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Journal Articles

Role of advection in atmospheric ammonia; A Case study at a Japanese lake basin influenced by agricultural ammonia sources

Kubota, Tomohiro; Kuroda, Hisao*; Watanabe, Mirai*; Takahashi, Akiko*; Nakazato, Ryoji*; Tarui, Mika*; Matsumoto, Shunichi*; Nakagawa, Keita*; Numata, Yasuko*; Ouchi, Takao*; et al.

Atmospheric Environment, 243, p.117856_1 - 117856_9, 2020/12

 Times Cited Count:0 Percentile:100(Environmental Sciences)

The dry and wet depositions of atmospheric ammonia (NH$$_{3}$$) is one of the important pathways of nitrogen loads to aquatic ecosystems. Crop and livestock agriculture, one of the largest emitters of NH$$_{3}$$ in Asian countries, are known to cause high spatial and seasonal variation of NH$$_{3}$$ and influence the surrounding lake basin areas via its dry and wet deposition. However, the spatial characteristics of the NH$$_{3}$$ concentration in basin scale are not completely understood for regulation in NH$$_{3}$$ emission. Here we aim to clarify dominant factors of spatial and seasonal variations of the NH$$_{3}$$ concentration in a eutrophic lake basin surrounded by agricultural areas in Japan. Passive sampling over various land use categories in the basin was conducted at 36 sites in total from October 2018 to January 2020. Interestingly, the observed NH$$_{3}$$ concentration near the livestock houses were higher in winter than summer, which was inconsistent with knowledge of seasonal changes of current NH$$_{3}$$ emission inventory based on temperature-driven volatilization process. Comparing monthly NH$$_{3}$$ concentrations with various meteorological factors, we suggested the importance of seasonal advection of NH$$_{3}$$ from high emission sources to which has been rarely paid attention by the previous past studies. As for this, should be considered for lake ecosystem management since deposition of NH$$_{3}$$ is known to be closely related to the ecological processes such as phytoplankton blooming.

JAEA Reports

Practical guide on soil sampling, treatment, and carbon isotope analysis for carbon cycle studies

Koarashi, Jun; Atarashi-Andoh, Mariko; Nagano, Hirohiko*; Sugiharto, U.*; Saengkorakot, C.*; Suzuki, Takashi; Kokubu, Yoko; Fujita, Natsuko; Kinoshita, Naoki; Nagai, Haruyasu; et al.

JAEA-Technology 2020-012, 53 Pages, 2020/10


There is growing concern that recent rapid changes in climate and environment could have a significant influence on carbon cycling in terrestrial ecosystems (especially forest ecosystems) and could consequently lead to a positive feedback for global warming. The magnitude and timing of this feedback remain highly uncertain largely due to a lack of quantitative understanding of the dynamics of organic carbon stored in soils and its responses to changes in climate and environment. The tracing of radiocarbon (natural and bomb-derived $$^{14}$$C) and stable carbon ($$^{13}$$C) isotopes through terrestrial ecosystems can be a powerful tool for studying soil organic carbon (SOC) dynamics. The primary aim of this guide is to promote the use of isotope-based approaches to improve our understanding of the carbon cycling in soils, particularly in the Asian region. The guide covers practical methods of soil sampling; treatment and fractionation of soil samples; preparation of soil samples for $$^{13}$$C (and stable nitrogen isotope, $$^{15}$$N) and $$^{14}$$C analyses; and $$^{13}$$C, $$^{15}$$N, and $$^{14}$$C measurements by the use of isotope ratio mass spectrometry and accelerator mass spectrometry (AMS). The guide briefly introduces ways to report $$^{14}$$C data, which are frequently used for soil carbon cycling studies. The guide also reports results of a case study conducted in a Japanese forest ecosystem, as a practical application of the use of isotope-based approaches. This guide is mainly intended for researchers who are interested but are not experienced in this research field. The guide will hopefully encourage readers to participate in soil carbon cycling studies, including field works, laboratory experiments, isotope analyses, and discussions with great interest.

