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This study was conducted to evaluate the performance of a paper drier operating on solar-heated hotwater. A small-scale prototype of a flat tank paper drier was built and tested in a variety of conditions and witha variety of handmade paper types. The tests showed consistent performance, with a specific energyconsumption of about 3.5 MJ per kg of water evaporated from the paper. This corresponds to a drier efficiencyof up to 80%, with reference to the latent heat of evaporation. Drier temperature variations were minimal, andthe performance was considered satisfactory to continue with further development of the drier for localhandmade paper production facilities. Measured drying rates compared well with predicted values calculatedusing correlations based on Stefan's law.DOI: http://dx.doi.org/10.3329/jme.v44i1.19491

We here reflect on two important articles on stratospheric ozone depletion written by P. J. Crutzen (1974) and P. J. Crutzen and D. H. Ehhalt (1977) in the early 1970s. These articles provide a clear description of the stratosphere and the most important chemical reactions involved in stratospheric ozone depletion. They present modeling results and provide recommendations for future research on stratospheric ozone depletion caused by chloro-fluoro-carbons, supersonic transport, nitrous oxide, and nuclear explosions. These two articles represent the beginning of a scientific era, which led to discovery of the Antarctic ozone hole and political action in the form of the Montreal Protocol and its amendments.

The peculiarities of the radial growth of pine in the conditions of air pollution in the Arctic zone are considered. The results of measurements of the width of annual rings of pine growing at different distances from the emission source are presented. The variability of annual radial growth of pine trees varies in a wide range: from moderate to very high. Age changes in the width of annual rings of pine are corresponding to the regularities of the curve of the "large growth". The average annual radial growth begins to decrease in plants older than 70 years. The dependence of the average annual radial growth of pine on age is approximated by an exponential equation. The accuracy of the approximation (coefficient of determination) is very high. Comparative analysis of the width of the annual rings and the value of gross emissions of the APPM in the year of formation of the annual layer did not show a clear synchronicity or asynchrony in the dynamics of these indicators for all plots. In most cases, the relationship between the total annual emissions of the APPM into the atmosphere and the width of the annual rings of pine was insignificant. The analysis of dendrochronology did not reveal a significant influence of atmospheric emissions of the Arkhangelsk pulp and paper mill on the growth of pine. The correlation coefficients between total annual atmospheric emissions and radial annual increments did not show a relationship between them, both when comparing these parameters year-on-year and with a delay of one year. For the period from 2001 to 2018 significant direct or delayed negative effect of emissions from Arkhangelsk pulp and paper mill in the atmosphere in the investigated areas of pine forests have not been identified.

Motivated by the need to predict how the Arctic atmosphere will change in a warming world, this article summarizes recent advances made by the research consortium NETCARE (Network on Climate and Aerosols: Addressing Key Uncertainties in Remote Canadian Environments) that contribute to our fundamental understanding of Arctic aerosol particles as they relate to climate forcing. The overall goal of NETCARE research has been to use an interdisciplinary approach encompassing extensive field observations and a range of chemical transport, earth system, and biogeochemical models. Several major findings and advances have emerged from NETCARE since its formation in 2013. (1) Unexpectedly high summertime dimethyl sulfide (DMS) levels were identified in ocean water (up to 75 nM) and the overlying atmosphere (up to 1 ppbv) in the Canadian Arctic Archipelago (CAA). Furthermore, melt ponds, which are widely prevalent, were identified as an important DMS source (with DMS concentrations of up to 6 nM and a potential contribution to atmospheric DMS of 20 % in the study area). (2) Evidence of widespread particle nucleation and growth in the marine boundary layer was found in the CAA in the summertime, with these events observed on 41 % of days in a 2016 cruise. As well, at Alert, Nunavut, particles that are newly formed and grown under conditions of minimal anthropogenic influence during the months of July and August are estimated to contribute 20 % to 80 % of the 30–50 nm particle number density. DMS-oxidation-driven nucleation is facilitated by the presence of atmospheric ammonia arising from seabird-colony emissions, and potentially also from coastal regions, tundra, and biomass burning. Via accumulation of secondary organic aerosol (SOA), a significant fraction of the new particles grow to sizes that are active in cloud droplet formation. Although the gaseous precursors to Arctic marine SOA remain poorly defined, the measured levels of common continental SOA precursors (isoprene and monoterpenes) were low, whereas elevated mixing ratios of oxygenated volatile organic compounds (OVOCs) were inferred to arise via processes involving the sea surface microlayer. (3) The variability in the vertical distribution of black carbon (BC) under both springtime Arctic haze and more pristine summertime aerosol conditions was observed. Measured particle size distributions and mixing states were used to constrain, for the first time, calculations of aerosol–climate interactions under Arctic conditions. Aircraft- and ground-based measurements were used to better establish the BC source regions that supply the Arctic via long-range transport mechanisms, with evidence for a dominant springtime contribution from eastern and southern Asia to the middle troposphere, and a major contribution from northern Asia to the surface. (4) Measurements of ice nucleating particles (INPs) in the Arctic indicate that a major source of these particles is mineral dust, likely derived from local sources in the summer and long-range transport in the spring. In addition, INPs are abundant in the sea surface microlayer in the Arctic, and possibly play a role in ice nucleation in the atmosphere when mineral dust concentrations are low. (5) Amongst multiple aerosol components, BC was observed to have the smallest effective deposition velocities to high Arctic snow (0.03 cm s−1).

