Internet and Technology | Computers and Technology | * Written by Cruz Zachary | Wednesday, 01 August 2012 02:29 | Word Count: 472
Requirements management is one of the important phases of the software development lifecycle as requirements form the foundation for developing high quality software products. For development and testing teams to deliver effectively, there is the need of proper requirements. Wikipedia defines requirements management as ?the process of documenting, analyzing, tracing, prioritizing and agreeing on requirements and then controlling change and communicating to relevant stakeholders. ? As requirements management is increasingly important for software project success there is the need of effective requirements management tools to ease the workload of the software development team. Here is a quick look at some of the important features that good requirements management software must possess.
A Useful Tool for Geographically Dispersed Team
Being web based it allows developers to work from the same platform, no matter where they are located, whether it is between buildings on a campus, or at sites around the world.
? More effective telecommuting
? Better management and control of offshore projects
? Better collaboration with different internal functional groups and service partners
Comprehensive Traceability Relation Features
The availability of comprehensive traceability relation features allows multiple types of relations, including custom ones, between Requirements thereby facilitating the creation of logical links (?depending?, ?affecting?, and ?bi-directional?) between Requirements and view them in a number of visualizing tools.
Proactive and Reactive Impact Analysis
It automatically forwards impact of changes to stakeholders to ensure synchronization and to undertake corrective actions at the earliest to minimize the cost of changes at the end of the lifecycle.
Requirements Reuse
Reuse of well-written and implemented requirements help project teams to cut down on development time and enhance project quality
Automated Change Management
Automated change management process works in harmony with the automated Requirements Management process thereby helping in reviewing, approving, implementing, and testing requirement changes within acceptable costs and timelines.
Requirements Reporting
It helps to produce reports and requirements documents of various kinds such as marketing Requirements Document (MRD), System Requirements Specifications (SRS), Product Roadmap Document, Test Compliance Report, Trend Charts, Burn Down Charts, Requirements Stability Chart, and Graphical Charts.
Integrated Requirements Management and Test Management
Integrated Requirements Management and Test Management work together to give the users the power of QA- driven Requirements Management.
Customer Satisfaction and Competitive Edge
It helps enterprises to enhance customer satisfaction, bring a competitive edge to its product lines, and improve business and market share by setting up an excellent system for capturing customer inputs both for new product ideas as well as for improvements in existing products.
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Read more about : Application?Lifecycle?Management &??requirements traceability matrix
It is insanely hot again. Thanks to Sarah Chandler for these indoor family game ideas for all ages.
"When the mosquitoes begin to fly and the hot, humid Illinois air becomes too much to bear in the summer, it?s time to break out the games indoors. My family played lots of games when I was growing up, starting with classic Candyland and Memory, then moving on to Battleship, Life, Monopoly and Scrabble. One of my fondest/funniest memories was my brother Mark laughed so hard when he landed on the ?Skunk Farm Inheritance? square during a game of Life, that he literally made himself ?sick? on my brand new game. Ah, memories?
For me, I couldn?t wait until my own children could talk and comprehend simple instructions because that meant we could play board games together as a family. And there are really great ones for every age level. Here is my short list, but I?m sure there are many more you played as a child, so dive into those memory banks and let the games begin!
Ages 2?3 ?
Candyland: Helps with learning colors and numbers, and who doesn?t love Gramma Nut?
Memory: My kids have a better memory than me and started playing much younger than I thought possible.
Go Fish: A classic
Hide and Seek: No pieces necessary
Cat & the Hat, I can do that: Helps with coordination
Ages 3 ? ?5
Puzzles, 24-100 pieces: My kids have done a ton of these in past few years. We even made a photo book of all of the puzzles they had worked, just like their great-grandfather who is a master puzzle worker.
Uno: While traditional Uno is fun, there are now character themed ones, such a CARS and Barbie
Chutes & Ladders: I put it in this age group because of coordinating the counting, climbing and sliding.
War or High Low is another name for this game: You just need a standard deck of playing cards for this classic, and the game can go on forever! The highest card takes the turn.
Bingo: We have a wildlife bingo where kids match photos of animals rather than numbers, which allows for younger kids to play.
Cooties: Let?s face it?kids love a game about making bugs!
Busytown: The game board for this is about 4-5 feet long and just like the book, you have to find things hidden in the long picture board.
Elementary Age
Trouble: Love the pop-o-matic bubble!
Sorry: Teaches strategy and how kids can gang up on their parents during a board game.
Racko: Helps you learn to manipulate cards to get them in number order.
Connect Four: The newer version has more options for playing.
Yahtzee: Like Uno, this classic now has character versions.
Twister: This is a fun age to start it at, but really, any age can play if you are flexible!
Guess Who?: This is similar to the game where you guess if it is an animal, mineral or vegetable, but with people.
Wii: We have started playing the bowling game and it has been super fun.
Tweens & Up
Monopoly: Many versions of this game are available. We even have a golf one and an Illini version.
Life
Scrabble
Pictionary
Battleship: I still remember the commercial introducing this game? ?You sunk my battleship!?
