A. McMinn and K. M. Swadling: Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia;
D. Lannuzel and P. van derMerwe: Antarctic Climate and Ecosystems Cooperative Research Centre, University of Tasmania, Hobart, Tasmania, Australia and Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia;
W. O. Smith Jr.: Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, Virginia, USA;
I. Melnikov: P. P. Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia.
3. Central European summer temperature variability to increase
More extreme heat waves have been observed in central Europe in recent years as summer temperature variability has increased on both daily and interannual timescales. Models project that as the climate warms throughout the 21st century, this increased variability will continue.
To evaluate the robustness of those previous findings, which are based on regional climate models from the Prediction of Regional Scenarios and Uncertainties for Defining European Climate Change Risks and Effects (PRUDENCE) project or a small sample of models from the ENSEMBLES project, Fischer et al. revisit model projections using the full set of ENSEMBLES regional climate models. These models cover a larger uncertainty range than previous studies. They note that PRUDENCE regional climate models are all driven by the same global climate model, while ENSEMBLES regional climate models are driven by six different global climate models.
They find that PRUDENCE models all projected a substantial increase in interannual summer temperature variability in central Europe by the end of the 21st century, while different ENSEMBLES models projected different amounts of interannual summer temperature variability, with the mean of ENSEMBLES models projecting no clear increase. However, those ENSEMBLES models that most realistically represented present-day interannual summer temperature variability did project an increase in temperature variability over central Europe by the end of the 21st century. Under the assumption that a model with a better representation of the present-day conditions provides a more credible estimate of future changes, the reduced set of well-performing models yields a robust projection.
The study also indicates that the largest increases in interannual summer temperature variability would occur mainly in the central European region that is a transition zone between dry climates in the south and moist climates in the north. They also find that all ENSEMBLES regional climate models project an increase in daily summer temperature variability over central Europe. They emphasize that hot extremes are expected to warm more strongly than the summer mean temperature.
Source: Geophysical Research Letters, doi:10.1029/2012GL052730, 2012
http://dx.doi.org/10.1029/2012GL052730
Title: Changes in European summer temperature variability revisited
Authors: E. M. Fischer, J. Rajczak, and C. Schr: Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland.
4. Global ocean salinity changing due to anthropogenic climate change
Rising sea surface temperatures, climbing sea levels, and ocean acidification are the most commonly discussed consequences of anthropogenic climate change for the global oceans. They are not, however, the only potentially important shifts observed over recent decades. Drawing on observations from 1955 to 2004, Pierce et al. find that the oceans' salinity changed throughout the study period, that the changes were independent of known natural variability, and that the shifts were consistent with the expected effects of anthropogenic climate change.
The authors analyzed 50 years of salinity and temperature observations drawn from the National Oceanographic Data Center's records. The observations spanned the top 700 meters (2,300 feet) of the water column from 60 degrees North to 60 degrees South. Using 20 global general circulation models, they assessed whether the observed changes in ocean salinity and temperature could be explained by known natural cycles: the El Nio-Southern Oscillation, the Pacific Decadal Oscillation, the effects of volcanic eruptions, and changes in solar activity. They find that the observed trends, which varied regionally, did not relate to any of these forcings. However, the observed trends are consistent with model estimates of the effects of human-caused climate change.
The slowly shifting global salinity field is known to be affected by changes in the hydrological cycle, including changes in evaporation and precipitation rates, ocean currents, river discharge, and other forces. As such, the authors suggest that the observed human-driven trends in the global salinity field demonstrate an ongoing, long-term shift in the global hydrological cycle that is likely to continue into the future.
