Solar Radiation Balance Research Articles

Warming effects of reduced sulfur emissions from shipping

Abstract. The regulation introduced in 2020 that limits the sulfur content in shipping fuel has reduced sulfur emissions over global open oceans by about 80 %. This is expected to have reduced aerosols that both reflect solar radiation directly and affect cloud properties, with the latter also changing the solar radiation balance. Here we investigate the impacts of this regulation on aerosols and climate in the HadGEM3-GC3.1-LL climate model. The global aerosol effective radiative forcing caused by reduced shipping emissions is estimated to be 0.13 W m−2, which is equivalent to an additional ∼50 % to the net positive forcing resulting from the reduction in all anthropogenic aerosols from the late-20th century to the pre-2020 era. Ensembles of global coupled simulations from 2020–2049 predict a global mean warming of 0.04 K averaged over this period. Our simulations are not clear on whether the global impact is yet to emerge or has already emerged because the present-day impact is masked by variability. Nevertheless, the impact of shipping emission reductions either will have already committed us to warming above the 1.5 K Paris target or will represent an important contribution that may help explain part of the rapid jump in global temperatures over the last 12 months. Consistent with previous aerosol perturbation simulations, the warming is greatest in the Arctic, reaching a mean of 0.15 K Arctic-wide and 0.3 K in the Atlantic sector of the Arctic (which represents a greater than 10 % increase in the total anthropogenic warming since pre-industrial times).

МЕТОДЫ ОПРЕДЕЛЕНИЯ РАДИАЦИОННОГО БАЛАНСА ПОЧВЕННОГО И РАСТИТЕЛЬНОГО ПОКРОВА СЕЛЬСКОХОЗЯЙСТВЕННЫХ УГОДИЙ

In this article, an analysis of calculation methods for determining the radiation balance and photosynthetically active radiation of soil and vegetation cover of agricultural land is conducted. The lack of continuous actinometric observations of solar radiation and radiation balance at meteorological stations in the Eurasian region leads to the widespread use of empirical and semi-empirical models based on climatic and geographical indicators. Mathematical models based on climatic indicators, which vary in spatial and temporal aspects and are formed on the basis of the principle of natural analogies, provide reliable and accurate data. However, calculation methods that use geographical indicators do not have physical and mathematical meaning, resulting in significant errors in the data. The aim of the research is to analyze indirect methods to identify their physical and mathematical justification. The need for the development of quantitative methods for assessing the effective use of photosynthetically active radiation to improve forecasting and management of agricultural land is emphasized.

Volatile Organic Compound Metabolism on Early Earth

Biogenic volatile organic compounds (VOCs) constitute a significant portion of gas-phase metabolites in modern ecosystems and have unique roles in moderating atmospheric oxidative capacity, solar radiation balance, and aerosol formation. It has been theorized that VOCs may account for observed geological and evolutionary phenomena during the Archaean, but the direct contribution of biology to early non-methane VOC cycling remains unexplored. Here, we provide an assessment of all potential VOCs metabolized by the last universal common ancestor (LUCA). We identify enzyme functions linked to LUCA orthologous protein groups across eight literature sources and estimate the volatility of all associated substrates to identify ancient volatile metabolites. We hone in on volatile metabolites with confirmed modern emissions that exist in conserved metabolic pathways and produce a curated list of the most likely LUCA VOCs. We introduce volatile organic metabolites associated with early life and discuss their potential influence on early carbon cycling and atmospheric chemistry.