Taboo: The buzzer has changed its tune since the original, but it is still fun to watch people try and describe a word without saying certain words listed on the game card.
Upwards: A bit like scrabble, except you can stack tiles on one another.
Charades: Get those kids to be a little silly acting out things and maybe they won?t grow up so fast.
Crazy Eights: Rules are as follows: http://boardgames.about.com/od/cardgames/a/crazy_eights.htm
Submitted by Sarah Chandler. Sarah is a Springfield native, wife to Jeff and mom to Levi and Anne. She loves to spend time outdoors biking, hiking, skiing and playing golf. When she needs a break, you?ll find her in the purple painted walls of her craft room writing, creating quilts, swaddle blankets and scrapbooks.
The cellular phone has become an amazingly popular and extremely beneficial electronic device based on its versatility and ability to make itself almost near indispensable. They have done this primarily by making a hectic life for most consumers better and easier to live. The ability for instant communications from almost any location at any time has long been the pride and selling point for cellular phones and cell plans. However with the many new features incorporated into the more sophisticated cell phones that are available on the market, just enabling family and friends to stay close through communication ins no longer the primary reason for owning a cell phone.
The fact is, with the many mind boggling and innovative developments that have taken place with the technology used in cell phones they have now morphed into a vary valuable business tool that is more then capable of handling advanced features such as, multimedia messaging and functions, web browsing, organizing and even for use as a global positioning system (GPS). Gone are the days when the cell phone was only viewed as a device to talk and occasionally play a game on for entertainment. Instead they have now developed a cult like status for communication and limitless information storing and business deal making.
It wasn?t to long ago that sending text messages was the talk of the cellular phone community. It was an amazing feeling being able to send and receive messages in real time on your cell phone just like you send on a computer everyday. However, even more exciting and high tech is the ability to now send and receive multimedia messages to include the impressive capability of sending pictures and video clips. Voice messaging is another feature that the latest cell phones offer as part of their programming and packaging.
Even though the cell phone has made itself an impact player when it comes to assisting in business deals there are still a large amount of cell phone users that love being entertained by their cell phone. The newest mobile phones allow you download the latest cell phone games from the Internet via a network or wireless connection. In fact, many new cell phones ship preloaded with a large selection of playable games for your entertainment.
Cell phones are also starting to ship with enough on board memory capacity enabling them to function as a standard palm pilot and MP3 player. The MP3 songs are downloaded and stored in your cell phone memory banks. You now have the ability to avoid purchasing a hand held PDA and MP3 player based on the cell phone?s newest functions. Other nice features include the ability of the cell phone to function as a radio, TV, camera and even as a global positioning satellite.
As you can see the new features and capabilities of the latest cell phones truly establish them as a dominant player on the market able to function effectively as an entertainment tool while at the same time capable of performing well as an indispensable business tool.
Redesigning is often as straightforward as painting a room or maybe more difficult like redecorating the house. Irrespective, they are many ways you could find beneficial to prevent unnecessary aggravation and/or severe headaches.
If your door must endure torrents of warm weather, ensure that you choose an gas centered painting rather than latex to avoid the painting from peeling away. A shedding front door is reasonably unattractive, so commit some money in good quality gas centered paint to maintain your door hunting fresh in the heat.
Use window covers, for example drapes to complete your home design appear to make your home windows appearance wonderful. You should choose window curtains which can be thrice broader than your home window and enable for ample windowpane insurance coverage. Should you be looking to let far more lighting in your house select window curtains which are absolute.
If you?re contemplating undertaking redecorating job, get a house examination first. If you?ve possessed your home for about decade there may be some injury that can change the safety of your residence. Possess a home inspector arrive via and look your complete property, then pay money for any fixes before you decide to devote all your funds on improvements.
Creating a power area with your original property design and style is a very clever thought. In this way you may put all of your current application home appliances in a single. If you can keep your cooling and heating program, hot water heater, and electric powered board all in one conveniently found location, it will be simpler to services them, and you will steer clear of spending plenty of space for storage with them in different locations of your house.
There are lots of residence-improvement duties that are simple to do, and may definitely boost the advantage of your house. Swapping the previous hardware on the kitchen cabinets with new updated hardware, is really a relatively simple task and can give your cabinets a brand new fresh look. Dealing with modest house-development projects can help provide you with the confidence to consider even bigger assignments in the foreseeable future.
Among the finest home improvements for your house is a wood deck inclusion. Not simply is it an awesome destination to take advantage of the in the open air, furthermore, it provide a fantastic give back in your investment if you re-offer your own home. Most homeowners get back 81 pct of your funds that they used on this home remodeling. Just be sure you do appropriate maintenance each year to the outdoor patio to optimize it?s return possible.
Unpleasant drive-ways and definite might be fixed without having to spend the time and money to replace them. Definite refinishing has become a new option for the chipped drive way or walkway. They could use a new topcoat, staining, mark habits or any other elements of design that may give your property a completely new look for a lot less.
