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31.
The factors which affect the formation of new sulphuric acid particles in different atmospheric conditions are investigated. An atmospheric chemistry gas phase box model coupled to a three mode integral aerosol dynamics model is used. The simulations show the dependence of the concentration of nucleation mode particles on initial pre-existing particles, the intensity of UV radiation, the emissions of dimethylsulphide (DMS) and the ratio of emissions of hydrocarbons (HC) and NOx present in the atmosphere. Eight different basic cases are simulated in urban, rural and marine conditions. The effects of pre-existing particles as a sink of sulphuric acid are clearly seen. The increased UV radiation is also seen to enhance particle formation via sulphuric acid route significantly. 相似文献
32.
Masahiko Shimmo Karri Saarnio Pasi Aalto Kari Hartonen Tuulia Hyötyläinen Markku Kulmala Marja-Liisa Riekkola 《Journal of Atmospheric Chemistry》2004,47(3):223-241
Ambient concentrations of polycyclic aromatic hydrocarbons (PAHs) were measured in Helsinki (Finland). Particle mass size
distributions were obtained with a cascade impactor (12 stages) with glass fibre filters as substrates. Simultaneously with
the impactor measurements, particulate and gaseous PAHs were collected on a quartz filter and XAD-2 adsorbent, respectively,
for evaluation of gas-partition coefficients. Samples were analysed for PAHs by on-line coupled supercritical fluid extraction
— liquid chromatography — gas chromatography — mass spectrometry. The impactor results showed that most of the PAHs in Helsinki
urban area were concentrated in fine particles (<2.5 μm diameter) with unimode peak at about 1 μm. The results were comparable
with the number distribution measured with a differential mobility particle sizer. Total amounts of PAHs (gas + particle)
varied from 15 (acenaphthylene) to 1990 (fluorene) pg/m3. The PAHs lighter than 202 amu (pyrene and fluoranthene) were exclusively in gas phase, whereas those heavier than 202 amu
were mostly associated with particles. A plot of the partition coefficients (logKp) versus the temperature dependent sub-cooled
vapour pressures (logp
L
0
) showed a gradient of −0.66, which deviated from equilibrium state (gradient = −1). 相似文献
33.
Reijo Salminen Igor Bogatyrev Victor Chekushin Sergey P. Glavatskikh Virgilija Gregorauskiene Heikki Niskavaara Lubov Selenok Markku Tenhola Olga Tomilina 《Geostandards and Geoanalytical Research》2004,28(2):333-341
The geochemical baselines of nickel and chromium were studied from the data produced by the Barents Ecogeochemistry project, a large international regional geochemical mapping exercise. The project surveyed major and trace element distributions in stream water, organic and mineralogically-modified soil horizons, and terrestrial moss in the northwestern part of Russia and in Finland. Other materials were collected during the pilot phase and later from thirty special sites. The results on respective materials by XRF, ICP-MS and ICP-AES showed that both geological and anthropogenic factors have an influence on the geochemical baseline concentrations of Ni and Cr in organic soil and stream water. The main explanation of the observed distribution patterns in terrestrial moss is human activity, but geological factors can also affect the baselines. The variation of geochemical baselines in the mineral-rich soil horizon depends only on variations in bedrock. The mineralogy of samples mainly controls the leachability properties of soil samples. 相似文献
34.
Anna Suuronen Anssi Lensu Markku Kuitunen Rodrigo Andrade-Alvear Natalia Guajardo Celis Marcelo Miranda Marcelo Perez Jussi V. K. Kukkonen 《Environmental Earth Sciences》2017,76(24):824
The optimization of photovoltaic solar power plants location in Atacama Desert, Chile, is presented in this study. The study considers three objectives: (1) Find sites with the highest solar energy potential, (2) determine sites with the least impact on the environment, and (3) locate the areas which produce small social impact. To solve this task, multi-criteria decision analyses (MCDAs) such as analytical hierarchy process and ordered weighted averaging were applied in a GIS environment. In addition, survey results of social impacts were analyzed and included into the decision-making process, including landscape values. The most suitable sites for solar energy projects were found near roads and power lines throughout the study area. Large suitable areas were found also from central valley from Arica and Parinacota to the north edge of Atacama region. In Atacama region, most suitable sites were found in the Andes. On the contrary, Andes were also found to have high environmental values and scenically valuable landscapes. Moderate and low suitability were found on the coast, especially in Atacama region. Factors such as slope and distance to power lines and roads influenced largely the sensitivity analysis. Area of high suitability increased by 15% when distance to roads was excluded and 18% when distance to power lines or slope was removed. MCDA-GIS method was found to be useful and applicable to the optimization of solar power plant locations in northern Chile. 相似文献
35.
36.
Pekka Kolmonen Larisa Sogacheva Timo H. Virtanen Markku Kulmala 《International Journal of Digital Earth》2016,9(6):545-561
An advanced along-track scanning radiometer (AATSR) global multi-year aerosol retrieval algorithm is described. Over land, the AATSR dual-view (ADV) algorithm utilizes the measured top of the atmosphere (TOA) reflectance in both the nadir and forward views to decouple the contributions of the atmosphere and the surface to retrieve aerosol properties. Over ocean, the AATSR single-view (ASV) algorithm minimizes the discrepancy between the measured and modelled TOA reflectances in one of the views to retrieve the aerosol information using an ocean reflectance model. Necessary steps to process global, multi-year aerosol information are presented. These include cloud screening, the averaging of measured reflectance, and post-processing. Limitations of the algorithms are also discussed. The main product of the aerosol retrieval is the aerosol optical depth (AOD) at visible/near-infrared wavelengths. The retrieved AOD is validated using data from the surface-based AERONET and maritime aerosol network (MAN) sun photometer networks as references. The validation shows good agreement with the reference (r?=?0.85, RMSE?=?0.09 over land; r?=?0.83, RMSE?=?0.09 at coasts and r?=?0.96, RMSE?=?0.06 over open ocean). The results of the aerosol retrievals are presented for the full AATSR mission years 2002–2012 with seasonally averaged time series for selected regions. 相似文献
37.