Journal Articles

Wintertime grassland dynamics may influence belowground biomass under climate change; A Model analysis

Katata, Genki*; Grote, R.*; Mauder, M.*; Zeeman, M. J.*; Ota, Masakazu

Biogeosciences, 17(4), p.1071 - 1085, 2020/02

 Times Cited Count:1 Percentile:38.34(Ecology)

Mountain grassland productivity is limited by cold and long winters; thus, rising temperatures and changes in snow cover expected in the future may have large impacts on the grassland yields. To investigate this, we enhanced land surface model (SOLVEG) to account for snow, freeze-thaw events, and grass growth, and the model was applied to the managed grasslands affected by extremely warm winter. The model reproduced temporal variability of observed heat fluxes, soil temperatures and snow depth throughout the 3-year simulation period. High physiological activity during the extremely warm winter led to a CO$$_{2}$$ uptake of 100 g-C m$$^{-2}$$, which was, surprisingly, mainly allocated into the below-ground biomass and rarely used for plant growth during spring. This process, which is so far largely unaccounted for in global terrestrial biosphere models, may lead to carbon accumulation in the soil and/or heterotrophic respiration as a response to global warming.

Journal Articles

Estimation of radionuclide deposition process by cloud and fog water at mountainous area; Comparison of observed data of airborne radiation monitoring and reproduction calculation

Sanada, Yukihisa; Katata, Genki*; Kaneyasu, Naoki*

Isotope News, (759), p.18 - 21, 2018/10

no abstracts in English

Journal Articles

Impacts of anthropogenic source from the nuclear fuel reprocessing plants on global atmospheric iodine-129 cycle; A Model analysis

Kadowaki, Masanao; Katata, Genki*; Terada, Hiroaki; Suzuki, Takashi; Hasegawa, Hidenao*; Akata, Naofumi*; Kakiuchi, Hideki*

Atmospheric Environment, 184, p.278 - 291, 2018/07

 Times Cited Count:8 Percentile:42.68(Environmental Sciences)

The long-lived radioactive iodine ($$^{129}$$I) is a useful geochemical tracer in the atmospheric environment. We recently observed clear seasonal trends in air concentration and deposition of $$^{129}$$I in Japan. Using these data, we developed a global atmospheric $$^{129}$$I transport model to reveal key processes for the global atmospheric $$^{129}$$I cycle. The model generally reproduced the observed seasonal change in air concentration and deposition of $$^{129}$$I in Japan, and the global distribution of $$^{129}$$I concentration in rain as presented in past literature. Numerical experiments changing the intensity of anthropogenic and natural sources were conducted to quantify the impact of anthropogenic sources on the global $$^{129}$$I cycle. The results indicated that the atmospheric $$^{129}$$I from the anthropogenic sources was deposited in winter and can be accumulated mainly in the northern part of Eurasia. In contrast, the atmospheric $$^{129}$$I from the natural sources dominated the deposition in summer. These results suggested that the re-emission process of $$^{129}$$I from the Earth's surface may be important as a secondary impact of $$^{129}$$I in the global-scaled environment. Furthermore, although wet deposition dominated the total deposition in the Northern hemisphere, dry deposition regionally and seasonally contributed to the total deposition over arctic and northern part of Eurasia in winter, suggesting that the dry deposition may play a key role in the seasonal change of $$^{129}$$I deposition in the Northern hemisphere high latitudes.

