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The Robert  H Smith Faculty
of Food, Agriculture and Environment
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Publications

2019
Gabay, M. ; Tas, E. Dispersion-box modeling investigation of the influences of gasoline, diesel, M85 and E85 vehicle exhaust emission on photochemistry. Environmental Pollution 2019. Publisher's VersionAbstract
Alternative transportation fuels (ATFs) can reduce air pollution. However, the influence of conventional fuels—diesel and gasoline, and particularly ATFs on photochemical air pollution is not well-characterized, limiting assessments of ATFs and air quality. This is mainly due to frequent use of lumped chemical mechanisms by related atmospheric modeling. Here we hypothesized that applying a chemical mechanism that is specifically developed according to both emission fractions and photochemical ozone creation potential of volatile organic compounds (VOCs) is key to gaining reliable insights into the impact of transportation fuels on photochemistry. We used a heterogeneous chemical mechanism with 927 reactions and relatively detailed emission inventories to specifically meet the requirements for reliable simulation of the effect of exhaust emissions from vehicles fueled by selected model fuels—diesel, gasoline, and mixtures of 15% gasoline with 85% ethanol (E85) or 85% methanol (M85)—on photochemistry. These dispersion-box model simulations revealed a strong influence of atmospheric background balance between VOCs and nitrogen oxides (NOX = [NO] + [NO2]) on the impact of exhaust emissions on photochemistry, with higher tendency toward ozone (O3) formation or destruction for more VOC-limited or NOX-limited conditions, respectively. Accordingly, higher [NOX]/[VOC] exhaust emission, such as from diesel and M85, resulted in lower O3, not only locally but also downwind of the emission. This offers a new perspective and measure for transportation fuel assessment. Rapid conversion of O3 to hydroxyl and hydroperoxyl radicals downwind of the exhaust emission indicates the importance of simulating the impact of road transportation on photochemistry at high spatial and temporal resolution. Peroxyacetyl nitrate formation was more sensitive to VOC emission under VOC-limited conditions than to NOX emission under NOX-limited conditions. Secondary formaldehyde dominated over primary emitted formaldehyde several minutes after emission. These findings should be verified using a 3D modeling study under varying meteorological conditions.
Shechner, M. ; Guenther, A. ; Rhew, R. ; Wishkerman, A. ; Li, Q. ; Blake, D. ; Lerner, G. ; Tas, E. Emission of volatile halogenated organic compounds over various Dead Sea landscapes. Atmospheric Chemistry and Physics 2019, 19, 7667–7690. Publisher's Version
Bughici, T. ; Lazarovitch, N. ; Fredj, E. ; Tas, E. Evaluation and Bias Correction in WRF Model Forecasting of Precipitation and Potential Evapotranspiration. Journal of Hydrometeorology 2019, 20, 965 - 983. Publisher's VersionAbstract
AbstractA reliable forecast of potential evapotranspiration (ET0) is key to precise irrigation scheduling toward reducing water and agrochemical use while optimizing crop yield. In this study, we examine the benefits of using the Weather Research and Forecasting (WRF) Model for ET0 and precipitation forecasts with simulations at a 3-km grid spatial resolution and an hourly temporal resolution output over Israel. The simulated parameters needed to calculate ET0 using the Penman?Monteith (PM) approach, as well as calculated ET0 and precipitation, were compared to observations from a network of meteorological stations. WRF forecasts of all PM meteorological parameters, except wind speed Ws, were significantly sensitive to seasonality and synoptic conditions, whereas forecasts of Ws consistently showed high bias associated with strong local effects, leading to high bias in the evaluated PM?ET0. Local Ws bias correction using observations on days preceding the forecast and interpolation of the resulting PM?ET0 to other locations led to significant improvement in ET0 forecasts over the investigated area. By using this hybrid forecast approach (WRFBC) that combines WRF numerical simulations with statistical bias corrections, daily ET0 forecast bias was reduced from an annual mean of 13% with WRF to 3% with WRFBC, while maintaining a high model?observation correlation. WRF was successful in predicting precipitation events on a daily event basis for all four forecast lead days. Considering the benefit of the hybrid approach for forecasting ET0, the WRF Model was found to be a high-potential tool for improving crop irrigation management.AbstractA reliable forecast of potential evapotranspiration (ET0) is key to precise irrigation scheduling toward reducing water and agrochemical use while optimizing crop yield. In this study, we examine the benefits of using the Weather Research and Forecasting (WRF) Model for ET0 and precipitation forecasts with simulations at a 3-km grid spatial resolution and an hourly temporal resolution output over Israel. The simulated parameters needed to calculate ET0 using the Penman?Monteith (PM) approach, as well as calculated ET0 and precipitation, were compared to observations from a network of meteorological stations. WRF forecasts of all PM meteorological parameters, except wind speed Ws, were significantly sensitive to seasonality and synoptic conditions, whereas forecasts of Ws consistently showed high bias associated with strong local effects, leading to high bias in the evaluated PM?ET0. Local Ws bias correction using observations on days preceding the forecast and interpolation of the resulting PM?ET0 to other locations led to significant improvement in ET0 forecasts over the investigated area. By using this hybrid forecast approach (WRFBC) that combines WRF numerical simulations with statistical bias corrections, daily ET0 forecast bias was reduced from an annual mean of 13% with WRF to 3% with WRFBC, while maintaining a high model?observation correlation. WRF was successful in predicting precipitation events on a daily event basis for all four forecast lead days. Considering the benefit of the hybrid approach for forecasting ET0, the WRF Model was found to be a high-potential tool for improving crop irrigation management.
