334 research outputs found
Echoes of cosmic events and global politics in moominvalley : Cosmic and astronomical sources of incitement in Tove Jansson's comet in Moominland1
Tove Jansson is known worldwide as the mother of the Moomins. She was a visual artist and writer. The first Moomin books deal with the threat of apocalypse. The 1946 book about the comet approaching the Earth is interesting because of the changes Jansson made in the later versions (1956 and 1968). The first edition is shown to reflect the fear of possible Soviet occupation of Finland after World War II. In the last, 1968 edition this was replaced by a fear of a global nuclear war. In her illustrations and texts, Jansson drew inspiration from several scientific sources, many of which are identified in the article. The case of a meteorite falling in Finland in 1899 is also discussed.Peer reviewe
Evaluating two soil carbon models within the global land surface model JSBACH using surface and spaceborne observations of atmospheric CO<sub>2</sub>
The trajectories of soil carbon (C) in the changing climate are of utmost importance, as soil carbon is a substantial carbon storage with a large potential to impact the atmospheric carbon dioxide (CO2) burden. Atmospheric CO2 observations integrate all processes affecting C exchange between the surface and the atmosphere. Therefore they provide a benchmark for carbon cycle models. We evaluated two distinct soil carbon models (CBALANCE and YASSO) that were implemented to a global land surface model (JSBACH) against atmospheric CO2 observations. We transported the biospheric carbon fluxes obtained by JSBACH using the atmospheric transport model TM5 to obtain atmospheric CO2. We then compared these results with surface observations from Global Atmosphere Watch (GAW) stations as well as with column XCO2 retrievals from the GOSAT satellite. The seasonal cycles of atmospheric CO2 estimated by the two different soil models differed. The estimates from the CBALANCE soil model were more in line with the surface observations at low latitudes (0 N–45 N) with only 1 % bias in the seasonal cycle amplitude (SCA), whereas YASSO was underestimating the SCA in this region by 32 %. YASSO gave more realistic seasonal cycle amplitudes of CO2 at northern boreal sites (north of 45 N) with underestimation of 15 % compared to 30 % overestimation by CBALANCE. Generally, the estimates from CBALANCE were more successful in capturing the seasonal patterns and seasonal cycle amplitudes of atmospheric CO2 even though it overestimated soil carbon stocks by 225 % (compared to underestimation of 36 % by YASSO) and its predictions of the global distribution of soil carbon stocks was unrealistic. The reasons for these differences in the results are related to the different environmental drivers and their functional dependencies of these two soil carbon models. In the tropical region the YASSO model showed earlier increase in season of the heterotophic respiration since it is driven by precipitation instead of soil moisture as CBALANCE. In the temperate and boreal region the role of temperature is more dominant. There the heterotophic respiration from the YASSO model had larger annual variability, driven by air temperature, compared to the CBALANCE which is driven by soil temperature. The results underline the importance of using sub-yearly data in the development of soil carbon models when they are used in shorter than annual time scales
Comparison of conventional Lagrangian stochastic footprint models against LES driven footprint estimates
In this study we introduce a comparison method for footprint model results by evaluating the performance of conventional Lagrangian stochastic (LS) footprint models that use parameterised flow field characteristics with results of a Lagrangian trajectory model embedded in a large eddy simulation (LES) framework. The two conventional models follow the particles backward and forward in time while the trajectories in LES only evolve forward in time. We assess their performance in two unstably stratified boundary layers at observation levels covering the whole depth of the atmospheric boundary layer. We present a concept for footprint model comparison that can be applied for 2-D footprints and demonstrate that comparison of only cross wind integrated footprints is not sufficient for purposes facilitating two dimensional footprint information. Because the flow field description among the three models is most realistic in LES we use those results as the reference in the comparison. We found that the agreement of the two conventional models against the LES is generally better for intermediate measurement heights and for the more unstable case, whereas the two conventional flux footprint models agree best under less unstable conditions. The model comparison in 2-D was found quite sensitive to the grid resolution
Koboltin ja kuparin määrittäminen pyyhintänäytteistä ICP-OES-tekniikalla
Tiivistelmä. Koboltti ja kupari ovat elimistöön joutuessaan erittäin haitallisia aineita, ja ne saattavat pitkäaikaisen altistuminen seurauksena aiheuttaa ihmisille jopa hengenvaarallisia kroonisia terveyshaittoja. Koboltin ja kuparin runsas käyttö varsinkin teollisuudessa aiheuttavat pakostakin altistumista niiden haitallisille pölymäisille yhdisteille, jonka vuoksi koboltti- ja kuparipitoisuuksien seuraaminen esimerkiksi teollisuushallin ilmassa sekä pinnoilla on todella tärkeää, jotta näiltä alkuaineilta sekä niiden yhdisteiltä osataan suojautua tarvittavien suojavarusteiden avulla.
