The characteristics of ultraviolet radiation in arid and semi-arid regions of China

Measurements of the broadband global solar radiation (R _S) and total ultraviolet radiation (the sum of UV-A and UV-B) were conducted from 2005 to 2010 at 9 sites in arid and semi-arid regions of China. These data were used to determine the temporal variability of UV and UV/R _S and their dependence on the water vapor content and clearness index. The dependence of UV/R _S on aerosol optical depth (AOD) and water vapor content was also investigated. In addition, a simple and efficient empirically model suited for all-weather conditions was developed to estimate UV from R _s. The annual average daily UV level in arid and semi-arid areas is 0.61 and 0.59 MJ m^?2 d^?1, respectively. The highest value (0.66?±?0.25 MJ m^?2 d^?1) was recorded at an arid area at Linze. The lowest value (0.53?±?0.22 MJ m^?2 d^?1) was recorded at a semi-arid area at Ansai. The highest daily value of UV radiation was measured in May, whereas the lowest value was measured in December. The monthly variation of the UV/R _s ratio ranged from 0.41 in Aksu to 0.35 in Qira. The monthly mean value of UV/R _s gradually increased from November and then decreased in August. A small decreasing trend of UV/R _s was observed in the arid and semi-arid regions due to recently increasing amounts of fine aerosol. A simple and efficient empirically model suit for all-weather condition was developed to estimate UV from R _s. The slope a and intercept b of the regression line between the estimated and measured values were close to 1 and zero, respectively. The relative error between the estimated and measured values was less than 11.5%. Application of the model to data collected from different locations in this region also resulted in reasonable estimates of UV.     

Evaluation of the antarctic surface wind climate from ERA reanalyses and RACMO2/ANT simulations based on automatic weather stations

A continental scale evaluation of Antarctic surface winds is presented from global ERA-40 and ERA-Interim reanalyses and RACMO2/ANT regional climate model at 55 and 27 km horizontal resolution, based on a comparison with observational data from 115 automatic weather stations (AWS). The Antarctic surface wind climate can be classified based on the Weibull shape factor k _w . Very high values (k _w  > 3) are found in the interior plateaus, typical of very uniform katabatic-dominated winds with high directional constancy. In the coast and all over the Antarctic Peninsula the shape factors are similar to the ones found in mid-latitudes (k _w  < 3) typical of synoptically dominated wind climates. The Weibull shape parameter is systematically overpredicted by ERA reanalyses. This is partly corrected by RACMO2/ANT simulations which introduce more wind speed variability in complex terrain areas. A significant improvement is observed in the performance of ERA-Interim over ERA-40, with an overall decrease of 14 % in normalized mean absolute error. In escarpment and coastal areas, where the terrain gets rugged and katabatic winds are further intensified in confluence zones, ERA-Interim bias can be as high as 10 m s^?1. These large deviations are partly corrected by the regional climate model. Given that RACMO2/ANT is an independent simulation of the near-surface wind speed climate, as it is not driven by observations, it compares very well to the ERA-Interim and AWS-115 datasets.     

GNSS remote sensing of the Australian tropopause

Radio occultation (RO) techniques that use signals transmitted by Global Navigation Satellite Systems (GNSS) have emerged over the past decade as an important tool for measuring global changes in tropopause temperature and height, a valuable capacity given the tropopause??s sensitivity to temperature variations. This study uses 45,091 RO data from the CHAMP (CHAllenging Minisatellite Payload, 80 months), GRACE (Gravity Recovery And Climate Experiment, 23 months) and COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate, 20 months) satellites to analyse the variability of the tropopause??s height and temperature over Australia. GNSS RO temperature profiles from CHAMP, GRACE, and COSMIC are first validated using radiosonde observations provided by the Bureau of Meteorology (Australia). These are compared to RO soundings from between 2001 and 2007 that occurred within 3 h and 100 km of a radiosonde. The results indicate that RO soundings provide data of a comparable quality to radiosonde observations in the tropopause region, with temperature deviations of less than 0.5 ± 1.5 K. An analysis of tropopause height and temperature anomalies indicates a height increase over Australia as a whole of ca. 4.8 ± 1.3 m between September 2001 and April 2008, with a corresponding temperature decrease of ?0.019 ± 0.007 K. A similar pattern of increasing height/decreasing temperature was generally observed when determining the spatial distribution of the tropopause height and temperature rate of change over Australia. Although only a short period has been considered in this study, a function of the operating time of these satellites, the results nonetheless show an increase in the height of the tropopause over Australia during this period and thus may indicate regional warming. Several mechanisms could be responsible for these changes, such as an increase in the concentration of greenhouse gases in the atmosphere, and lower stratospheric cooling due to ozone loss, both of which have been observed during the last decades.     