Spruce is sensitive to atmospheric pollution and can serve as a bioindicator of environmental quality. Dendrochronological studies revealed no significant changes in the radial growth of spruce in the zone of influence of the Arkhangelsk PPM. Correlation coefficients between the total annual emissions of the Arkhangelsk PPM into the atmosphere and the values of the radial annual growth of individual trees during the period from 2001 to 2016 did not prove the connection between them, both when comparing these parameters in the year of the event and with the delay for the year.

TDIM ionospheric model was run for the year 2018 at 10-day intervals and 2-hr intervals in UT.

The STatistical Analogue Resampling Scheme (STARS) statistical approach was recently used to project changes of climate variables in Germany corresponding to a supposed degree of warming. We show by theoretical and empirical analysis that STARS simply transforms interannual gradients between warmer and cooler seasons into climate trends. According to STARS projections, summers in Germany will inevitably become dryer and winters wetter under global warming. Due to the dominance of negative interannual correlations between precipitation and temperature during the year, STARS has a tendency to generate a net annual decrease in precipitation under mean German conditions. Furthermore, according to STARS, the annual level of global radiation would increase in Germany. STARS can be still used, e.g., for generating scenarios in vulnerability and uncertainty studies. However, it is not suitable as a climate downscaling tool to access risks following from changing climate for a finer than general circulation model (GCM) spatial scale.

Radiation exposure estimates for crew members on the surface of Mars may vary widely because of the large variations in terrain altitude. The maximum altitude difference between the highest (top of Olympus Mons) and the lowest (bottom of the Hellas impact basin) points on Mars is about 32 km. In this work estimates of radiation exposures as a function of altitude, from the Hellas impact basin to Olympus Mons, are made for a solar particle event proton radiation environment comparable to the Carrington event of 1859. We assume that the proton energy distribution for this Carrington-type event is similar to that of the Band Function fit of the February 1956 event. In this work we use the HZETRN 2010 radiation transport code, originally developed at NASA Langley Research Center, and the Computerized Anatomical Male and Female human geometry models to estimate exposures for aluminum shield areal densities similar to those provided by a spacesuit, surface lander, and permanent habitat as a function of altitude in the Mars atmosphere. Comparisons of the predicted organ exposures with current NASA Permissible Exposure Limits (PELs) are made.

SUMMARY 1. de Senerpont Domis et al. (2013, Freshwater Biology, 58, 463–482) forecasted changes in plankton dynamics in temperate, polar and tropical regions resulting from climate change. For tropical regions, they predicted an increase in precipitation intensity that would increase nutrient loading, increasing phytoplankton biomass and select for plankton adapted to flushing. 2. We do not agree with these predictions, as regional projections from the IPCC did not forecast a major increase in precipitation in tropical regions. The only regions where a slight increase in precipitation was projected were eastern Africa and South-East Asia. In eastern Africa, the major freshwater bodies are large, deep lakes that have very long residence times and are unlikely to be affected by flushing. Moreover, nutrient inputs from their catchment represent a small fraction of their total nutrient loading. 3. Several independent studies carried out in this region have provided evidence of a decrease in primary productivity in some of these large tropical lakes due to climate change. The major process providing nutrients to the euphotic layer is internal loading, which has been reduced as warming of the surface waters has increased the temperature gradient and the water column stability. Moreover, reduced velocity of trade winds during the dry season has affected the mixed layer depth and decreased internal nutrient fluxes. Therefore, the trend for large tropical lakes in a warming climate is oligotrophication, not eutrophication. 4. In tropical South America, the rainfall increase is not the dominant scenario; thus, the predicted changes in plankton dynamics do not stand. 5. Therefore, we believe that the predictions presented in the paper for tropical systems under a changing climate are invalid for most tropical systems.

