WSibIso

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Home About the project WSibIso

About the project WSibIso

      Terrestrial wetland ecosystems were the major source of methane into the atmosphere during the Holocene. Present wetland of subarctic Western Siberia (55-70°N; 55-90°E) including permafrost zone is a largest pool of both biological and geological methane which is sensitive to global warming and environmental change. The actual role of pristine peatlands of Western Siberia in global carbon balance has not been quantified at this time. In particular the sub-arctic peatlands, as extensively present in Western Siberia, are white spaces in knowledge of carbon exchange with the atmosphere. Perturbation of water cycle due to climate change in subarctic and permafrost regions and its influence on carbon balance have not been understood yet. The question is open about the possibility of explosive emission of methane from the Carbon deposited in the soil of Western Siberia. It is currently highly uncertain to predict the effects of climate change through changes in summer temperature, permafrost and hydrology on carbon balance of sub-arctic peatlands.

       The project is focusing on the climate in permafrost regions and pristine peatlands of Western Siberia. Its aims to investigate the water and carbon cycles in these regions and their projected changes under a warming climate. One of its specificity is the comprehensive use of the information that can be extracted from isotopic distributions both for water and carbon gases (CO2 and CH4), in the atmosphere, at the land surface, in the soil and vegetation, and in the permafrost. It will be based on an approach combining observations (using both surface measurements and satellite data), and modeling including atmospheric, land surface, and permafrost models that are or will be implemented with the various isotopic species of interest). Our research will be developed along three complementary axes that share an optimal use of the isotopic approach.

Concerning the water cycle, which is at the heart of Earth’s climate system, water isotopes of interest are H218O and HD16O. They are long­existing tools in climate science with their main application in paleo­climate research and surface hydrology. However novel approaches, remote sensing and in­situ measuring techniques, now offer completely new opportunities for atmospheric sounding while recently developed infared laser spectrometers allow for continuous measurements of H218O and HD16O in water vapour. The project is built on this important technological progress and proposes a systematic analysis of the new information in terms of climate relevant parameters over the pristine peatlands and permafrost of Western Siberia. To this end we will combine data on the isotopic composition of vapour obtained by surface measurements, by ground-based sounding and by satellite based remote sensing techniques with results obtained from two up-date Atmospheric General Circulation Models embedded with water isotopomers (IGCMs). This should help constraining the regional budget of the water isotopomers and to learn about evaporation processes and their seasonal characteristics.

Concerning the carbon cycle, data of new generation hyper-spectral satellite sensors combined with several ground-based remote sensing and in-situ observations will be used to quantify the methane and carbon dioxide concentration including their isotopomers in the atmosphere. Satellite data will be retrieved from sensors like currently working on the Earth’s orbit: French IASI on board METOP-A, Japanese TANSO-FTS on GOSAT (Greenhouse gases Observing SATellite), American AIRS on AQUA, TES on AURA and future OCO-2 (Orbiting Carbon Observatory) and IASI on METOP-B. This combined approach will be developed in order to estimate the annual carbon balance of the sub-arctic and the pristine peatlands of Western Siberia as well as to estimate natural and anthropogenic fractions of carbon greenhouse gases in the atmosphere. Technology of the ground-based FTIR (like Bruker Optics IFS125M installed at Ural Atmospheric Fourier Station, UAFS, at Kourovka astronomical observatory of UrFU) observations to validate the methods and results obtained by the satellite remote sensing technology will be used. The validated methods and data will enable to analyze the variation in time and space of the atmospheric carbon greenhouse gases concentrations of the large target area of Western Siberia.

Concerning continental surfaces, it is now urgent to develop coupled cryosphere-hydrology-vegetation models and datasets for validation and calibration in order to better quantify and understand the regional vulnerability of boreal and arctic ecosystems to future warming. This is also necessary to estimate, the magnitude of the physical and biogeochemical feedbacks that these regions will in turn exert on the global climate system. The current vegetation models are not well adapted to tackle this problem, because they generally miss, or describe in a very crude way, the basic processes of the response of high-northern latitude continental surfaces to climate change. As a result, the recommendations of the Arctic Monitoring and Assessment Program working group (ACIA, 2005) are to develop 3-dimensional models able to understand, quantify the main arctic physical and biogeochemical processes and assess climate feedbacks. These processes include: (1) the freeze / thaw processes of permafrosts, which govern changes in rivers runoff, wetlands and lakes formation, (2) the surface albedo changes linked to seasonal snow coverage and snow properties, which is the main ‘climate amplifier’ of these regions, (3) the decomposition of frozen carbon in permafrost layers, including Pleistocene-age permafrost carbon, (4) the northward migration of forest ecosystems and changes in forest fire regimes, which may cause re-arrangements in albedo and regional greenhouse gas fluxes. We will contribute to such a project under development using the French ORCHIDEE land-surface model in order to capture the most important “natural” biophysical processes at stake in the boreal regions: the interactions between snow and vegetation cover, the freezing and thawing of the permafrost and its impact on hydrology, and the carbon balance. Our specific contribution will be to implement isotopic species in this model and to apply it in our regional context under different climatic conditions.

       By this project advanced satellite, ground-based remote sensing and surface in-situ measurements as well as novel modeling techniques will be used for scientific research to clarify links between water and carbon cycles in Western Siberia and to quantify the impact of global climate change on water and carbon cycles of pristine peatlands and melting permafrost in this area. The project will help constraining the regional budget of the water isotopes and to learn about evaporation processes and their seasonal characteristics. These developments will serve a common objective of optimally using water and carbon isotopes to address key uncertainties in the parameterisation of the hydrological and carbon cycles in the all area of Western Siberia.