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N H Batjes - One of the best experts on this subject based on the ideXlab platform.
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total carbon and nitrogen in the Soils of the world
European Journal of Soil Science, 1996Co-Authors: N H BatjesAbstract:Summary The Soil is important in sequestering atmospheric CO2 and in emitting trace gases (e.g. CO2, CH4 and N2O) that are radiatively active and enhance the ‘greenhouse’ effect. Land use changes and predicted global warming, through their effects on net primary productivity, the plant community and Soil conditions, may have important effects on the size of the organic matter pool in the Soil and directly affect the atmospheric concentration of these trace gases. A discrepancy of approximately 350 × 1015 g (or Pg) of C in two recent estimates of Soil carbon reserves worldwide is evaluated using the geo-referenced database developed for the World Inventory of Soil Emission Potentials (WISE) project. This database holds 4353 Soil profiles distributed globally which are considered to represent the Soil units shown on a 1/2° latitude by 1/2° longitude version of the corrected and digitized 1:5 M FAO–UNESCO Soil Map of the World. Total Soil carbon pools for the entire land area of the world, excluding carbon held in the litter layer and charcoal, amounts to 2157–2293 Pg of C in the upper 100 cm. Soil organic carbon is estimated to be 684–724 Pg of C in the upper 30 cm, 1462–1548 Pg of C in the upper 100 cm, and 2376–2456 Pg of C in the upper 200 cm. Although deforestation, changes in land use and predicted climate change can alter the amount of organic carbon held in the superficial Soil layers rapidly, this is less so for the Soil carbonate carbon. An estimated 695–748 Pg of carbonate-C is held in the upper 100 cm of the world's Soils. Mean C: N ratios of Soil organic matter range from 9.9 for arid Yermosols to 25.8 for Histosols. Global amounts of Soil nitrogen are estimated to be 133–140 Pg of N for the upper 100 cm. Possible changes in Soil organic carbon and nitrogen dynamics caused by increased concentrations of atmospheric CO2 and the predicted associated rise in temperature are discussed.
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development of a world data set of Soil water retention properties using pedotransfer rules
Geoderma, 1996Co-Authors: N H BatjesAbstract:The World Inventory of Soil Emission Potentials (WISE) database is used to compile a standardized and spatially explicit data set of Soil water retention properties. WISE holds 4353 globally distributed profiles considered to be representative of the Soil units shown on a 1/2° latitude by 1/2° longitude version of the corrected and digitized 1:5 M FAO-Unesco Soil Map of the World. Pedotransfer functions (PTFs) are presented for the prediction of (a) volumetric Soil-water content (θ) at 9 pre-selected Soil-water potentials (h), and (b) available water capacity (AWC) from measured silt, clay and organic matter content. All regressions for θh are significant (0.88 < r2 < 0.94; P < 0.001). The predictive capability of the regression for the calculation of AWC, however, was relatively low and this PTF systematically underestimated AWC for the independent data set. An alternative approach, which uses pedotransfer rules (PTRs) and functional grouping for estimating AWC from FAO-Unesco Soil unit type, horizon textural class and organic matter class, was developed and tested for its predictive capability. For the independent data set, the PTR-derived AWC values showed a better correlation (r2 = 0.80) with measured AWC values than was the case for the PTF-derived AWC values. In addition to this, the median of the relative difference between predicted and measured AWC values was smaller (−3%) than for the PTF-predicted AWC values (−13%). Nonetheless, both methods showed a fairly large scatter between the predicted and measured AWC values. The PTRs were used for the estimation of profile available AWC to a depth of 100 cm, except for shallow Lithosols, Rankers and Rendzinas. Median AWC to a depth of 1 m is 42 mm for coarse-textured Arenosols, 80 mm for strongly weathered Ferralsols, 130 mm for Vertisols, 187 mm for Andosols, and 480 mm for Histosols. Correction factors were introduced to account for effects of coarse fragments and presence of groundwater at shallow depth. The “corrected” values were used to generate a 1/2° latitude by 1/2° longitude world data set of AWC properties. This raster image file uses the general format of the Global Ecosystems Database (Kineman, 1993). The resolution of the spatial data set is considered appropriate for water balance studies in global assessments of crop production potentials, Soil vulnerability to pollution, and Soil gaseous Emissions.