Predicting ozone-induced reduction of carbon sequestration of forests under elevated tropospheric ozone concentrations requires robust mechanistic leaf-level models, scaled up to whole tree and stand level. As ozone effects depend on genotype, the ability to predict these effects on forest carbon cycling via competitive response between genotypes will also be required. This study tests a process-based model that predicts the relative effects of ozone on the photosynthetic rate and growth of an ozone-sensitive aspen clone, as a first step in simulating the competitive response of genotypes to atmospheric and climate change. The resulting composite model simulated the relative above ground growth response of ozone-sensitive aspen clone 259 exposed to square wave variation in ozone concentration. This included a greater effect on stem diameter than on stem height, earlier leaf abscission, and reduced stem and leaf dry matter production at the end of the growing season. Further development of the model to reduce predictive uncertainty is discussed.

Peak stratospheric chlorofluorocarbon (CFC) and other ozone depleting substance (ODS) concentrations were reached in the mid to late 1990s. Detection and attribution of the expected recovery of the stratospheric ozone layer in an atmosphere with reduced ODSs as well as efforts to understand the evolution of stratospheric ozone in the presence of increasing greenhouse gases are key current research topics. These require a critical examination of the ozone changes with an accurate knowledge of the spatial (geographical and vertical) and temporal ozone response. For such an examination, it is vital that the quality of the measurements used be as high as possible and measurement uncertainties well quantified. In preparation for the 2014 United Nations Environment Programme (UNEP)/World Meteorological Organization (WMO) Scientific Assessment of Ozone Depletion, the SPARC/IO3C/IGACO-O3/NDACC (SI2N) initiative was designed to study and document changes in the global ozone profile distribution. This requires assessing long-term ozone profile data sets in regards to measurement stability and uncertainty characteristics. The ultimate goal is to establish suitability for estimating long-term ozone trends to contribute to ozone recovery studies. Some of the data sets have been improved as part of this initiative with updated versions now available. This summary presents an overview of stratospheric ozone profile measurement data sets (ground- and satellite-based) available for ozone recovery studies. Here we document measurement techniques, spatial and temporal coverage, vertical resolution, native units and measurement uncertainties. In addition, the latest data versions are briefly described (including data version updates as well as detailing multiple retrievals when available for a given satellite instrument). Archive location information is for each data set is also given.

Declines of seed viability in storage and losses of stored commodities due to fungal spoilage and insect pests are promoted by high moisture content. However, measuring seed or grain moisture content in the field can be difficult, particularly in rural locations in developing countries. Because seed/commodity moisture content is uniquely related to equilibrium relative humidity at a given temperature, moisture content can be estimated by measuring the relative humidity of a sample enclosed in a sealed container. Relative humidity can be measured using electronic meters, or even more inexpensively using indicator paper that changes color in response to relative humidity. We describe this method and provide a spreadsheet to convert relative humidity to moisture content for many common seeds and commodities. This simple method can be used in the field for quickly estimating seed or commodity moisture content to determine whether further drying is needed or is suitable for storage, milling or other uses.

If stratospheric temperature trends are to be understood, coupled chemistry climate models will need to be run. Simulations with fixed ozone trends might provide a misleading indication of future temperature trends. Copyright © 2005 Royal Meteorological Society

Flynn and Martin-Jezequel (J. Plankton Res., 22, 447-472, 2000) derived a mechanistic model for nitrogen and silicon physiology of diatoms. During their analysis, they compared the output of this model with that of the co-nutrient model of Davidson and Gurney (J. Plankton Res., 21, 839-858, 1999). They highlighted some discrepancies between the predictions of the two models, which occurred subsequent to exhaustion of the yield-limiting nutrient, and suggested that the co-nutrient model contained technical inaccuracies in its output. Here it is shown that by simply modifying the numerical values of two of the parameters of the co-nutrient model, while retaining exactly the same model structure, it is possible to produce similar dynamics to those exhibited by the model of Flynn and Martin-Jezequel.