Measurement and calculation of OH reactivity at a United Kingdom coastal site

Measurements of OH reactivity were made at the Weybourne Atmospheric Observatory on the North Norfolk coast, UK in May 2004. A wide range of supporting species was also measured concurrently as part of the TORCH-2 field campaign, allowing a detailed study of the OH oxidation chemistry to be carried out. Measurements were made in a variety of air masses, with the 3 most prevalent being air from the Atlantic that arrived at the site from over mainland UK in a South Westerly direction, and much cleaner Northerly air that originated over the far North Sea or Arctic, passed over the North Sea and arrived at the site from a North/North Easterly direction. Direct OH reactivity measurements were made on 6 days during the campaign and with influence of 2 of the 3 air masses prevalent during the study period. The average, minimum and maximum measured OH reactivity are: 4.9, 1.3 and 9.7 respectively. The measured OH reactivity was compared to key OH sinks such as NO₂ and CO and a general positive correlation was observed. OH reactivity (k′) was then calculated using the full range of OH sinks species that were measured (including >30 NMHCs) and their pseudo first order rate constants for reaction with OH. For much of the measurement period there is a significant difference between the measured and calculated k′, with an average value of k′_meas- k′_calc?=?1.9 s^-1, indicative of unmeasured OH sinks. A zero-dimensional box model containing a subset of the Master Chemical Mechanism was used to calculate the OH reactivity more accurately. The simultaneously measured trace species were used as inputs to the model and their oxidative degradation was described by a chemical mechanism containing ~5,000 species. The extra OH sinks species produced by the model, resulted in an improvement in the agreement between k′_meas and k′_calc, however the averaged missing OH reactivity across the entire measurement period remained at 1.4 s^-1. Speculation is made as to the source of this missing reactivity, including reference to studies showing that a potentially large number of high molecular weight aromatic species could be unmeasured by standard instrumentation.     

On the magnitude and apparent range of variation of the von Karman constant in the atmospheric surface layer

The half-century history of the experimental evaluation of the von Karman constant in the atmospheric surface layer is reviewed, an evidence indicating that this well-known scaling factor,k, is actually a weak variable that decreases with increasing Reynolds number is discussed. A combined average ofk=0.390 with a standard error of ±0.010 is found from two field studies, a result which indicates that there is only one chance in 40 that the true value of the scaling factor in the population from which the experimental sample was drawn could have been as large as the laboratory value of 0.40. Based on experimental and theoretical results given by others, it is suggested thatk varies from a maximum of 0.41 in light winds over open water and smooth land surfaces, to a minimum near 0.37 in stronger winds over forests and cities. This range is shown to imply that a working value ofk=0.39±1% is appropriate for flows over surfaces characterized by 0.7<z ₀<8.7 cm, a roughness subrange which corresponds to a wide variety of terrain types from sparsely vegetated level plains to mixed croplands with occasional hedges and trees.sponsored in part by the Global Change Post Doctoral Program, Office of Health and Environmental Research, U. S. Department of Energy.Work sponsored by the National Science Foundation under Grant No. ATM-9019682.     

