The following highlights summarize research papers that have been recently published in Geochemistry, Geophysics, Geosystems (G3), Geophysical Research Letters (GRL), Journal of Geophysical Research-Atmospheres (JGR-D), and Water Resources Research (WRR).
In this release:
1. Heart Lake holds water for Yellowstone's hydrothermal diversity theory
2. Martian carbon dioxide clouds tied to atmospheric gravity waves
3. Effects of sea spray geoengineering on global climate
4. Abrupt decline in East African long rains
5. Small dams need better management
6. Improving forecasts of volcanic ash concentrations
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1. Heart Lake holds water for Yellowstone's hydrothermal diversity theory
Within Yellowstone National Park, the water emanating from the park's famous hot springs and geysers seems to belong to either one of two distinct types. In some areas, subterranean waters rich in chlorine and dissolved silicates burst from the ground to create the park's iconic geysers. In other areas, highly acidic mud pools form from chlorine-deprived waters rich with sulfate ions. In the 1950s, researchers proposed that these two distinct surface features actually stem from a single type of underground water. Across Yellowstone, geysers and mud pools are often separated by defined geographic boundaries, making a test of their interrelatedness difficult. In northwestern Wyoming, however, acid-rich and silica-rich waters coexist within a roughly 12 square kilometers (4.6 square kilometers) watershed that drains into nearby Heart Lake.
Drawing water and gas samples from pools and steam vents distributed throughout the Heart Lake Geyser Basin, Lowenstern et al. find support for the single-water-source hypothesis. On the basis of a wide array of chemical and hydrological analyses, including measurements of the concentrations of various dissolved minerals, isotope ratios, flow rates, and gas fluxes, the authors find that the diverse features in the Heart Lake Geyser Basin could stem from a single source of 205-degrees-Celsius (401-degrees-Fahrenheit) subsurface water. The authors suggest that the chlorine-depleted, acidic mud pools, which populate the upper reaches of the basin, form as thermophilic bacteria to break down dissolved hydrogen sulfide. That sulfur is carried from the water as it boils below the surface. Further downstream, after subsurface flow, boiling, and dilution with rain water, the original source water arrives at the surface as the chlorine- and silica- rich waters typically associated with Yellowstone's geysers.
Source: Geochemistry, Geophysics, Geosystems, doi:10.1029/2011GC003835, 2012 http://dx.doi.org/10.1029/2011GC003835
Title: Generation and evolution of hydrothermal fluids at Yellowstone
Authors: J. B. Lowenstern and D. Bergfeld: Volcano Science Center, U.S. Geological Survey, Menlo Park, California, USA;
W. C. Evans and S. Hurwitz: National Research Program, U.S. Geological Survey, Menlo Park, California, USA.
2. Martian carbon dioxide clouds tied to atmospheric gravity waves
On 4 March 1997 the Mars Pathfinder lander fell through the thin Martian atmosphere. During its descent, instrumentation aboard the lander recorded the changing atmospheric temperature, pressure, and density. Within this atmospheric profile, researchers identified anomalous cold air packets within the Martian mesosphere (60-90 kilometers, or 37-56 miles, altitude). Later orbital measurements confirmed the existence of these cold pockets, adding to the mystery the detection of clouds made from carbon dioxide. Researchers in 1998 suspected that the cold air pockets, and thus conditions favorable for carbon dioxide condensation, were the product of atmospheric gravity waves in the Martian mesosphere. That hypothesis remained largely untested until advances in global- and intermediate-scale atmospheric models allowed Spiga et al. to confirm that gravity waves were a potentially viable mechanism to produce the necessary mesospheric conditions.
The authors find that gravity waves, produced in the model when wind rose up and over a mountain, could cause temperature variations in the mesosphere of up to 12 degrees Kelvin (21 degrees Fahrenheit). They suggest that this amount of cooling, if it happens to coincide with a larger atmospheric temperature shift, could push mesospheric temperatures a few degrees below the -80 degrees Celsius (-112 degrees Fahreneheit) condensation point of carbon dioxide. Combining the results of their smaller-scale model with those of a Martian general circulation model, the authors find that they can account for carbon dioxide cloud distribution patterns consistent with observational records.
