Tuula Aalto

Tuula Aalto
Finnish Meteorological Institute · Climate Change Research

PhD

About

140
Publications
19,032
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3,516
Citations
Citations since 2017
39 Research Items
1699 Citations
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2017201820192020202120222023050100150200250300
2017201820192020202120222023050100150200250300
2017201820192020202120222023050100150200250300

Publications

Publications (140)
Article
The effect of the 2018 extreme meteorological conditions in Europe on methane (CH 4 ) emissions is examined using estimates from four atmospheric inversions calculated for the period 2005–2018. For most of Europe, we find no anomaly in 2018 compared to the 2005–2018 mean. However, we find a positive anomaly for the Netherlands in April, which coinc...
Preprint
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Better monitoring, reporting and verification (MRV) of the amount, additionality and persistence of the sequestered soil carbon is needed to understand the best carbon farming practices for different soils and climate conditions, as well as their actual climate benefits or cost-efficiency in mitigating greenhouse gas emissions. This paper presents...
Article
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Reliable quantification of the sources and sinks of greenhouse gases, together with trends and uncertainties, is essential to monitoring the progress in mitigating anthropogenic emissions under the Paris Agreement. This study provides a consolidated synthesis of CH4 and N2O emissions with consistently derived state-of-the-art bottom-up (BU) and top...
Article
Full-text available
While wetlands are the largest natural source of methane (CH4) to the atmosphere, they represent a large source of uncertainty in the global CH4 budget due to the complex biogeochemical controls on CH4 dynamics. Here we present, to our knowledge, the first multi‐site synthesis of how predictors of freshwater wetland CH4 fluxes (FCH4) vary across we...
Preprint
Full-text available
Atmospheric inversion approaches are expected to play a critical role in future observation-based monitoring systems for surface greenhouse gas (GHG) fluxes. In the past decade, the research community has developed various inversion softwares, mainly using variational or ensemble Bayesian optimization methods, with various assumptions on uncertaint...
Article
Full-text available
Reliable quantification of the sources and sinks of greenhouse gases, together with trends and uncertainties, is essential to monitoring the progress in mitigating anthropogenic emissions under the Paris Agreement. This study provides a consolidated synthesis of CH4 and N2O emissions with consistently derived state-of-the-art bottom-up (BU) and top...
Article
Full-text available
The trajectories of soil carbon in our changing climate are of the utmost importance as soil is a substantial carbon reservoir with a large potential to impact the atmospheric carbon dioxide (CO 2) burden. Atmospheric CO 2 observations integrate all processes affecting carbon exchange between the surface and the atmosphere and therefore are suitabl...
Article
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Methane emissions from natural wetlands tend to increase with temperature and therefore may lead to a positive feedback under future climate change. However, their temperature response includes confounding factors and appears to differ on different time scales. Observed methane emissions depend strongly on temperature on a seasonal basis, but if th...
Article
Full-text available
Forest ecosystems are already responding to changing environmental conditions that are driven by increased atmospheric CO2 concentrations. These developments affect how societies can utilise and benefit from the woodland areas in the future, be it for example climate change mitigation as carbon sinks, lumber for wood industry, or preserved for natu...
Preprint
Full-text available
Abstract. The trajectories of soil carbon (C) in the changing climate are of utmost importance, as soil carbon is a substantial carbon storage with a large potential to impact the atmospheric carbon dioxide (CO<sub>2</sub>) burden. Atmospheric CO<sub>2</sub> observations integrate all processes affecting C exchange between the surface and the atmos...
Preprint
Full-text available
Abstract. The forest ecosystems are already responding to increased CO<sub>2</sub> concentrations and changing environmental conditions. These ongoing developments affect how societies can utilise and benefit from the woodland areas in the future, be it e.g. climate change mitigation as carbon sinks, lumber for wood industry or preserved for nature...
Article
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We calibrated the JSBACH model with six different stomatal conductance formulations using measurements from 10 FLUXNET coniferous evergreen sites in the boreal zone. The parameter posterior distributions were generated by the adaptive population importance sampler (APIS); then the optimal values were estimated by a simple stochastic optimisation al...
Article
Full-text available
Natural wetlands constitute the largest and most uncertain source of methane (CH4) to the atmosphere and a large fraction of them are found in the northern latitudes. These emissions are typically estimated using process (“bottom-up”) or inversion (“top-down”) models. However, estimates from these two types of models are not independent of each oth...
