An improved estimation of daily clear-sky biologically EER from broadband global solar radiation

To establish a relation between biologically effective erythemal radiation (EER) and global solar radiation, the hourly and daily clear-sky broadband (310–2,800 nm) global solar radiation (G) and spectral ultraviolet radiation incident on a horizontal surface at Esfahan, Iran (32°37′N, 51°40′E) were measured during the period 2001–2005. Good correlations at statistically significant levels between the daily values of EER and the daily G were found. The seasonal variability of EER/G is also discussed and the correction factors are determined for inclusion of vertical column ozone and solar zenith angle (SZA) cycles. The comparison of the estimated daily EER against the independent observed EER revealed that under clear sky conditions the estimations are accurate to 10% or better over SZA of 10–60° and column ozone of 250–350 Dobson. The comparison of the results with the similar works that have used shorter period of experimental data showed more accurate estimates. The deduced relations could be used to a rough estimate of the daily EER from G in arid climate regions, where there is no measured UV radiation or there are instrumental and other difficulties encountered in measuring UV radiation.     

Estimating mean monthly incident solar radiation on horizontal and inclined slopes from mean monthly temperatures extremes

Although satellite-borne sensors are now available to estimate cloud cover and incoming short-wave radiation across the Earth’s surface, the study of climatic variation and its impact on terrestrial and marine ecosystems involves historical analyses of data from networks of weather stations that only record extremes in temperatures and precipitation on a daily basis. Similarly, when projections are made with global atmospheric circulation models, the spatial resolution of predicted radiation is too coarse to incorporate the effects of heterogeneous topography. In this paper, we review the development and set forth a set of general equations that allow both diffuse and direct solar radiation to be estimated for each month on the basis of mean daily maximum and minimum temperatures, latitude, elevation, slope, and aspect. Adjustments for differences in slope, aspect, and elevation are made by varying the fraction of diffuse and direct solar beam radiation. To test the equations on various slopes and under different climatic conditions, we drew on high-quality radiation data recorded at a number of sites on three continents. On horizontal surfaces the set of equations predicted both direct and diffuse components of solar radiation within 1%–7% of recorded values. On slopes, estimates of monthly mean solar radiation were with 13% of observed values with a mean error of less than 2 MJ m^–2day^–1 over any given month. Received: 22 October 1999 / Revised: 14 May 2000 / Accepted: 5 June 2000     

Using a Simple Apparatus to Measure Direct and Diffuse Photosynthetically Active Radiation at Remote Locations

Plant canopy interception of photosynthetically active radiation (PAR) drives carbon dioxide (CO₂), water and energy cycling in the soil-plant-atmosphere system. Quantifying intercepted PAR requires accurate measurements of total incident PAR above canopies and direct beam and diffuse PAR components. While some regional data sets include these data, e.g. from Atmospheric Radiation Measurement (ARM) Program sites, they are not often applicable to local research sites because of the variable nature (spatial and temporal) of environmental variables that influence incoming PAR. Currently available instrumentation that measures diffuse and direct beam radiation separately can be cost prohibitive and require frequent adjustments. Alternatively, generalized empirical relationships that relate atmospheric variables and radiation components can be used but require assumptions that increase the potential for error. Our goal here was to construct and test a cheaper, highly portable instrument alternative that could be used at remote field sites to measure total, diffuse and direct beam PAR for extended time periods without supervision. The apparatus tested here uses a fabricated, solar powered rotating shadowband and other commercially available parts to collect continuous hourly PAR data. Measurements of total incident PAR had nearly a one-to-one relationship with total incident radiation measurements taken at the same research site by an unobstructed point quantum sensor. Additionally, measurements of diffuse PAR compared favorably with modeled estimates from previously published data, but displayed significant differences that were attributed to the important influence of rapidly changing local environmental conditions. The cost of the system is about 50% less than comparable commercially available systems that require periodic, but not continual adjustments. Overall, the data produced using this apparatus indicates that this instrumentation has the potential to support ecological research via a relatively inexpensive method to collect continuous measurements of total, direct beam and diffuse PAR in remote locations.     

