Intraseasonal to decadal variability of Rossby wave packet properties

2021 ◽  
Author(s):  
Georgios Fragkoulidis ◽  
Volkmar Wirth
Keyword(s):  
Rossby Wave ◽  
Large Scale ◽  
Decadal Variability ◽  
Phase Speed ◽  
Diagnostic Methods ◽  
Temperature And Precipitation ◽  
Ongoing Work ◽  
Large Scale Flow

<p>The large-scale extratropical upper-tropospheric flow tends to organize itself into eastward-propagating Rossby wave packets (RWPs). Investigating the spatiotemporal evolution of RWPs and the underlying physical processes has been beneficial in showcasing the role of the upper-tropospheric flow in temperature and precipitation extremes. The use of recently developed diagnostics of local in space and time wave properties has provided further insight in this regard. Motivated by the above, these diagnostic methods are now being employed to investigate the intraseasonal to decadal variability of key RWP properties such as their amplitude, phase speed, and group velocity in reanalysis datasets. It is shown that these properties exhibit a distinct seasonal and interregional variability, while interesting patterns thereof emerge. Moreover, the interannual and long-term variability in these RWP properties is explored and significant decadal trends for specific regions and seasons are highlighted. Ongoing work aims at further utilizing the presented diagnostics and analyses toward an improved understanding of the extratropical large-scale flow variability from weather to climate time scales.</p>

Approaches to Supporting Local and Community Development

2018 ◽  
Author(s):  
Liesel Mack Filgueiras ◽  
Andreia Rabetim ◽  
Isabel Aché Pillar
Keyword(s):  
Large Scale ◽  
Mining Company ◽  
The Sustainable Development ◽  
Social Partnership ◽  
The Public ◽  
Mining Investment ◽  
The Social ◽  
Corporate Social

Reflection about the role of community engagement and corporate social investment in Brazil, associated with the presence of a large economic enterprise, is the major stimulus of this chapter. It seeks to present how cross-sector governance can contribute to the social development of a city and how this process can be led by a partnership comprising a corporate foundation, government, and civil society. The concept of the public–private social partnership (PPSP) is explored: a strategy for building a series of inter-sectoral alliances aimed at promoting the sustainable development of territories where the company has large-scale enterprises, through joint efforts towards integrated long-term strategic planning, around a common agenda. To this end, the case of Canaã dos Carajás is introduced, a municipality in the State of Pará, in the Amazon region, where large-scale mining investment is being carried out by the mining company Vale SA.

The Role of Equatorial Rossby Waves in Tropical Cyclogenesis. Part I: Idealized Numerical Simulations in an Initially Quiescent Background Environment

2010 ◽  
Vol 138 (4) ◽  
pp. 1368-1382 ◽  
Author(s):  
Jeffrey S. Gall ◽  
William M. Frank ◽  
Matthew C. Wheeler
Keyword(s):  
Tropical Cyclone ◽  
Large Scale ◽  
Phase Speed ◽  
Tropical Cyclogenesis ◽  
Initial Amplitude ◽  
Low Level ◽  
Wave Simulation ◽  
Horizontal Momentum ◽  
Good Agreement

Abstract This two-part series of papers examines the role of equatorial Rossby (ER) waves in tropical cyclone (TC) genesis. To do this, a unique initialization procedure is utilized to insert n = 1 ER waves into a numerical model that is able to faithfully produce TCs. In this first paper, experiments are carried out under the idealized condition of an initially quiescent background environment. Experiments are performed with varying initial wave amplitudes and with and without diabatic effects. This is done to both investigate how the properties of the simulated ER waves compare to the properties of observed ER waves and explore the role of the initial perturbation strength of the ER wave on genesis. In the dry, frictionless ER wave simulation the phase speed is slightly slower than the phase speed predicted from linear theory. Large-scale ascent develops in the region of low-level poleward flow, which is in good agreement with the theoretical structure of an n = 1 ER wave. The structures and phase speeds of the simulated full-physics ER waves are in good agreement with recent observational studies of ER waves that utilize wavenumber–frequency filtering techniques. Convection occurs primarily in the eastern half of the cyclonic gyre, as do the most favorable conditions for TC genesis. This region features sufficient midlevel moisture, anomalously strong low-level cyclonic vorticity, enhanced convection, and minimal vertical shear. Tropical cyclogenesis occurs only in the largest initial-amplitude ER wave simulation. The formation of the initial tropical disturbance that ultimately develops into a tropical cyclone is shown to be sensitive to the nonlinear horizontal momentum advection terms. When the largest initial-amplitude simulation is rerun with the nonlinear horizontal momentum advection terms turned off, tropical cyclogenesis does not occur, but the convectively coupled ER wave retains the properties of the ER wave observed in the smaller initial-amplitude simulations. It is shown that this isolated wave-only genesis process only occurs for strong ER waves in which the nonlinear advection is large. Part II will look at the more realistic case of ER wave–related genesis in which a sufficiently intense ER wave interacts with favorable large-scale flow features.