Journal Articles

Altitudinal characteristics of atmospheric deposition of aerosols in mountainous regions; Lessons from the Fukushima Daiichi Nuclear Power Station accident

Sanada, Yukihisa; Katata, Genki*; Kaneyasu, Naoki*; Nakanishi, Chika*; Urabe, Yoshimi*; Nishizawa, Yukiyasu*

Science of the Total Environment, 618, p.881 - 890, 2018/03

 Times Cited Count:7 Percentile:45.58(Environmental Sciences)

Although the reconstruction of atmospheric deposition processes of radiocesium during the Fukushima Daiichi Nuclear Power Station (FDNPS) accident is essential, the whole picture of the deposition mechanism in complex topography has not been well understood yet. To understand atmospheric deposition processes of aerosols over the complex mountainous topography, we analyzed altitudinal characteristics of radiocesium released during the accident. At five selected mountainous areas in the eastern Japan, altitudinal characters of air dose rate observed by our high-resolution airborne surveys after the accident was analyzed based on the results of three typical (dry, wet, and cloud water) deposition obtained from the latest atmospheric dispersion.

Journal Articles

Improvement of atmospheric dispersion simulation using an advanced meteorological data assimilation method to reconstruct the spatiotemporal distribution of radioactive materials released during the Fukushima Daiichi Nuclear Power Station accident

Kadowaki, Masanao; Nagai, Haruyasu; Terada, Hiroaki; Katata, Genki*; Akari, Shusaku*

Energy Procedia, 131, p.208 - 215, 2017/12


 Times Cited Count:3 Percentile:5.48

When radioactive materials are released into the atmosphere due to nuclear accidents, numerical simulations that can reproduce temporal and spatial distribution of radioactive materials are useful to provide the information for emergency responses and radiological dose assessment. In this study, we attempt to improve the atmospheric dispersion simulation using an advanced meteorological data assimilation method and reconstruct the spatiotemporal distribution of radioactive materials released due to the Fukushima Daiichi Nuclear Power Station (FDNPS) accident. The atmospheric dispersion simulations were carried out by the Lagrangian particle dispersion model GEARN developed by Japan Atomic Energy Agency. To obtain meteorological fields for GEARN calculation, we used the Weather Research and Forecasting model WRF with meteorological data assimilation using four-dimensional variational method (4D-Var). GEARN calculations of the surface deposition and air concentration of radionuclides were compared with measurements. In the area close to FDNPS, the spatial distribution of the deposition of Cs-137 and I-131 simulated by GEARN agreed with the measured one. The accuracy of modeled deposition in northwest and south directions from FDNPS was particularly improved. This results were mainly attributed to the better reproducibility of wind field by using the meteorological data assimilation with 4D-Var. The improvement of the accuracy of modeled deposition distribution of Cs-137 in the East Japan area was also apparent under the meteorological fields modified by 4D-Var. The information of atmospheric dispersion processes reconstructed in this study is used for updating the existing assessment of radiological dose resulting from the FDNPS accident based on atmospheric simulations by our previous studies. It can also provide useful suggestions to make emergency response plans for nuclear facilities in Japan.

Journal Articles

Updating source term and atmospheric dispersion simulations for the dose reconstruction in Fukushima Daiichi Nuclear Power Station accident

Nagai, Haruyasu; Terada, Hiroaki; Tsuzuki, Katsunori; Katata, Genki; Ota, Masakazu; Furuno, Akiko; Akari, Shusaku

EPJ Web of Conferences, 153, p.08012_1 - 08012_7, 2017/09

 Times Cited Count:2 Percentile:11.38

In order to assess the radiological dose to the public resulting from the Fukushima Daiichi Nuclear Power Station (FDNPS) accident in Japan, the spatiotemporal distribution of radioactive materials in the environment are reconstructed by computer simulations. In this study, by refining the source term of radioactive materials and modifying the atmospheric dispersion model (ATDM), the atmospheric dispersion simulation of radioactive materials is improved. Then, a database of spatiotemporal distribution of radioactive materials in the air and on the ground surface is developed from the output of the simulation. This database is used in other studies for the dose assessment by coupling with the behavioral pattern of evacuees from the FDNPS accident. The ATDM simulation was improved to use a new meteorological model and sophisticated deposition scheme. Although the improved ATDM simulations reproduced well the $$^{137}$$Cs deposition pattern in the eastern Japan scale, the reproducibility of deposition pattern was decreased in the vicinity of FDNPS. This result indicated the necessity of further refinement of the source term by optimization to the improved ATDM simulations.