Li, Q. ; Gabay, M. ; Rubin, Y. ; Raveh-Rubin, S. ; Rohatyn, S. ; Tatarinov, F. ; Rotenberg, E. ; Ramati, E. ; Dicken, U. ; Preisler, Y. ; et al. Investigation of ozone deposition to vegetation under warm and dry conditions near the Eastern Mediterranean coast. Science of The Total Environment 2019, 658, 1316 - 1333. Publisher's VersionAbstract
Dry deposition of ozone (O3) to vegetation is an important removal pathway for tropospheric O3, while O3 uptake through plant stomata negatively affects vegetation and leads to climate change. Both processes are controlled by vegetation characteristics and ambient conditions via complex mechanisms. Recent studies have revealed that these processes can be fundamentally impacted by coastal effects, and by dry and warm conditions in ways that have not been fully characterized, largely due to lack of measurements under such conditions. Hence, we hypothesized that measuring dry deposition of O3 to vegetation along a sharp spatial climate gradient, and at different distances from the coast, can offer new insights into the characterization of these effects on O3 deposition to vegetation and stomatal uptake, providing important information for afforestation management and for climate and air-quality model improvement. To address these hypotheses, several measurement campaigns were performed at different sites, including pine, oak, and mixed Mediterranean forests, at distances of 20–59 km from the Eastern Mediterranean coast, under semiarid, Mediterranean and humid Mediterranean climate conditions. The eddy covariance technique was used to quantify vertical O3 flux (Ftot) and its partitioning to stomatal flux (Fst) and non-stomatal flux (Fns). Whereas Fst tended to peak around noon under humid Mediterranean and Mediterranean conditions in summer, it was strongly limited by drought under semiarid conditions from spring to early winter, with minimum average Fst/Ftot of 8–11% during the summer. Fns in the area was predominantly controlled by relative humidity (RH), whereas increasing Fns with RH for RH < 70% indicated enhancement of Fns by aerosols, via surface wetness stimulation. At night, efficient turbulence due to sea and land breezes, together with increased RH, resulted in strong enhancement of Ftot. Extreme dry surface events, some induced by dry intrusion from the upper troposphere, resulted in positive Fns events.
Bughici, T. ; Tas, E. ; Fredj, E. ; Lazarovitch, N. Field Crop Irrigation - Multi-Objective Optimization and Sensitivity to Weather Forecast Accuracy. The 13th Dahlia Greidinger International Symposium 2019, 2019.
