Influence d'un changement climatique dû à une hausse de gaz à effet de serre sur l'agriculture au quebec     

Bhawan Singh  Mustapha El Maayar  Pierre André  Jean‐Pierre Thouez  Christopher Bryant  Denis Provençal 《大气与海洋》2013,51(2):379-399

Abstract

This study, using a climate change scenario generated by the Canadian Climate Centre (CCC) general circulation model (GCM) examines the impacts of such a climate change on agriculture in southern Quebec. Using a crop model from the Food and Agriculture Organization (FAO), yield responses of a variety of cereals, legumes, oleaginous and special crops to climate change are analysed and discussed.

Results show that under the 2 × CO₂ climate scenario the growing season would be longer and accumulation of corn heat units and growing degree days would be more important than under actual climate (1961–1990). One of the more important results of this study is that, on the one hand yield of C₃ cereals would be lower and that of C₄ cereals higher in most agricultural regions. On the other hand, the direct fertilisation effect of increased CO₂ is not considered. It must be cautioned however that we can not generalise results obtained for one legume crop to all legumes.  相似文献   

Climate and climate change in western canada as simulated by the Canadian regional climate model     

Rene Laprise  Daniel Caya  Michel Giguere  Guy Bergeron  Hélène Côté  Jean‐Pierre Blanchet 《大气与海洋》2013,51(2):119-167

Abstract

A þrst climate simulation performed with the novel Canadian Regional Climate Model (CRCM) is presented. The CRCM is based on fully elastic non‐hydrostatic þeld equations, which are solved with an efþcient semi‐implicit semi‐Lagrangian (SISL) marching algorithm, and on the parametrization package of subgrid‐scale physical effects of the second‐generation Canadian Global Climate Model (GCMII). Two 5‐year integrations of the CRCM nested with GCMII simulated data as lateral boundary conditions are made for conditions corresponding to current and doubled CO₂ scenarios. For these simulations the CRCM used a grid size of 45 km on a polar‐stereographic projection, 20 scaled‐height levels and a time step of 15 min; the nesting GCMII has a spectral truncation of T32, 10 hybrid‐pressure levels and a time step of 20 min. These simulations serve to document: (1) the suitability of the SISL numerical scheme for regional climate modelling, (2) the use of GCMII physics at much higher resolution than in the nesting model, (3) the ability of the CRCM to add realistic regional‐scale climate information to global model simulations, and (4) the climate of the CRCM compared to that of GCMII under two greenhouse gases (GHG) scenarios.  相似文献   

Potential consequences of projected climate change impacts on hydroelectricity generation     

Pierre Mukheibir 《Climatic change》2013,121(1):67-78

There is a growing concern that countries should reduce their dependence on fossil fuels for electricity generation and look to other cleaner technologies. Hydroelectricity is one such option. However, given that hydropower is dependent on rainfall and associated runoff for power generation, it is susceptible to both the positive and negative impacts of climate change, such as increases in temperature and changes in precipitation and runoff. In this paper, impacts on hydropower generation have been organised as either changes in long-term trends or short-term variability and shocks. These impacts could either manifest themselves as direct impacts on hydropower generation potential or as indirect impacts (or ancillary impacts) such as increased competition for water. Citing examples from around the world, this paper investigates the scale of these projected impacts, and the potential cost implication of inaction. It concludes by making recommendations for possible adaptive options to build resilience in response to local impacts.  相似文献   

THz photometers for solar flare observations from space     

Pierre Kaufmann  Rogério Marcon  André Abrantes  Emilio C. Bortolucci  Luis Olavo T. Fernandes  Grigory I. Kropotov  Amauri S. Kudaka  Nelson Machado  Adolfo Marun  Valery Nikolaev  Alexandre Silva  Claudemir S. da Silva  Alexander Timofeevsky 《Experimental Astronomy》2014,37(3):579-598

The search for the still unrevealed spectral shape of the mysterious THz solar flare emissions is one of the current most challenging research issues. The concept, fabrication and performance of a double THz photometer system, named SOLAR-T, is presented. Its innovative optical setup allows observations of the full solar disk and the detection of small burst transients at the same time. The detecting system was constructed to observe solar flare THz emissions on board of stratospheric balloons. The system has been integrated to data acquisition and telemetry modules for this application. SOLAR-T uses two Golay cell detectors preceded by low-pass filters made of rough surface primary mirrors and membranes, 3 and 7 THz band-pass filters, and choppers. Its photometers can detect small solar bursts (tens of solar flux units) with sub second time resolution. Tests have been conducted to confirm the entire system performance, on ambient and low pressure and temperature conditions. An artificial Sun setup was developed to simulate performance on actual observations. The experiment is planned to be on board of two long-duration stratospheric balloon flights over Antarctica and Russia in 2014–2016.  相似文献   

Magnetic properties of the LL5 ordinary chondrite Chelyabinsk (fall of February 15, 2013)     