Source: Geophysical Research Letters, doi:10.1029/2012GL053389, 2012
http://dx.doi.org/10.1029/2012GL053389
Title: The fingerprint of human-induced changes in the ocean's salinity and temperature fields
Authors: David W. Pierce and Tim P. Barnett: Division of Climate, Atmospheric Sciences, and Physical Oceanography, Scripps Institution of Oceanography, La Jolla, California, USA;
Peter J. Gleckler, Benjamin D. Santer and Paul J. Durack: Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory, Livermore, California, USA.
5. Chamber measurements find plants potentially important methane sink
As a greenhouse gas, methane has a much higher heat-trapping potential than carbon dioxide when considered over the course of a few decades. In recent years, researchers discovered a potentially important new source of atmospheric methane-emissions from green plants. Though estimates of the extent of vegetative methane emissions vary greatly, previous research suggests they could amount to as much as a tenth of global annual emissions. The mechanism behind such emissions is a matter of considerable debate, with questions remaining regarding the effects of atmospheric or soil conditions, local hydrological influences, and variability for different plant species. Also under investigation are various potential plant methane uptake mechanisms, or the effects of methane- consuming bacteria-aspects of the methane cycle that could dampen plants' role as a methane source.
To determine the overall effect of some boreal tree species on atmospheric methane, Sundqvist et al. used branch chamber measurements to directly assess the net gas exchange for birch, spruce, pine, and rowan trees in a Swedish forest. The authors find that all four tree species were net absorbers of atmospheric methane, meaning they served as a sink rather than a source. The authors analyzed how the methane exchange varied with changes in the availability of photosynthetically active radiation (PAR), temperature, photosynthesis rate, and ultraviolet radiation levels. For birch, spruce and rowan trees, but not pine, they find that an increase in PAR caused the trees to take up more methane. They find that temperature changes had inconsistent effects on methane exchange. The authors suggest that plants could actually be an important global sink, rather than source, for atmospheric methane.
Source: Geophysical Research Letters, doi: 10.1029/2012GL053592, 2012
http://dx.doi.org/10.1029/2012GL053592
Title: Atmospheric methane removal by boreal plants
Authors: Elin Sundqvist, Meelis Mlder, Patrik Vestin and Anders Lindroth: Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden;
Patrick Crill: Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
6. Low-frequency radio emissions from high-altitude sprite discharge
When lightning strikes from a towering cumulonimbus cloud down to the ground, the electrical discharge can perturb the atmosphere's electric field, potentially triggering a second event-sprite discharge. This more elusive type of electrical discharge, which produces lightning that is red in color, initiates from high altitudes, with streamers propagating down toward the top of the cumulonimbus cloud. Coincident with the dramatic displays, researchers have previously identified low-frequency radio emissions, which they suggest may be produced in association with the sprite discharge. Investigating this hypothesis, Qin et al. used a two-dimensional plasma model to calculate the radio emissions that should be produced by a single sprite streamer.
The authors find the frequency of the radio emissions that should be produced by a sprite streamer depends on two main factors: the air density (which decreases with altitude) and the background electric field through which the streamer is propagating. The authors find that sprite streamers that initiate from 75 kilometers (47 miles) altitude emit radio waves with frequencies from 0 to 3 kilohertz (up to the "very low frequency" range). If the sprite streamers spawned at 40 kilometers (25 miles) altitude, they would emit low-frequency radiowaves, with frequencies up to 300 kilohertz. Further, the authors suggest that the sprite streamers branching mechanism could act as a band-pass filter, with the radio wave frequencies being lower at high altitudes than at low altitudes.
Source: Geophysical Research Letters, doi:10.1029/2012GL053991, 2012
http://dx.doi.org/10.1029/2012GL053991
Title: Low frequency electromagnetic radiation from sprite streamers
Authors: Jianqi Qin, Sebastien Celestin, and Victor P. Pasko: Communications and Space Sciences Laboratory, Department of Electrical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA.
Contact:
Kate Ramsayer
Phone (direct): +1 202 777 7524
E-mail: kramsayer@agu.org
###
[ | E-mail | Share ]
?

AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.

AGU: Journal highlights 17 Dec., 2012 Public release date: 17-Dec-2012
[ | E-mail | Share ]
Contact: Kate Ramsayer
kramsayer@agu.org
202-777-7524
American Geophysical Union

Highlights, including authors and their institutions
The following highlights summarize research papers that have been recently published in Geophysical Research Letters (GRL).
In this release:
1. First satellite detection of volcanogenic carbon monoxide
2. Antarctic sea ice thickness affects algae populations
3. Central European Summer Temperature Variability to Increase
4. Global ocean salinity changing due to anthropogenic climate change
5. Chamber measurements find plants potentially important methane sink
6. Low-frequency radio emissions from high-altitude sprite discharge
Anyone may read the scientific abstract for any already-published paper by clicking on the link provided at the end of each Highlight. You can also read the abstract by going to http://www.agu.org/pubs/search_options.shtml and inserting into the search engine the full doi (digital object identifier), e.g. 10.1029/2012GL053275. The doi is found at the end of each Highlight below.
Journalists and public information officers (PIOs) at educational or scientific institutions who are registered with AGU also may download papers cited in this release by clicking on the links below. Instructions for members of the news media, PIOs, and the public for downloading or ordering the full text of any research paper summarized below are available at http://www.agu.org/news/press/papers.shtml.
1. First satellite detection of volcanogenic carbon monoxide
Measuring and tracking the gases that vent from an erupting volcano is a project wrought with potential dangers and difficulties. On the ground measurements place researchers in harm's way, as do airborne sampling surveys. These approaches may also suffer from issues around accurately representing the spatial and temporal shifts in gas emissions rates. As such, satellite-based remote sensing techniques are becoming a favorite way to assess the dispersion and concentrations of various volcanic gases. Devising a functional remote sensing scheme, however, depends on identifying a satellite sensor that can reliably identify the chemical species in question and pick the volcanic emissions out from the background concentrations. Such efforts have so far been successful for only a few volcanic gases: sulfuric acid, hydrochloric acid, and hydrogen sulfide.
Working from satellite observational records from the 2010 Eyjafjallajkull and 2011 Grmsvtn eruptions, Martnez-Alonso et al. find that the Measurements of Pollution in the Troposphere sensor aboard NASA's Terra satellite and the Infrared Atmospheric Sounding Interferometer on the European Space Agency's Meteorological Operational satellite MetOp-A could be used to remotely detect volcanic carbon monoxide emissions. The two sensors measured atmospheric carbon monoxide in different ways and hence could be used to support the other's observations. The authors find that the remotely sensed volcanogenic carbon monoxide is not a misdiagnosis of atmospheric water vapor or aerosols. Further, their concentration measurements aligned with airborne surveys.
Based on their detections, the authors estimate that the global emission of volcanic carbon monoxide is approximately 5.5 teragrams per year, a small but not insignificant fraction of total annual emissions.
Source: Geophysical Research Letters, doi:10.1029/2012GL053275, 2012
http://dx.doi.org/10.1029/2012GL053275
Title: First satellite identification of volcanic carbon monoxide
Authors: Sara Martnez-Alonso, Merritt N. Deeter, Helen M. Worden, Debbie Mao, and John C. Gille: Atmospheric Chemistry Division, National Center for Atmospheric Research, Boulder, Colorado, USA;
Cathy Clerbaux: LATMOS, IPSL, CNRS/INSU, UPMC Universit Paris 06, Universit Versailles St.-Quentin, Paris, France.
2. Antarctic sea ice thickness affects algae populations
In the waters off Antarctica, algae grow and live in the sea ice that surrounds the southern continent-a floating habitat sure to change as the planet warms. As with most aquatic ecosystems, microscopic algae form the base of the Southern Ocean food web. Distinct algae populations reside in the sea ice surface layers, on the ice's underside, and within the floating ice itself. The algae that reside on the floating ice's underside are particularly important for the region's krill population, while those on the interior or surface layers are less accessible. How changing sea ice properties will affect the regional biology, then, depends on understanding how algae populations interact with the ice.
Drawing together samples collected by previous researchers, and through their own efforts, Meiners et al. developed the Antarctic Sea Ice Processes and Climate-Biology database, a collection of 1,300 Antarctic sea ice core samples collected from 1983 to 2008. By melting core samples and measuring the concentration of chlorophyll a, researchers can estimate the amount of algae living in the ice, with vertical profiles indicating where ice algal biomass peaks.
Using their database, the authors find that algae populations vary seasonally, peaking in the spring and late summer. They find that though algal biomass is distributed evenly among surface, interior, and underside populations, there is a distinct relationship between sea ice thickness and the likelihood of biomass maxima in different layers. They find that on thin ice, less than 0.4 meters (1.3 feet) thick, algae live on both the surface and the underside. For ice from 0.4 to 1 m (1.3 to 3.3 feet) thick, however, the majority of the algae were on the ice's underside. Thick ice, often formed by rafting of ice floes, showed a more homogeneous distribution of ice algal biomass.