亚热带人工林松树13C/12C比率和水分利用效率

The ¹³C/¹²Cratio, photosynthetic rate and stomatie conductivity of leaves of Pinus massoniana, Schima superba,Psychotria rubra, Evodia lepta and Rhodomyrtus tomentasa are measured. No significant deviation (at 5% level) is observed between water use efficiencies calculated by these items. The¹³C/¹²Cis 25.41±0.61‰. In average for treerings of Pinus massoniana from 1971 to 1983(n=6), with the maximum in1977 when the lowest precipitation was recorded. The average water use efficiency of Pinus massoniana is 8.28±0.38 in1977—1983, which is higher than that of trees in natural site and might be caused by the changes of solar radiation and water condition. ¹³C/¹²Cratio ana lysis could provide usefull informations for studying water use efficiency of artificial forest.     

美国黑核桃实生苗生态生理过程对环境因素响应的数值模拟(Ⅱ):气象要素日变化进程的数理模型

在建立植物生态生理模型（如光合作用、蒸腾作用数理模型）的过程中,气温、太阳辐射、相对湿度等气象要素的日变化及瞬时资料是必不可少的．本文根据常规台站的日常观测资料,建立了气温、太阳辐射、风速、相对湿度等气象要素日变化的数理模型．并应用实测资料对所建模型进行了验证．实践表明：（1）描述气温日变化的正弦一指数模型通常其模拟结果不甚理想,但通过引用最高温度的时间延迟参数及惯性系数,可增加模拟结果的准确性．（2）根据测量的太阳辐射日总量值以及太阳高度的日变化值等,可准确地模拟太阳辐射的日变化;（3）根据实际水汽压的日均值和气温常规资料可准确模拟相对湿度的日变化．如果区域参数已知或被正确估计。上述方法可得到较为理想的气象要素日变化的模拟结果．     

Comparison of different methods of estimating the mean radiant temperature in outdoor thermal comfort studies

Correlations between outdoor thermal indices and the calculated or measured mean radiant temperature T_mrt are in general of high importance because of the combined effect on human energy balance in outdoor spaces. The most accurate way to determine T_mrt is by means of integral radiation measurements, i.e. measuring the short- and long-wave radiation from six directions using pyranometers and pyrgeometers, an expensive and not always an easily available procedure. Some studies use globe thermometers combined with air temperature and wind speed sensors. An alternative way to determine T_mrt is based on output from the RayMan model from measured data of incoming global radiation and morphological features of the monitoring site in particular sky view factor (SVF) data. The purpose of this paper is to compare different methods to assess the mean radiant temperature T_mrt in terms of differences to a reference condition (T_mrt calculated from field measurements) and to resulting outdoor comfort levels expressed as PET and UTCI values. The T_mrt obtained from field measurements is a combination of air temperature, wind speed and globe temperature data according to the forced ventilation formula of ISO 7726 for data collected in Glasgow, UK. Four different methods were used in the RayMan model for T_mrt calculations: input data consisting exclusively of data measured at urban sites; urban data excluding solar radiation, estimated SVF data and solar radiation data measured at a rural site; urban data excluding solar radiation with SVF data for each site; urban data excluding solar radiation and including solar radiation at the rural site taking no account of SVF information. Results show that all methods overestimate T_mrt when compared to ISO calculations. Correlations were found to be significant for the first method and lower for the other three. Results in terms of comfort (PET, UTCI) suggest that reasonable estimates could be made based on global radiation data measured at the urban site or as a surrogate of missing SR data or globe temperature data recorded at the urban area on global radiation data measured at a rural location.     

Feral sheep and cattle and royal albatrosses on Campbell Island; population trends and habitat changes

Abstract

Sheep farming on Campbell Island began in 1895 and ended in 1931. The sheep population peaked at 8500 in 1910; only 1000 feral sheep were counted in 1961, but by 1969 there were 3000. The island was divided with a fence in 1970 and the sheep on the northern half were shot. Sheep continued to increase south of the fence, from 2088 in 1969 to 2521 in 1971 and, after a decline to 2400 in 1976, to 2861 in 1977. Breeding pairs of royal albatrosses numbered 2278 in 1958, 4344 in 1969, 5336 in 1976, and 4906 in 1977 - the first time the breeding population of this normally biennial breeder had been counted in two consecutive years. The number of feral cattle decreased from 20 in 1971 to 11 in 1977. These population trends are discussed in the context of changes to the flora in grazed and stock-free areas.     