Natural Resources and Problems of Development

1974 ◽  
Vol 9 (2-3) ◽  
pp. 179-184
Author(s):  
Per Antonsen
Keyword(s):  
Developing Countries ◽  
Third World ◽  
Large Scale ◽  
Mineral Resources ◽  
World Market ◽  
Economic Security ◽  
Industrial Enterprises ◽  
The Third World

The author focuses on problems in the economy of the developing countries likely to arise as a consequence of mineral exploitation in the new territories. A general shortage of mineral resources, although predicted, should not uncritically be adopted as a sufficient explanation of the demonstrated interest of industrial enterprises in undertaking heavy investments in the new territories. The economic security claimed by institutions financing large-scale investments, may just as likely force the companies to seek options for long-term supplies from these areas, unhampered by the politically caused instabilities perceived in the Third World. This development may tend to push the developing countries into the role of subsidiary suppliers in the world market. The committees preparing the UN Conference on the Law of the Sea have so far taken no realistic measures to counteract this possibility, which may prove detrimental to the economies of several developing countries. The Conference will, in the opinion of the author, provide little but a settlement of disputed interests among the coastal states.

Planning or Improvisation

2020 ◽  
pp. 116-120
Author(s):  
Alasdair Roberts
Keyword(s):  
United States ◽  
Twentieth Century ◽  
Large Scale ◽  
The United States ◽  
Unintended Consequences ◽  
Governance Strategies ◽  
The Face ◽  
Imperfect Knowledge

This chapter assesses the role of planning in the design of governance strategies. Enthusiasm for large-scale planning—also known as overall, comprehensive, long-term, economic, or social planning—boomed and collapsed in twentieth century. At the start of that century, progressive reformers seized on planning as the remedy for the United States' social and economic woes. By the end of the twentieth century, enthusiasm for large-scale planning had collapsed. Plans could be made, but they were unlikely to be obeyed, and even if they were obeyed, they were unlikely to work as predicted. The chapter then explains that leaders should make plans while being realistic about the limits of planning. It is necessary to exercise foresight, set priorities, and design policies that seem likely to accomplish those priorities. Simply by doing this, leaders encourage coordination among individuals and businesses, through conversation about goals and tactics. Neither is imperfect knowledge a total barrier to planning. There is no “law” of unintended consequences: it is not inevitable that government actions will produce entirely unexpected results. The more appropriate stance is modesty about what is known and what can be achieved. Plans that launch big schemes on brittle assumptions are more likely to fail. Plans that proceed more tentatively, that allow room for testing, learning, and adjustment, are less likely to collapse in the face of unexpected results.

scholarly journals Identification of possible dynamical drivers for long-term changes in temperature and rainfall patterns over Europe

2020 ◽  
Vol 143 (1-2) ◽  
pp. 177-191
Author(s):  
Peter Hoffmann ◽  
Arne Spekat
Keyword(s):  
Decadal Variability ◽  
Meteorological Data ◽  
Weather Type ◽  
Seasonal Rainfall ◽  
Weather Types ◽  
Temperature And Precipitation ◽  
Long Term Changes ◽  
Rainfall Patterns ◽  
Climate Station

AbstractThis study looks into the question to what extent long-term change patterns of observed temperature and rainfall over Europe can be attributed to dynamical causes, in other words: Are the observed changes due to a change in frequency of the patterns or have the patterns’ dynamical properties changed? By using a combination of daily meteorological data and a European weather-type classification, the long-term monthly mean temperature and precipitation were calculated for each weather-type. Subsequently, the observed weather-type sequences were used to construct analogue time series for temperature and precipitation which only include the dynamical component of the long-term variability since 1961. The results show that only a fraction of about 20% of the past temperature rise since 1990, which for example amounted to 1 °C at the Potsdam Climate Station can be explained by dynamical changes, i.e. most of the weather-types have become warmer. Concerning long-term changes of seasonal rainfall patterns, a fraction of more than 60% is considerably higher. Moreover, the results indicate that for rainfall compared with temperature, the decadal variability and trends of the dynamical component follow the observed ones much stronger. Consequently, most of the explained seasonal rainfall variances can be linked to changes in weather-type sequences in Potsdam and over Europe. The dynamical contribution to long-term changes in annual and seasonal rainfall patterns dominates due to the fact that the alternation of wet and dry weather-types (e.g. the types Trough or High pressure over Central Europe), their frequencies and duration has significantly changed in the last decades.

scholarly journals Northern Eurasian Heat Waves and Droughts

2014 ◽  
Vol 27 (9) ◽  
pp. 3169-3207 ◽  
Author(s):  
Siegfried D. Schubert ◽  
Hailan Wang ◽  
Randal D. Koster ◽  
Max J. Suarez ◽  
Pavel Ya. Groisman
Keyword(s):  
Soil Moisture ◽  
Heat Wave ◽  
Extreme Events ◽  
Decadal Variability ◽  
Heat Waves ◽  
Precipitation Variability ◽  
Northern Eurasia ◽  
Temperature And Precipitation ◽  
Warming World