Source: Geophysical Research Letters, doi: 10.1029/2011GL050343, 2012 http://dx.doi.org/10.1029/2011GL050343
Title: Gravity waves, cold pockets and CO2 clouds in the Martian mesosphere
Authors: A. Spiga and F. Forget: Laboratoire de Meteorologie Dynamique, Universite Pierre et Marie Curie, Institut Pierre-Simon Laplace, Paris, France;
F. Gonzalez-Galindo and M.-A. Lopez-Valverde: Instituto de Astrofisica de Andalucia, Consejo Superior de Investigaciones Cientifica, Granada, Spain.
3. Effects of sea spray geoengineering on global climate
Anthropogenic climate warming is leading to consideration of options for geoengineering to offset rising carbon dioxide levels. One potential technique involves injecting artificial sea spray into the atmosphere. The sea salt particles would affect Earth's radiation budget directly, by scattering incoming solar radiation, and indirectly, by acting as cloud condensation nuclei, which could lead to whiter clouds that reflect more radiation.
But the potential effects of this method, especially the direct effects, are not fully known. Partanen et al. studied the effects of artificial sea spray using climate model simulations. They find that outside of the most heavily clouded regions the direct effect of scattering of radiation is an important part of the total effect. They also examined the effect of particle size and find that decreasing the size of injected particles could improve the efficiency of the geoengineering technique.
In addition, they conducted one simulation with aerosols injected over all Earth's oceans to identify regions that were most susceptible to cloud whitening, then carried out simulations with aerosol injections just in those specific regions. They find that geoengineering in just those regions would not be enough to offset the warming from the doubling of carbon dioxide since preindustrial times, but if enough sea salt were injected into the atmosphere over all oceans, it would be possible to compensate for much of the warming due to higher atmospheric carbon dioxide levels.
The authors stress, however, that their study did not address some of the potential side effects of this geoengineering technique, such as changes in the hydrological cycle, and they note that models of sea spray geoengineering still have significant uncertainties.
Source: Journal of Geophysical Research-Atmospheres, doi:10.1029/2011JD016428, 2012 http://dx.doi.org/10.1029/2011JD016428
Title: Direct and indirect effects of sea spray geoengineering and the role of injected particle size
Authors: Antti-Ilari Partanen and Harri Kokkola: Kuopio Unit, Finnish Meteorological Institute, Kuopio, Finland;
Sami Romakkaniemi: Department of Applied Physics, University of Eastern Finland, Kuopio, Finland;
Veli-Matti Kerminen: Climate Change, Finnish Meteorological Institute, Helsinki, Finland;
Kari E. J. Lehtinen: Kuopio Unit, Finnish Meteorological Institute, Kuopio, Finland, Department of Applied Physics, University of Eastern Finland, Kuopio, Finland;
Tommi Bergman, Antti Arola, and Hannele Korhonen: Kuopio Unit, Finnish Meteorological Institute, Kuopio, Finland.
4. Abrupt decline in East African long rains
In 2010-2011 the East African region suffered a severe drought that affected millions of people. The drought was a consequence of the failure of both the seasonal "short rains," which typically run from October to December, and the following "long rains," which typically run from March to May. The failure of the short rains was predictable given a well-established connection with La Nina, but the failure of the long rains was not. In a new study, Lyon and DeWitt show that the most recent long rains failure is consistent with a recurrent large-scale precipitation pattern that began with an abrupt shift around 1999. The authors use observations and climate model simulations to show that the abrupt decline in the East African long rains was linked to similarly abrupt changes in sea surface temperatures, mainly in the tropical Pacific basin.
Source: Geophysical Research Letters, doi:10.1029/2011GL050337, 2012 http://dx.doi.org/10.1029/2011GL050337
Title: A recent and abrupt decline in the East African long rains
Authors: Bradfield Lyon and David G. DeWitt: International Research Institute for Climate and Society, Lamont-Doherty Earth Observatory, Earth Institute at Columbia University, Palisades, New York, USA.