To guarantee that you generally know who is knocking, install vast-angle peepholes on every one of your exterior doors. These particular contact lenses enable you to see that is sitting on your porch or outdoor patio without starting the door or tugging back the drapes. In addition, they can be fairly simple to install.
An incredible home remodeling task that can save you a bundle is always to install an automated thermostat. These thermostats can allow you to system in a variety of distinct adjustments so that you are using your heating and air conditioning program only when you really need it and while not having to keep an eye on it continually.
In case you have employed an outside company to aid you a home development project ? usually examine the completed operate completely ? just before make payment on closing installment to the services. By doing this inspection, you will have a greater chance of obtaining discrepancies and insufficiencies in the contracted operate corrected. When you have compensated in full, it is more difficult to get these issues treated!
Home remodeling jobs are something many feel ill-outfitted to do alone. The main thing to consider, however, is that with the proper information and facts, anything at all can be done in this particular realm. Leverage the recommendations within this bit, and you will quickly be ready to execute a broad selection of redecorating jobs that will raise the attractiveness of your home.
There is more content available about Bolier Repair Nottingham read Albina M. Sin?s site there is a lot of details not covered in this article, take a look at Author?s blog to locate more.
Contact: Kate Ramsayer kramsayer@agu.org 202-777-7524 American Geophysical Union
The following highlights summarize research papers that have been recently published in Water Resources Research (WRR),Geophysical Research-Atmospheres (JGR-D), Journal of Geophysical Research-Space Physics (JGR-A), Journal of Geophysical Research-Biogeosciences (JGR-G), and Journal of Geophysical Research-Oceans (JGR-C).
In this release:
1. The random walk of pollutants through river catchments
2. Atmospheric CO2 drove climate change during longest interglacial
3. Shear layers in solar winds affect Earth's magnetosphere
4. Dams impact carbon dynamics in U.S. rivers
5. Comparison with observations shows cloud simulations improving
6. Turbulent forces within river plumes affect spread
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. 10.1029/2011WR011367. 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. The random walk of pollutants through river catchments
River catchments play critical roles in regional economies and in the global economy. In addition, rivers carry large volumes of nutrients, pollutants, and several other forms of tracers into the ocean. An intricate system of pathways and channels, both on the surface and in the subsurface of catchments, allows rivers to carry large volumes of tracers. However, scientists do not yet fully understand how pollutants and other tracers travel through the intricate web of channels in the catchment areas of rivers.
In a new study, Cvetkovic et al. show that the travel path of tracers through channels can be modeled as a random walk, which is mathematically similar to the path an animal would trace when foraging. Previous studies have applied the random walk approach to understand the behavior of fluids flowing through aquifers and soils but not to model the transport mechanism of tracers that travel passively with water flowing through catchments.
The authors also show that the random walk behavior of tracers in river catchments depends on how the velocity of particles in the catchment has varied over time; the variability in velocity in turn depends on how the physical space of the channel itself has evolved over a long time. Their study provides a new approach to understanding transport of tracers, such as pollutants and nutrients, within a river catchment.
Source:
Water Resources Research, doi:10.1029/2011WR011367, 2012
http://dx.doi.org/10.1029/2011WR011367
Title:
Water and solute transport along hydrological pathways
Authors:
Vladimir Cvetkovic and Christoffer Carstens: Department of Land and Water Resources Engineering, Royal Institute of Technology, Stockholm, Sweden;
Jan-Olof Selroos: Department of Geoscience and Safety, Swedish Nuclear Fuel and Waste Management Co., Stockholm, Sweden;
Georgia Destouni: Department of Physical Geography and Quaternary Geology, Stockholm University, Stockholm, Sweden.
2. Atmospheric CO2 drove climate change during longest interglacial
Known as the marine isotope stage 11 (MIS 11), the interglacial period centered around 400,000 years ago was the longest and possibly the warmest interglacial in the past 0.5 million years. Because the orbital configurations, atmospheric greenhouse gas concentrations, climate, and faunal characteristics during MIS 11 closely resemble those of the past 5,000 years, paleoclimatologists use MIS 11 as a geological analogue of the present and the near future.
There exist several high-resolution records documenting almost all aspects of terrestrial and marine climate through MIS 11. However, there is neither a clear understanding about how climactic parameters such as atmospheric carbon dioxide (CO2), sea surface temperature, the isotopic makeup of carbon in marine and terrestrial reservoirs, and annual air temperature interact, nor a consensus regarding the major drivers of climate change during this interval.
Using 15 of the most robust proxy records of marine and terrestrial climate, Das Sharma et al. employ new statistical and mathematical techniques to quantify the interactions among climatic parameters and to investigate which of these parameters could be the primary drivers of climate change during MIS 11. The authors find that atmospheric CO2 concentration was indeed the primary driver of both terrestrial and marine climate: Sea surface temperature and the isotopic makeup of carbon in terrestrial and marine reservoirs responded "instantaneously" (i.e., within 1,000 years) to changes in atmospheric CO2 content.