The sensitivity of topoclimatic models to fine-scale microclimatic variability and the relevance for ecological studies

Microclimatic loggers are increasingly used to collect data from various habitats and interpolate ecologically meaningful landscape-scale topoclimatic grids. However, it is unknown how sensitive these grids are to finer-scale variations in microclimate. We performed a sensitivity analysis using three microclimatic loggers at 27 sites for 5 months in a semi-arid region of Western Australia. We partitioned the within- and between-site variance in temperature and produced 100 different topoclimatic models using a random sensor from each site. For the coldest temperatures, we found within-site variance was negligible (3 %), and models were strong (r ²?=?0.74) and the coefficients consistent. However, for the hottest temperatures, there was substantial within-site variance (39 %), and models were weaker (r ²?=?0.27) and more sensitive. We concluded that careful site design is needed to maximise the reliability of topoclimatic grids, including using large sample sizes, ensuring there is low predictor collinearity and sampling full environmental gradients.     

Numerical Simulations of the Microscale Heterogeneities of Turbulence Observed on a Complex Site

We simulate the microscale heterogeneities of turbulent variables observed at a complex site for different wind directions. The atmospheric computational fluid dynamics (CFD) results are compared with an ensemble of 36 months of data collected at the experimental site SIRTA “Site Instrumental de Recherche par Télédétection Atmosphérique”, located near Paris (France) in a semi-urban environment. The experimental data show that the normalized turbulent kinetic energy (TKE) k/U ² (where k is TKE and U is the wind speed) at 10-m height, for two different locations, is highly dependent on wind direction and strongly influenced by trees. These measurements show a strong increase of the normalized TKE downstream of the forest canopies with a large variability within the 36-month period in part due to the variation of the tree foliage. The numerical simulations are carried out using the CFD code Code_Saturne with the standard k?ε closure, in neutral stratification. The buildings are taken into account explicitly in the mesh and the forested areas are modelled with two approaches: the classical roughness wall law and a drag porosity. A comparison has been performed between the calculated values and the median of measured values of the normalized TKE and the normalized friction velocity, for each wind sector of 10°. A very good agreement is obtained with the drag porosity model, whereas the classical roughness law leads to a strong underestimation downstream of the forested areas. However, this large improvement of the results using the drag porosity model can only be obtained with a refinement of the grid, especially in forested areas, and an accurate land-use map.     

Linear response functions to project contributions to future sea level

We propose linear response functions to separately estimate the sea-level contributions of thermal expansion and solid ice discharge from Greenland and Antarctica. The response function formalism introduces a time-dependence which allows for future rates of sea-level rise to be influenced by past climate variations. We find that this time-dependence is of the same functional type, R(t) ～ t ^α, for each of the three subsystems considered here. The validity of the approach is assessed by comparing the sea-level estimates obtained via the response functions to projections from comprehensive models. The pure vertical diffusion case in one dimension, corresponding to α =  ?0.5, is a valid approximation for thermal expansion within the ocean up to the middle of the twenty first century for all Representative Concentration Pathways. The approximation is significantly improved for α =  ? 0.7. For the solid ice discharge from Greenland we find an optimal value of α =  ?0.7. Different from earlier studies we conclude that solid ice discharge from Greenland due to dynamic thinning is bounded by 0.42 m sea-level equivalent. Ice discharge induced by surface warming on Antarctica is best captured by a positive value of α = 0.1 which reflects the fact that ice loss increases with the cumulative amount of heat available for softening the ice in our model.     