Article
Full-text available
Forests regulate climate, as carbon, water and nutrient fluxes are modified by physiological processes of vegetation and soil. Forests also provide renewable raw material, food, and recreational possibilities. Rapid climate warming projected for the boreal zone may change the provision of these ecosystem services. We demonstrate model based estimat...
Article
Full-text available
Natural wetlands constitute the largest and most uncertain source of methane (CH4) to the atmosphere and a large fraction of them are in the northern latitudes. These emissions are typically estimated using process (bottom-up) or inversion (top-down) models, yet the two are not independent of each other since the top-down estimates rely on the a pr...
Article
Full-text available
We calibrated the JSBACH model with six different stomatal conductance formulations using measurements from 10 FLUXNET coniferous evergreen sites in the Boreal zone. The parameter posterior distributions were generated by adaptive population importance sampler and the optimal values by a simple stochastic optimisation algorithm. The observations us...
Article
Full-text available
We estimated the CH4 budget in Finland for 2004–2014 using the CTE-CH4 data assimilation system with an extended atmospheric CH4 observation network of seven sites from Finland to surrounding regions (Hyytiälä, Kjølnes, Kumpula, Pallas, Puijo, Sodankylä, and Utö). The estimated average annual total emission for Finland is 0.6 ± 0.5 Tg CH4 yr−1. Sen...
Article
Full-text available
The surface albedo time series, CLARA-A2 SAL, was used to study trends in the snowmelt start and end dates, the melting season length and the albedo value preceding the melt onset in Finland during 1982–2016. In addition, the melt onset from the JSBACH land surface model was compared with the timing of green-up estimated from Moderate Resolution Im...
Article
Full-text available
The surface albedo time series CLARA-A2 SAL was used to study trends in the snow melt start and end dates, the melting season length and the albedo value preceding the melt onset in Finland during 1982–2016. The results were compared with corresponding snow melt timing calculated using the land ecosystem model JSBACH. In addition, the melt onset wa...
Article
Full-text available
Estimating methane (CH4) emissions from natural wetlands is complex, and the estimates contain large uncertainties. The models used for the task are typically heavily parameterized and the parameter values are not well known. In this study, we perform a Bayesian model calibration for a new wetland CH4 emission model to improve the quality of the pr...
Article
Full-text available
The inverse models infer total CH4 emissions of 26.8 (20.2–29.7) Tg CH4 yr−1 (mean, 10th and 90th percentiles from all inversions) for the EU-28 for 2006–2012 from the four inversion experiments. For comparison, total anthropogenic CH4 emissions reported to UNFCCC (bottom up, based on statistical data and emissions factors) amount to only 21.3 Tg C...
Article
Full-text available
Wetlands are one of the most significant natural sources of methane (CH4) to the atmosphere. They emit CH4 because decomposition of soil organic matter in waterlogged anoxic conditions produces CH4, in addition to carbon dioxide (CO2). Production of CH4 and how much of it escapes to the atmosphere depend on a multitude of environmental drivers. Mod...
Article
Full-text available
Significance We quantified a 36-y trend of advanced spring recovery of carbon uptake across the northern hemisphere boreal evergreen forest zone. From this trend, we estimated the corresponding change in global gross primary production (GPP) and further quantified the magnitude and spatiotemporal variability of spring GPP, that is, the cross-photos...
Article
Full-text available
The influence of drought on plant functioning has received considerable attention in recent years, however our understanding of the response of carbon and water coupling to drought in terrestrial ecosystems still needs to be improved. A severe soil moisture drought occurred in southern Finland in the late summer of 2006. In this study, we investiga...
Article
Full-text available
Methane (CH4) emission estimation for natural wetlands is complex and the estimates contain large uncertainties. The models used for the task are typically heavily parametrized and the parameter values are not well known. In this study we perform a Bayesian model calibration for a new wetland CH4 model to improve quality of the predictions and to u...
Article
Full-text available
Recent satellite observations of sun-induced chlorophyll fluorescence (SIF) are thought to provide a large-scale proxy for gross primary production (GPP), thus providing a new way to assess the performance of land surface models (LSMs). In this study, we assessed how well SIF is able to predict GPP in the Fenno-Scandinavian region and what potentia...