They further report that MIS 11 had warm and cool phases that can be detected from sea surface temperature records alone. During the relatively cold phases, sea surface and air temperatures behave coherently and respond to atmospheric CO2 faster. However, during warmer intervals, ocean surface and air temperatures behave more independently of each other and atmospheric CO2. The authors suggest that over the course of the next century, air and sea surface temperatures are likely to change in ways that will be difficult to predict.
Source:
Journal of Geophysical Research-Atmospheres, doi:10.1029/2012JD017725, 2012
http://dx.doi.org/10.1029/2012JD017725
Title:
Sea surface temperatures in cooler climate stages bear more similarity with atmospheric CO2 forcing
Authors:
S. Das Sharma, D. S. Ramesh, C. Bapanayya, and P. A. Raju: National Geophysical Research Institute, Council of Scientific and Industrial Research, Hyderabad, India.
3. Shear layers in solar winds affect Earth's magnetosphere
Human society is increasingly reliant on technology that can be disrupted by space weather. For instance, geomagnetic storms can cause high-latitude air flights to be rerouted, costing as much as $100,000 per flight; induce errors of up to 46 meters (151 feet) in GPS systems; and affect satellites and the International Space Station. Space weather is determined by how the solar wind, a stream of hot plasma from the Sun, interacts with Earth's magnetic field. In studying space weather, scientists have largely neglected the fact that the solar wind contains layers of very strong velocity shear. Scientists understand very little about how these wind shears affect space weather.
Combining statistical analysis of solar wind data from the Advanced Composition Explorer satellite, which measures solar particles approaching Earth, with a series of magnetohydrodynamic simulations, used to model the behavior of the Earth's magnetosphere, Borovsky characterizes the properties of the shear layers that travel past the Earth and the reaction of the Earth to those passing layers.
The author finds that as many as 60 of these shear zones can pass by Earth each day at velocities above 50 kilometers per second (31 miles per second). Passage of a shear layer perturbs the entire magnetosphere and ionosphere, which could produce a comet-like disconnection of the Earth's magnetotail (the tail-like extension of Earth's magnetic field on the side facing away from the Sun). Although the velocity shears will not cause a geomagnetic storm, they may determine how such a storm works. Hence, the author recommends several follow-up studies of the reaction of Earth to sudden wind shear.
Source:
Journal of Geophysical Research-Space Physics, doi:10.1029/2012JA017623, 2012
http://dx.doi.org/10.1029/2012JA017623
Title:
The effect of sudden wind shear on the Earth's magnetosphere: Statistics of wind shear events and CCMC simulations of magnetotail disconnections
Author:
Joseph E. Borovsky: Space Science Institute, Boulder, Colorado, USA, Also at Department Atmospheric, Oceanic and Space Sciences, University of Michigan,
Ann Arbor, Michigan, USA.
4. Dams impact carbon dynamics in U.S. rivers
Dissolved organic carbon (DOC)which leaches into freshwater systems from plants, soils, and sediments, and from other detritus present in the water itselfis the major food supplement for microorganisms and plays an important role in several environmental processes and in the global carbon cycle. In some aquatic systems such as estuaries the optically measurable colored component of dissolved organic matter (CDOM) is often proportional to the concentration of DOC.
CDOM forms when light-absorbing compounds are released into the water by decaying organic material and through photochemical degradation of certain organic compounds. Hence, CDOM reflects not just the environment and ecosystem, which is the source of the detritus, but also processes that deliver the organic matter into aquatic systems. Human activities, such as logging, agriculture, and waste water treatment, also affect CDOM levels in aquatic systems. It is relatively easy and inexpensive to measure the CDOM content in small volumes of water.
To examine the circumstances under which CDOM reflects DOC concentration, Spencer et al. measured CDOM and DOC concentrations in water collected from 30 rivers across the United States; the rivers represent a wide range of climate, watershed environments, ecosystems, and anthropogenic influence. Overall, the authors find that the CDOM level reflects the DOC concentration in the river water, except in four large rivers, namely, the Colorado, Columbia, Rio Grande, and St. Lawrence rivers.
These four rivers either drain from the Great Lakes or have significant restrictions within their watersheds such as dam building and other similar modifications. These activities result in long residence times of water, which may increase phytoplankton production, the relative contribution from human sources, or degradation of land-derived material by photochemical processes. As a result, there may have been a decoupling of CDOM from DOC, i.e., the amount of CDOM in these four rivers may have decreased without a concomitant decrease in DOC content. On the basis of their findings, the authors suggest that CDOM measurements in rivers are a useful way to investigate water quality and to monitor delivery of DOC into coastal regions as ecosystems respond to human activity and changes in climate in the near future.
Source:
Journal of Geophysical Research-Biogeosciences, doi:10.1029/2011JG001928, 2012
http://dx.doi.org/10.1029/2011JG001928
Title:
Dissolved organic carbon and chromophoric dissolved organic matter properties of rivers in the USA
Authors:
Robert G. M. Spencer: Global Rivers Group, Woods Hole Research Center, Falmouth, Massachusetts, USA;
Kenna D. Butler and George R. Aiken: United States Geological Survey,
Boulder, Colorado, USA.
