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Publications
Publications (20)
High quality atmospheric CO2 measurements are sparse in Amazonia, but can provide critical insights into the spatial and temporal variability of sources and sinks of CO2. In this study we present the first six years (2014‐2019) of continuous, high‐precision measurements of atmospheric CO2 at the Amazon Tall Tower Observatory (ATTO, 2.1◦S, 58.9◦W)....
The recent development and improvement of commercial laser-based spectrometers have expanded in situ continuous observations of water vapour (H2O) stable isotope compositions (e.g. δ18O and δ2H) in a variety of sites worldwide. However, we still lack continuous observations in the Amazon, a region that significantly influences atmospheric and hydro...
Separate evaluation of methane (CH4) emission dynamics (e.g., oxidation, production, and transportation) at the soil‐plant‐atmosphere and soil‐water‐atmosphere interfaces has been limited in tropical rice paddies, but it is crucial for comprehending the entire CH4 cycles. We investigated CH4 oxidation, production, and transportation through plant a...
The gas seeps from the seafloor were presumed as a potential source of methane(CH4)to the atmosphere. Numerous gas plumes have also been reported around Japanese archipelago. During spring and summer in each 2014 and 2015, we have conducted the unique high-resolution measurements of CH4 in the atmosphere above the seas(eastern margin of Japan sea a...
Although bubble ebullition through water in rice paddy fields dominates direct methane (CH
4
) emissions from paddy soil to the atmosphere in tropical regions, the temporal changes and regulating factors of this ebullition are poorly understood. Bubbles in a submerged paddy soil also contain high concentrations of carbon dioxide (CO
2
), implying t...
In 2023, the biogeographic Amazon experienced temperature anomalies of 1.5°C above the 1991-2020 average from September to November. These conditions were driven by high sea surface temperature in the Atlantic and Pacific oceans, together with reduced moisture advection from the Atlantic, causing large vapor pressure and water deficits in the secon...
This study investigates the rain-initiated mixing and variability in the mixing ratio of selected trace gases in the atmosphere over the central Amazon rain forest. It builds on comprehensive data from the Amazon Tall Tower Observatory (ATTO), spanning from 2013 to 2020 and comprising the greenhouse gases (GHGs) carbon dioxide (CO2) and methane (CH...
We developed a soil gas measurement system with a non-dispersive infrared CO2 sensor, a low-flow pump, and solenoid valves, designed to assess variations in soil CO2 concentrations within a macropore under specific cultivation conditions. The system’s efficacy was evalu- ated through tests on the sensor’s response to water vapor concentration, the...
In tropical South America there has been substantial progress on atmospheric monitoring capacity, but the region still has a limited number of continental atmospheric stations relative to its large area, hindering net carbon flux estimates using atmospheric inversions. In this study, we use dry air CO2 mole fractions measured at the Amazon Tall Tow...
How are rainforest photosynthesis and turbulent fluxes influenced by clouds? To what extent are clouds affected by local processes driven by rainforest energy, water and carbon fluxes? These interrelated questions were the main drivers of the intensive field experiment CloudRoots-Amazon22 which took place at the ATTO/Campina supersites in the Amazo...
This study investigates the rain-initiated mixing and variability in the concentration of selected trace gases in the atmosphere over the central Amazon rain forest. It builds on comprehensive data from the Amazon Tall Tower Observatory (ATTO), spanning from 2013 to 2020 and comprising the greenhouse gases (GHG) carbon dioxide (CO2) and methane (CH...
Isoprene emissions are a key component in biosphere–atmosphere interactions, and the most significant global source is the Amazon rainforest. However, intra- and interannual variations in biological and environmental factors that regulate isoprene emission from Amazonia are not well understood and, thereby, are poorly represented in models. Here, w...
Isoprene is a chemical compound emitted naturally by soil, microorganisms, plants, and animals into the atmosphere. But plants are the largest emission source, and the amount of emission depends on plant species, weather conditions, and environmental conditions, including exposure to environmental stresses such as heat and drought. Isoprene is very...
The recent development and improvement of commercial laser-based spectrometers have expanded in situ continuous observations of water vapour (H 2 O) stable isotope ratios (e.g., δ 18 O, δ 2 H, etc.) in a variety of sites worldwide. However, we still lack continuous observations in the Amazon, a region that significantly influences atmospheric and h...
Interannual variations in the global atmospheric carbon dioxide (CO 2) growth rate are significantly influenced by fluctuations of carbon fluxes in tropical land areas such as the Amazon forest, which is subject to recurring droughts, rising temperatures and deforestation. Methane (CH 4) has large natural sources in Amazon's wetlands, as well as fr...
Greenhouse gas flux monitoring in ecosystems is mostly conducted by closed chamber and eddy covariance techniques. To determine the relevance of the two methods in rice paddy fields at different growing stages, closed chamber (CC) and eddy covariance (EC) methods were used to measure the methane (CH4) fluxes in a flooded rice paddy field. Intensive...
A plant growth system for crop production under microgravity is part of a life supporting system designed for long-duration space missions. A plant growth in soil in space requires the understanding of water movement in soil void spaces under microgravity. Under 1G-force condition, on earth, water movement in porous media is driven by gradients of...
Rice paddy fields are one of the major anthropogenic methane (CH 4) sources during irrigated growth periods. CH 4 produced in anaerobic flooded soil is released into the atmosphere through plant-and water-mediated pathways, and the CH 4 emission dynamics are mainly regulated by CH 4 production, oxidation and transportation. In the past, most CH 4 e...
Rice paddy fields are a major anthropogenic source for methane (CH4), one of the dominant green- house gases (GHGs). Recently, micrometeorological techniques for measuring GHG flux in a field scale have been developed. We evaluated a relaxed eddy accumulation (REA) method, a micrometeorological technique, to measure methane (CH4) flux in a rice pad...
Greenhouse gas emissions from rice paddy fields may be influenced by climatic or soil environment conditions. In this study, we investigated greenhouse gas emissions associated with climatic impacts. Experiments were conducted in Thailand and Japan. Emissions of CO 2 , CH 4 and N 2 O in rice paddy fields were continuously measured using the relaxed...