2018
Li, Q. ; Gabay, M. ; Rubin, Y. ; Fredj, E. ; Tas, E. Measurement-based investigation of ozone deposition to vegetation under the effects of coastal and photochemical air pollution in the Eastern Mediterranean. Science of The Total Environment 2018, 645, 1579 - 1597. Publisher's VersionAbstract
Dry deposition of ozone (O3) to vegetation is an important pathway for its removal from the troposphere, and it can lead to adverse effects in plants and changes in climate. However, our mechanistic understanding of O3 dry deposition is insufficient to adequately account for it in global and regional models, primarily because this process is highly complicated by feedback mechanisms and sensitivity to specific characteristics of vegetative environment and atmospheric dynamics and composition. We hypothesized that measuring dry deposition of O3 to vegetation near the Eastern Mediterranean (EM) coast, where large variations in meteorological conditions and photochemical air pollution frequently occur, would enable identifying the mechanisms controlling O3 deposition to vegetation. Moreover, we have only limited knowledge of O3 deposition to vegetation occurring near a coastline, under air pollution, or in the EM. This study investigated O3 deposition to mixed Mediterranean vegetation between the summers of 2015 and 2017, 3.6 km away from the EM coast, using the eddy covariance technique to quantify vertical flux of O3 and its partitioning to stomatal and non-stomatal flux, concurrent with nitrogen oxide (NOx), sulfur dioxide and carbon monoxide. Surprisingly, nighttime O3-deposition velocity (Vd) was smaller than daytime Vd by only ~20–37% on average for all measurement periods, primarily related to moderate nighttime atmospheric stability due to proximity to the seashore. We provide evidence for the role of sea-salt aerosols in enhancing O3 deposition via surface-wetness buildup at low relative humidity near the coast, and for daytime enhancement of O3 deposition by the combined effects of biogenic volatile organic compound emission and surface-wetness buildup. We further show that NOx emitted from elevated emission sources can reduce O3 deposition, and even lead to a positive O3 flux, demonstrating the importance of adequately taking into account the impact of air pollution on O3 deposition to vegetation.
Tas, E. ; Shechner, M. Ozone Formation Induced by Reactive Bromine and Iodine Species in a polluted marine environment. AGU Fall Meeting Abstracts 2018.
Rohatyn, S. ; Rotenberg, E. ; Ramati, E. ; Tatarinov, F. ; Tas, E. ; Yakir, D. Differential Impacts of Land Use and Precipitation on “Ecosystem Water Yield”. Water Resources Research 2018, 54, 5457 - 5470. Publisher's VersionAbstract
Abstract Ecosystem evapotranspiration (ET) can approach annual precipitation (P) often leaving a residual [P-ET], referred to as an ecosystem water yield (WYe). Using a mobile lab, we estimate ET and WYe, in paired forest and nonforest (shrub or grassland) sites along the precipitation gradient (285?755 mm a?1) in Israel. WYe was 69 mm in the dry sites and was further reduced by ?51 mm by forestation. Both WYe and the impact of forestation increased in the wetter sites, with forestation reducing WYe by >200 mm, equivalent to ?30% of the local P. This was associated with increase in ET by a factor of 2.2 and 1.8 in the forest and nonforest sites, respectively, along the rainfall gradient. Losses in WYe due to forestation approached a maximum of ?200 mm above P ? 500 mm, but the forest WYe could vary between ?300 mm at P?=?900 mm and ?100 mm at P?=?500 mm (with equivalent change in WYe between 500 and 300 mm in the nonforest sites), reflecting the increasing ?hydrological cost? associated with vegetation ET and the expected climate change in these regions. The results quantify the interactions of land use and climate on ecosystem ET, indicating that in dry climates, afforestation impact on WYe varies significantly across small spatial scales and can reduce WYe with significant impacts on local hydrology. Such impact may be diminished by management (e.g., plant species, thinning, and grazing) but should also consider the trade-offs with other ecosystem services (e.g., carbon sequestration, soil protection, and surface cooling).
Dayan, C. ; Fredj, E. ; Misztal, P. ; Goldstein, A. ; Tas, E. BVOC from natural vegetation at the eastern Mediterranean and its interaction with local and regional photochemistry. In EGU General Assembly Conference Abstracts; EGU General Assembly Conference Abstracts; 2018; Vol. 20, pp. 4535.
Li, Q. ; Gabay, M. ; Fredj, E. ; Tas, E. Ozone deposition to natural vegetation in the Easterm Mediterranean. In EGU General Assembly Conference Abstracts; EGU General Assembly Conference Abstracts; 2018; Vol. 20, pp. 4734.