The Role of Light in the Emergence of Weeds: Using Camelina microcarpa as an Example

When modelling the emergence of weeds, two main factors are considered that condition this process: temperature and soil moisture. Optimum temperature is necessary for metabolic processes that generate energy for growth, while turgor pressure is necessary for root and shoot elongation which eventually leads to seedling emergence from the soil. Most emergence models do not usually consider light as a residual factor, but it could have an important role as it can alter directly or indirectly the dormancy and germination of seeds. In this paper, inclusion of light as an additional factor to photoperiod and radiation in emergence models is explored and compared with the classical hydrothermal time (HTT) model using Camelina microcarpa as an example. HTT based on hourly estimates is also compared with that based on daily estimates. Results suggest that, although HTT based models are accurate enough for local applications, the precision of these models is improved when HTT is estimated hourly and solar radiation is included as a factor.     

Rate of synthesis and half-life of globin messenger ribonucleic acid. Rate of synthesis of globin messenger ribonucleic acid calculated from data of cell haemoglobin content

By the use of the favoured models defining mRNA synthesis and half-life from the preceding paper (Hunt, 1974) and the known content of globin in a reticulocyte it is possible to estimate the absolute rate of mRNA and globin synthesis and the mRNA and globin content in each type of erythroid cell. The best model requires an mRNA-synthetic rate of 3000 molecules per h/cell. This rate compares favourably with the estimated chain-extension rate of 43 nucleotides/s in Escherichia coli (Manor et al., 1969) provided that the four alpha- and beta-chain cistrons per cell are transcribed by polymerases spaced 50 nucleotide base pairs apart. Similar calculations can be made for erythropoiesis in the chick embryo, where cell times and relative globin content at each mitosis have been measured (Campbell et al., 1971), but where no reliable estimates of mRNA half-life have been made. In this case it was estimated that a constant rate of mRNA synthesis at 10000 molecules per h/cell through six cell divisions is necessary if the mRNA half-life is 15h; after the sixth mitosis the mRNA synthesis would stop and its half-life would increase to approx. 20h. If an mRNA half-life of 4.5h is used, the synthesis rate through the six mitoses would be 21000 molecules per h/cell, ceasing at the sixth mitosis, when the half-life would need to increase to 25h. The chain-elongation rate for the four alpha- and beta-globin cistrons per cell would be 1-2 times higher than in E. coli and would either require a greater rate, polymerases spaced between 25 and 50 nucleotide base pairs apart on the DNA, or limited gene replication. These possibilities are discussed in the light of the low values found for globin cistron multiplicity in ducks and mice.     

Estimating stomatal conductance with thermal imagery

Most thermal methods for the study of drought responses in plant leaves are based on the calculation of 'stress indices'. This paper proposes and compares three main extensions of these for the direct estimation of absolute values of stomatal conductance to water vapour (gs) using infrared thermography (IRT). All methods use the measured leaf temperature and two environmental variables (air temperature and boundary layer resistance) as input. Additional variables required, depending on the method, are the temperatures of wet and dry reference surfaces, net radiation and relative humidity. The methods were compared using measured gs data from a vineyard in Southern Portugal. The errors in thermal estimates of conductance were of the same order as the measurement errors using a porometer. Observed variability was also compared with theoretical estimates of errors in estimated gs determined on the basis of the errors in the input variables (leaf temperature, boundary layer resistance, net radiation) and the partial derivatives of the energy balance equations used for the gs calculations. The full energy balance approach requires accurate estimates of net radiation absorbed, which may not be readily available in field conditions, so alternatives using reference surfaces are shown to have advantages. A new approach using a dry reference leaf is particularly robust and recommended for those studies where the specific advantages of thermal imagery, including its non-contact nature and its ability to sample large numbers of leaves, are most apparent. Although the results suggest that estimates of the absolute magnitude of gs are somewhat subjective, depending on the skill of the experimenter at selecting evenly exposed leaves, relative treatment differences in conductance are sensitively detected by different experimenters.     