5. Comparison with observations shows cloud simulations improving
Climate projections, such as those used by the Intergovernmental Panel on Climate Change, rely on models that simulate physical properties that affect climate, including clouds and water vapor content. Clouds and water vapor are difficult to simulate in global climate models because they are affected by small-scale physical processes, and cloud feedback on climate is therefore a large source of uncertainty in climate predictions.
A new study finds that model simulations of vertically averaged cloud water amount have improved in recent years. Jiang et al. develop a quantitative scoring method to evaluate the accuracy of 19 climate models at various vertical heights between the surface and the tropopause (16 to 18 kilometers (10 to 11 miles) in altitude) over the tropical oceans (30 degrees North to 30 degrees South). They compare the models' simulated multiyear mean of cloud water content and water vapor with observations made using several NASA satellites.
Many of the new models, which were submitted to phase 5 of the Coupled Model Intercomparison Project (CMIP5), have attempted to improve representation of clouds using finer-scale simulations. The authors find that more than half of the models did show improvement over previous models from CMIP3 in simulating the amount and distribution of clouds and water vapor over the tropical oceans. In addition, they find that the models simulated boundary layer water vapor amounts accurately. However, there are large differences among the models and between the models and observations at high altitudes in the upper troposphere.
Source:
Journal of Geophysical Research-Atmospheres, doi:10.1029/2011JD017237, 2012
http://dx.doi.org/10.1029/2011JD017237
Title:
Evaluation of cloud and water vapor simulations in CMIP5 climate models using NASA "A-Train" satellite observations
Authors:
Jonathan H. Jiang, Hui Su, Chengxing Zhai, and Vincent S. Perun: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA;
Anthony Del Genio and Larissa S. Nazarenko: Goddard Institute for Space Studies, New York, New York, USA;
Leo J. Donner, Larry Horowitz, and Charles Seman: Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey, USA;
Jason Cole: Canadian Centre for Climate Modeling and Analysis, Environment Canada, Toronto, Ontario, Canada;
Andrew Gettelman: National Center for Atmospheric Research, Boulder, Colorado, USA;
Mark A. Ringer: Met Office Hadley Centre, Exeter, UK;
Leon Rotstayn: Commonwealth Scientific and Industrial Research Organisation,
Clayton South, Victoria, Australia;
Stephen Jeffrey: Queensland Climate Change Centre of Excellence, Dutton Park, Queensland, Australia;
Tongwen Wu: Beijing Climate Center, China Meteorological Administration,
Beijing, China;
Florent Brient and Jean-Louis Dufresne: Laboratoire de Mtorologie Dynamique, Institute Pierre Simon Laplace, Paris, France;
Hideaki Kawai and Tsuyoshi Koshiro: Meteorological Research Institute, Japan Meteorological Agency, Tsukuba, Japan;
Masahiro Watanabe: Model for Interdisciplinary Research on Climate, Atmospheric and Ocean Research Institute, University of Tokyo, Chiba, Japan;
Tristan S. Lcuyer: University of Wisconsin-Madison, Madison, Wisconsin, USA;
Evgeny M. Volodin: Institute for Numerical Mathematics, Russian Academy of Sciences, Moscow, Russia;
Trond Iversen: Norwegian Climate Centre, Meteorologisk Institutt, Oslo, Norway;
Helge Drange and Michel D. S. Mesquita: Bjerknes Centre for Climate Research, Uni Research, Bergen, Norway;
William G. Read, Joe W. Waters, Baijun Tian, Joao Teixeira, and Graeme L. Stephens: JPL, California Institute of Technology, Pasadena, California, USA.
6. Turbulent forces within river plumes affect spread
When rivers drain into oceans through narrow mouths, hydraulic forces squeeze the river water into buoyant plumes that are clearly visible in satellite images. Worldwide, river plumes not only disperse freshwater, sediments, and nutrients but also spread pollutants and organisms from estuaries into the open ocean. In the United States the Columbia River, the largest river by volume draining into the Pacific Ocean from North America, generates a plume at its mouth that transports juvenile salmon and other fish into the ocean. Clearly, the behavior and spread of river plumes, such as the Columbia River plume, affect the nation's fishing industry as well as the global economy.
A delicate balance between density and velocity controls turbulent mixing within the plume and how far river plumes extend into the deep ocean. On the other hand, coastal winds and currents affect the shape and orientation of the plumes. However, current understanding of momentum changes along a river plume is limited by poorly constrained numerical models and sparse remote sensing data.
In a new study, Kilcher et al. document velocity, density, and turbulence along the centerline of the Columbia River plume at a high resolution for 10 tidal cycles. The authors find that turbulence varied by 2 to 3 orders of magnitude within a single tidal cycle as well as between cycles. The authors also show that turbulence, which is most vigorous at the beginning of the strongest ebbs, dramatically reduces the velocity of water at the river mouth. The quickly decelerating plumes tend to spread less into the deep ocean. Their observations supplement satellite data and could help to fine-tune numerical models that predict the behavior and spread of river plumes as they drain into coastal waters.
