Evelise Bourlon

Bio: Evelise Bourlon is an academic researcher from St. Francis Xavier University. The author has contributed to research in topics: Environmental science & Methane. The author has an hindex of 6, co-authored 9 publications receiving 210 citations.

Spatial patterns of ground heat gain in the Northern Hemisphere

Abstract: Variations in the Earth's surface energy balance are recorded in the subsurface as perturbations of the steady state thermal field. Here we invert 558 temperature-depth profiles in the Northern Hemisphere (NH), in order to estimate the energy balance history at the continental surface from heat flux anomalies in the subsurface. The heat gain is spatially variable and does not appear to have been persistent for the last 200 years at all locations, but overall continental areas have absorbed energy in the last 50 years. Results indicate a mean surface heat flux of 20.6 mWm^-2 over the last 200 years. The total heat absorbed by the ground is 4.8 x 10^21 J and 13.3 x 10^2 J for the last 50 and 200 years respectively. We suggest that our results may be useful for state-of-the-art General Circulation Model (GCM) validation and for land-surface coupling schemes.

Methane emissions from upstream oil and gas production in Canada are underestimated.

Abstract: Methane emissions were measured at 6650 sites across six major oil and gas producing regions in Canada to examine regional emission trends, and to derive an inventory estimate for Canada’s upstream oil and gas sector. Emissions varied by fluid type and geographic region, with the heavy oil region of Lloydminster ranking highest on both absolute and intensity-based scales. Emission intensities varied widely for natural gas production, where older, low-producing developments such as Medicine Hat, Alberta showed high emission intensities, and newer developments in Montney, British Columbia showed emission intensities that are amongst the lowest in North America. Overall, we estimate that the Canadian upstream oil and gas methane inventory is underestimated by a factor of 1.5, which is consistent with previous studies of individual regions.

Ground warming patterns in the northern hemisphere during the last five centuries

Abstract: Changes in the Earth's surface energy balance recorded underground were used to reconstruct the temperature of the ground surface for the last 500 years in the Northern Hemisphere. We reconstructed ground surface temperature histories (GSTHs) from temperature versus depth profiles measured at 558 sites distributed between 30° and 60°N in the Northern Hemisphere. We show that the ground has warmed about 0.5 K in the last 100 years. Spatial analysis reveals that spatial variability is important and that the weighted average Northern Hemisphere GSTH shows some consistency with multiproxy and meteorological records reconstructions for the last two centuries.

Comparison of observed and general circulation model derived continental subsurface heat flux in the Northern Hemisphere

Abstract: Received 8 September 2009; revised 9 February 2010; accepted 19 February 2010; published 18 June 2010. [1] Heat fluxes in the continental subsurface were estimated from general circulation model (GCM) simulations of the climate of the last millennium and compared to those obtained from subsurface geothermal data. Since GCMs have bottom boundary conditions (BBCs) that are less than 10 m deep and thus may be thermodynamically restricted in the continental subsurface, we used an idealized land surface model (LSM) with a very deep BBC to estimate the potential for realistic subsurface heat storage in the absence of bottom boundary constraints. Results indicate that there is good agreement between observed fluxes and GCM simulated fluxes for the 1780–1980 period when the GCM simulated temperatures are coupled to the LSM with deep BBC. These results emphasize the importance of placing a deep BBC in GCM soil components for the proper simulation of the overall continental heat budget. In addition, the agreement between the LSM surface fluxes and the borehole temperature reconstructed fluxes lends additional support to the overall quality of the GCM (ECHO‐G) paleoclimatic simulations. Citation: MacDougall, A. H., H. Beltrami, J. F. Gonzalez‐Rouco, M. B. Stevens, and E. Bourlon (2010), Comparison of observed and general circulation model derived continental subsurface heat flux in the Northern Hemisphere, J. Geophys. Res., 115, D12109, doi:10.1029/2009JD013170.

High-resolution palaeoclimatology of the last millennium: a review of current status and future prospects:

Abstract: This review of late-Holocene palaeoclimatology represents the results from a PAGES/CLIVAR Intersection Panel meeting that took place in June 2006. The review is in three parts: the principal high-resolution proxy disciplines (trees, corals, ice cores and documentary evidence), emphasizing current issues in their use for climate reconstruction; the various approaches that have been adopted to combine multiple climate proxy records to provide estimates of past annual-to-decadal timescale Northern Hemisphere surface temperatures and other climate variables, such as large-scale circulation indices; and the forcing histories used in climate model simulations of the past millennium. We discuss the need to develop a framework through which current and new approaches to interpreting these proxy data may be rigorously assessed using pseudo-proxies derived from climate model runs, where the `answer' is known. The article concludes with a list of recommendations. First, more raw proxy data are required from the diverse disciplines and from more locations, as well as replication, for all proxy sources, of the basic raw measurements to improve absolute dating, and to better distinguish the proxy climate signal from noise. Second, more effort is required to improve the understanding of what individual proxies respond to, supported by more site measurements and process studies. These activities should also be mindful of the correlation structure of instrumental data, indicating which adjacent proxy records ought to be in agreement and which not. Third, large-scale climate reconstructions should be attempted using a wide variety of techniques, emphasizing those for which quantified errors can be estimated at specified timescales. Fourth, a greater use of climate model simulations is needed to guide the choice of reconstruction techniques (the pseudo-proxy concept) and possibly help determine where, given limited resources, future sampling should be concentrated.