Source: Geophysical Research Letters, doi: 10.1029/2012GL053478, 2012
http://dx.doi.org/10.1029/2012GL053478
Title: Chlorophyll a in Antarctic sea ice from historical ice core data
Authors: K. M. Meiners and B. Raymond: Australian Antarctic Division, Department of Sustainability, Environment, Water, Population and Communities, Kingston, Tasmania, Australia, and Antarctic Climate and Ecosystems Cooperative Research Centre, University of Tasmania, Hobart, Tasmania, Australia;
M. Vancoppenolle: Laboratoire d'Ocanographie et du Climat (CNRS/UPMC/IRD/MNHN), IPSL, Paris, France;
S. Thanassekos: Commission for the Conservation of Antarctic Marine Living Resources, Hobart, Tasmania, Australia;
G. S. Dieckmann: Alfred Wegener Institute for Polar and Marine Science, Bremerhaven, Germany;
D. N. Thomas: School of Ocean Sciences, Bangor University, Anglesey, UK, and Finnish Environment Institute, Helsinki, Finland and Arctic Centre, Aarhus University, Aarhus, Denmark;
J.-L. Tison: Laboratoire de Glaciologie, Universit Libre de Bruxelles, Brussels, Belgium;
K. R. Arrigo: Department of Environmental Earth System Science, Stanford University, Stanford, California, USA;
D. L. Garrison: Biological Oceanography Program, Division of Ocean Sciences, National Science Foundation, Arlington, Virginia, USA;
A. McMinn and K. M. Swadling: Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia;
D. Lannuzel and P. van derMerwe: Antarctic Climate and Ecosystems Cooperative Research Centre, University of Tasmania, Hobart, Tasmania, Australia and Institute for Marine and Antarctic Studies, University of Tasmania, Hobart, Tasmania, Australia;
W. O. Smith Jr.: Virginia Institute of Marine Science, College of William and Mary, Gloucester Point, Virginia, USA;
I. Melnikov: P. P. Shirshov Institute of Oceanology, Russian Academy of Sciences, Moscow, Russia.
3. Central European summer temperature variability to increase
More extreme heat waves have been observed in central Europe in recent years as summer temperature variability has increased on both daily and interannual timescales. Models project that as the climate warms throughout the 21st century, this increased variability will continue.
To evaluate the robustness of those previous findings, which are based on regional climate models from the Prediction of Regional Scenarios and Uncertainties for Defining European Climate Change Risks and Effects (PRUDENCE) project or a small sample of models from the ENSEMBLES project, Fischer et al. revisit model projections using the full set of ENSEMBLES regional climate models. These models cover a larger uncertainty range than previous studies. They note that PRUDENCE regional climate models are all driven by the same global climate model, while ENSEMBLES regional climate models are driven by six different global climate models.
They find that PRUDENCE models all projected a substantial increase in interannual summer temperature variability in central Europe by the end of the 21st century, while different ENSEMBLES models projected different amounts of interannual summer temperature variability, with the mean of ENSEMBLES models projecting no clear increase. However, those ENSEMBLES models that most realistically represented present-day interannual summer temperature variability did project an increase in temperature variability over central Europe by the end of the 21st century. Under the assumption that a model with a better representation of the present-day conditions provides a more credible estimate of future changes, the reduced set of well-performing models yields a robust projection.
The study also indicates that the largest increases in interannual summer temperature variability would occur mainly in the central European region that is a transition zone between dry climates in the south and moist climates in the north. They also find that all ENSEMBLES regional climate models project an increase in daily summer temperature variability over central Europe. They emphasize that hot extremes are expected to warm more strongly than the summer mean temperature.
Source: Geophysical Research Letters, doi:10.1029/2012GL052730, 2012
http://dx.doi.org/10.1029/2012GL052730
Title: Changes in European summer temperature variability revisited
Authors: E. M. Fischer, J. Rajczak, and C. Schr: Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland.
4. Global ocean salinity changing due to anthropogenic climate change
Rising sea surface temperatures, climbing sea levels, and ocean acidification are the most commonly discussed consequences of anthropogenic climate change for the global oceans. They are not, however, the only potentially important shifts observed over recent decades. Drawing on observations from 1955 to 2004, Pierce et al. find that the oceans' salinity changed throughout the study period, that the changes were independent of known natural variability, and that the shifts were consistent with the expected effects of anthropogenic climate change.
The authors analyzed 50 years of salinity and temperature observations drawn from the National Oceanographic Data Center's records. The observations spanned the top 700 meters (2,300 feet) of the water column from 60 degrees North to 60 degrees South. Using 20 global general circulation models, they assessed whether the observed changes in ocean salinity and temperature could be explained by known natural cycles: the El Nio-Southern Oscillation, the Pacific Decadal Oscillation, the effects of volcanic eruptions, and changes in solar activity. They find that the observed trends, which varied regionally, did not relate to any of these forcings. However, the observed trends are consistent with model estimates of the effects of human-caused climate change.