Abstract This article reviews the understanding of the characteristics and causes of northern Eurasian summertime heat waves and droughts. Additional insights into the nature of temperature and precipitation variability in Eurasia on monthly to decadal time scales and into the causes and predictability of the most extreme events are gained from the latest generation of reanalyses and from supplemental simulations with the NASA Goddard Earth Observing System model, version 5 (GEOS-5). Key new results are 1) the identification of the important role of summertime stationary Rossby waves in the development of the leading patterns of monthly Eurasian surface temperature and precipitation variability (including the development of extreme events such as the 2010 Russian heat wave); 2) an assessment of the mean temperature and precipitation changes that have occurred over northern Eurasia in the last three decades and their connections to decadal variability and global trends in SST; and 3) the quantification (via a case study) of the predictability of the most extreme simulated heat wave/drought events, with some focus on the role of soil moisture in the development and maintenance of such events. A literature survey indicates a general consensus that the future holds an enhanced probability of heat waves across northern Eurasia, while there is less agreement regarding future drought, reflecting a greater uncertainty in soil moisture and precipitation projections. Substantial uncertainties remain in the understanding of heat waves and drought, including the nature of the interactions between the short-term atmospheric variability associated with such extremes and the longer-term variability and trends associated with soil moisture feedbacks, SST anomalies, and an overall warming world.

scholarly journals The role of crystal fabric in flow near an ice divide

2007 ◽  
Vol 53 (181) ◽  
pp. 277-288 ◽  
Author(s):  
Erin C. Pettit ◽  
Throstur Thorsteinsson ◽  
H. Paul Jacobson ◽  
Edwin D. Waddington
Keyword(s):  
Flow Pattern ◽  
Large Scale ◽  
Cone Angle ◽  
West Antarctica ◽  
Crystal Preferred Orientation ◽  
Siple Dome ◽  
Polycrystalline Ice ◽  
Measured Profile ◽  
Large Scale Flow

AbstractPolycrystalline ice near an ice divide typically shows a crystal fabric (crystal preferred orientation) with c axes clustered vertically. We explore the effect of this fabric on the large-scale flow pattern near an ice divide. We incorporate an analytical formulation for anisotropy into a non-linear flow law within a finite-element ice-sheet flow model. With four different depth profiles of crystal fabric, we find that the effect of fabric is significant only when a profile has a minimum cone angle of less than ~25º. For a steady-state divide, the shape and size of the isochrone arch can depend as much on the crystal fabric as it does on the non-linearity of ice flow. A vertically oriented fabric tends to increase the size of the isochrone arch, never to reduce it. Also, non-random fabric has little effect on the ice-divide-flow pattern when ice is modeled as a linear (Newtonian) fluid. Finally, when we use a crystal-fabric profile that closely approximates the measured profile for Siple Dome, West Antarctica, the model predicts concentrated bed-parallel shearing 300 m above the bed.

The role of connectivity in Australian conservation

2004 ◽  
Vol 10 (4) ◽  
pp. 266 ◽  
Author(s):  
M. E. Soulé ◽  
B. G. Mackey ◽  
H. F. Recher ◽  
J. E. Williams ◽  
J. C. Z. Woinarski ◽  
...  
Keyword(s):  
Large Scale ◽  
Biological Diversity ◽  
Ecological Resilience ◽  
Landscape Permeability ◽  
Conservation Assessment ◽  
Ecological Processes ◽  
Trophic Relations ◽  
Scientific Framework

The existing system of nature reserves in Australia is inadequate for the long-term conservation and restoration of native biological diversity because it fails to accommodate, among other elements, large scale and long-term ecological processes and change, including physical and biotic transport in the landscape. This paper is an overview of the connectivity elements that inform a scientific framework for significantly improving the prospects for the long-term conservation of Australia's biodiversity. The framework forms the basis for the WildCountry programme. This programme has identified connectivity at landscape, regional and continental scales as a critical component of an effective conservation system. Seven categories of ecological phenomena are reviewed that require landscape permeability and that must be considered when planning for the maintenance of biological diversity and ecological resilience in Australia: (1) trophic relations at regional scales; (2) animal migration, dispersal, and other large scale movements of individuals and propagules; (3) fire and other forms of disturbance at regional scales; (4) climate variability in space and time and human forced rapid climate change; (5) hydroecological relations and flows at all scales; (6) coastal zone fluxes of organisms, matter, and energy; and, (7) spatially-dependent evolutionary processes at all scales. Finally, we mention eight cross-cutting themes that further illuminate the interactions and implications of the seven connectivity-related phenomena for conservation assessment, planning, research, and management, and we suggest how the results might be applied by analysts, planners, scientists, and community conservationists.

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