5. Small dams need better management
Many small dams around the world are poorly maintained and represent a safety hazard, according to Pisaniello et al. Better oversight of small dams is needed, the authors argue. The researchers reviewed literature, conducted case studies in four states in Australia, and developed policy benchmarks and best practices for small dam management.
Small dams, often just several meters high and typically privately owned by individual farmers, have historically caused major damage when they fail. For instance, in China in 1975, 230,000 people died when two large dams failed because of the cumulative failure of 60 smaller upstream dams. In the United States, in 1977 the 8-meter (26-feet) high Kelly Barnes Lake dam failed, killing 39 people. Many other small dam failures around the world have resulted in casualties and severe ecological and economic damage.
Dam management practices vary between and within countries; though in many places, few regulations exist to require farmers to maintain their dams at safe standards, the authors note. In their case studies, the researchers found many dams that were unsafe because they were improperly designed, poorly maintained, or had spillways that were blocked by natural vegetation or deliberately blocked by farmers to retain extra water. The authors argue that government regulation and education efforts, which can include the use of insurance mechanisms and cost- effective technology, are needed to get individual dam owners to bring dams up to a safe standard.
Source: Water Resources Research, doi:10.1029/2011WR011155, 2012 http://dx.doi.org/10.1029/2011WR011155
Title: Appropriate small dam management for minimizing catchment-wide safety threats: International benchmarked guidelines and demonstrative cases studies
Authors: John D. Pisaniello, Joanne Tingey-Holyoak, and Roger L. Burritt: Centre for Accounting, Governance and Sustainability, School of Commerce, University of South Australia, Adelaide, South Australia, Australia.
6. Improving forecasts of volcanic ash concentrations
Volcanic ash can severely damage airplanes, and eruptions such as the 2010 Eyjafjallajokull eruption may result in major disruption to air travel. Improved forecasting of ash cloud locations and concentrations could benefit the aviation industry and reduce delays, but forecasting is challenging because eruptions and atmospheric transport of volcanic ash are complex processes.
The UK Met Office recently improved its modeling procedures, enabling peak ash concentrations to be estimated during the 2010 Eyjafjallajokull eruption. Webster et al. describe the Met Office's method of ash concentration forecasting and how it has evolved from simply predicting regions of ash to also estimating peak ash concentrations. They compared the forecasted ash concentrations with ground- based and aircraft-based observations collected during the Eyjafjallajokull eruption and evaluated the sources of errors. Although there were challenges with predicting ash concentrations and the errors were, at times, large, the authors conclude that their ash forecasting method gives useful information on likely ash concentrations. The study provides guidance for further improvements in operational forecasting.
Source: Journal of Geophysical Research-Atmospheres, doi:10.1029/2011JD016790, 2012 http://dx.doi.org/10.1029/2011JD016790
Title: Operational prediction of ash concentrations in the distal volcanic cloud from the 2010 Eyjafjallajökull eruption
Authors: H. N. Webster, D. J. Thomson, B. T. Johnson, I. P. C. Heard, K. Turnbull, and F. Marenco: Met Office, Exeter, UK;
N. I. Kristiansen: NILU, Norwegian Institute for Air Research, Kjeller, Norway;
J. Dorsey: NCAS, University of Manchester, Manchester, UK;
A. Minikin, B. Weinzierl, and U. Schumann: Deutsches Zentrum fur Luft- und Raumfahrt, Institut fur Physik der Atmosphare, Oberpfaffenhofen, Germany;
R. S. J. Sparks: Department of Earth Sciences, University of Bristol, Bristol, UK;
S. C. Loughlin: British Geological Survey, Edinburgh, UK;
M. C. Hort, S. J. Leadbetter, B. J. Devenish, A. J. Manning, C. S. Witham, J. M. Haywood, and B. W. Golding: Met Office, Exeter, UK.
Contact:
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Journal
Geophysical Research Letters