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potential Emissions of radiatively active gases from Soil to atmosphere with special reference to methane development of a global database wise
Journal of Geophysical Research, 1994Co-Authors: N H Batjes, E M BridgesAbstract:The role of Soil in controlling production and fluxes of biotic greenhouse gases is the focus of research in progress at the International Soil Reference and Information Centre (ISRIC). There are two main goals in this project on World Inventory of Soil Emission Potentials (WISE). The first is to assemble a global Soil database in association with the Land and Water Division of the Food and Agricultural Organization (FAO), using a ½° × ½° grid of geographic Soil data (1:5 M scale). This “area” data will be linked to a database of Soil profile “attribute” data using a geographical information system. The foundations for this work have now been put in place and, providing the Soil profile collection programme proceeds satisfactorily, it is anticipated that a preliminary database should begin to emerge by the end of 1993. When the Soil database is complete, the second thrust will be to make an inventory of the world's poorly drained Soils, providing the geographical framework for an improved estimate of methane production potentials. To do this, controlled long-term field experiments are required and modeling techniques must be developed and tested. ISRIC is cooperating with the International Rice Research Institute (IRRI) in the Philippines for these aspects of the work. An important corollary to the development of a global Soil database is that many requests are being received for Soil information relevant for studies of “global change.” At present, much of this information does not exist in an adequate format, so ISRIC is proceeding as rapidly as possible to implement the WISE digital database in a format which is compatible and user-friendly, for ultimate distribution in the public domain.
Benoit Montpetit - One of the best experts on this subject based on the ideXlab platform.
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in situ passive microwave Emission model parameterization of sub arctic frozen organic Soils
Remote Sensing of Environment, 2018Co-Authors: Benoit Montpetit, Alexandre Roy, Alain Royer, Alexandre LangloisAbstract:Abstract Many passive microwave remote sensing applications such as land surface temperature, snow water equivalent and Soil moisture retrievals need to take into account a Soil parameterization to the overall surface signal Emission. Soil Emission modeling presents large uncertainties when the Soil is frozen. In this paper, an empirical retrieval method is presented, specifically for rough frozen Soil permittivity estimates at 10.7, 19 and 37 GHz. The method was tested and validated using in-situ passive microwave measurements at incidence angles from 0 to 60° of sub-arctic frozen organic Soils in Northeastern Canada. The retrieved permittivity values give an overall RMSE between the measured and simulated brightness temperatures of 4.6 K for all frequencies combined. A sensitivity analysis was conducted on the different Soil parameters optimized in this study. This analysis suggests that the accuracy of the retrieved parameters, using the method given here, is of ± 1.00 for the permittivity and ± 0.12 cm for surface roughness. Also, a comparison was conducted between the parameterization used in this study and the one of Wegmuller and Matzler (1999) to estimate the Soil contribution to the emitted brightness temperature of snowpacks. An improvement of 66% of the RMSE between the modeled and measured snow brightness temperatures was observed when using the approach of this study compared to the previous work. The method shows great potential to improve the estimation of the frozen Soil contribution to the measured passive microwave brightness temperature.
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Snow Microwave Emission Modeling of Ice Lenses Within a Snowpack Using the Microwave Emission Model for Layered Snowpacks
IEEE Transactions on Geoscience and Remote Sensing, 2013Co-Authors: Benoit Montpetit, Alexandre Roy, Alain Royer, Alexandre Langlois, Chris DerksenAbstract:Ice lens formation, which follows rain on snow events or melt-refreeze cycles in winter and spring, is likely to become more frequent as a result of increasing mean winter temperatures at high latitudes. These ice lenses significantly affect the microwave scattering and Emission properties, and hence snow brightness temperatures that are widely used to monitor snow cover properties from space. To understand and interpret the spaceborne microwave signal, the modeling of these phenomena needs improvement. This paper shows the effects and sensitivity of ice lenses on simulated brightness temperatures using the microwave Emission model of layered snowpacks coupled to a Soil Emission model at 19 and 37 GHz in both horizontal and vertical polarizations. Results when considering pure ice lenses show an improvement of 20.5 K of the root mean square error between the simulated and measured brightness temperature (Tb) using several in situ data sets acquired during field campaigns across Canada. The modeled Tbs are found to be highly sensitive to the vertical location of ice lenses within the snowpack.