A new perennial forage module coupled with the ECOSMOS terrestrial ecosystem model: Calibration and evaluation for Urochloa (syn. Brachiaria) brizantha

Pastures represent the main land use type in Brazil and are used for livestock production and maintenance of land ownership. Most pasture areas exhibit signs of degradation related to inadequate management, which affects pasture biomass production. Terrestrial ecosystem models are effective tools for evaluating the economic and ecological returns associated with distinct management scenarios. In this paper, a new forage module implemented in the ECOSystem MOdel Simulator (ECOSMOS) is formulated, and ECOSMOS-Forage model calibration and evaluation results were obtained for estimating tropical forage growth under continuous and rotational stocking methods subject to grazing or cutting regimes. A set of equations to simulate the daily carbon allocation, growth, senescence, and morphological characteristics of Urochloa (syn. Brachiaria) brizantha cvs. Marandu and Piatã were proposed. Biophysical and physiological parameters, including the solar radiation balance, soil water content, evapotranspiration and carbon assimilation, were calibrated and evaluated with one micrometeorological experiment. Additionally, two sets of parameters were calibrated for Marandu grass growth under continuous and rotational stocking. Based on the Marandu parameterization, a third set of parameters, thereby adjusting a few parameters, was derived for the Piatã grass under rotational stocking. The ECOSMOS-Forage model could successfully capture the energy, carbon and water fluxes and biomass dynamics during growth cycles. The net radiation, evapotranspiration and gross primary production were simulated with agreement index (d) values of 0.97, 0.89, and 0.95, respectively, during the calibration phase and 0.98, 0.90, and 0.93, respectively, during the evaluation phase. Regarding model application to simulate forage growth under rotational stocking, the model could estimate aboveground, leaf and stem dry matter accumulation levels with d values ranging from 0.91 to 0.98. Although forage growth is relatively difficult to simulate, compared with annual crops, the results suggested that the model could provide high potential for simulating tropical perennial forage grasses.

Bioindication for Ecosystem Regeneration towards Natural conditions: the BERN data base and BERN model

The primary task of the BERN database is to document reference data on typical site parameters for the occurrence of plant communities in which their diagnostic species are in competitive equilibrium with each other and in homeostatic equilibrium with the site factors. Common approaches for the creation of a site-plant database such as ordination or bioindication based on individual species like PROPS or MultiMOVE model are of limited use because it is not possible to determine the potential occurrence of a plant species on the basis of site factors, since the competitive influences cannot be determined in advance according to current knowledge. Therefore, the BERN database takes into account the structure of plant communities with the abundance and dominance of species in the competitive equilibrium of plant communities as a reference for determining anthropogenically induced changes. Qualitative knowledge on the relationship between site types and vegetation communities is widely available, as can be seen from the extensive phytosociological publications. For this purpose, synoptic tables and their location descriptions of around 50,000 relevés were evaluated. The BERN database includes currently 887 central European plant communities and links to their diagnostically defining species composition. The database defines the niche of 2210 central European plant species for the soil properties pH, base saturation, carbon to nitrogen ratio, and wetness index and the climatic properties continentality, length of vegetation period, solar radiation and climatic water balance. The BERN model recombines the realised species niches that mainly form the competitively homeostatic structure of a plant community in order to determine the fundamental multifactorial niche of this community. The BERN database contains mainly historical recordings of more or less undisturbed sites. The BERN model (Bioindication for Ecosystem Regeneration towards Natural conditions) as an application module of the BERN database was developed to integrate ecological cause-effect relationships into studies on environmental status assessment and forecasting. The BERN database now has been published for the first time. The methodology of creating the BERN database and the BERN model are documented and applications are demonstrated with examples. The freely available database should invite you to supplement and modify it.

Benthic Fluxes of Fluorescent Dissolved Organic Material, Salt, and Heat Measured by Multiple-Sensor Aquatic Eddy Covariance.