Source:
Journal of Geophysical Research-Oceans, doi:10.1029/2011JC007398, 2012
http://dx.doi.org/10.1029/2011JC007398
Title:
The role of turbulence stress divergence in decelerating a river plume
Authors:
Levi F. Kilcher, Jonathan D. Nash, and James N. Moum: College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon, USA.
###
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Contact: Kate Ramsayer kramsayer@agu.org 202-777-7524 American Geophysical Union
The following highlights summarize research papers that have been recently published in Water Resources Research (WRR),Geophysical Research-Atmospheres (JGR-D), Journal of Geophysical Research-Space Physics (JGR-A), Journal of Geophysical Research-Biogeosciences (JGR-G), and Journal of Geophysical Research-Oceans (JGR-C).
In this release:
1. The random walk of pollutants through river catchments
2. Atmospheric CO2 drove climate change during longest interglacial
3. Shear layers in solar winds affect Earth's magnetosphere
4. Dams impact carbon dynamics in U.S. rivers
5. Comparison with observations shows cloud simulations improving
6. Turbulent forces within river plumes affect spread
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. 10.1029/2011WR011367. 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. The random walk of pollutants through river catchments
River catchments play critical roles in regional economies and in the global economy. In addition, rivers carry large volumes of nutrients, pollutants, and several other forms of tracers into the ocean. An intricate system of pathways and channels, both on the surface and in the subsurface of catchments, allows rivers to carry large volumes of tracers. However, scientists do not yet fully understand how pollutants and other tracers travel through the intricate web of channels in the catchment areas of rivers.
In a new study, Cvetkovic et al. show that the travel path of tracers through channels can be modeled as a random walk, which is mathematically similar to the path an animal would trace when foraging. Previous studies have applied the random walk approach to understand the behavior of fluids flowing through aquifers and soils but not to model the transport mechanism of tracers that travel passively with water flowing through catchments.
The authors also show that the random walk behavior of tracers in river catchments depends on how the velocity of particles in the catchment has varied over time; the variability in velocity in turn depends on how the physical space of the channel itself has evolved over a long time. Their study provides a new approach to understanding transport of tracers, such as pollutants and nutrients, within a river catchment.
Source:
Water Resources Research, doi:10.1029/2011WR011367, 2012
http://dx.doi.org/10.1029/2011WR011367
Title:
Water and solute transport along hydrological pathways
Authors:
Vladimir Cvetkovic and Christoffer Carstens: Department of Land and Water Resources Engineering, Royal Institute of Technology, Stockholm, Sweden;
Jan-Olof Selroos: Department of Geoscience and Safety, Swedish Nuclear Fuel and Waste Management Co., Stockholm, Sweden;
Georgia Destouni: Department of Physical Geography and Quaternary Geology, Stockholm University, Stockholm, Sweden.
2. Atmospheric CO2 drove climate change during longest interglacial
Known as the marine isotope stage 11 (MIS 11), the interglacial period centered around 400,000 years ago was the longest and possibly the warmest interglacial in the past 0.5 million years. Because the orbital configurations, atmospheric greenhouse gas concentrations, climate, and faunal characteristics during MIS 11 closely resemble those of the past 5,000 years, paleoclimatologists use MIS 11 as a geological analogue of the present and the near future.
There exist several high-resolution records documenting almost all aspects of terrestrial and marine climate through MIS 11. However, there is neither a clear understanding about how climactic parameters such as atmospheric carbon dioxide (CO2), sea surface temperature, the isotopic makeup of carbon in marine and terrestrial reservoirs, and annual air temperature interact, nor a consensus regarding the major drivers of climate change during this interval.
Using 15 of the most robust proxy records of marine and terrestrial climate, Das Sharma et al. employ new statistical and mathematical techniques to quantify the interactions among climatic parameters and to investigate which of these parameters could be the primary drivers of climate change during MIS 11. The authors find that atmospheric CO2 concentration was indeed the primary driver of both terrestrial and marine climate: Sea surface temperature and the isotopic makeup of carbon in terrestrial and marine reservoirs responded "instantaneously" (i.e., within 1,000 years) to changes in atmospheric CO2 content.
They further report that MIS 11 had warm and cool phases that can be detected from sea surface temperature records alone. During the relatively cold phases, sea surface and air temperatures behave coherently and respond to atmospheric CO2 faster. However, during warmer intervals, ocean surface and air temperatures behave more independently of each other and atmospheric CO2. The authors suggest that over the course of the next century, air and sea surface temperatures are likely to change in ways that will be difficult to predict.
Source:
Journal of Geophysical Research-Atmospheres, doi:10.1029/2012JD017725, 2012
http://dx.doi.org/10.1029/2012JD017725
Title:
Sea surface temperatures in cooler climate stages bear more similarity with atmospheric CO2 forcing
Authors:
S. Das Sharma, D. S. Ramesh, C. Bapanayya, and P. A. Raju: National Geophysical Research Institute, Council of Scientific and Industrial Research, Hyderabad, India.