Shechner, M. ; Tas, E. Correction to Ozone Formation Induced by the Impact of Reactive Bromine and Iodine Species on Photochemistry in a Polluted Marine Environment. Environmental Science & Technology 2018, 52, 1679 - 1679. Publisher's Version
2017
Bluvshtein, N. ; Lin, P. ; Flores, J. M. ; Segev, L. ; Mazar, Y. ; Tas, E. ; Snider, G. ; Weagle, C. ; Brown, S. S. ; Laskin, A. ; et al. Broadband optical properties of biomass-burning aerosol and identification of brown carbon chromophores. Journal of Geophysical Research: Atmospheres 2017, 122, 5441-5456. Publisher's VersionAbstract
Abstract The radiative effects of biomass-burning aerosols on regional and global scales can be substantial. Accurate modeling of the radiative effects of smoke aerosols requires wavelength-dependent measurements and parameterizations of their optical properties in the UV and visible spectral ranges along with improved description of their chemical composition. To address this issue, we used a recently developed approach to retrieve the time- and spectral-dependent optical properties of ambient biomass-burning aerosols from 300 to 650 nm wavelengths during a regional nighttime bonfire festival in Israel. During the biomass burning event, the overall absorption at 400 nm increased by about 2 orders of magnitude, changing the single scattering albedo from a background level of 0.95 to 0.7. Based on the new retrieval method, we provide parameterizations of the wavelength-dependent effective complex refractive index from 350 to 650 nm for freshly emitted and slightly aged biomass-burning aerosols. In addition, PM2.5 filter samples were collected for detailed offline chemical analysis of the water-soluble organics that contribute to light absorption. Nitroaromatics were identified as major organic species responsible for the increased absorption at 400 to 500 nm. Typical chromophores include 4-nitrocatechol, 4-nitrophenol, nitrosyringol, and nitroguaiacol; oxidation-nitration products of methoxyphenols; and known products of lignin pyrolysis. Our findings emphasize the importance of both primary and secondary organic aerosols from biomass burning in absorption of solar radiation and in effective radiative forcing.
Shechner, M. ; Tas, E. Ozone Formation Induced by the Impact of Reactive Bromine and Iodine Species on Photochemistry in a Polluted Marine Environment. Environmental Science & TechnologyEnvironmental Science & Technology 2017, 51, 14030 - 14037. Publisher's VersionAbstract
Reactive iodine and bromine species (RIS and RBS, respectively) are known for altering atmospheric chemistry and causing sharp tropospheric ozone (O3) depletion in polar regions and significant O3 reduction in the marine boundary layer (MBL). Here we use measurement-based modeling to show that, unexpectedly, both RIS and RBS can lead to enhanced O3 formation in a polluted marine environment under volatile organic compound (VOC)-limited conditions associated with high nitrogen oxide (NOX = [NO] + [NO2]) concentrations. Under these conditions, the daily average O3 mixing ratio increased to ∼44 and ∼28% for BrO and IO mixing ratios of up to ∼6.8 and 4.7 ppt, respectively. The increase in the level of O3 was partially induced by enhanced ClNO3 formation for higher Br2 and I2 emission flux. The increase in the level of O3 was associated with an increased mixing ratio of hydroperoxyl radical to hydroxyl radical ([HO2]/[OH]) and increased [NO2]/[NO] with higher levels of RBS and/or RIS. NOX-rich conditions are typical of the polluted MBL, near coastlines and ship plumes. Considering that O3 is toxic to humans, plants, and animals and is a greenhouse gas, our findings call for adequate updating of local and regional air-quality models with the effects of activities of RBS and RIS on O3 mixing ratios in the polluted MBL.Reactive iodine and bromine species (RIS and RBS, respectively) are known for altering atmospheric chemistry and causing sharp tropospheric ozone (O3) depletion in polar regions and significant O3 reduction in the marine boundary layer (MBL). Here we use measurement-based modeling to show that, unexpectedly, both RIS and RBS can lead to enhanced O3 formation in a polluted marine environment under volatile organic compound (VOC)-limited conditions associated with high nitrogen oxide (NOX = [NO] + [NO2]) concentrations. Under these conditions, the daily average O3 mixing ratio increased to ∼44 and ∼28% for BrO and IO mixing ratios of up to ∼6.8 and 4.7 ppt, respectively. The increase in the level of O3 was partially induced by enhanced ClNO3 formation for higher Br2 and I2 emission flux. The increase in the level of O3 was associated with an increased mixing ratio of hydroperoxyl radical to hydroxyl radical ([HO2]/[OH]) and increased [NO2]/[NO] with higher levels of RBS and/or RIS. NOX-rich conditions are typical of the polluted MBL, near coastlines and ship plumes. Considering that O3 is toxic to humans, plants, and animals and is a greenhouse gas, our findings call for adequate updating of local and regional air-quality models with the effects of activities of RBS and RIS on O3 mixing ratios in the polluted MBL.