Aquatic eddy covariance (AEC) is an in situ technique for measuring fluxes in marine and freshwater systems that is based on the covariance of velocity and concentration measurements. To date, AEC has mainly been applied to the measurement of benthic oxygen fluxes. Here, development of a fast multiple-channel sensor enables the use of AEC for measurement of benthic fluxes of fluorescent material, salt, and heat at three distinct sites in Massachusetts, USA, including the Connecticut River, the Concord River, and Upper Mystic Lake. Benthic fluxes of salt, useful as a tracer for groundwater input (submarine groundwater discharge), were consistent with independent measurements made with seepage meters. Eddy fluxes of heat were consistent with the balance of incoming solar radiation and thermal conduction at the sediment surface. Benthic eddy fluxes of fluorescent dissolved organic material (FDOM) revealed a substantial net downward flux in the humic-rich Concord River, suggesting that microbial consumption of dissolved organic carbon in the sediment was significant. Simultaneous measurement of several fluxes expands the utility of AEC as a biogeochemical tool while enabling checks for mutual consistency among data channels.

Fluorescence characteristics, absorption properties, and radiative effects of water-soluble organic carbon in seasonal snow across northeastern China

Abstract. Water-soluble organic carbon (WSOC) in the cryosphere can significantly influence the global carbon cycle and radiation budget. However, WSOC in the snowpack has received little scientific attention to date. This study reports the fluorescence characteristics, absorption properties, and radiative effects of WSOC based on 34 snow samples collected from sites in northeastern China. A significant degree of regional WSOC variability is found, with concentrations ranging from 0.5±0.2 to 5.7±3.7 µg g−1 (average concentration: 3.6±3.2 µg g−1). The three principal fluorescent components of WSOC are identified as (1) the high-oxygenated humic-like substances (HULIS-1) of terrestrial origin, (2) the low-oxygenated humic-like substances (HULIS-2) of mixed origin, and (3) the protein-like substances (PRLIS) derived from autochthonous microbial activity. In southeastern Inner Mongolia (SEIM), a region dominated by desert and exposed soils, the WSOC exhibits the highest humification index (HIX) but the lowest fluorescence (FI) and biological (BIX) indices; the fluorescence signal is mainly attributed to HULIS-1 and thus implicates soil as the primary source. By contrast, the HIX (FI and BIX) value is the lowest (highest), and the percentage of PRLIS is the highest in the remote area of northeastern Inner Mongolia (NEIM), suggesting a primarily biological source. For south and north of northeastern China (SNC and NNC), both of which are characterized by intensive agriculture and industrial activity, the fluorescence signal is dominated by HULIS-2, and the HIX, FI, and BIX values are all moderate, indicating the mixed origins for WSOC (anthropogenic activity, microbial activity, and soil). We also observe that, throughout northeastern China, the light absorption of WSOC is dominated by HULIS-1, followed by HULIS-2 and PRLIS. The contribution of WSOC to albedo reduction (average concentration: 3.6 µg g−1) in the ultraviolet–visible (UV–Vis) band is approximately half that of black carbon (BC average concentration: 0.6 µg g−1). Radiative forcing is 3.8 (0.8) W m−2 in old (fresh) snow, equating to 19 % (17 %) of the radiative forcing of BC. These results indicate that WSOC has a profound impact on snow albedo and the solar radiation balance.

Development of a Clear‐Sky 3D Sub‐Grid Terrain Solar Radiative Effect Parameterization Scheme Based on the Mountain Radiation Theory

AbstractTerrains strongly affect the surface solar radiation (SSR) and energy balance, and further greatly modulate the weather and climate in rugged areas. In this study, we have developed a clear‐sky 3‐dimensional sub‐grid terrain solar radiative effect (3DSTSRE) parameterization scheme based on the mountain radiation theory with full consideration of the influences of 3‐dimensional configuration of terrains. Results show that the 3DSTSRE scheme achieves the equivalent effect of the downward SSR flux at the model grids derived from those explicitly calculated at the sub‐grids without reducing the calculating efficiency of numerical models. It performs well at model grids with different horizontal resolutions. The instant downward SSR flux calculated by the 3DSTSRE scheme at 76.8%, 84.8%, 88.7%, 91.6%, 93.0%, and 87.1% model grids with the horizontal resolution of 0.025°, 0.05°, 0.1°, 0.2°, 0.4°, and 0.8° in the areas featured by complex terrains shows relative errors within ±1.0% against those derived from the explicit calculations at sub‐grids, respectively. The normalized mean absolute errors of the instant downward SSR flux calculated by the 3DSTSRE scheme are below 1% (2%) throughout the day and the year for the model grids with resolutions ranging from 0.05° to 0.8° (of 0.025°). Although the performance of 3DSTSRE scheme decreases slightly under the conditions with much lower solar zenith angle and finer model horizontal resolution, the 3DSTSRE scheme developed in current study shows broad application prospects in various numerical models with the advantages of a solid physical foundation, high accuracy, strong portability and flexibility.