Pyyhintänäyteanalytiikkaa on pitkään käytetty erilaisten kontaminaatiotekijöiden ja epäpuhtauksien seurantaan, mutta sen hyödyntäminen teollisuudessa on alkanut vasta viime vuosien aikana. Pyyhintänäytemenetelmä mahdollistaa helpon ja nopean tavan kerätä pölymäisiä näytteitä. Yksi suurimmista eduista ovat myös lukuisat näytteenkäsittelymenetelmät, kun kiinteä pyyhintänäyteliina saatetaan liuosmaiseen muotoon. Pyyhintänäytemenetelmä on todella tehokas kvalitatiivisten analyysien suorittamiseen, mutta sen hyödyntäminen täysin luotettavien kvantitatiivisten analyysien tulosten saamiseksi vaatii vielä lisää tutkimusta.
Induktiivisesti kytketty plasma optinen emissiospektrometria (ICP-OES) on yleisesti käytetty mittaustekniikka. Sen avulla voidaan määrittää nopeasti ja helposti jopa kymmeniä alkuaineita todella alhaisilla alkuainepitoisuuksilla. Tekniikka perustuu plasman kykyyn hajottaa molekyylit atomeiksi ja ioneiksi, jonka jälkeen plasman korkea energia virittää ne ylemmille viritystiloille. Viritystilojen purkautuessa vapautuva polykromaattinen emissiosäteily jaetaan aallonpituuksiin ja mitataan emissiospektrometrin avulla. Ongelmana ICP-OES-tekniikassa ovat lukuisat spektraaliset häiriöt.
Tässä tutkielmassa luodaan katsaus pyyhintänäyteanalytiikkaan yleisellä tasolla ja tarkastellaan koboltille ja kuparille tehtyjä tutkimuksia pyyhintänäytteiden osalta. Lisäksi tutkielmassa käsitellään koboltin ja kuparin kontaminaatioriskejä sekä terveyshaittoja. Lopuksi perehdytään ICP-OES-tekniikan teoriaan, häiriöihin ja häiriöiden minimointiin
Application of Tomographic Inversion in Studying Airglow in the Mesopause Region
It is pointed out that observations of periodic nightglow structures give excellent information on atmospheric gravity waves in the mesosphere and lower thermosphere. The periods, the horizontal wavelengths and the phase speeds of the waves can be determined from airglow images and, using several cameras, the approximate altitude of the luminous layer can also be determined by triangulation. In this paper the possibility of applying tomographic methods for reconstructing the airglow structures is investigated using numerical simulations. A ground-based chain of cameras is assumed, two-dimensional airglow models in the vertical plane above the chain are constructed, and simulated data are calculated by integrating the models along a great number of rays with different elevation angles for each camera. After addition of random noise, these data are then inverted to obtain reconstructions of the models. A tomographic analysis package originally designed for satellite radiotomography is used in the inversion. The package is based on a formulation of stochastic inversion which allows the input of a priori information to the solver in terms of regularization variances. The reconstruction is carried out in two stages. In the first inversion, constant regularization variances are used within a wide altitude range. The results are used in determining the approximate altitude range of the airglow structures. Then, in the second inversion, constant non-zero regularization variances are used inside this region and zero variances outside it. With this method reliable reconstructions of the models are obtained. The number of cameras as well as their separations are varied in order to find out the limitations of the method
9286 Stars: An Agglomeration of Stellar Polarization Catalogs
This is a revision. The revisions are minor. The new version of the catalog
should be used in preference to the old. The most serious error in the older
version was that was incorrect, being sometimes far too large,
for Reiz and Franco entries; the correct values are all zero for that
reference.
We present an agglomeration of stellar polarization catalogs with results for
9286 stars. We have endeavored to eliminate errors, provide accurate
(arcsecond) positions, sensibly weight multiple observations of the same star,
and provide reasonable distances. This catalog is included as an ASCII file
(catalog.txt) in the source of this submission.Comment: The most serious error in the older version was that
was incorrect, being sometimes far too large, for Reiz and Franco entries;
the correct values are all zero for that reference. 11 pages, no figures.
Accepted for Astronomical Journal. Catalog also available as an ASCII file by
anonymous FTP from ftp://vermi.berkeley.edu/pub/polcat/p14.ou
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