Journal Articles

Development of the Eulerian atmospheric transport model GEARN-FDM; Validation against the European tracer experiment

Kadowaki, Masanao; Katata, Genki; Terada, Hiroaki; Nagai, Haruyasu

Atmospheric Pollution Research, 8(2), p.394 - 402, 2017/03

 Times Cited Count:2 Percentile:86.43(Environmental Sciences)

We developed a dispersion model based on the finite difference method, GEARN-FDM, for long-range dispersion, which solves the advection-diffusion equation using numerical schemes with low artificial diffusion. The advection and diffusion terms are modeled using a fully mass conservative scheme and the Crank-Nicolson method, respectively. GEARN-FDM was validated using the dataset from the European Tracer Experiment. In the entire domain throughout the simulation period of the observed dataset, GEARN-FDM showed high performance with factors of 2 and 5 of 39% and 78%, respectively. While testing the sensitivity of the horizontal diffusivity with this model, the simulated horizontal diffusivity was distributed heterogeneously in the model domain. High diffusivity was primarily seen over the coastal and mountainous regions. Therefore, for the long-range simulations of radionuclides, we need to consider to the transport caused by horizontal diffusion.

JAEA Reports

A Terrestrial ecosystem model (SOLVEG) coupled with atmospheric gas and aerosol exchange processes

Katata, Genki; Ota, Masakazu

JAEA-Data/Code 2016-014, 35 Pages, 2017/01


In order to predict the impact of atmospheric pollutants (gases and aerosols) to the terrestrial ecosystem, new schemes for calculating the processes of dry deposition of gases and aerosols, and water and carbon cycles in terrestrial ecosystems were implemented in the one-dimensional atmosphere-SOiL-VEGetation model, SOLVEG. We made performance tests at various vegetation areas to validate the newly developed schemes. In this report, the detail in each modeled process is described with an instruction how to use the modified SOLVEG. The framework of "terrestrial ecosystem model" was developed for investigation of a change in water, energy, and carbon cycles associated with global warming and air pollution and its impact on terrestrial ecosystems.

Journal Articles

Numerical simulation of surface energy and water balances over a semiarid grassland ecosystem in the West African Savanna

Quansah, E.*; Katata, Genki; Mauder, M.*; Annor, T.*; Amekudzi, L. K.*; Bliefernicht, J.*; Heinzeller, D.*; Balogun, A.*; Kunstmann, H.*

Advances in Meteorology, 2017, p.6258180_1 - 6258180_11, 2017/00


 Times Cited Count:2 Percentile:87.41(Meteorology & Atmospheric Sciences)

An accurate prediction in the energy partitioning of the net solar radiation into latent and sensible heat fluxes over arid and semiarid regions is one of the challenges in land surface study in weather and climate simulations. Numerical simulations of surface energy and water balances were carried out using a one-dimensional multi-layer atmosphere-SOil-VEGetation (SOLVEG) model for selected days of the dry and rainy seasons over a savanna grassland ecosystem in Sumbrungu in the Upper East region of Ghana. The results for the investigated period between both seasons showed that the model overall reproduced the diurnal changes in the observed net radiation, sensible heat flux, latent heat flux, and ground heat flux. The statistics for the above variables as the correlation coefficient, root mean square error, and normalized standard deviation between the observations and calculations in the dry and wet periods suggest that the model was able to simulate the observed energy fluxes, soil evaporation, and transpiration in savanna grassland ecosystems.