Article
We present inverse modelling (top-down) estimates of European methane (CH4) emissions for 2006–2012 based on a new quality-controlled and harmonized in-situ data set from 18 European atmospheric monitoring stations. We applied an ensemble of seven inverse models and performed four inversion experiments, investigating the impact of different sets of...
Article
Full-text available
We present inverse modelling (top-down) estimates of European methane (CH4) emissions for 2006–2012 based on a new quality-controlled and harmonized in-situ data set from 18 European atmospheric monitoring stations. We applied an ensemble of seven inverse models and performed four inversion experiments, investigating the impact of different sets of...
Article
Full-text available
We present a global distribution of surface methane (CH4) emission estimates for 2000–2012 derived using the CarbonTracker Europe-CH4 (CTE-CH4) data assimilation system. In CTE-CH4, anthropogenic and biospheric CH4 emissions are simultaneously estimated based on constraints of global atmospheric in situ CH4 observations. The system was configured t...
Article
Full-text available
Wetlands are one of the most significant natural sources of methane (CH4) to the atmosphere. They emit CH4 because decomposition of soil organic matter in waterlogged anoxic conditions produces CH4, in addition to carbon dioxide (CO2). Production of CH4 and how much of it escapes to the atmosphere depend on a multitude of environmental drivers. Mod...
Article
Full-text available
We present methane (CH4) flux estimates for 2005 to 2013 from a Bayesian inversion focusing on the high northern latitudes (north of 50° N). Our inversion is based on atmospheric transport modelled by the Lagrangian particle dispersion model FLEXPART and CH4 observations from 17 in situ and five discrete flask-sampling sites distributed over northe...
Article
Isotopic data provide powerful constraints on regional and global methane emissions and their source profiles. However, inverse modeling of spatially-resolved methane flux is currently constrained by a lack of information on the variability of source isotopic signatures. In this study, isotopic signatures of emissions in the Fennoscandian Arctic ha...
Article
Full-text available
We examined parameter optimisation in the JSBACH (Kaminski et al., 2013; Knorr and Kattge, 2005; Reick et al., 2013) ecosystem model, applied to two boreal forest sites (Hyytiälä and Sodankylä) in Finland. We identified and tested key parameters in soil hydrology and forest water and carbon-exchange-related formulations, and optimised them using th...
Article
Full-text available
Recent satellite observations of sun-induced chlorophyll fluorescence (SIF) are thought to provide a large-scale proxy for gross primary production (GPP), thus providing a new way to assess the performance of land surface models (LSMs). In this study, we assessed how well SIF is able to predict GPP in the Fenno-Scandinavian region and what potentia...
Article
Full-text available
We present methane (CH4) flux estimates for 2005 to 2013 from a Bayesian inversion focusing on the high northern latitudes (north of 50°N). Our inversion is based on atmospheric transport modelled by the Lagrangian particle dispersion model, FLEXPART, and CH4 observations from 17 in-situ and 5 discrete flask-sampling sites distributed over northern...
Article
Full-text available
Digital repeat photography has become a widely used tool for assessing the annual course of vegetation phenology of different ecosystems. By using the green chromatic coordinate (GCC) as a greenness measure, we examined the feasibility of digital repeat photography for assessing the vegetation phenology in two contrasting high-latitude ecosystems....
Article
Full-text available
Gobal methane emissions were estimated for 2000-2012 using the CarbonTracker Europe-CH4 (CTE-CH4) data assimilation system. In CTE-CH4, the anthropogenic and biosphere emissions of CH4 are simultaneously constrained by global atmospheric in-situ methane mole fraction observations. We use three configurations developed in Tsuruta et al. (2016) to as...
Article
Full-text available
CarbonTracker Europe-CH4 (CTE-CH4) inverse model versions 1.0 and 1.1 are presented. The model optimizes global surface methane emissions from biosphere and anthropogenic sources using an ensemble Kalman filter (EnKF) based optimization method, using the TM5 chemistry transport model as an observation operator, and assimilating global in-situ atmos...
Article
Full-text available
The objective of this study was to assess the performance of the simulated start of the photosynthetically active season by a large-scale biosphere model in boreal forests in Finland with remote sensing observations. The start of season for two forest types, evergreen needle- and deciduous broad-leaf, was obtained for the period 2003–2011 from regi...