Multi-year investigation on the rate, timing, and use of surfactant for thinning apples with post-bloom applications of metamitron

Several experiments were conducted in Simcoe, Ontario, to evaluate the efficacy of metamitron (MET) as a post-bloom thinner for Ambrosia, Gala, and Honeycrisp apple trees. Trees were treated with rates of MET ranging from 165–480 mg·L−1, as well as different timings ranging from 5–22 mm fruit diameter. The effect of including a non-ionic surfactant on thinning efficacy with MET was also evaluated. Treatments were compared with untreated trees and industry standard sprays of carbaryl, 1-naphthalene acetic acid (NAA), 6-benzyladenine (6-BA), or combinations thereof. Response to MET varied by cultivar and season. In six of the seven experiments MET reduced fruit set, but only in four experiments did MET reduce the number of fruit per tree or crop load compared with the untreated control trees. Petal fall (5–7 mm) applications of MET were less effective than later timings. Thinning response increased with higher rates of MET in four of the seven studies. For Honeycrisp and Ambrosia, 175 mg·L−1 MET was effective in reducing fruit set and crop load, while rates at or above 263 mg·L−1 MET were required to thin Gala. MET improved fruit size distribution into larger categories and caused minimal leaf phytotoxicity with or without a non-ionic surfactant. Environmental factors such as nighttime temperature and solar radiation largely could not account for the seasonal or application timings in thinning response to MET. Greater understanding of the carbon balance and interplay of solar radiation, nighttime temperature, cultivar and fruitlet size on thinning response is required to improve the predictive thinning response of apple to MET.

Spectrum of Light as a Determinant of Plant Functioning: A Historical Perspective.

The significance of the spectral composition of light for growth and other physiological functions of plants moved to the focus of “plant science” soon after the discovery of photosynthesis, if not earlier. The research in this field recently intensified due to the explosive development of computer-controlled systems for artificial illumination and documenting photosynthetic activity. The progress is also substantiated by recent insights into the molecular mechanisms of photo-regulation of assorted physiological functions in plants mediated by photoreceptors and other pigment systems. The spectral balance of solar radiation can vary significantly, affecting the functioning and development of plants. Its effects are evident on the macroscale (e.g., in individual plants growing under the forest canopy) as well as on the meso- or microscale (e.g., mutual shading of leaf cell layers and chloroplasts). The diversity of the observable effects of light spectrum variation arises through (i) the triggering of different photoreceptors, (ii) the non-uniform efficiency of spectral components in driving photosynthesis, and (iii) a variable depth of penetration of spectral components into the leaf. We depict the effects of these factors using the spectral dependence of chloroplast photorelocation movements interlinked with the changes in light penetration into (light capture by) the leaf and the photosynthetic capacity. In this review, we unfold the history of the research on the photocontrol effects and put it in the broader context of photosynthesis efficiency and photoprotection under stress caused by a high intensity of light.