Helama Samuli Stoffel Markus Hall Richard J. Jones Phil D. Arppe Laura Matskovsky Vladimir V. Timonen Mauri N&#;jd Pekka Mielik&#;inen Kari Oinonen Markku 《Climate Dynamics》2021,56(11):3817-3833
Holocene climate variability is punctuated by episodic climatic events such as the Little Ice Age (LIA) predating the industrial-era warming. Their dating and forcing mechanisms have however remained controversial. Even more crucially, it is uncertain whether earlier events represent climatic regimes similar to the LIA. Here we produce and analyse a new 7500-year long palaeoclimate record tailored to detect LIA-like climatic regimes from northern European tree-ring data. In addition to the actual LIA, we identify LIA-like ca. 100–800 year periods with cold temperatures combined with clear sky conditions from 540 CE, 1670 BCE, 3240 BCE and 5450 BCE onwards, these LIA-like regimes covering 20% of the study period. Consistent with climate modelling, the LIA-like regimes originate from a coupled atmosphere–ocean–sea ice North Atlantic-Arctic system and were amplified by volcanic activity (multiple eruptions closely spaced in time), tree-ring evidence pointing to similarly enhanced LIA-like regimes starting after the eruptions recorded in 1627 BCE, 536/540 CE and 1809/1815 CE. Conversely, the ongoing decline in Arctic sea-ice extent is mirrored in our data which shows reversal of the LIA-like conditions since the late nineteenth century, our record also correlating highly with the instrumentally recorded Northern Hemisphere and global temperatures over the same period. Our results bridge the gaps between low- and high-resolution, precisely dated proxies and demonstrate the efficacy of slow and fast components of the climate system to generate LIA-like climate regimes.
相似文献38.
Marko Vana Mikael Ehn Tuukka Petj Henri Vuollekoski Pasi Aalto Gerrit de Leeuw Darius Ceburnis Colin D. O'Dowd Markku Kulmala 《Atmospheric Research》2008,90(2-4):278-ICNAA07
Coastal nucleation events and behavior of cluster ions were characterized through the measurements of air ion mobility distributions at the Mace Head research station on the west coast of Ireland in 2006. We measured concentrations of cluster ions and charged aerosol particles in the size range of 0.34–40 nm. These measurements allow us to characterize freshly nucleated charged particles with diameters smaller than 3 nm. The analysis shows that bursts of intermediate ions (1.6–7 nm) are a frequent phenomenon in the marine coastal environment. Intermediate ion concentrations were generally close to zero, but during some nucleation episodes the concentrations increased to several hundreds per cm3. Nucleation events occurred during most of the measurement days. We classified all days into one of seven classes according to the occurrence and type of new particle formation. Nucleation events were observed during 207 days in 2006, most prominently in the spring and summer months. Rain-induced events, in turn, were observed during 132 days. Particle formation and growth events mostly coincided with the presence of low tide. Also small cluster ions (0.34–1.6 nm) were characterized. Average concentrations of small ions were 440 cm− 3 for the negative ions and 423 cm− 3 for the positive ions. Average mean mobilities of small ions were 1.86 cm2V− 1s− 1 and 1.49 cm2V− 1s− 1 for the negative and positive polarities, respectively. Concentrations of small ions were observed to be strongly dependent on the variations of meteorological parameters including wind speed and direction. 相似文献
39.
Markku Sotarauta 《Geoforum》2009,40(5):895-905
Increased complexity and rapid pace of change demand more from people responsible for regional development at various levels of activity. This paper has its roots in a belief that the more complex situations are, the more regional development is dependent on the leadership and network management capacity of key individuals. Studying more deeply the roles that various individuals, and the coalitions formed by them, have in institutionalisation, deinstitutionalisation and reinstitutionalisation processes might provide us with additional analytical leverage in regional development studies. This paper focuses on diffuse networks of dispersed powers from a Finnish regional development officer’s point of view. Regional development officers are those people whose job it is to boost the economic development of their respective regions in Finland.The research questions discussed here are: (a) What kind of power is exercised by Finnish regional development officers; and (b) how do regional development officers aim to gain influence for their efforts to promote regional development? The empirical research is based on data gathered (a) through 41 interviews with Finnish actors responsible for the promotion of economic development in city governments, technology centres, regional development agencies, and ministries and other national bodies, and (b) through internet survey of development officers at local, regional and national levels (531 respondents, response rate 51.8%). The survey was designed to solicit information about power and influence tactics in the context of regional development. The empirical analysis shows, for example, how interpretive power and network power are more important for regional development officers than institutional and resource power, and how indirect influence tactics surpass direct tactics. 相似文献
40.
Two experimental techniques have been used for study of mass transfer from a drop of 1-hexanol evaporating into air. In the first technique, liquid is added to the drop by a supporting capillary. When the rate of liquid adding counterbalances the evaporation rate, the drop size remains constant and the evaporation takes place at steady state. In the second case with drop suspended from a thermocouple, the rate of evaporation is determined from variation of drop diameter with time. Since the combination of both methods should allow to measure at the broader range of experimental conditions, the differences and their impact on experimental determination of mass transfer are discussed. The results are compared with results of previous experimental and theoretical works reported in the literature. 相似文献