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Logofet D.O.,Am Obukhov Institute Of Atmospheric Physics
Ecological Complexity

Linear matrix models of stage-structured population dynamics are widely used in plant and animal demography as a tool to evaluate the growth potential of a population in a given environment. The potential is identified with λ1, the dominant eigenvalue of the projection matrix, which is compiled of stage-specific transition and fertility rates. Advanced botanical studies reveal polyvariant ontogeny in perennial plants, i.e., multiple different versions of individual development within a local population of a single species. This phenomenon complicates any standard, successive-stage, life cycle graph to a digraph defined on a 2D lattice in the age and stage dimensions, the pattern of projection matrix becoming more complex too. In a kind of experimental design, the transition rates can be calculated directly from the data for two successive time moments, but the age-stage-specific rates of reproduction still remain uncertain, adding more complexity to the calibration problem. Simple additional assumptions could technically eliminate the uncertainty, but they contravene the biology of a species in which polyvariant ontogeny is considered to be the major mechanism of adaptation. Given the data and expert constraints, the calibration can be reduced instead to a nonlinear maximization problem, yet with linear constraints. I prove that it has a unique solution to be attained at a vertex of the constraint polyhedral. To facilitate searching for the solution in practice, I use the net reproductive rate R0, a well-known indicator for the principal property of λ1 to be greater or less than 1. The method is exemplified with the calibration of a projection matrix in an age-stage-structured model (published elsewhere) for Calamagrostis canescens, a perennial herbaceous species with a complex (multivariant) life cycle that features unlimited growth when colonizing open areas. © 2013 Elsevier B.V. Source

Salazar R.,University of Concepcion | Kurgansky M.V.,University of Concepcion | Kurgansky M.V.,Am Obukhov Institute Of Atmospheric Physics
Journal of Physics A: Mathematical and Theoretical

Concrete examples of the construction of Nambu brackets for equations of motion (both 3D and 2D) of Boussinesq stratified fluids and also for magnetohydrodynamical equations are given. It serves a generalization of Hamiltonian formulation for the considered equations of motion. Two alternative Nambu formulations are proposed, first by using fluid dynamical (kinetic) helicity and/or enstrophy as constitutive elements and second, by using the existing conservation laws of the governing equation. © 2010 IOP Publishing Ltd. Source

Polyakov I.V.,University of Alaska Fairbanks | Alexeev V.A.,University of Alaska Fairbanks | Ashik I.M.,Arctic and Antarctic Research Institute | Bacon S.,UK National Oceanography Center | And 17 more authors.
Bulletin of the American Meteorological Society

Observations show the warm pulse of Atlantic Water (AW) that entered the Arctic Ocean in the early 1990s has reached the Canada Basin during the 2000s. Observations from 2008-09 suggest that the recent warm surge has passed its peak in the Eurasian Basin, Data show apparently synchronous warming of the AW and the overlying layer (OL) at 125°E, which is consistent with a rapid communication of heat between the AW and the OL. Data from the West Spitsbergen Current showed that intensive AW warming culminated in 2006 with AW temperature anomalies up to 1.2°C in the vicinity of Svalbard. Coherent changes in local atmospheric and oceanic thermodynamic forcing and multiyear ice coverage suggest a plausible role of anomalous oceanic heat in recent changes of the Arctic ice cover. Indications of an increasing role for both local atmosphere-ocean and shelf-basin interactions is also clear. Source

Zilitinkevich S.S.,Finnish Meteorological Institute | Zilitinkevich S.S.,Gc Rieber Climate Institute | Zilitinkevich S.S.,Helsinki Institute of Physics | Esau I.,Gc Rieber Climate Institute | And 5 more authors.
Boundary-Layer Meteorology

We give a new derivation of the familiar linear relation for the dimensionless velocity gradient in the stably stratified surface layer and provide physical and empirical grounds for its universal applicability in stationary homogeneous turbulence over the whole range of static stabilities from Ri = 0 to very large Ri. Combining this relation with the budget equation for the turbulent kinetic energy we obtain the "equilibrium formulation" of the turbulent dissipation length scale, and recommend it for use in turbulence closure models. © The Author(s) 2010. Source

Gruzdev A.N.,Am Obukhov Institute Of Atmospheric Physics | Elokhov A.S.,Am Obukhov Institute Of Atmospheric Physics
International Journal of Remote Sensing

We present the results of comparison between Ozone Monitoring Instrument (OMI) data of NO2 measurements (Collection 3) onboard the NASA EOS-Aura satellite and correlative ground-based twilight measurements at Zvenigorod station in Russia in 2004-2008. Compared quantities are unpolluted column and tropospheric column amounts of NO2 which are standard products of OMI measurements. The NO2 columns observed by our ground-based instrument have been interpolated to the time of OMI measurements using a one-dimensional photochemical model. According to our comparison, the OMI unpolluted NO2 columns underestimate ground-based measurements by (0.084 ± 0.025) × 1015 molecules/cm2, or (3.2 ± 0.9)%. The correlation coefficient between the OMI and ground-based unpolluted NO2 columns is 0.92. The tropospheric NO2 columns derived from OMI measurements are on average by (1.8 ± 0.5) × 1015 cm-2, or approximately 40%, less than those derived from ground-based measurements. The correlation coefficient between these data is about 0.3. Reasons for this discrepancy are discussed. © 2010 Taylor & Francis. Source

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