Natalia S. Bezaeva  Dmitry D. Badyukov  Mikhail A. Nazarov  Pierre Rochette  Joshua M. Feinberg  Gennadiy P. Markov  Daniel Borschneck  François Demory  Jérôme Gattacceca  Sergey E. Borisovskiy  Anna Ya Skripnik 《Meteoritics & planetary science》2014,49(6):958-977

Here we characterize the magnetic properties of the Chelyabinsk chondrite (LL5, S4, W0) and constrain the composition, concentration, grain size distribution, and mineral fabric of the meteorite's magnetic mineral assemblage. Data were collected from 10 to 1073 K and include measurements of low‐field magnetic susceptibility (χ₀), the anisotropy of χ₀, hysteresis loops, first‐order reversal curves, Mössbauer spectroscopy, and X‐ray microtomography. The REM and REM′ paleointensity protocols suggest that the only magnetizations recorded by the chondrite are components of the Earth's magnetic field acquired during entry into our planet's atmosphere. The Chelyabinsk chondrite consists of light and dark lithologies. Fragments of the light lithology show logχ₀ = 4.57 ± 0.09 (s.d.) (n = 135), while the dark lithology shows 4.65 ± 0.09 (n = 39) (where χ₀ is in 10^?9 m³ kg^?1). Thus, Chelyabinsk is three times more magnetic than the average LL5 fall, but is similar to a subgroup of metal‐rich LL5 chondrites (Paragould, Aldsworth, Bawku, Richmond) and L/LL5 chondrites (Glanerbrug, Knyahinya). The meteorite's room‐temperature magnetization is dominated by multidomain FeNi alloys taenite and kamacite (no tetrataenite is present). However, below approximately 75 K remanence is dominated by chromite. The metal contents of the light and dark lithologies are 3.7 and 4.1 wt%, respectively, and are based on values of saturation magnetization.  相似文献   

Automated Analysis of Light Curves of OGLE LMC Binaries: The Period distribution     

Tsevi Mazeh  Omer Tamuz  Pierre North 《Astrophysics and Space Science》2006,304(1-4):343-346

We present a new algorithm, the Eclipsing Binary Automated Solver (EBAS) to analyse lightcurves of eclipsing binaries. To replace human visual assessment, we introduce a new ‘alarm’ goodness-of-fit statistic that takes into account correlation between neighbouring residuals. We apply the new algorithm to the whole sample of 2580 binaries found in the OGLE photometric survey of the LMC and derive the photometric elements for 1931 systems. To obtain the statistical properties of the short-period binaries of the LMC we construct a well defined subsample of 938 eclipsing binaries with main-sequence B-type primaries. Correcting for observational selection effects, we derive the distributions of the fractional radii of the two components and their sum, the brightness ratios and the periods of the short-period binaries. Somewhat surprisingly, the results are consistent with a flat distribution in log P between 2 and 10 days.  相似文献   

Flow modelling in a high mountain valley equipped with hydropower plants: Rio Zongo Valley,Cordillera Real,Bolivia     

Yvan Caballero  Pierre Chevallier  Robert Gallaire  Ramiro Pillco 《水文研究》2004,18(5):939-957

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A re-analysis of the 1971 Beta Scorpii occultation by Jupiter: study of temperature fluctuations and detection of wave activity     

Elisabeth Raynaud  Pierre Drossart  Françoise Roques  Bruno Sicardy 《Icarus》2004,168(2):324-335

Data from the 13 May 1971 β Scorpii occultation by the southern polar region of Jupiter (Vapillon et al., 1973, Astron. Astrophys. 29, 135-149) are re-analyzed with current methods. We correct the previous results for an inacurrate background estimation and calculate new temperature profiles, that are now consistent with the results of other observers of this occultation, as well as with the current knowledge of the jovian atmosphere. The characteristics of the profiles of temperature gradient and the spectral behavior of the temperature fluctuations are found to be similar to the results of previous investigations of planetary atmospheres and in agreement with the presence of atmospheric propagating gravity waves in the jovian atmosphere. We use a wavelet analysis of the temperature profiles to identify the dominant modes of wave activity and compare the reconstructed temperature fluctuations to model-generated gravity waves.  相似文献   

Asteroseismic determination of helium abundance in stellar envelopes     

Sarbani Basu  Anwesh Mazumdar  H. M. Antia  Pierre Demarque 《Monthly notices of the Royal Astronomical Society》2004,350(1):277-286

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A note on the overall vorticity balance in wind-driven ocean circulation     

Pierre Welander 《Dynamics of Atmospheres and Oceans》1981,6(2):125-130

Some constraints resulting from a required overall vorticity balance in an ocean forced by a net wind-stress curl are considered. It is pointed out that the Sverdrup balance holds for Ekman-geostrophic flow in an area-averaged sense even in the presence of topography. It is suggested that nonlinear stretching and twisting of vorticity in an inertial boundary current may provide a source of vorticity which may balance a net wind-stress curl, without help of frictional effects at the bottom or sides. It is also suggested that potential vorticity generated by the wind-stress curl can be balanced by other local potential vorticity sources in the top layer. At this stage no proof for the need of bottom or side friction in a generally stratified ocean exists, and a counterexample is also lacking, leaving the question open for further studies.  相似文献