Climatology of water excesses and shortages in the La Plata Basin

This study presents a multitemporal climatology of water excess and shortage during the 20th century in the La Plata Basin. The climatology is based on 0.5^o?×?0.5^o grid across the region. We transform monthly precipitation series for each point into index series at different time scales using the Standardized Precipitation Index (SPI). A month is under water excess (shortage) conditions at different time scales (i?=?6, 9, 12, and 18 months), when SPI[i](j)?>?1.5 (SPI[i](j)?<?1.5), where j is the current month. Trends in precipitation were determined using mean regional series of average values over the entire basin. A month when more than 30% of the total basin is under water excesses (shortages) is defined as an excess (shortage) critical month. From the vulnerability point of view, we analyzed the occurrence of critical months. The number of excess critical months increase with time scale of index, and almost all the critical months occurred after 1950 as a consequence of the low-frequency precipitation pattern. That means a noticeable increase in the vulnerability to extended excesses (more than 30% of the area under water excesses) after 1950, especially over the Upper Paraná and the Uruguay basins. For shortage critical months, the behavior depends on time scales. At large time scale (18 and 12 months), almost all the shortage critical months occurred in the period 1901–1950 and only at shorter time scale (9 and 6 months), some critical months appeared after 1950. That means a noteworthy decrease in the basin vulnerability to extended water shortage after 1950 and a moderate decrease in vulnerability to generalized shortage. If we analyze the frequency and mean duration of water excess and shortage events across the basin, we can appreciate that there is a tendency to relate higher frequency regions with regions with lower mean duration events, and conversely.     

Long-lasting floods buffer the thermal regime of the Pampas

The presence of large water masses influences the thermal regime of nearby land shaping the local climate of coastal areas by the ocean or large continental lakes. Large surface water bodies have an ephemeral nature in the vast sedimentary plains of the Pampas (Argentina) where non-flooded periods alternate with flooding cycles covering up to one third of the landscape for several months. Based on temperature records from 17 sites located 1 to 700 km away from the Atlantic coast and MODIS land surface temperature data, we explore the effects of floods on diurnal and seasonal thermal ranges as well as temperature extremes. In non-flooded periods, there is a linear increase of mean diurnal thermal range (DTR) from the coast towards the interior of the region (DTR increasing from 10 to 16 K, 0.79 K/100 km, r ² = 0.81). This relationship weakens during flood episodes when the DTR of flood-prone inland locations shows a decline of 2 to 4 K, depending on surface water coverage in the surrounding area. DTR even approaches typical coastal values 500 km away from the ocean in the most flooded location that we studied during the three flooding cycles recorded in the study period. Frosts-free periods, a key driver of the phenology of both natural and cultivated ecosystems, are extended by up to 55 days during floods, most likely as a result of enhanced ground heat storage across the landscape (~2.7 fold change in day-night heat transfer) combined with other effects on the surface energy balance such as greater night evaporation rates. The reduced thermal range and longer frost-free periods affect plant growth development and may offer an opportunity for longer crop growing periods, which may not only contribute to partially compensating for regional production losses caused by floods, but also open avenues for flood mitigation through higher plant evapotranspirative water losses.     

The role of wave energy accumulation in tropical cyclogenesis over the tropical North Atlantic

A hierarchical modeling approach is used to study the process by which interactions of easterly waves with the background flow can result in a reduction in the longitudinal and vertical scale of the waves. Theory suggests that in flows that possess a negative longitudinal gradient (U _x  < 0) there is a reduction of longitudinal and vertical group speeds and an increase in regional wave action density (or “wave energy”). Relative vorticity increases locally leading to an increase in the likelihood of tropical cyclogenesis near the wave axis. Opposite impacts on the structure of the waves is expected in a U _x  > 0 domain. In the simplified framework of a free-surface and divergent shallow water model, Rossby wave properties are tracked through a range of background flow scenarios to determine the important scales of interaction. The importance of wave energy accumulation for tropical cyclogenesis is then studied in a full physics and dynamics model using a nested regional climate model simulation, at 12 km horizontal grid spacing, over the tropical North Atlantic region for the entire 2005 hurricane season. The dynamical environment within which 70% of easterly waves formed tropical cyclones exhibits coherent regions in which easterly winds increase towards the east, consistent with the occurrence of wave energy accumulation.     