Journal Articles

Impacts of C-uptake by plants on the spatial distribution of $$^{14}$$C accumulated in vegetation around a nuclear facility; Application of a sophisticated land surface $$^{14}$$C model to the Rokkasho reprocessing plant, Japan

Ota, Masakazu; Katata, Genki; Nagai, Haruyasu; Terada, Hiroaki

Journal of Environmental Radioactivity, 162-163, p.189 - 204, 2016/10

 Times Cited Count:4 Percentile:77.9(Environmental Sciences)

Impacts of plant C uptake on ($$^{14}$$C) distributions around a nuclear facility were investigated by a land surface $$^{14}$$C model (SOLVEG-II). The simulation combined the SOLVEG-II with a mesoscale model and an dispersion model was applied to $$^{14}$$CO$$_{2}$$ transfer at test operations of the Rokkasho reprocessing plant (RRP) in 2007. The calculated $$^{14}$$C-specific activities in rice grains agreed with the observations. Numerical experiment of chronic $$^{14}$$CO$$_{2}$$ release from the RRP showed that $$^{14}$$C-specific activities of rice plants at harvest differed from the annual mean ones in the air, which was attributed to seasonal variations in atmospheric $$^{14}$$CO$$_{2}$$ and plant growth. $$^{14}$$C accumulation in plant significantly increased when $$^{14}$$CO$$_{2}$$ releases were limited during daytime, compared with the results observed during nighttime, due to extensive $$^{14}$$CO$$_{2}$$ uptake by daytime photosynthesis. These results indicated that plant growth and photosynthesis should be considered in predictions of ingestion dose of $$^{14}$$C for long-term chronic and short-term diurnal releases of $$^{14}$$CO$$_{2}$$, respectively.

Journal Articles

Immediate and potential long-term effects of consecutive heat waves on the photosynthetic performance and water balance in Douglas-fir

Duarte, A. G.*; Katata, Genki; Hoshika, Yasutomo*; Hossain, M.*; Kreuzwieser, J.*; Arneth, A.*; Ruehr, N. K.*

Journal of Plant Physiology, 205, p.57 - 66, 2016/10

 Times Cited Count:16 Percentile:23.96(Plant Sciences)

The frequency and intensity of climatic extremes, such as heat waves, are predicted to increase globally, with severe implications for terrestrial carbon and water cycling. Temperatures may rise above critical thresholds that allow trees to function optimally, with unknown long-term consequences for forest ecosystems. In this context, we investigated how photosynthetic traits and the water balance in Douglasfir are affected by exposure to three heat waves. Photosynthetic carboxylation efficiency was mostly unaffected, but electron transport and photosynthetic rates under saturating light were strongly influenced by the heat waves, with lagging limitations on photosynthesis still being observed six weeks after the last heat wave. We also observed lingering heat-induced inhibitions on transpiration, minimum stomatal conductance, and nighttime stomatal conductance. Results from the stomatal models used to calculate minimum stomatal conductance were similar to gs-night and indicated changes in leaf morphology, such as stomatal occlusions and alterations in epicuticular wax. Our results show Douglas-fir's ability to restrict water loss following heat stress, but at the price of reduced photosynthetic performance. Such limitations indicate potential long-term restrictions that heat waves can impose on tree development and functioning under extreme climatic conditions.

Journal Articles

Utilization of $$^{134}$$Cs/$$^{137}$$Cs in the environment to identify the reactor units that caused atmospheric releases during the Fukushima Daiichi accident

Chino, Masamichi; Terada, Hiroaki; Nagai, Haruyasu; Katata, Genki; Mikami, Satoshi; Torii, Tatsuo; Saito, Kimiaki; Nishizawa, Yukiyasu

Scientific Reports (Internet), 6, p.31376_1 - 31376_14, 2016/08

 Times Cited Count:28 Percentile:2.08(Multidisciplinary Sciences)

Journal Articles

Montane ecosystem productivity responds more to global circulation patterns than climatic trends

Desai, A. R.*; Wohlfahrt, G.*; Zeeman, M. J.*; Katata, Genki; Eugster, W.*; Montagnani, L.*; Gianelle, D.*; Mauder, M.*; Schmid, H. P.*