Analysis of the cooling effects of higher albedo surfaces during heat waves coupling the Weather Research and Forecasting model with building energy models

In this paper, the numerical Weather Research and Forecasting (WRF) model is coupled with a Building Effect Parameterization (BEP) and Building Energy Model (BEM) to investigate the effects on the urban microclimate and building energy demand of increasing the albedo of urban surfaces. For the scope of this study, while the WRP performs real-data applications numerical weather prediction, the BEP serves to predict the heat and moisture fluxes from the urban canopies to the atmosphere and the BEM simulates the effects of anthropogenic heat emissions. As such the overall simulations are capable of taking into account the several factors that influence the urban microclimate and couple their mutual interactions. Outdoor microclimate results for the air temperature and wind speed are compared against measurements in Toronto, ON, during the 2018 heatwave period. The validation confirms the reliability of the WRF model and the selected approach. Then, in order to assess possible urban heat island mitigation strategies, the albedos of roofs, walls, and ground surfaces are increased from 0.2 to 0.65, 0.60, and 0.45, respectively. Results show that the maximum decrease in air temperature through these higher albedo values is nearly 2 °C at noon with a slight increase in wind speed. Moreover, the daily averaged decrease in the urban surface temperature and in the absolute humidity is 3.3 °C and 0.6 g/kg, respectively. Increasing the surface albedo would reduce the solar radiation balance at noon by almost 30 W/m2. Finally, the combined effect of decreased solar heat gains by urban surfaces and decreased air temperature would reduce the cooling energy demand by almost 10%.

Photoelectron Sheath on Lunar Sunlit Regolith and Dust Levitation

Abstract Photoelectron sheath formation and subsequent fine dust levitation over the sunlit lunar regolith have been investigated by consistently accounting for the continuous interaction of the solar wind and solar radiation with the Moon. In deriving the photoelectron sheath, the Poisson equation is coupled with the latitude-dependent population density of the Fermionic photoelectrons. The altitude and latitude profiles of the electric potential, electric field, and electron density within the photoelectron sheath have been derived. A larger sheath is predicted near the terminator compared to the subsolar point. Accounting for the sheath features, the charging of levitating particles under the kinetic balance of anisotropic photoelectron flux, solar radiation, and solar wind plasma has been calculated. The dust charge is coupled with a characteristic sheath field to evaluate the altitude profile of the particle size, displaying levitation under its electrostatic equilibrium with the lunar gravity. Our analysis suggests that in equilibrium, the submicron particles may levitate up to a couple of meters above the lunar surface; for instance, at the subsolar point (0° latitude) 200 and 50 nm particles may float up to an altitude of ∼64 and ∼194 cm, respectively, while at 70° latitude near the terminator these particles are estimated to levitate at an altitude of ∼18 and ∼227 cm, respectively. The floating charged submicron dust may electrostatically interact with the functioning of experiments and can significantly affect the instrument operation.

The influence of aerosol on the sunlight divergence in the atmospheric Indonesia

Solar radiation is the source of energy for the earth. The amount of solar radiation that reaching the earth’s surface, is strongly influenced by the interaction of solar radiation with the atmospheric that is passed through. This paper analyzes the effect of aerosols on solar radiation balance in the Indonesian atmosphere using radiation data from the Clouds and the Earth’s Radiant Energy System (CERES) and aerosol optical depth that is obtained from the Moderate Resolution Imaging Spectroradiometer (MODIS) - Terra, from March 2000 to February 2016. Aerosol optical depth data (AOD) and shortwave (SW) radiation that reach the top of atmosphere and the earth’s surface were analyzed spatially and temporally with the observation area of the 150S – 150N and 900W – 1500E. Moreover, the sample of several locations was analyzed such as Palangkaraya, Pontianak, Banjarmasin and Samarinda, to look at the cases of forest fires which generate aerosols that quite high. Results of data analysis showed a significant influence of aerosols on the divergence of short-wave solar radiation in the atmosphere of Indonesia. The divergence of short-wave radiation shows how much solar radiation is absorbed in the atmosphere. Some cities such as Palangkaraya and Pontianak showed a strong correlation (0.7 - 0.95) between AOD and the value of shortwave radiation divergence. Temporal pattern from time series analysis showed that the increase in the value of AOD due to the fires incident, give the biggest influence on the decrease in solar radiation that reaches the earth’s surface.