The slowly shifting global salinity field is known to be affected by changes in the hydrological cycle, including changes in evaporation and precipitation rates, ocean currents, river discharge, and other forces. As such, the authors suggest that the observed human-driven trends in the global salinity field demonstrate an ongoing, long-term shift in the global hydrological cycle that is likely to continue into the future.
Source: Geophysical Research Letters, doi:10.1029/2012GL053389, 2012
http://dx.doi.org/10.1029/2012GL053389
Title: The fingerprint of human-induced changes in the ocean's salinity and temperature fields
Authors: David W. Pierce and Tim P. Barnett: Division of Climate, Atmospheric Sciences, and Physical Oceanography, Scripps Institution of Oceanography, La Jolla, California, USA;
Peter J. Gleckler, Benjamin D. Santer and Paul J. Durack: Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory, Livermore, California, USA.
5. Chamber measurements find plants potentially important methane sink
As a greenhouse gas, methane has a much higher heat-trapping potential than carbon dioxide when considered over the course of a few decades. In recent years, researchers discovered a potentially important new source of atmospheric methane-emissions from green plants. Though estimates of the extent of vegetative methane emissions vary greatly, previous research suggests they could amount to as much as a tenth of global annual emissions. The mechanism behind such emissions is a matter of considerable debate, with questions remaining regarding the effects of atmospheric or soil conditions, local hydrological influences, and variability for different plant species. Also under investigation are various potential plant methane uptake mechanisms, or the effects of methane- consuming bacteria-aspects of the methane cycle that could dampen plants' role as a methane source.
To determine the overall effect of some boreal tree species on atmospheric methane, Sundqvist et al. used branch chamber measurements to directly assess the net gas exchange for birch, spruce, pine, and rowan trees in a Swedish forest. The authors find that all four tree species were net absorbers of atmospheric methane, meaning they served as a sink rather than a source. The authors analyzed how the methane exchange varied with changes in the availability of photosynthetically active radiation (PAR), temperature, photosynthesis rate, and ultraviolet radiation levels. For birch, spruce and rowan trees, but not pine, they find that an increase in PAR caused the trees to take up more methane. They find that temperature changes had inconsistent effects on methane exchange. The authors suggest that plants could actually be an important global sink, rather than source, for atmospheric methane.
Source: Geophysical Research Letters, doi: 10.1029/2012GL053592, 2012
http://dx.doi.org/10.1029/2012GL053592
Title: Atmospheric methane removal by boreal plants
Authors: Elin Sundqvist, Meelis Mlder, Patrik Vestin and Anders Lindroth: Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden;
Patrick Crill: Department of Geological Sciences, Stockholm University, Stockholm, Sweden.
6. Low-frequency radio emissions from high-altitude sprite discharge
When lightning strikes from a towering cumulonimbus cloud down to the ground, the electrical discharge can perturb the atmosphere's electric field, potentially triggering a second event-sprite discharge. This more elusive type of electrical discharge, which produces lightning that is red in color, initiates from high altitudes, with streamers propagating down toward the top of the cumulonimbus cloud. Coincident with the dramatic displays, researchers have previously identified low-frequency radio emissions, which they suggest may be produced in association with the sprite discharge. Investigating this hypothesis, Qin et al. used a two-dimensional plasma model to calculate the radio emissions that should be produced by a single sprite streamer.
The authors find the frequency of the radio emissions that should be produced by a sprite streamer depends on two main factors: the air density (which decreases with altitude) and the background electric field through which the streamer is propagating. The authors find that sprite streamers that initiate from 75 kilometers (47 miles) altitude emit radio waves with frequencies from 0 to 3 kilohertz (up to the "very low frequency" range). If the sprite streamers spawned at 40 kilometers (25 miles) altitude, they would emit low-frequency radiowaves, with frequencies up to 300 kilohertz. Further, the authors suggest that the sprite streamers branching mechanism could act as a band-pass filter, with the radio wave frequencies being lower at high altitudes than at low altitudes.
Source: Geophysical Research Letters, doi:10.1029/2012GL053991, 2012
http://dx.doi.org/10.1029/2012GL053991
Title: Low frequency electromagnetic radiation from sprite streamers
Authors: Jianqi Qin, Sebastien Celestin, and Victor P. Pasko: Communications and Space Sciences Laboratory, Department of Electrical Engineering, Pennsylvania State University, University Park, Pennsylvania, USA.
Contact:
Kate Ramsayer
Phone (direct): +1 202 777 7524
E-mail: kramsayer@agu.org
###
[ | E-mail | Share ]
?

AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.

Source: http://www.eurekalert.org/pub_releases/2012-12/agu-ajh121712.php
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Sandy Hook shooting: Parenting common sense and solace

In the Sandy Hook shooting aftermath, parents can make their own logical solace: focus on the good and that happened that day, like the bravery and strength of the teachers; stop rehearsing the horror by watching the endless media loop; and don't forget? ... think of Sandy Hook two months from now.

By Madora Kibbe,?Guest Blogger / December 17, 2012

Sandy Hook put us all in uncharted territory. And in our fast paced, Wikipedia world we want to make sense of the senseless now. Well, we can?t. But there are some things we can do. Beginning with ourselves.

Illustration by Barrie Maguire

Enlarge

Most parents are very good at comforting their children. They look under beds and in closets to prove no monsters are lurking. They dry tears, hug and hold on, because they know instinctively that the words they say are never as important as the acts of kindness parents perform on a daily hourly, moment-by-moment basis. That's why they became parents, because parenting equals love. And most of the time our children's fears aren't our own. So we can handle them calmly and rationally.? We say, "See you in the morning light," and mean it.?

Skip to next paragraph Madora Kibbe

Guest Blogger

Madora Kibbe has been a contributing writer for?The Christian Science Monitor for more than 35 years. A full-time Christian Science practitioner, she blogs in both a serious and humorous vein about all things mundane, sublime, and spiritual. She writes the "Thinking Makes It So" blog for Psychology Today.? She and her husband Jon moved back to Manhattan after raising their family in the suburbs.

Purines fend off surgery-related damage

Public release date: 17-Dec-2012
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Share ]

Contact: Dan Meyers
dan.meyers@ucdenver.edu
University of Colorado Denver

Anesthesia is quite safe these days. But sometimes putting a patient under to fix one problem, such as heart damage, can harm a different organ, such as a kidney.

Now a group of researchers led by Holger Eltzschig, MD, PhD, a professor of anesthesiology at the University Colorado School of Medicine, has found a group of molecules that fend off damage during anesthesia.

"This is a promising discovery," says Eltzschig, who practices at University of Colorado Hospital. "It suggests a new way to promote healing."

In an article published Dec. 12 in the New England Journal of Medicine, Eltzschig and colleagues at Harvard Medical School and Northeastern University report hopeful findings about a group of molecules called purines. Purines are basic molecular building blocks in the body they help produce DNA and RNA and they assist with short-term storage of energy. One variety of purine is called adenosine.

The researchers determined that generating adenosine outside of cells can help protect organs from damage. And they saw that activating adenosine receptors on the lungs, the intestine, or the heart can help protect these organs.