3. Shear layers in solar winds affect Earth's magnetosphere
Human society is increasingly reliant on technology that can be disrupted by space weather. For instance, geomagnetic storms can cause high-latitude air flights to be rerouted, costing as much as $100,000 per flight; induce errors of up to 46 meters (151 feet) in GPS systems; and affect satellites and the International Space Station. Space weather is determined by how the solar wind, a stream of hot plasma from the Sun, interacts with Earth's magnetic field. In studying space weather, scientists have largely neglected the fact that the solar wind contains layers of very strong velocity shear. Scientists understand very little about how these wind shears affect space weather.
Combining statistical analysis of solar wind data from the Advanced Composition Explorer satellite, which measures solar particles approaching Earth, with a series of magnetohydrodynamic simulations, used to model the behavior of the Earth's magnetosphere, Borovsky characterizes the properties of the shear layers that travel past the Earth and the reaction of the Earth to those passing layers.
The author finds that as many as 60 of these shear zones can pass by Earth each day at velocities above 50 kilometers per second (31 miles per second). Passage of a shear layer perturbs the entire magnetosphere and ionosphere, which could produce a comet-like disconnection of the Earth's magnetotail (the tail-like extension of Earth's magnetic field on the side facing away from the Sun). Although the velocity shears will not cause a geomagnetic storm, they may determine how such a storm works. Hence, the author recommends several follow-up studies of the reaction of Earth to sudden wind shear.
Source:
Journal of Geophysical Research-Space Physics, doi:10.1029/2012JA017623, 2012
http://dx.doi.org/10.1029/2012JA017623
Title:
The effect of sudden wind shear on the Earth's magnetosphere: Statistics of wind shear events and CCMC simulations of magnetotail disconnections
Author:
Joseph E. Borovsky: Space Science Institute, Boulder, Colorado, USA, Also at Department Atmospheric, Oceanic and Space Sciences, University of Michigan,
Ann Arbor, Michigan, USA.
4. Dams impact carbon dynamics in U.S. rivers
Dissolved organic carbon (DOC)which leaches into freshwater systems from plants, soils, and sediments, and from other detritus present in the water itselfis the major food supplement for microorganisms and plays an important role in several environmental processes and in the global carbon cycle. In some aquatic systems such as estuaries the optically measurable colored component of dissolved organic matter (CDOM) is often proportional to the concentration of DOC.
CDOM forms when light-absorbing compounds are released into the water by decaying organic material and through photochemical degradation of certain organic compounds. Hence, CDOM reflects not just the environment and ecosystem, which is the source of the detritus, but also processes that deliver the organic matter into aquatic systems. Human activities, such as logging, agriculture, and waste water treatment, also affect CDOM levels in aquatic systems. It is relatively easy and inexpensive to measure the CDOM content in small volumes of water.
To examine the circumstances under which CDOM reflects DOC concentration, Spencer et al. measured CDOM and DOC concentrations in water collected from 30 rivers across the United States; the rivers represent a wide range of climate, watershed environments, ecosystems, and anthropogenic influence. Overall, the authors find that the CDOM level reflects the DOC concentration in the river water, except in four large rivers, namely, the Colorado, Columbia, Rio Grande, and St. Lawrence rivers.
These four rivers either drain from the Great Lakes or have significant restrictions within their watersheds such as dam building and other similar modifications. These activities result in long residence times of water, which may increase phytoplankton production, the relative contribution from human sources, or degradation of land-derived material by photochemical processes. As a result, there may have been a decoupling of CDOM from DOC, i.e., the amount of CDOM in these four rivers may have decreased without a concomitant decrease in DOC content. On the basis of their findings, the authors suggest that CDOM measurements in rivers are a useful way to investigate water quality and to monitor delivery of DOC into coastal regions as ecosystems respond to human activity and changes in climate in the near future.
Source:
Journal of Geophysical Research-Biogeosciences, doi:10.1029/2011JG001928, 2012
http://dx.doi.org/10.1029/2011JG001928
Title:
Dissolved organic carbon and chromophoric dissolved organic matter properties of rivers in the USA
Authors:
Robert G. M. Spencer: Global Rivers Group, Woods Hole Research Center, Falmouth, Massachusetts, USA;
Kenna D. Butler and George R. Aiken: United States Geological Survey,
Boulder, Colorado, USA.
5. Comparison with observations shows cloud simulations improving
Climate projections, such as those used by the Intergovernmental Panel on Climate Change, rely on models that simulate physical properties that affect climate, including clouds and water vapor content. Clouds and water vapor are difficult to simulate in global climate models because they are affected by small-scale physical processes, and cloud feedback on climate is therefore a large source of uncertainty in climate predictions.