Energy balance of an isolated scots pine

The transpiration of an isolated Scots pine (P. sylvestris), determined by weighing, was related to stomatal resistance and environmental factors. The tree had been sheared to 1.5 m diameter at the base and 1.8 m high. The transpiration (2.97 MJ for 12h) was rather constant throughout the day and similar in shape to direct beam radiation incident upon the side of a cone. Transpiration rates calculated with the gradient equation duplicated measured values when vapor density gradients (obtained from measured needle temperature), measured stomatal resistance, and characteristic width of 3 mm in aerodynamic resistance were used in the calculations. Net radiation (Q*) for the tree was calculated by replacing the direct beam component of measured net radiation with the direct beam component incident upon a cone. The sensible heat flux, calculated with needle temperatures, was large (50.8 MJ) and nearly equal to Q* (53.85). The resulting Bowen ratio was 17. Transpiration calculated with a modified Penman-Monteith type equation simulated measured values.Presented at the Eighth International Congress of Biometeorology, 9–14 September 1979, Shefayim, Israel.     

Comparing global models of terrestrial net primary productivity (NPP): analysis of differences in light absorption and light-use efficiency

Twelve global net primary productivity (NPP) models were compared: BIOME3, CASA, CARAIB, FBM, GLO-PEM, HYBRID, KGBM, PLAI, SDBM, SIB2, SILVAN and TURC. These models all use solar radiation as an input, and compute either absorbed solar radiation directly, or the amount of leaves used to absorb solar radiation, represented by the leaf area index (LAI). For all models, we obtained or estimated photosynthetically active radiation absorbed by the canopy (APAR). We then computed the light use efficiency for NPP (LUE) on an annual basis as the ratio of NPP to APAR. We analysed the relative importance for NPP of APAR and LUE. The analyses consider the global values of these factors, their spatial patterns represented by latitudinal variations, and the overall grid cell by grid cell variability. Spatial variability in NPP within a model proved to be determined by APAR, and differences among models by LUE. There was a compensation between APAR and LUE, so that global NPP values fell within the range of ‘generally accepted values’. Overall, APAR was lower for satellite driven models than for the other models. Most computed values of LUE were within the range of published values, except for one model.     

The effects of solar radiation on thermal comfort

The aim of this study was to investigate the relationship between simulated solar radiation and thermal comfort. Three studies investigated the effects of (1) the intensity of direct simulated solar radiation, (2) spectral content of simulated solar radiation and (3) glazing type on human thermal sensation responses. Eight male subjects were exposed in each of the three studies. In Study 1, subjects were exposed to four levels of simulated solar radiation: 0, 200, 400 and 600 Wm⁻². In Study 2, subjects were exposed to simulated solar radiation with four different spectral contents, each with a total intensity of 400 Wm⁻² on the subject. In Study 3, subjects were exposed through glass to radiation caused by 1,000 Wm⁻² of simulated solar radiation on the exterior surface of four different glazing types. The environment was otherwise thermally neutral where there was no direct radiation, predicted mean vote (PMV)=0±0.5, [International Standards Organisation (ISO) standard 7730]. Ratings of thermal sensation, comfort, stickiness and preference and measures of mean skin temperature (t_sk) were taken. Increase in the total intensity of simulated solar radiation rather than the specific wavelength of the radiation is the critical factor affecting thermal comfort. Thermal sensation votes showed that there was a sensation scale increase of 1 scale unit for each increase of direct radiation of around 200 Wm⁻². The specific spectral content of the radiation has no direct effect on thermal sensation. The results contribute to models for determining the effects of solar radiation on thermal comfort in vehicles, buildings and outdoors.     

Using respirometric techniques and fluorescent in situ hybridization to evaluate the heterotrophic active biomass in activated sludge

The separation and accurate quantification of active biomass components in activated sludge is of paramount importance in models, used for the management and design of waste water (WW) treatment plants. Accurate estimates of microbial population concentrations and the direct, in situ determination of kinetic parameters could improve the calibration and validation of existing models of biological nutrient removal activated sludge systems. The aim of this study was to obtain correlations between heterotrophic active biomass (Z(BH)) concentrations predicted by mathematical models and quantitative information obtained by Fluorescent in situ hybridizations (FISH). Respirometric batch test were applied to mixed liquors drawn from a well-defined parent anoxic/aerobic activated sludge system to quantify the Z(BH) concentrations. Similarly fluorescent labeled, 16S rRNA-targeted oligonucleotide probes specific for ammonia and nitrite oxidizers were used in combination with DAPI staining to validate the Z(BH) active biomass component in activate sludge respirometric batch tests. For the direct enumeration and simultaneous in situ analysis of the distribution of nitrifying bacteria, in situ hybridization with oligonucleotide probes were used. Probes (NSO 1225, NSR 1156, and NIT3) were used to target the nitrifiers and the universal probe (EUB MIX) was used to target all Eubacteria. Deducting the lithoautotrophic population from the total bacteria population revealed the Z(BH) population. A conversion factor of 8.49 x 10(-11) mg VSS/cell was applied to express the Z(BH) in terms of COD concentration. Z(BH) values obtained by molecular probing correlated closely with values obtained from the modified batch test. However, the trend of consistently poor correspondence of measured and theoretical concentrations were evident. Therefore, the focus of this study was to investigate alternative technology, such as FISH to validate or replace kinetic parameters which are invariably incorporated into models.     