Article
Full-text available
The influence of drought on plant functioning has received considerable attention in recent years, 10 although our understanding of the response of carbon and water coupling in terrestrial ecosystems remains unclear. In this study, we investigated the response of water use efficiency to summer drought in boreal forests at daily time scales mainly u...
Article
Full-text available
We examined parameter optimization in JSBACH ecosystem model, applied for two boreal forest sites in Finland. We identified and tested key parameters in soil hydrology and forest water and carbon exchange related formulations and optimized them using the Adaptive Metropolis algorithm for a five year calibration period (2000–2004) followed by a four...
Article
Upland forest soils affect the atmospheric methane (CH4) balance, not only through the soil sink but also due to episodic high emissions in wet conditions. We measured methane fluxes and found that during a wet fall the forest soil turned from a CH4 sink into a large source for several months, while the CH4 emissions from a nearby wetland did not i...
Article
Full-text available
Digital repeat photography has become a widely used tool for assessing the annual course of vegetation phenology of different ecosystems. A greenness measure derived from digital images potentially provides an inexpensive and powerful means to analyze the annual cycle of ecosystem phenology. By using the Green Chromatic Coordinate (GCC), we examine...
Article
Full-text available
Droughts can impact on forest functioning and production, and even lead to tree mortality. However, drought is an elusive phenomenon that is difficult to quantify and define universally. In this study, we assessed the performance of a set of indicators that have been used to describe drought conditions in the summer months (June, July, August) over...
Article
Full-text available
The Pallas area in northern Finland has served as a meteorological monitoring site for 80 years and, more recently, as a platform for atmospheric, ecological and hydrological research. Currently, Pallas comprises one of the most important research infrastructures in Finland and in the wider circumpolar region. Moreover, it is a successful example o...
Article
Full-text available
A state-of-the-art inverse model, CarbonTracker Data Assimilation Shell (CTDAS), was used to optimize estimates of methane (CH4) surface fluxes using atmospheric observations of CH4 as a constraint. The model consists of the latest version of the TM5 atmospheric chemistry-transport model and an ensemble Kalman filter based data assimilation system....
Article
The FLEXTRA and SILAM models were utilized in estimating the influence regions (IR) for the measured CO2 concentration ([CO2]) at Pallas together with tracers for anthropogenic emissions. The models produced similar synoptic features and associated background [CO2] with marine IR and elevated [CO2] with continental IR, but there were also differenc...
Article
Full-text available
We simulated Gross Primary Production (GPP) of Finnish forests using a landsurface model (LSM), JSBACH, and a semi-empirical stand-flux model PRELES, and compared their predictions with the MODIS GPP product. JSBACH used information about plant functional type fractions in 0.167° pixels. PRELES applied inventory-scaled information about forest stru...
Article
Full-text available
European CH4 and N2O emissions are estimated for 2006 and 2007 using four inverse modelling systems, based on different global and regional Eulerian and Lagrangian transport models. This ensemble approach is designed to provide more realistic estimates of the overall uncertainties in the derived emissions, which is particularly important for verify...
Article
Four new ground-based atmospheric monitoring stations in Finland were examined for local and large-scale signals in carbon dioxide mole fraction, and the results were compared with the corresponding values obtained from WMO/GAW site Pallas, northern Finland and NOAA/ESRL marine boundary layer reference time series. The measurements were filtered wi...
Article
The Finnish Centre of Excellence (FCoE) in “Physics, Chemistry, Biology and Meteorology of Atmospheric Composition and Climate Change” (2008–2013) completed its research activity at the end of 2013. The FCoE research was originally focused on enhanced process-level understanding of various couplings between atmospheric CO2 concentrations, photosynt...
Article
We aimed to assess the feasibility of an affordable instrumentation, based on a non-dispersive infrared analyser, to obtain atmospheric CO2 mole fraction data for background CO2 measurements from a flux tower site in southern Finland. The measurement period was November 2006–December 2011. We describe the instrumentation, calibration, measurements...
Article
Full-text available
We present lower/middle tropospheric column-averaged CH4 mole fraction time series measured by nine globally distributed ground-based FTIR (Fourier transform infrared) remote sensing experiments of the Network for the Detection of Atmospheric Composition Change (NDACC). We show that these data are well representative of the tropospheric regional-sc...