Linear Differential Operators. By C. Lanczos. Pp. 580. 80s. 1961. (Van Nostrand, London)

Abstract: Preface Bibliography 1. Interpolation. Introduction The Taylor expansion The finite Taylor series with the remainder term Interpolation by polynomials The remainder of Lagrangian interpolation formula Equidistant interpolation Local and global interpolation Interpolation by central differences Interpolation around the midpoint of the range The Laguerre polynomials Binomial expansions The decisive integral transform Binomial expansions of the hypergeometric type Recurrence relations The Laplace transform The Stirling expansion Operations with the Stirling functions An integral transform of the Fourier type Recurrence relations associated with the Stirling series Interpolation of the Fourier transform The general integral transform associated with the Stirling series Interpolation of the Bessel functions 2. Harmonic Analysis. Introduction The Fourier series for differentiable functions The remainder of the finite Fourier expansion Functions of higher differentiability An alternative method of estimation The Gibbs oscillations of the finite Fourier series The method of the Green's function Non-differentiable functions Dirac's delta function Smoothing of the Gibbs oscillations by Fejer's method The remainder of the arithmetic mean method Differentiation of the Fourier series The method of the sigma factors Local smoothing by integration Smoothing of the Gibbs oscillations by the sigma method Expansion of the delta function The triangular pulse Extension of the class of expandable functions Asymptotic relations for the sigma factors The method of trigonometric interpolation Error bounds for the trigonometric interpolation method Relation between equidistant trigonometric and polynomial interpolations The Fourier series in the curve fitting 3. Matrix Calculus. Introduction Rectangular matrices The basic rules of matrix calculus Principal axis transformation of a symmetric matrix Decomposition of a symmetric matrix Self-adjoint systems Arbitrary n x m systems Solvability of the general n x m system The fundamental decomposition theorem The natural inverse of a matrix General analysis of linear systems Error analysis of linear systems Classification of linear systems Solution of incomplete systems Over-determined systems The method of orthogonalisation The use of over-determined systems The method of successive orthogonalisation The bilinear identity Minimum property of the smallest eigenvalue 4. The Function Space. Introduction The viewpoint of pure and applied mathematics The language of geometry Metrical spaces of infinitely many dimensions The function as a vector The differential operator as a matrix The length of a vector The scalar product of two vectors The closeness of the algebraic approximation The adjoint operator The bilinear identity The extended Green's identity The adjoint boundary conditions Incomplete systems Over-determined systems Compatibility under inhomogeneous boundary conditions Green's identity in the realm of partial differential operators The fundamental field operations of vector analysis Solution of incomplete systems 5. The Green's Function. Introduction The role of the adjoint equation The role of Green's identity The delta function -- The existence of the Green's function Inhomogeneous boundary conditions The Green's vector Self-adjoint systems The calculus of variations The canonical equations of Hamilton The Hamiltonisation of partial operators The reciprocity theorem Self-adjoint problems Symmetry of the Green's function Reciprocity of the Green's vector The superposition principle of linear operators The Green's function in the realm of ordinary differential operators The change of boundary conditions The remainder of the Taylor series The remainder of the Lagrangian interpolation formula

Sensitivity of a model projection of near‐surface permafrost degradation to soil column depth and representation of soil organic matter

Abstract: [1] The sensitivity of a global land-surface model projection of near-surface permafrost degradation is assessed with respect to explicit accounting of the thermal and hydrologic properties of soil organic matter and to a deepening of the soil column from 35 to 50 or more m Together these modifications result in substantial improvements in the simulation of near-surface soil temperature in the Community Land Model (CLM) When forced off-line with archived data from a fully coupled Community Climate System Model (CCSM3) simulation of 20th century climate, the revised version of CLM produces a near-surface permafrost extent of 107 × 106 km2 (north of 45°N) This extent represents an improvement over the 85 × 106 km2 simulated in the standard model and compares reasonably with observed estimates for continuous and discontinuous permafrost area (112–135 × 106 km2) The total extent in the new model remains lower than observed because of biases in CCSM3 air temperature and/or snow depth The rate of near-surface permafrost degradation, in response to strong simulated Arctic warming (∼ +75°C over Arctic land from 1900 to 2100, A1B greenhouse gas emissions scenario), is slower inthe improved version of CLM, particularly during the early 21st century (81,000 versus 111,000 km2 a−1, where a is years) Even at the depressed rate, however, the warming is enough to drive near-surface permafrost extent sharply down by 2100 Experiments with a deep soil column exhibit a larger increase in ground heat flux than those without because of stronger near-surface vertical soil temperature gradients This appears to lessen the sensitivity of soil temperature change to model soil depth

CO2 emission sources, greenhouse gases, and the global warming effect

Abstract: This chapter discusses the concepts of CO2 emission, global warming, and climate change with an emphasis on their environmental impacts. Specifically, the chapter reviews different sources of atmospheric CO2 emissions and recent advances in the implementation of carbon capture and storage (CCS) technology to mitigate greenhouse gas emissions. In this chapter, the intricate relationship between CO2 emission, global warming, and climate change was explicitly explained, and CO2 mitigation strategies in selected industrial sectors such as power, cement, iron, and steel as well as the petrochemical industry were presented. An overview of process integration concepts for energy minimization in environmental sustainability studies was highlighted. The current state of research in this field was reviewed, while future prospects in the application of process synthesis techniques to decrease the high energy and material requirement during CO2 capture were suggested. Finally, CO2 emission trend since the beginning of the first industrial revolution was discussed alongside current international treaties, limitations, and forecasts about greenhouse gas emission.