Chris Derksen - One of the best experts on this subject based on the ideXlab platform.
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Snow Microwave Emission Modeling of Ice Lenses Within a Snowpack Using the Microwave Emission Model for Layered Snowpacks
IEEE Transactions on Geoscience and Remote Sensing, 2013Co-Authors: Benoit Montpetit, Alexandre Roy, Alain Royer, Alexandre Langlois, Chris DerksenAbstract:Ice lens formation, which follows rain on snow events or melt-refreeze cycles in winter and spring, is likely to become more frequent as a result of increasing mean winter temperatures at high latitudes. These ice lenses significantly affect the microwave scattering and Emission properties, and hence snow brightness temperatures that are widely used to monitor snow cover properties from space. To understand and interpret the spaceborne microwave signal, the modeling of these phenomena needs improvement. This paper shows the effects and sensitivity of ice lenses on simulated brightness temperatures using the microwave Emission model of layered snowpacks coupled to a Soil Emission model at 19 and 37 GHz in both horizontal and vertical polarizations. Results when considering pure ice lenses show an improvement of 20.5 K of the root mean square error between the simulated and measured brightness temperature (Tb) using several in situ data sets acquired during field campaigns across Canada. The modeled Tbs are found to be highly sensitive to the vertical location of ice lenses within the snowpack.
M W Gallagher - One of the best experts on this subject based on the ideXlab platform.
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factors controlling regional differences in forest Soil Emission of nitrogen oxides no and n 2 o
Biogeosciences, 2006Co-Authors: Kim Pilegaard, J R Dorsey, J H Duyzer, U Skiba, Per Ambus, Claus Beier, Nicolas Bruggemann, Klaus Butterbachbahl, J Dick, M W GallagherAbstract:Abstract. Soil Emissions of NO and N2O were measured continuously at high frequency for more than one year at 15 European forest sites as part of the EU-funded project NOFRETETE. The locations represent different forest types (coniferous/deciduous) and different nitrogen loads. Geographically they range from Finland in the north to Italy in the south and from Hungary in the east to Scotland in the west. The highest NO Emissions were observed from coniferous forests, whereas the lowest NO Emissions were observed from deciduous forests. The NO Emissions from coniferous forests were highly correlated with N-deposition. The site with the highest average annual Emission (82 μg NO-N m−2 h−1) was a spruce forest in South-Germany (Hoglwald) receiving an annual N-deposition of 2.9 g m−2. NO Emissions close to the detection limit were observed from a pine forest in Finland where the N-deposition was 0.2 g N m−2 a−1. No significant correlation between N2O Emission and N-deposition was found. The highest average annual N2O Emission (20 μg N2O-N m−2 h−1) was found in an oak forest in the Matra mountains (Hungary) receiving an annual N-deposition of 1.6 g m−2. N2O Emission was significantly negatively correlated with the C/N ratio. The difference in N-oxide Emissions from Soils of coniferous and deciduous forests may partly be explained by differences in N-deposition rates and partly by differences in characteristics of the litter layer and Soil. NO was mainly derived from nitrification whereas N2O was mainly derived from denitrification. In general, Soil moisture is lower at coniferous sites (at least during spring time) and the litter layer of coniferous forests is thick and well aerated favouring nitrification and thus release of NO. Conversely, the higher rates of denitrification in deciduous forests due to a compact and moist litter layer lead to N2O production and NO consumption in the Soil. The two factors Soil moisture and Soil temperature are often explaining most of the temporal variation within a site. When comparing annual Emissions on a regional scale, however, factors such as nitrogen deposition and forest and Soil type become much more important.