Environmental Research Letters, 11(2), p.024013_1 - 024013_9, 2016/02


 Times Cited Count:13 Percentile:38.7(Environmental Sciences)

Regional ecosystem productivity is highly sensitive to inter-annual climate variability, both within and outside the primary carbon uptake period. However, Earth system models lack sufficient spatial scales and ecosystem processes to resolve how these processes may change in a warming climate. Here, we show, how for the European Alps, mid-latitude Atlantic ocean winter circulation anomalies drive high-altitude summer forest and grassland productivity, through feedbacks among orographic wind circulation patterns, snowfall, winter and spring temperatures, and vegetation activity. Therefore, to understand future global climate change influence to regional ecosystem productivity, Earth systems models need to focus on improvements towards topographic downscaling of changes in regional atmospheric circulation patterns and to lagged responses in vegetation dynamics to non-growing season climate anomalies.

Journal Articles

Source term estimation for the Fukushima Daiichi Nuclear Power Station accident by combined analysis of environmental monitoring and plant data through atmospheric dispersion simulation

Nagai, Haruyasu; Terada, Hiroaki; Chino, Masamichi; Katata, Genki; Mikami, Satoshi; Saito, Kimiaki

Proceedings of 16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics (NURETH-16) (USB Flash Drive), p.4044 - 4052, 2015/08

JAEA has estimated the atmospheric releases of radionuclide during the Fukushima Daiichi Nuclear Power Station (FNPS1) accident by comparing measurements of air concentration of a radionuclide or its dose rate in the environment with the ones calculated by atmospheric transport and deposition model (ATDM). To improve our source term, we are trying to develop more sophisticated estimation method and use new information from severe accident analysis and observation data. As the first step of new trial, we used $$^{134}$$Cs/$$^{137}$$Cs ratios of inventories in FNPS1 reactors Unit 1 to 3 and those in surface deposition. By considering temporal change in $$^{134}$$Cs/$$^{137}$$Cs ratio of released plume and ATDM simulations, spatial distribution of $$^{134}$$Cs/$$^{137}$$Cs ratio in surface deposition was explained. This result can be used to specify from which reactor the dominant release occurred for each time period, and consequently provide useful information to severe accident analysis for the FNPS1 case.

Journal Articles

Ozone-induced stomatal sluggishness changes carbon and water balance of temperate deciduous forests

Hoshika, Yasutomo*; Katata, Genki; Deushi, Makoto*; Watanabe, Makoto*; Koike, Takayoshi*; Paoletti, E.*

Scientific Reports (Internet), 5, p.9871_1 - 9871_8, 2015/05

 Times Cited Count:64 Percentile:5.2(Multidisciplinary Sciences)

The phytotoxic nature of tropospheric ozone can impair forest productivity and affects stomatal functions. Although a delay in stomatal responses (ozone-induced stomatal sluggishness) to fluctuating stimuli has a potential to change carbon and water balance in forests, this effect is not included in the current models for ozone risk assessment to forest. Here we examined effects of ozone-induced stomatal sluggishness on carbon gain and transpiration of global deciduous forests by combining land surface model and global atmospheric chemistry model. Ozone-induced stomatal sluggishness enhances stomatal ozone uptake resulting in facilitating a decline of forest carbon acquisition and also enhancing transpiration. Our findings are consistent with previous experimental and field observational results, indicating that forest trees suffer significant impairment of carbon and water balance through ozone-induced stomatal sluggishness.

Journal Articles

Detailed source term estimation of the atmospheric release for the Fukushima Daiichi Nuclear Power Station accident by coupling simulations of an atmospheric dispersion model with an improved deposition scheme and oceanic dispersion model

Katata, Genki; Chino, Masamichi; Kobayashi, Takuya; Terada, Hiroaki; Ota, Masakazu; Nagai, Haruyasu; Kajino, Mizuo*; Draxler, R.*; Hort, M.*; Malo, A.*; et al.