SOLAR RADIATION EFFECT ON THE MORBIDITY OF MALIGNANT SKIN NEOPLASMS AND MORTALITY FROM THEM

We studied the solar radiation effect on the morbidity of malignant skin neoplasms and mortality from them in the Irkutsk region population as one of risk factors. It is established that population’s morbidity rates of skin melanoma from 3.3 ± 0.3 to 5.0 ± 0.4 per 100 thousand and other malignant skin neoplasms from 26.0 ± 0.9 to 32.4 ± 0.9 per 100 thousand increased; the mortality rates from them became respectively from 1.6 ± 0.2 to 1.8 ± 0.2 per 100 thousand and from 0.2 ± 0.1 to 0.5 ± 0.1 per 100 thousand in the region during the 2007–2017 period. According to the results of the correlation-regression analysis we found the effect on the morbidity of malignant skin neoplasms for such parameters as direct solar radiation on a horizontal surface, total solar radiation, radiation balance and longwave radiation balance; direct and measured solar radiation influenced mortality from malignant skin neoplasms. To reduce the morbidity of malignant skin neoplasms of the Irkutsk region population, it is necessary to widely educate the population about the dangers of excessive exposure to ultraviolet radiation and inform about local levels of solar radiation according to quality monitoring data.

Efisiensi Penggunaan Radiasi Matahari dan Respon Tanaman Kedelai (Glycine max L.) terhadap Penggunaan Mulsa Reflektif

One of factors affecting the productivity of soybean crop is the availability of solar radiation. Reduction of solar radiation reaching soybean crop by cloud cover especially during rainy season or by shade of trees could potentially decrease soybean production. The availability of radiation for the crop can be increased through the use of reflective mulch to reflect back transmitted radiation to the crop canopy. This study aimed to determine the effect of shade and reflective mulch on crop solar radiation balance and crop productivity responses. A field experiment in Bogor, Indonesia in July 2016 to January 2017, was conducted, applying a Nested Design-two factors model with three replications. The first factor was two levels of shading, i.e., without and with 50% shade; and the second factor was three levels, i.e., without mulch, black silver mulch, and metallic mulch. The results showed that the use of mulch influenced the radiation balance of plants, increasing distribution of radiation reception in plants, solar radiation interception and RUE. The use of mulch caused changes in canopy structure by increase LAI, so that the inhibited radiation was higher. The reflected radiation from the mulch increased production per plants and weight of 1,000 seeds in shaded plants.Keywords: black silver mulch, metallic mulch, radiation balance, radiation interception, shading

Spatiotemporal patterns of street-level solar radiation estimated using Google Street View in a high-density urban environment

This study presents a method for calculating solar irradiance of street canyons using Google Street View (GSV) images and investigates its spatiotemporal patterns in a high-density urban environment. In this method, GSV images provide a unique way to characterize the street morphology from which the diurnal solar path and solar radiation exposure can be estimated in a street canyon. Verifications of our developed method using free-horizon HKO observations and street-level field measurements show that both the calculated clear-sky and all-sky solar irradiance of street canyons well capture the diurnal and seasonal cycles. In the high-density urban areas of Hong Kong, we found that (1) the lowest monthly averaged solar irradiations in winter are 6.6 (December) and 4.6 (February) MJ/m2/day, and the highest values in summer are 17.3 (July) and 10.8 (June) MJ/m2/day for clear-sky and all-sky calculations, respectively; (2) The spatial variability of solar irradiation is closely related to sky view factor (SVF). In summer, the irradiation in a low-rise region (SVF≥0.7) on average is about three times that in a high-rise region (SVF≤0.3), and they differ by about five times in winter; (3) Street orientation has a significant impact on the solar radiation received in a high-density street canyon. In general, street canyons with West-East orientation receive higher solar irradiation during summer and lower during winter compared to those with South-North orientation. The generated maps of street-level solar irradiation may help researchers investigate the interactions between solar radiation, human health and urban thermal balance in high-density urban environments.