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oxidized nitrogen and ozone interaction with forests ii multi layer process oriented modelling results and a sensitivity study for douglas fir
Quarterly Journal of the Royal Meteorological Society, 2004Co-Authors: J H Duyzer, J R Dorsey, Kim Pilegaard, M W Gallagher, S WaltonAbstract:An existing process-oriented multi-layer canopy model is applied to data from an intensive NOx and O3 surface exchange experiment, and a sensitivity study is conducted. The canopy was a mature 22.5 m Douglas fir stand. Comparison of measured data and model results shows that the model represents the concentration and fluxes of ozone well above the canopy, with adequate accuracy for concentration and fluxes below the canopy. A similar pattern is demonstrated for NO2 concentration above and below a forest canopy, with the fluxes being calculated correctly to within at least an order of magnitude below the canopy, and more accurately above. The model can reproduce the processes leading to the observed NO2 Emission from forest stands. The sensitivity study demonstrates the complex interdependence of oxidized nitrogen flux controlling variables within the canopy, with NO2 Emission favoured by high NO Soil Emission and canopy resistance and by low global radiation, leaf area index and ambient NO2 concentrations. Realistic alterations of these variables can cause reversal of the NO2 flux, leading to an ‘ecosystem compensation point’ between 17 and 35 ppbv at night, and 5 to 10 ppbv during the day for the forest canopy investigated. This highlights our improved understanding of the controls on NO2 flux, explaining and quantifying some previously reported reversals in NO2 flux above forest canopies. The effect of Soil NO Emission on ozone flux is investigated. During the day, reaction with NO may account for only 10% of observed ozone deposition, however, at night, this figure can rise to around 50%. The effect of volatile organic compounds on forest ozone deposition was found not to be large. Copyright © 2004 Royal Meteorological Society.
Alexandre Langlois - One of the best experts on this subject based on the ideXlab platform.
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in situ passive microwave Emission model parameterization of sub arctic frozen organic Soils
Remote Sensing of Environment, 2018Co-Authors: Benoit Montpetit, Alexandre Roy, Alain Royer, Alexandre LangloisAbstract:Abstract Many passive microwave remote sensing applications such as land surface temperature, snow water equivalent and Soil moisture retrievals need to take into account a Soil parameterization to the overall surface signal Emission. Soil Emission modeling presents large uncertainties when the Soil is frozen. In this paper, an empirical retrieval method is presented, specifically for rough frozen Soil permittivity estimates at 10.7, 19 and 37 GHz. The method was tested and validated using in-situ passive microwave measurements at incidence angles from 0 to 60° of sub-arctic frozen organic Soils in Northeastern Canada. The retrieved permittivity values give an overall RMSE between the measured and simulated brightness temperatures of 4.6 K for all frequencies combined. A sensitivity analysis was conducted on the different Soil parameters optimized in this study. This analysis suggests that the accuracy of the retrieved parameters, using the method given here, is of ± 1.00 for the permittivity and ± 0.12 cm for surface roughness. Also, a comparison was conducted between the parameterization used in this study and the one of Wegmuller and Matzler (1999) to estimate the Soil contribution to the emitted brightness temperature of snowpacks. An improvement of 66% of the RMSE between the modeled and measured snow brightness temperatures was observed when using the approach of this study compared to the previous work. The method shows great potential to improve the estimation of the frozen Soil contribution to the measured passive microwave brightness temperature.
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Snow Microwave Emission Modeling of Ice Lenses Within a Snowpack Using the Microwave Emission Model for Layered Snowpacks
IEEE Transactions on Geoscience and Remote Sensing, 2013Co-Authors: Benoit Montpetit, Alexandre Roy, Alain Royer, Alexandre Langlois, Chris DerksenAbstract:Ice lens formation, which follows rain on snow events or melt-refreeze cycles in winter and spring, is likely to become more frequent as a result of increasing mean winter temperatures at high latitudes. These ice lenses significantly affect the microwave scattering and Emission properties, and hence snow brightness temperatures that are widely used to monitor snow cover properties from space. To understand and interpret the spaceborne microwave signal, the modeling of these phenomena needs improvement. This paper shows the effects and sensitivity of ice lenses on simulated brightness temperatures using the microwave Emission model of layered snowpacks coupled to a Soil Emission model at 19 and 37 GHz in both horizontal and vertical polarizations. Results when considering pure ice lenses show an improvement of 20.5 K of the root mean square error between the simulated and measured brightness temperature (Tb) using several in situ data sets acquired during field campaigns across Canada. The modeled Tbs are found to be highly sensitive to the vertical location of ice lenses within the snowpack.