Eltzschig and his fellow researchers looked at adenosine and related chemical processes in cancer, lung injury, bowel inflammation and platelet function, among others.

For patients who might face surgery with anesthesia, the findings are good news.

"Increasing developments in this arena will open up several new avenues for the treatment," the article says.

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Purines fend off surgery-related damage Public release date: 17-Dec-2012
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Contact: Dan Meyers
dan.meyers@ucdenver.edu
University of Colorado Denver

Anesthesia is quite safe these days. But sometimes putting a patient under to fix one problem, such as heart damage, can harm a different organ, such as a kidney.

Now a group of researchers led by Holger Eltzschig, MD, PhD, a professor of anesthesiology at the University Colorado School of Medicine, has found a group of molecules that fend off damage during anesthesia.

"This is a promising discovery," says Eltzschig, who practices at University of Colorado Hospital. "It suggests a new way to promote healing."

In an article published Dec. 12 in the New England Journal of Medicine, Eltzschig and colleagues at Harvard Medical School and Northeastern University report hopeful findings about a group of molecules called purines. Purines are basic molecular building blocks in the body they help produce DNA and RNA and they assist with short-term storage of energy. One variety of purine is called adenosine.

The researchers determined that generating adenosine outside of cells can help protect organs from damage. And they saw that activating adenosine receptors on the lungs, the intestine, or the heart can help protect these organs.

Eltzschig and his fellow researchers looked at adenosine and related chemical processes in cancer, lung injury, bowel inflammation and platelet function, among others.

For patients who might face surgery with anesthesia, the findings are good news.

"Increasing developments in this arena will open up several new avenues for the treatment," the article says.

###

[ | E-mail | Share ]
?

AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert! system.

Source: http://www.eurekalert.org/pub_releases/2012-12/uocd-pfo121712.php
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সোমবার, ১৭ ডিসেম্বর, ২০১২

Homeland, Season 2

Damian Lewis as Nicholas Brody

Photograph by Kent Smith/Showtime.

In Slate?s Homeland TV Club, June Thomas will IM each week with a different partner?policy experts, intelligence researchers, critics, and even Slate commenters. In this final exchange, she chats with Ross Gottesman, who comments in Slate under the name BriefWit. He also writes at brief-wit.com and tweets under the same handle.

June Thomas: Hi Ross, thanks for coming back and working the early shift in the Slate Homeland opinion mines. Last night, David Haglund and I shared our initial responses to the finale; this morning our task is to consider the series as a whole. As much as I've enjoyed (and defended) the show throughout Season 2, I admit to being disappointed overall. Even as the writers were asking us to go along with some tough-to-swallow plot points, I retained my faith in them. I thought they were going to make some important points about some of the big issues of the day. The finale left me disappointed overall. After feinting at a lot of topics, the only one they took seriously was the love affair between Brody and Carrie. And, frankly, even that wasn't terribly convincing.

Ross Gottesman: Thanks for having me back, June.?I'm of a similar mindset. The finale had one or two notable moments, but overall, the episode and the season bugged me.?Season 1 of Homeland came out of nowhere and floored me. I was initially attracted because of the great characters and a provocative,?audience-challenging set-up?that cut to the heart of nationalism, terrorism, and surveillance. Now that this season is over, I'm left asking, why did the writers go in this direction? What was the point?

Thomas: My sense is that after the response to the amazing penultimate episode of Season 1 (the one that if it were an episode of Friends would be titled "The One With the Vest"), the writers became thrill-seekers. They got addicted to twists and turns?and in the end all that did was make some viewers sick to our stomachs.

Having said that, I don't want to let my disappointment color me too negative. The bright spot for me this season was the Brody family?yes, even Dana's hit and run. Homeland was always "inspired by" the Israeli show Hatufim rather than being an American version of it, but I was glad to see the writers return to the issue at the center of the Israeli show: how coming back affects?and messes up?everyone involved. The question of whether Jess could do the right thing?a vague but real imperative, policed by everyone from Cynthia Walden to Dana and Chris?and make her marriage work finally got the focus it deserved. The decision to split, and the general acceptance that having Mike in the family would be better for everyone involved, was one of the few things that felt fully credible.