Atmospheric Chemistry and Physics, 15(2), p.1029 - 1070, 2015/01

 Times Cited Count:140 Percentile:0.97(Environmental Sciences)

We estimated a detailed time trend of atmospheric releases during the Fukushima Dai-ichi Power Station (FNPS1) accident by combining environmental monitoring data with coupling simulation of atmospheric model of WSPEEDI-II, and oceanic dispersion model of SEA-GEARN-FDM. The new scheme of dry and fogwater depositions, in-cloud scavenging, cloud condensation nuclei activity, and wet scavenging by ice phase for radioactive iodine gas and other particles was incorporated into WSPEEDI-II. The results revealed that the major releases of radionuclides occurred in the following periods: afternoon on 12 March when the wet venting and hydrogen explosion at Unit 1, morning on 13 March after the venting event at Unit 3, midnight on 14 March when three-time openings of SRV were conducted at Unit 2, morning and night on 15 March, and morning on 16 March.

Journal Articles

Long-term observation of fog chemistry and estimation of fog water and nitrogen input via fog water deposition at a mountainous site in Hokkaido, Japan

Yamaguchi, Takashi*; Katata, Genki; Noguchi, Izumi*; Sakai, Shigekatsu*; Watanabe, Yoko*; Uematsu, Mitsuo*; Furutani, Hiroshi*

Atmospheric Research, 151, p.82 - 92, 2015/01

 Times Cited Count:11 Percentile:52.81(Meteorology & Atmospheric Sciences)

To evaluate water and nitrogen input via fog water deposition, fog chemistry and deposition around a crater lake (Mashu) in northern Japan were investigated in the growing seasons of trees in 2006-2012. The fog samples were collected using an active fog collector and droplet size distribution was measured by a droplet size spectrometer. Compared to previous iterature of exposure experiments of acid mist on plants, fog acidity in this study did not seem to injure plant leaves. The visibility (VIS)-liquid water content of fog (LWC) relationship differed between summer and autumn. Fog water deposition was calculated from LWC empirically derived from past VIS data and deposition velocity estimated using wind speed and vegetation parameters. The water and nitrogen inputs via fog water deposition accumulated for each growing season were estimated as 107-161 mm and 20-41 meq m$$^{-2}$$, respectively.

Journal Articles

A Numerical study of the effects of aerosol hygroscopic properties to dry deposition on a broad-leaved forest

Katata, Genki; Kajino, Mizuo*; Matsuda, Kazuhide*; Takahashi, Akira*; Nakaya, Ko*

Atmospheric Environment, 97, p.501 - 510, 2014/11

 Times Cited Count:10 Percentile:59.99(Environmental Sciences)

To investigate the impact of hygroscopic growth on dry deposition onto forest canopies, numerical simulations of PM2.5 sulfate deposition using a multi-layer atmosphere-SOiL-VEGetation model (SOLVEG) ware performed. The scheme of particle dry deposition in SOLVEG was extended for application to a broad-leaved forest. An aerosol hygroscopic model based on the widely used $$kappa$$-K$"o$hler theory was incorporated into the model to calculate water uptake by the aerosols. The model accurately reproduced essential turbulent exchange fluxes (momentum, heat, and water vapor) over the canopies and the soil temperature and moisture for a deciduous broad-leaved forest in central Japan. Temporal variations in the measured PM2.5 sulfate deposition velocity were generally reproduced by the model. By considering an increase in particle diameter due to hygroscopic growth, the prediction accuracy of the modeled deposition velocity under humid conditions was improved. Numerical experiments for varying aerosol size distributions and hygroscopic properties showed that the geometric mean diameter and hygroscopicity of particles have a large influence on hygroscopic growth levels. The results also suggested that the deposition velocity of wet particles increased due to hygroscopic growth when the relative humidity (RH) was approximately 50%, and that the velocity reached five times greater than that under dry conditions when RH exceeded 95%.

140 (Records 1-20 displayed on this page)