Radiowave propagation measurements in Nigeria (preliminary reports)

International conferences on frequency coordination have, in recent years, required new information on radiowave propagation in tropical regions and, in particular, on propagation in Africa. The International Telecommunications Union (ITU-R) initiated ‘radio-wave propagation measurement campaign’ in some African countries some years back. However, none of the ITU-initiated experiments were mounted in Nigeria, and hence, there is lack of adequate understanding of the propagation mechanisms associated with this region of the tropics. The Centre for Basic Space Science (CBSS) of NASRDA has therefore embarked on propagation data collection from the different climatic zones of Nigeria (namely Coastal, Guinea Savannah, Midland, and Sahelian) with the aim of making propagation data available to the ITU, for design and prediction purposes in order to ensure a qualitative and effective communication system in Nigeria. This paper focuses on the current status of propagation data from Nigeria (collected by CBSS), identifying other parameters that still need to be obtained. The centre has deployed weather stations to different locations in the country for refractivity measurements in clear atmosphere, at the ground surface and at an altitude of 100 m, being the average height of communication mast in Nigeria. Other equipments deployed are Micro Rain Radar and Nigerian Environmental and Climatic Observing Program equipments. Some of the locations of the measurement stations are Nsukka (7.4°?E, 6.9°?N), Akure (5.12°?E, 7.15°?N), Minna (6.5°?E, 9.6°?N), Sokoto (5.25°?E, 13.08°?N), Jos (8.9°?E, 9.86°?N), and Lagos (3.35°?E, 6.6°?N). The results obtained from the data analysis have shown that the refractivity values vary with climatic zones and seasons of the year. Also, the occurrence probability of abnormal propagation events, such as super refraction, sub-refraction, and ducting, depends on the location as well as the local time. We have also attempted to identify and calculate the most important propagation factors and associated data, such as k factor, that are relevant in considerations of propagation in tropical regions like Nigeria.     

A spatial and temporal drought risk assessment of three major tree species in Britain using probabilistic climate change projections

Probabilistic climate data have become available for the first time through the UK Climate Projections 2009, so that the risk of change in tree growth can be quantified. We assessed the drought risk spatially and temporally using drought probabilities calculated from the weather generator data and tree species vulnerabilities using Ecological Site Classification model across Britain. We evaluated the drought impact on the potential yield class of three major tree species (Picea sitchensis, Pinus sylvestris, and Quercus robur), which cover around 59 % (400,700 ha) of state-managed forests, across the lowlands and uplands. We show that drought impacts result mostly in reduced tree growth over the next 80 years when using B1, A1B, and A1FI IPCC emissions scenarios, but varied spatially. We found a maximum reduction of 94 % but also a maximum increase of 56 % in potential stand yield class in the 2080s from the baseline climate (1961–1990). Furthermore, potential production over the state-managed forests for all three species in the 2080s is estimated to decrease due to drought by 42 % in the lowlands and by 32 % in the uplands in comparison to the baseline climate. Our results reveal that potential tree growth and forest production on the state-managed forests in Britain is likely to reduce, and indicate where and when adaptation measures are required. Moreover, this paper demonstrates the value of probabilistic climate projections for an important economic and environmental sector.     

Comparison of different methods for estimating soil surface evaporation in a bare field

In this paper, three methods for estimating soil evaporation in a bare field were evaluated: evaporation ratio method (k ratio), complementary relationship and bulk equation. Micro-lysimeters were used to measure the actual evaporation for validation of the three methods. For the k ratio method, pan evaporation was used as the reference evaporation instead of the value obtained from the Penman–Monteith equation. This result is important for areas where meteorological data are unavailable. The results showed that, for daytime evaporation, the k ratio and bulk equation produced a good fit with the observation data, while the complementary relationship generated a larger deviation from the measured data. We recommend that the k ratio method and bulk equation could be used to calculate daytime soil evaporation with high accuracy when soil water content and pan evaporation data or meteorological data are available, while the complementary relationship could be used for a rough estimation when pan evaporation is available. All the methods could be applied to calculate cumulative evaporation.     

