Nonlinear dynamics of global atmospheric and Earth-system processes

Researchers are continuing their studies of the nonlinear dynamics of global weather systems. Sensitivity analyses of large-scale dynamical models of the atmosphere (i.e., general circulation models i.e., GCM's) were performed to establish the role of satellite-signatures of soil moisture, sea surface temperature, snow cover, and sea ice as crucial boundary conditions determining global weather variability. To complete their study of the bimodality of the planetary wave states, they are using the dynamical systems approach to construct a low-order theoretical explanation of this phenomenon. This work should have important implications for extended range forecasting of low-frequency oscillations, elucidating the mechanisms for the transitions between the two wave modes. Researchers are using the methods of jump analysis and attractor dimension analysis to examine the long-term satellite records of significant variables (e.g., long wave radiation, and cloud amount), to explore the nature of mode transitions in the atmosphere, and to determine the minimum number of equations needed to describe the main weather variations with a low-order dynamical system. Where feasible they will continue to explore the applicability of the methods of complex dynamical systems analysis to the study of the global earth-system from an integrative viewpoint involving the roles of geochemical cycling and the interactive behavior of the atmosphere, hydrosphere, and biosphere

Nonlinear dynamics of global atmospheric and Earth-system processes

General Circulation Model (GCM) studies of the atmospheric response to change boundary conditions are discussed. Results are reported on an extensive series of numerical studies based on the National Center for Atmospheric Research (NCAR) Community Climate Model (CCM) general circulation model. In these studies the authors determined the response to systematic changes in atmospheric CO2 ranging from 100 to 1000 ppm; to changes in the prescribed sea surface temperature (SST) in the Gulf of Mexico, such as occurred during the deglaciation phase of the last ice age; to changes in soil moisture over North America; and to changes in sea ice extent in the Southern Hemisphere. Study results show that the response of surface temperature and other variables is nearly logarithmic, with lower levels of CO2 implying greater sensitivity of the atmospheric state to changes in CO2. It was found that the surface temperature of the Gulf of Mexico exerts considerable control over the storm track and behavior of storm systems over the North Atlantic through its influence on evaporation and the source of latent heat. It was found that reductions in soil moisture can play a significant role in amplifying and maintaining North American drought, particularly when a negative soil moisture anomaly prevails late in the spring

Barry Saltzman and the Theory of Climate

Barry Saltzman was a giant in the fields of meteorology and climate science. A leading figure in the study of weather and climate for over 40 yr, he has frequently been referred to as the father of modern climate theory. Ahead of his time in many ways, Saltzman made significant contributions to our understanding of the general circulation and spectral energetics budget of the atmosphere, as well as climate change across a wide spectrum of time scales. In his endeavor to develop a unified theory of how the climate system works, lie played a role in the development of energy balance models, statistical dynamical models, and paleoclimate dynamical models. He was a pioneer in developing meteorologically motivated dynamical systems, including the progenitor of Lorenz\u27s famous chaos model. In applying his own dynamical-systems approach to long-term climate change, he recognized the potential for using atmospheric general circulation models in a complimentary way. In 1998, he was awarded the Carl-Gustaf Rossby medal, the highest honor of the American Meteorological Society for his life-long contributions to the study of the global circulation and the evolution of the earth\u27s climate. In this paper, the authors summarize and place into perspective some of the most significant contributions that Barry Saltzman made during his long and distinguished career. This short review also serves as an introduction to the papers in this special issue of the Journal of Climate dedicated to Barry\u27s memory

Application of dynamical systems theory to global weather phenomena revealed by satellite imagery

Theoretical studies of low frequency and seasonal weather variability; dynamical properties of observational and general circulation model (GCM)-generated records; effects of the hydrologic cycle and latent heat release on extratropical weather; and Earth-system science studies are summarized

Quantification of Reef Fish Assemblages: A Comparison of Several In Situ Methods

On two coral reef biotopes off St. Croix in the U.S. Virgin Islands a total of 41 in situ visual assessments of reef fish assemblages were conducted using six different methods. These methods included: transect, quadrat, random count, clnetransect, cineturret, and still photography. The dependent variables (numbers of species and species diversity) were examined for possible influence by the independent sample variables (time of day, amount of observation, time, reef site, and census method). Cluster analyses indicated that all methods gather data which allow community separation based on the sample variables. However, methods which tend to produce more information in terms of more species and numbers of individuals tend to recognize these sample variables more distinctly. Census assessment methods strongly Influenced the dependent variables. It is suspected that the amount of time employed for each method may be the most Important feature influencing in situ reef fish assemblage assessments

Method and Apparatus for Jet-Assisted Drilling or Cutting

An abrasive cutting or drilling system, apparatus and method, which includes an upstream supercritical fluid and/or liquid carrier fluid, abrasive particles, a nozzle and a gaseous or low-density supercritical fluid exhaust abrasive stream. The nozzle includes a throat section and, optionally, a converging inlet section, a divergent discharge section, and a feed section

Understanding and Assessing Climate Change: Implications for Nebraska

This report was commissioned by the UNL Institute of Agriculture and Natural Resources (IANR) with the objective of evaluating and summarizing the existing scientific literature related to our changing climate. Scientists from the IANR’s School of Natural Resources and the Department of Earth and Atmospheric Sciences in the College of Arts and Sciences have been the principal contributors to the report under the able leadership of long-time, internationally leading applied climate scientist Professor Don Wilhite. Their efforts have resulted in a timely and seminal reference for state and local policy-makers, government agency leaders, private industry, and indeed all citizens of our great state. Globally, we face significant economic, social, and environmental risks as we confront the challenges associated with climate change. The body of scientific evidence confirms with a high degree of certainty that human activities in the form of increased concentrations of greenhouse gases (GHGs) since the beginning of the Industrial Revolution, changes in land use, and other factors are the primary cause for the warming that the planet has experienced, especially in recent decades. Is there a debate within the scientific community with regard to observed changes in climate and human activities as the principal causal factor? The short answer here is “no”, at least certainly not among climate scientists—that is, those scientists who have actual expertise in the study of climate and climate change. For more than a decade, there has been broad and overwhelming consensus within the climate science community that the human-induced effects on climate change are both very real and very large. The debate in 2014 is restricted to precisely how these changes will play out and what actions we will need to take to adapt to and mitigate the effects of these changes. The magnitude and rapidity of the projected changes in climate are unprecedented. The implications of these changes for the health of our planet, and the legacy we will leave to our children, our grandchildren and future generations are of vital concern. Therefore, it is imperative that we develop strategies now to adapt to the multitude of changes we are experiencing and will continue to experience in our climate. This process of adaptation must begin at the local level, where these changes are being observed and their impacts felt. However, global agreements on the reduction of GHG emissions are a critical part of the solution in terms of mitigating as much future warming as possible. The approach taken in this report is to review the voluminous scientific literature on the subject and interpret—given time and resource constraints—our current understanding of the science of climate change and the implications of projections of climate change for Nebraska. The goal of this report is to inform policy makers, natural resource managers, and the public about 1) the state of the science on climate change, 2) current projections for ongoing changes over the twenty-first century, 3) current and potential future impacts, and 4) the management and policy implications of these changes. Hopefully, this report will lead to a higher degree of awareness and the initiation of timely and appropriate strategic actions that enable Nebraskans to prepare for and adapt to current and future changes in our climate