Impact of air-sea drag coefficient for latent heat flux on large scale climate in coupled and atmosphere stand-alone simulations

The turbulent fluxes across the ocean/atmosphere interface represent one of the principal driving forces of the global atmospheric and oceanic circulation. Despite decades of effort and improvements, representation of these fluxes still presents a challenge due to the small-scale acting turbulent processes compared to the resolved scales of the models. Beyond this subgrid parameterization issue, a comprehensive understanding of the impact of air-sea interactions on the climate system is still lacking. In this paper we investigates the large-scale impacts of the transfer coefficient used to compute turbulent heat fluxes with the IPSL-CM4 climate model in which the surface bulk formula is modified. Analyzing both atmosphere and coupled ocean–atmosphere general circulation model (AGCM, OAGCM) simulations allows us to study the direct effect and the mechanisms of adjustment to this modification. We focus on the representation of latent heat flux in the tropics. We show that the heat transfer coefficients are highly similar for a given parameterization between AGCM and OAGCM simulations. Although the same areas are impacted in both kind of simulations, the differences in surface heat fluxes are substantial. A regional modification of heat transfer coefficient has more impact than uniform modification in AGCM simulations while in OAGCM simulations, the opposite is observed. By studying the global energetics and the atmospheric circulation response to the modification, we highlight the role of the ocean in dampening a large part of the disturbance. Modification of the heat exchange coefficient modifies the way the coupled system works due to the link between atmospheric circulation and SST, and the different feedbacks between ocean and atmosphere. The adjustment that takes place implies a balance of net incoming solar radiation that is the same in all simulations. As there is no change in model physics other than drag coefficient, we obtain similar latent heat flux between coupled simulations with different atmospheric circulations. Finally, we analyze the impact of model tuning and show that it can offset part of the feedbacks.

Coupled land surface–subsurface hydrogeophysical inverse modeling to estimate soil organic carbon content and explore associated hydrological and thermal dynamics in the Arctic tundra

Abstract. Quantitative characterization of soil organic carbon (OC) content is essential due to its significant impacts on surface–subsurface hydrological–thermal processes and microbial decomposition of OC, which both in turn are important for predicting carbon–climate feedbacks. While such quantification is particularly important in the vulnerable organic-rich Arctic region, it is challenging to achieve due to the general limitations of conventional core sampling and analysis methods, and to the extremely dynamic nature of hydrological–thermal processes associated with annual freeze–thaw events. In this study, we develop and test an inversion scheme that can flexibly use single or multiple datasets – including soil liquid water content, temperature and electrical resistivity tomography (ERT) data – to estimate the vertical distribution of OC content. Our approach relies on the fact that OC content strongly influences soil hydrological–thermal parameters and, therefore, indirectly controls the spatiotemporal dynamics of soil liquid water content, temperature and their correlated electrical resistivity. We employ the Community Land Model to simulate nonisothermal surface–subsurface hydrological dynamics from the bedrock to the top of canopy, with consideration of land surface processes (e.g., solar radiation balance, evapotranspiration, snow accumulation and melting) and ice–liquid water phase transitions. For inversion, we combine a deterministic and an adaptive Markov chain Monte Carlo (MCMC) optimization algorithm to estimate a posteriori distributions of desired model parameters. For hydrological–thermal-to-geophysical variable transformation, the simulated subsurface temperature, liquid water content and ice content are explicitly linked to soil electrical resistivity via petrophysical and geophysical models. We validate the developed scheme using different numerical experiments and evaluate the influence of measurement errors and benefit of joint inversion on the estimation of OC and other parameters. We also quantify the propagation of uncertainty from the estimated parameters to prediction of hydrological–thermal responses. We find that, compared to inversion of single dataset (temperature, liquid water content or apparent resistivity), joint inversion of these datasets significantly reduces parameter uncertainty. We find that the joint inversion approach is able to estimate OC and sand content within the shallow active layer (top 0.3 m of soil) with high reliability. Due to the small variations of temperature and moisture within the shallow permafrost (here at about 0.6 m depth), the approach is unable to estimate OC with confidence. However, if the soil porosity is functionally related to the OC and mineral content, which is often observed in organic-rich Arctic soil, the uncertainty of OC estimate at this depth remarkably decreases. Our study documents the value of the new surface–subsurface, deterministic–stochastic inversion approach, as well as the benefit of including multiple types of data to estimate OC and associated hydrological–thermal dynamics.