Sources of Variability in Net Primary Production Predictions at a Regional Scale: A Comparison Using PnET-II and TEM 4.0 in Northeastern US Forests

Because model predictions at continental and global scales are necessarily based on broad characterizations of vegetation, soils, and climate, estimates of carbon stocks and fluxes made by global terrestrial biosphere models may not be accurate for every region. At the regional scale, we suggest that attention can be focused more clearly on understanding the relative strengths of predicted net primary productivity (NPP) limitation by energy, water, and nutrients. We evaluate the sources of variability among model predictions of NPP with a regional-scale comparison between estimates made by PnET-II (a forest ecosystem process model previously applied to the northeastern region) and TEM 4.0 (a terrestrial biosphere model typically applied to the globe) for the northeastern US. When the same climate, vegetation, and soil data sets were used to drive both models, regional average NPP predictions made by PnET-II and TEM were remarkably similar, and at the biome level, model predictions agreed fairly well with NPP estimates developed from field measurements. However, TEM 4.0 predictions were more sensitive to regional variations in temperature as a result of feedbacks between temperature and belowground N availability. In PnET-II, the direct link between transpiration and photosynthesis caused substantial water stress in hardwood and pine forest types with increases in solar radiation; predicted water stress was relieved substantially when soil water holding capacity (WHC) was increased. Increasing soil WHC had little effect on TEM 4.0 predictions because soil water storage was already sufficient to meet plant demand with baseline WHC values, and because predicted N availability under baseline conditions in this region was not limited by water. Because NPP predictions were closely keyed to forest cover type, the relative coverage of low- versus high-productivity forests at both fine and coarse resolutions was an important determinant of regional NPP predictions. Therefore, changes in grid cell size and differences in the methods used to aggregate from fine to coarse resolution were important to NPP predictions insofar as they changed the relative proportions of forest cover. We suggest that because the small patches of high-elevation spruce-fir forest in this region are substantially less productive than forests in the remainder of the region, more accurate NPP predictions will result if models applied to this region use land cover input data sets that retain as much fine-resolution forest type variability as possible. The differences among model responses to variations in climate and soil WHC data sets suggest that the models will respond quite differently to scenarios of future climate. A better understanding of the dynamic interactions between water stress, N availability, and forest productivity in this region will enable models to make more accurate predictions of future carbon stocks and fluxes. Received 19 June 1998; accepted 25 June 1999.     

Response of body temperature to solar radiation in restrained nymphal migratory grasshoppers (Orthoptera: Acrididae): influences of orientation and body size

Abstract. .We restrained forty-nine nymphal migratory grasshoppers (Melanoplus sanguinipes) in a series of orientations to the sun and measured rate of temperature change due to radiation intercepted, compensating for temperature loss by convection and greybody reradiation. Direct solar radiation affected body temperature significantly, but diffuse radiation did not. The coefficient of direct solar heating ( H _dir), varied from 0.603 to 0.690 depending on how radiation interception was estimated, and on whether insect size was expressed as mass or as a function of length. H is the rate of temperature change as a proportion of the maximum rate assuming complete conversion of all incident radiation to heat. None of the H_dir estimates was significantly different from visible-spectrum absorbance to (0.722), suggesting that the latter is a reasonable approximation of H _dir
In simulations, equilibrium body temperature elevation decreased with body size where energy influx was expressed as the amount intercepted (W) , but increased with body size when expressed as insolation as (W m-²) because at a specified insolation, the amount of energy intercepted increases with body size. Expressing energy influx as the amount intercepted reveals the underlying biophysical mechanisms which determine body temperature.
This paper presents a model of body temperature elevation in which fundamental physical processes are assembled to provide good estimates. This basis in physics implies that the model can can be applied with confidence to conditions other than those in which it was derived.     