The impact of the MJO on clusters of wintertime circulation anomalies over the North American region

Recent studies have shown that the Madden–Julian Oscillation (MJO) impacts the leading modes of intraseasonal variability in the northern hemisphere extratropics, providing a possible source of predictive skill over North America at intraseasonal timescales. We find that a k-means cluster analysis of mid-level geopotential height anomalies over the North American region identifies several wintertime cluster patterns whose probabilities are strongly modulated during and after MJO events, particularly during certain phases of the El Niño-Southern Oscillation (ENSO). We use a simple new optimization method for determining the number of clusters, k, and show that it results in a set of clusters which are robust to changes in the domain or time period examined. Several of the resulting cluster patterns resemble linear combinations of the Arctic Oscillation (AO) and the Pacific/North American (PNA) teleconnection pattern, but show even stronger responses to the MJO and ENSO than clusters based on the AO and PNA alone. A cluster resembling the positive (negative) PNA has elevated probabilities approximately 8–14 days following phase 6 (phase 3) of the MJO, while a negative AO-like cluster has elevated probabilities 10–20 days following phase 7 of the MJO. The observed relationships are relatively well reproduced in the 11-year daily reforecast dataset from the National Centers for Environmental Prediction (NCEP) Climate Forecast System version 2 (CFSv2). This study statistically links MJO activity in the tropics to common intraseasonal circulation anomalies over the North American sector, establishing a framework that may be useful for improving extended range forecasts over this region.     

Impact of climate change on human-wildlife-ecosystem interactions in the Trans-Himalaya region of Nepal

The Trans-Himalaya region boasts an immense biodiversity which includes several threatened species and supports the livelihood of local human populations. Our aim in this study was to evaluate the impact of recent climate change on the biodiversity and human inhabitants of the upper Mustang region of the Trans-Himalaya, Nepal. We found that the average annual temperature in the upper Mustang region has increased by 0.13 °C per year over the last 23 years; a higher annual temperature increase than experienced in other parts of Himalaya. A predictive model suggested that the mean annual temperature will double by 2161 to reach 20 °C in the upper Mustang region. The combined effects of increased temperature and diminished snowfall have resulted in a reduction in the area of land suitable for agriculture. Most seriously affected are Samjung village (at 4,100 m altitude) and Dhey village (at 3,800 m) in upper Mustang, where villagers have been forced to relocate to an area with better water availability. Concurrent with the recent change in climate, there have been substantial changes in vegetation communities. Between 1979 and 2009, grasslands and forests in the Mustang district have diminished by 11 and 42 %, respectively, with the tree line having shifted towards higher elevation. Further, grasses and many shrub species are no longer found in abundance at higher elevations and consequently blue sheep (Pseduois nayaur) move to forage at lower elevations where they encounter and raid human crops. The movement of blue sheep attracts snow leopard (Panthera uncia) from their higher-elevation habitats to lower sites, where they encounter and depredate livestock. Increased crop raiding by blue sheep and depredations of livestock by snow leopard have impacted adversely on the livelihoods of local people.     

Seasonal variation of lightning activity over the Indian subcontinent

The seasonal variation of lightning flash activity over the Indian subcontinent (0°N–35°N and 60°E–100°E) is studied using the quality checked monthly lightning flash data obtained from lightning imaging sensor on board the Tropical Rainfall Measuring Mission satellite. This paper presents results of spatio-temporal variability of lightning activity over the Indian subcontinent. The study of seasonal total lightning flashes indicates that the lightning flash density values are in qualitative agreement with the convective activity observed over this region. Maximum seasonal total flash counts are observed during the monsoon season. The propagation of the inter-tropical convergence zone over this region is also confirmed. Synoptic conditions responsible for variation of lightning activity are also investigated with the help of an observed dataset. The mean monthly flash counts show a peak in the month of May, which is the month of maximum temperatures over this region. Maximum flash density (40.2 km^?2 season^?1) is observed during the pre-monsoon season at 25.2°N/91.6°E and the annual maximum flash density of 28.2 km^?2 year^?1 is observed at 33.2°N/74.6°E. The study of the inter-annual variability of flash counts exhibits bimodal nature with the first maximum in April/May and second maximum in August/September.     