Differential Haematobia irritans infestation levels in beef cattle raised in silvopastoral and conventional pasture systems

The use of silvopastoral systems (SPS) can be a good alternative to reduce the environmental impacts of livestock breeding in Brazil. One of the reasons for its scarce adoption is the lack of information on health and productivity of cattle raised under these conditions. The experiment reported here was designed to compare the infestation by external parasites – the cattle tick (Rhipicephalus microplus), horn fly (Haematobia irritans), and larvae of the botfly (Dermatobia hominis) – in beef cattle raised in a SPS and a conventional pasture system (CPS), evaluated for 24 months. Data on air and soil temperature, solar radiation, wind incidence and water balance were used to characterize the SPS and CPS. R. microplus adult females and D. hominis larvae were counted on the body of each animal to determine the parasites burdens, but we did not find significant differences between the two systems. Horn flies counts on animals’ body, and analysis of the horn fly and its pupal parasitoids associated with the dung pats were obtained in the two systems. Horn fly infestation was significantly lower (p=0.01) in the SPS (13.17±3.46) in comparison with the CPS (24.02±4.43). In SPS and CPS, respectively, the mean densities of pupae of H. irritansin dung pats were 9.8 and 10.7; the mean density of adults of H. irritans, 3.7 and 3.5; and the density of its pupal parasitoids were 20.5 and 5.4. The effect of production system was significant (p<0.05) only for the occurrence of pupal parasitoids of the horn fly, where the greatest occurrences of these natural enemies were in the SPS. These data indicate that natural enemies were able to control, at least partially, the horn fly populations in the cattle.

Changes in Ocean Temperature in the Barents Sea in the Twenty-First Century

AbstractPossible modifications to ocean temperature in the Barents Sea induced by climate change are explored. The simulations were performed with a coupled ice–ocean model (CIOM) driven by the surface fields from the Canadian Regional Climate Model (CRCM) simulations. CIOM can capture the observed water volume inflow through the Barents Sea Opening. The CIOM simulation and observations suggest an increase in the Atlantic water volume inflow and heat transport into the Barents Sea in recent decades resulting from enhanced storm activity. While seasonal variations of sea ice and sea surface temperature in CIOM simulations are comparable with observations, CIOM results underestimate the sea surface temperature but overestimate ice cover in the Barents Sea, consistent with an underestimated heat transport through the Barents Sea Opening. Under the SRES A1B scenario, the loss of sea ice significantly increases the surface solar radiation and the ocean surface heat loss through turbulent heat fluxes and longwave radiation. Meanwhile, the lateral heat transport into the Barents Sea tends to increase. Thus, changes in ocean temperature depend on the heat balance of solar radiation, surface turbulent heat flux, and lateral heat transport. During the 130-yr simulation period (1970–2099), the average ocean temperature increases from 0° to 1°C in the southern Barents Sea, mostly due to increased lateral heat transport and solar radiation. In the northern Barents Sea, ocean temperature decreases by 0.4°C from the 2010s to the 2040s and no significant trend can be seen thereafter, when the surface heat flux is balanced by solar radiation and lateral heat transport and there is no notable net heat flux change.