A new study finds that model simulations of vertically averaged cloud water amount have improved in recent years. Jiang et al. develop a quantitative scoring method to evaluate the accuracy of 19 climate models at various vertical heights between the surface and the tropopause (16 to 18 kilometers (10 to 11 miles) in altitude) over the tropical oceans (30 degrees North to 30 degrees South). They compare the models' simulated multiyear mean of cloud water content and water vapor with observations made using several NASA satellites.
Many of the new models, which were submitted to phase 5 of the Coupled Model Intercomparison Project (CMIP5), have attempted to improve representation of clouds using finer-scale simulations. The authors find that more than half of the models did show improvement over previous models from CMIP3 in simulating the amount and distribution of clouds and water vapor over the tropical oceans. In addition, they find that the models simulated boundary layer water vapor amounts accurately. However, there are large differences among the models and between the models and observations at high altitudes in the upper troposphere.
Source:
Journal of Geophysical Research-Atmospheres, doi:10.1029/2011JD017237, 2012
http://dx.doi.org/10.1029/2011JD017237
Title:
Evaluation of cloud and water vapor simulations in CMIP5 climate models using NASA "A-Train" satellite observations
Authors:
Jonathan H. Jiang, Hui Su, Chengxing Zhai, and Vincent S. Perun: Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA;
Anthony Del Genio and Larissa S. Nazarenko: Goddard Institute for Space Studies, New York, New York, USA;
Leo J. Donner, Larry Horowitz, and Charles Seman: Geophysical Fluid Dynamics Laboratory, Princeton, New Jersey, USA;
Jason Cole: Canadian Centre for Climate Modeling and Analysis, Environment Canada, Toronto, Ontario, Canada;
Andrew Gettelman: National Center for Atmospheric Research, Boulder, Colorado, USA;
Mark A. Ringer: Met Office Hadley Centre, Exeter, UK;
Leon Rotstayn: Commonwealth Scientific and Industrial Research Organisation,
Clayton South, Victoria, Australia;
Stephen Jeffrey: Queensland Climate Change Centre of Excellence, Dutton Park, Queensland, Australia;
Tongwen Wu: Beijing Climate Center, China Meteorological Administration,
Beijing, China;
Florent Brient and Jean-Louis Dufresne: Laboratoire de Mtorologie Dynamique, Institute Pierre Simon Laplace, Paris, France;
Hideaki Kawai and Tsuyoshi Koshiro: Meteorological Research Institute, Japan Meteorological Agency, Tsukuba, Japan;
Masahiro Watanabe: Model for Interdisciplinary Research on Climate, Atmospheric and Ocean Research Institute, University of Tokyo, Chiba, Japan;
Tristan S. Lcuyer: University of Wisconsin-Madison, Madison, Wisconsin, USA;
Evgeny M. Volodin: Institute for Numerical Mathematics, Russian Academy of Sciences, Moscow, Russia;
Trond Iversen: Norwegian Climate Centre, Meteorologisk Institutt, Oslo, Norway;
Helge Drange and Michel D. S. Mesquita: Bjerknes Centre for Climate Research, Uni Research, Bergen, Norway;
William G. Read, Joe W. Waters, Baijun Tian, Joao Teixeira, and Graeme L. Stephens: JPL, California Institute of Technology, Pasadena, California, USA.
6. Turbulent forces within river plumes affect spread
When rivers drain into oceans through narrow mouths, hydraulic forces squeeze the river water into buoyant plumes that are clearly visible in satellite images. Worldwide, river plumes not only disperse freshwater, sediments, and nutrients but also spread pollutants and organisms from estuaries into the open ocean. In the United States the Columbia River, the largest river by volume draining into the Pacific Ocean from North America, generates a plume at its mouth that transports juvenile salmon and other fish into the ocean. Clearly, the behavior and spread of river plumes, such as the Columbia River plume, affect the nation's fishing industry as well as the global economy.
A delicate balance between density and velocity controls turbulent mixing within the plume and how far river plumes extend into the deep ocean. On the other hand, coastal winds and currents affect the shape and orientation of the plumes. However, current understanding of momentum changes along a river plume is limited by poorly constrained numerical models and sparse remote sensing data.
In a new study, Kilcher et al. document velocity, density, and turbulence along the centerline of the Columbia River plume at a high resolution for 10 tidal cycles. The authors find that turbulence varied by 2 to 3 orders of magnitude within a single tidal cycle as well as between cycles. The authors also show that turbulence, which is most vigorous at the beginning of the strongest ebbs, dramatically reduces the velocity of water at the river mouth. The quickly decelerating plumes tend to spread less into the deep ocean. Their observations supplement satellite data and could help to fine-tune numerical models that predict the behavior and spread of river plumes as they drain into coastal waters.
Source:
Journal of Geophysical Research-Oceans, doi:10.1029/2011JC007398, 2012
http://dx.doi.org/10.1029/2011JC007398
Title:
The role of turbulence stress divergence in decelerating a river plume
Authors:
Levi F. Kilcher, Jonathan D. Nash, and James N. Moum: College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, Oregon, USA.
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Public release date: 31-Jul-2012
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