Gottesman: That seems right. As the writers told the New York Times:?"Our motto is, give up the secret before the audience expects it. Because you guys know it?s coming. The only way we can surprise you is to deliver it ahead of schedule." The resolution towards a?semblance?of normal family life in the finale was responsible. The Finn (RIP) and Dana hit and run was gruesome (both as depicted and as a plot point), but it was redeemed in the way it revealed the true colors of the parents and the controversial wrench Carrie threw in its way.

Man, it would be great to see the characters from this show re-enact the opening of Friends in that fountain.

Thomas: Maybe that's what was going on in that surveillance scene with Roya and the leader of the raid on the Gettysburg tailor's shop. They made us think it was tradecraft that made Roya talk with Mysterious Bad Guy No. 1 next to the fountain so as to foil Max?s microphones. In fact, it was a Friends hommage. And really, is there any better summation of the state of Carrie's mind at the beginning of Season 2 than the following: "Your job's a joke, you're broke, your love life's DOA." Then by the end of the season, Brody was singing to her thusly: "I'll be there for you, when the rain starts to pour./ I'll be there for you, like I've been there before./ I'll be there for you, cause you're there for me too."

Gottesman: Ha! That Friends thought reminds me of the one when Rachel makes the trifle.?Joey says: "What's not to like? Custard, good. Jam, good. Meat, good!" That's a metaphor for this season of Homeland to me. It had ingredients that on their own can be tasty and satisfying, but the way they were prepared was not?palatable.

In the end, that should be the goal: Is it?satisfying? I mean, does the story resolve itself to an ending you are comfortable or pleased with as a viewer? Does it ask a compelling question or leave you with a cliffhanger you ask your friends about all summer?

Thomas: Exactly! A friend suggested to me that Saul was creating all this havoc to bring his wife back. My first thought was that it was a ridiculous idea?no one would unleash the forces of global terrorism to mend a broken heart. But after this Love, Actually kind of season, I wouldn't put it past them.

Gottesman: It was interesting to see Saul on both sides of Brody.?He braves Estes for Three Days of the Conference Room to defend Rep. Brody from assassination, but he tears into Carrie for pursuing a relationship with someone who will always be a terrorist.

Thomas: Yes, that was a flashback to the "good" Homeland, which could explore multiple sides of an issue. Saul's was a morally consistent position: You can't just kill U.S. citizens you perceive to be enemies, but that doesn't mean you can have a relationship with one?even if he has provided real, useful intelligence and has maybe returned his allegiances to our side?and still keep your job.

Gottesman: When a would-be terrorist tries to blow up a temple in New York City, but doesn't, we don't say, "Well, they didn't, so they can be redeemed.?

We should also say the acting still remains tip-top.?An?argument can be made that the performances were better?this season, and that the actors deserve to win Emmys again. What I don't get is, as terrific as Damian Lewis is onscreen, why should we care about Brody anymore?

Thomas: I agree about the acting, and that's why I'll keep watching this show come what may. The season finale was full of excellent performances: Brody and Carrie were awkward around each other, both trying desperately not to seem desperate about how things would go now that a lot of pressure was off. Lewis and Danes were absolutely convincing in those roles. And Saul's lop-sided grin when he saw that Carrie was alive and back by his side at the end of the episode was a glorious note to go out on.

Gottesman: Agreed. I would watch a show about Saul running the?CIA. I would watch a show about Saul running the NEA. I would watch a show about Saul running a P.F.?Chang's?franchise. Perhaps with Toby Ziegler from The West Wing in a perfect world. Imagine the beards and debates.

It takes a lot for me to quit on a show I liked so much. Homeland was a great show. For now, it's a good one.

Thomas: Thank goodness it's still a great one to talk about. Ross, thanks to you and the other regular commenters for making this TV Club so much fun. I especially appreciated your joining me in these IMs. As the great Saul Berenson (who I still have my suspicions about) put it: Thanks for the milk.

Source: http://feeds.slate.com/click.phdo?i=78ffa0f2013232fed429764574a5410a

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