Vertical Transport and Mixing in Complex Terrain Airsheds: Implementation of a Stable PBL Turbulence Parameterization for the Mesoscale Model MM5 The difficulties associated with parameterization of turbulence in the stable nocturnal atmospheric boundary layer have been a great challenge for the night-time predictions of mesoscale meteorological models such as MM5. As such, there is a general consensus on the need for better stable boundary-layer parameterizations. To this end, two new turbulence parameterizations based on the measurements of the Vertical Transport and Mixing (VTMX) field campaign were implemented and evaluated in MM5. A unique aspect of this parameterization is the use of a stability dependent turbulent Prandtl number that allows momentum to be transported by the internal waves, while heat diffusion is impeded by the stratification. This improvement alleviates the problem of over-prediction of heat diffusion under stable conditions, which is a characteristic of conventional PBL schemes, such as MRF and Blackadar schemes employed in MM5. The predictions made with the new PBL scheme for the complex terrain airshed of Salt Lake City were compared with those made with a default scheme of MM5 and with observations made during the VTMX campaign. The new schemes showed an improvement in predictions, particularly for the nocturnal near surface temperature. Surface wind predictions also improved slightly, but not to the extent of temperature predictions. The default MRF scheme showed a significantly warmer surface temperature than observed, which could be attributed to the enhanced vertical heat exchange brought about by its turbulence parameterization. The modified parameterizations reduced the surface sensible heat flux, thus enhancing the strength of the near surface inversion and lowering the temperature toward the observed values.

Atmospheric ozone columns are derived from historic stellar spectra observed between 1935 and 1942 at Mount Wilson Observatory, California. Comparisons with contemporary measurements in the Arosa database show a generally close correspondence, while a similar comparison with more sparse data from Table Mountain reveals a difference of ~15–20%, as has also been found by other researches of the latter data. The results of the analysis indicate that astronomy's archives command considerable potential for investigating the natural levels of ozone and its variability during the decades prior to anthropogenic interference.

The 13C concentration in atmospheric CO2 has been declining over the past 150 years as large quantities of 13C-depleted CO2 from fossil fuel burning are added to the atmosphere. Deforestation and other land use changes have also contributed to the trend. Looking at the 13C variations in the atmosphere and in annual growth rings of trees allows us to estimate CO2 uptake by land plants and the ocean, and assess the response of plants to climate. Here I show that the effects of the declining 13C trend in atmospheric CO2 are recorded in the isotopic composition of paper used in the printing industry, which provides a well-organized archive and integrated material derived from trees' cellulose. 13C analyses of paper from two European and two American publications showed, on average, a − 1.65 ± 1.00‰ trend between 1880 and 2000, compared with − 1.45 and − 1.57‰ for air and tree-ring analyses, respectively. The greater decrease in plant-derived 13C in the paper we tested than in the air is consistent with predicted global-scale increases in plant intrinsic water-use efficiency over the 20th century. Distinct deviations from the atmospheric trend were observed in both European and American publications immediately following the World War II period.

The effluents from a large Kraft-process paper mill were found to increase the concentration of large (0.2–2 μm diameter) and giant (>2 μm diameter) cloud condensation nuclei (CCN) above background concentrations; the concentrations of small (

Variations of annual and semiannual oscillations in rotation parameters have been investigated on the basis of length-f-ay(LOD) as well as atmospheric-ngular-omemtum (AAM) series. These oscillations were determined using band-ass filters. In order to show the character of variations of seaasonal oscillations, amplitudes, phases and periods were computed by a least-quares adjustment with the method of modified harmonic analysis at quarterly intervals. In addition, the seasonal imbalances in LOD and AAM budgets were determined and analysed in a similar way. These discrepancies were corrected for tidally excited effects. The non-tmospheric oscillations without the annual tide effect Sa and the semiannual tide effect Ssa have variable amplitudes between 0.02 and 0.10 msec.

The paper mill at Port Townsend, Wash., is a source of large and giant condensation nuclei (CCN). These CCN cause the concentrations of droplets ≥30 μm in diameter to be higher in small, nonraining warm clouds located in the plume of the mill than in similar clouds unaffected by the plume. Calculations based on a model for nonsheared, warm cumulus clouds and a model for warm stratus clouds indicate that the higher concentrations of large droplets in the clouds in the plume should not cause any significant changes in the rainfall from these clouds. These results indicate that the large and giant CCN emitted by the mill are not by themselves responsible for the increased rainfall measured in the vicinity of the mill. The heat and moisture emitted by the mill, in combination with the CCN, may have been responsible for the increased rainfall.

Harris and Chapman [2001; hereafter HC2001] recently presented a comparison between ground temperature records (temperature–depth profiles measured in many boreholes) and surface air temperature observations and reconstructions. Research such as theirs, attempting to reconcile or compare climate proxies that have high temporal resolution with those that have much lower temporal resolution, is important because it provides a way of assessing the fidelity with which the high-resolution proxies capture multicentury climate variability [Briffa and Osborn, 1999, highlighted some potential difficulties at capturing such long time scale variations]. Unfortunately, the paper by HC2001 contains a conspicuous error that requires highlighting in order that their results can be re-evaluated, but also to prevent the error from propagating in the literature.