Multifractal analysis of daily rainfall from a monsoon watershed in Eastern China

The multifractal behavior of daily rainfall was investigated for a watershed in Eastern China to better understand the temporal structure of rainfall under monsoonal climate. In this study, over periods of up to 46 years, daily rainfall recorded in 1962 to 2007 at 10 meteorological stations in the administrative area of Lin-Yi City in Shandong province were analyzed with focus on features of power spectra, standard statistical moments, and exceedance probability tails of these daily rainfall time series. Spectral analysis and study of the moments of the rainfall intensity showed that a scaling range from 1 day to 1 year is present. Empirical moment scaling functions of the rainfall intensity calculated for different moments of order suggested that the values of universal multifractal parameters α and C ₁ for all stations were approximated to 0.7 and 0.37, respectively. Comparing with the parameters estimated in other literatures, our results showed higher values for α but lower values for C ₁ in general, which suggested that the rainfall series in the study watershed influenced by the East-Asia monsoon climate have similarities to that in France, but are spikier and smoother than that in the semi-arid region in Portugal. The parameter H values were estimated as vary from ?0.18 to ?0.22, which is similar to the result obtained by Tessier et al. (J Geophys Res-Atmos 101:26427–26440, 1996).     

Cloud condensation nuclei (CCN) concentration in the Brazilian northeast semi-arid region: the influence of local circulation

Ground-based aerosol instrumentation covering particle size diameters from 25 nm to 32 µm was deployed to determine aerosol concentration and cloud condensation nuclei (CCN)-activation properties at water vapor supersaturations in the range of S = 0.20–1.50 % in the remote Brazilian northeast semi-arid region (NEB) in coastal (maritime) and continental (inland) regimes. The instruments measured aerosol number concentration and activation spectra for CCN and revealed that aerosol properties are sensitive with respect to the sources as a function of the local wind circulation system. The observations show that coastal aerosol total number concentrations are above 3,000 cm^?3 on average, exhibiting concentration peaks depending on the time of the day in a consistent daily pattern. The variation on aerosol concentration has also influences on the fraction of particles active as CCN. At 1.0 % water vapor supersaturation, the fraction can reach as high as 80 %. Inland aerosol total concentrations were about 1,800–1,900 cm^?3 and did not show much diurnal variation. The fraction of particles active as CCN observed inland depend on the history of the air masses, and was much higher when air masses were originated over the sea. It was found that (NH₄)₂SO₄ and NaCl are the major soluble inorganic fraction of the aerosols at the coast. The major fraction of NaCl was present in the coarse mode, while ammonium sulfate dominates the inorganic fraction at the submicron range, with about 10 % of the total aerosol mass at 0.32 µm. Inorganic compounds are almost absent in particles with sizes around 0.1 μm. The study suggests that the air masses with high concentration of CCN originate at the sea. The feasible explanation lies in the fact that the NEB’s beaches have a particular morphology that produces a wide surf zone and creates a large load of aerosols when combined with strong and permanent winds of the region.     

Pleurozium schreberi as bioindicator of mercury pollution in heavily industrialized region

This research is continuation of the investigation of metal accumulation in native and transplanted moss Pleurozium schreberi in the most industrialized and affected region in Poland (Upper Silesia). We tested the hypotheses that in Upper Silesia transplants of P. schreberi may be used in a 90 days bioindication experiment in case native specimens are absent; a 90 days exposure of transplanted P. schreberi was long enough for evaluation of Hg pollution of the environment. An assay was carried out with native mosses at 27 polluted sites and mosses from an uncontaminated control site transplanted to the same 27 polluted sites. P. schreberi collected from the same sites as classified for more and less polluted basing on Pb and Zn concentrations show quite different pattern of pollution with mercury; The accumulation of Hg by the transplants increased much faster in the first 45 days of the experiment (accumulation factor 1.5–6.7; mean 3.4?±?0.5) in comparison with the second period from day 45 to 90 (accumulation factor 1.0–1.6; mean 1.2?±?0.1). The 90 days exposure of transplanted P. schreberi was long enough for evaluation of Hg pollution of the environment. Transplants of P. schreberi may be used in a 90 days bioindication experiment in case native specimens are absent.