应用Wyatt-White方法计算寄生物种群γ_m的研究(英文)

本文是关于应用Wyatt-White方法计算寄生物种群内禀增长率的研究。研究表明:r_m的精确值与ln(M_d)/d或ln(M_(d/ 2))/d之间存在着线性关系,这种关系可表达如下:(1)r_m=0.845ln(M_d)/d;(2)r_m=0.880ln(M_(d/2)/d。这里d为生殖前期;M_d为生殖起d天内每个原始雌虫产下的平均雌性后代数;M_(d/2)为生殖起初d/2天内每个原始雌虫产下的平均雌性后代数。运用23组生殖力表资料,研究表明公式1—2可以给出r_m的精确估计值,公式2的估计效果更好。这种方法不要求组建生殖力表。该方法是否适用于其它寄生物种群或其它生物类群有待进一步研究。     

Solar radiation transmission in and around canopy gaps in an uneven-aged <Emphasis Type="Italic">Nothofagus betuloides</Emphasis> forest

The transmission of direct, diffuse and global solar radiation in and around canopy gaps occurring in an uneven-aged, evergreen Nothofagus betuloides forest during the growing season (October 2006–March 2007) was estimated by means of hemispherical photographs. The transmission of solar radiation into the forest was affected not only by a high level of horizontal and vertical heterogeneity of the forest canopy, but also by low angles of the sun’s path. The below-canopy direct solar radiation appeared to be variable in space and time. On average, the highest amount of transmitted direct solar radiation was estimated below the undisturbed canopy at the southeast of the gap centre. The transmitted diffuse and global solar radiation above the forest floor exhibited lower variability and, on average, both were higher at the centre of the canopy gaps. Canopy structure and stand parameters were also measured to explain the variation in the below-canopy solar radiation in the forest. The model that best fit the transmitted below-canopy direct solar radiation was a growth model, using plant area index with an ellipsoidal angle distribution as the independent variable (R ² = 0.263). Both diffuse and global solar radiation were very sensitive to canopy openness, and for both cases a quadratic model provided the best fit for these data (R ² = 0.963 and 0.833, respectively). As much as 75% and 73% of the variation in the diffuse and global solar radiation, respectively, were explained by a combination of stand parameters, namely basal area, crown projection, crown volume, stem volume, and average equivalent crown radius.     

Photoinhibition by solar radiation in the Mediterranean alga Peyssonnelia squamata measured on site

Photoinhibition of photosynthesis, defined as reversible decrease in the effective photosynthetic quantum yield, was measured in the Mediterranean red alga, Peyssonnelia squamata, using pulse amplitude modulation (PAM) chlorophyll fluorescence and oxygen production on site. This alga is adapted to very low fluence rates of solar radiation and is easily inhibited by exposure to excessive radiation. At high solar angles its photosynthetic capacity is impaired even in its natural habitat, in the protective shade of overhanging rocks. Oxygen production was maximal at 5 m depth and decreased to almost zero at the surface. When exposed at the surface oxygen production ceased within 16 min. The optimal photosynthetic quantum yield, defined as Fv/Fm, was about 0.45 in dark-adapted specimens. After 30 min of exposure to unattenuated solar radiation the (effective, Fv/Fm) quantum yield decreased to below 0.1. Removing solar UV (especially UV-B) significantly reduced photoinhibition: the quantum yield of a sample exposed under a UV-B cut-off filter was double that of a sample exposed to full solar radiation after 30 min exposure. Recovery from photoinhibition took several hours and was not complete after prolonged exposure (1.5 h) to direct solar radiation. The degree of photoinhibition depended on the depth at which the thalli were exposed. Recovery from photoinhibition was complete within 2 h except when the algae were exposed at the surface. When measured over the whole day, the effective photosynthetic quantum yield significantly decreased by about 25% from initially high values toward early afternoon and rose again towards evening. The data indicate that this alga is adapted to very low irradiances and is easily inhibited by excessive solar radiation; solar UV contributes substantially to the observed photoinhibition.