Ozone depletion in the plume of a solid-fueled rocket

The local effects of the emission of a solid-fueled rocket on the stratospheric ozone concentration have been investigated by photochemical model calculations. A one-dimensional horizontal model has been applied which calculates the trace gas composition at a single atmospheric altitude spatially resolved around the exhaust plume. Different cases were tested for the emissions of the Space Shuttle concerning the composition of the exhaust and the effects of heterogeneous reactions on atmospheric background aerosol.The strongest depletion of ozone is achieved when a high amount of the emitted chlorine is Cl₂. If it is purely HCl, the effect is smallest, though in this case the heterogeneous reactions show their largest influence. From the results it may be estimated whether ozone depletion caused by rocket launches can be detected by satellite instruments. It appears that the chance of coincidental detection of such an event is rather small.     

Influence Of Bedrock Geology On Elemental Fluxes In Two Forested Catchments Affected By High Acidic Deposition

Water samples have been collected from two forested catchments in the Slavkovsky les Mountains of western Bohemia, in the Czech Republic. The objective of the study was to compare and contrast elemental fluxes in two catchments with similar conditions of climate, topography, vegetation over and acidic atmospheric deposition, but very different bedrock geology. The Lysina catchment is underlain by slow-weathering leucocratic granite. Soils are podzolized brown earths and peaty gleys with small pools of exchangeable basic cations. Both soils and drainage water at Lysina are acidified by atmospheric deposition. Surface runoff was found to be dominated by sulphate and dissolved silica, accompanied by high concentrations of H⁺ (volume weighted pH = 3.87). Stream water also displayed extremely high concentrations of total aluminum (volume-weighted mean 66 7mol.l^у). Inorganic monomeric aluminum was the predominant aluminum fraction present, which contained mainly aquo-Al (Al³⁺ and fluoride complexes. The Pluhuv Bor catchment is characterized by ultramafic serpentinite and, in contrast to Lysina, soil and drainage waters have higher concentration of basic cations. Streamwater chemistry was dominated by magnesium, sulphate and silica. Stream-water at the site was not acidic (volume weighted pH = 7.25). The ratio of output/input of sulphate was similar at both catchments (1.16 for granite site and 1.07 for the serpentinite site). This pattern may be indicative of the conservative behaviour of sulphate in very different soil and bedrock environments under elevated loadings of acidic deposition. Résumé: Des eaux ont été échantillonnées dans deux bassins forestiers du massif de Slavkovsky les, en Bohême occidentale (République Tchèque). Le but de l'étude était de comparer les flux de matière dans les deux bassins, soumis à des conditions identiques de climat, de topographie, de couvert végétal et d'apports atmosphériques acides, mais à une géologie de leur substratum très différente. Le bassin de la Lysina est constitué d'un leucogranite peu altéré. Le couvert pédologique est formé de sols bruns podzolisés et de gleys de tourbières, qui son pauvres en cations de bases échangeables. Les sols et les eaux de drainage de la Lysina sont acidifiés par les apports atmosphériques. L'écoulement de surface est dominé par les sulfates et la silice, associés à de fortes teneurs en H⁺ (pH = 3.87). Les eaux de la rivière présentent en outre des teneurs particulièrement élevées en aluminium total (66 µmol.l^у). L'aluminium domine sous la forme d'un monomère minéral, surtout l'aluminium aqueus (Al³⁺) et des complexes fluorés. Le bassin de la Pluhuv Bor est caractérisé par une serpentinite ultrabasique et, au contraire de la Lysina, par des sols et des eaux de drainage à très fortes teneurs en cations basiques. Les eaux de la rivière sont dominées par le magnésium, les sulfates et la silice. Ces eaux ne sont pas acides (pH = 7.25). Le rapport des flux de sortie et d'entrée de sulfates est identique pour les deux bassins (1.16 pour le bassin granitique; 1.07 pour le bassin de serpentinite). Cette situation parait signifier que les sulfates présentent un comportement conservatif dans des environnements pédologiques et géologiques très différents, sous des apports acides importants.     

Urban vulnerability and adaptation to heatwaves: a case study of Graz (Austria)

The increasing frequency of heatwaves, particularly in urban contexts, is one of the perceptible consequences of climate change. A city’s vulnerability to these heatwaves must be determined to develop proper adaptation measures. This article addresses the vulnerability of a medium-sized city in Central Europe, Graz, to heatwaves. Based on secondary data and primary data gathered from expert interviews, we identified certain determinants of vulnerability for the city: temperature, proportion of open and green spaces to developed areas, construction period of buildings, distribution of age and poverty risk, adaptation strategies used, and risk perception levels assessed for decision makers in the city administration. Certain city districts can be classified as particularly vulnerable. A high level of risk perception was detected among all decision makers and some adaptation measures have already been enacted. In particular, inter-organizational collaboration in adaptation networks works effectively. A deficit in efficient communication between researchers, policy makers, and members of the public was perceived to be the main barrier. This case study exemplifies the assessment of a city’s vulnerability to heatwaves on the basis of particular determinants and can be applied to many other cities.

Policy relevance

The method applied revealed potential improvements and opportunities on the policy level. Strong networks for climate change adaptation are most effective if regular meetings take place, allowing trust and friendship to grow between decision makers. More target-group-oriented information is needed. Emergency organizations, in particular, need more information, because the perception of heatwave risks has only been based thus far on personal experiences. By establishing a central authority, more information could be provided on heatwaves in cities. The need to raise the perception of members of the population and motivate them to take personal responsibility during disasters was emphasized by interviewed decision makers. This can be supported by providing advice during heatwaves through newspapers, TV, and radio. People in risk groups and their relatives could be trained in workshops. City areas that are at high risk should be marked on maps to make relevant information more tangible for decision makers.     

Visualizing and quantifying the movement of vegetative drought using remote-sensing data and GIS

Remote-sensing-based drought monitoring methods provide fast and useful information for a sustainable management strategy of drought impact over a region. Common pixel-based monitoring methods are limited in the analysis of the dynamics of this impact at regional scale. For instance, these hardly allow us to quantify the movement of drought in space and time and to compare drought with rainfall deficits without losing the variability of these events within a region. This study proposed an object-based approach that allowed us to visualize and quantify the spatio-temporal movement of drought impact on vegetation, called vegetative drought, in a region. The GIS software Dynomap was used to extract and track objects. Measures of distance and angle were used for determining the speed and direction of vegetative drought and rainfall deficit objects, calculated from the National Oceanic and Atmospheric Administration's (NOAA's) normalized difference vegetation index and rainfall estimates data. The methods were applied to the two rainy seasons during the drought year 1999 in East Africa. Results showed that vegetative drought objects moved into the southwestern direction at an average angle of??138.5° during the first season and??144.5° during the second season. The speed of objects varied between 38 km dekad^?1 and 185 km dekad^?1 during the first season and between 33 km dekad^?1 and 144 km dekad^?1 during the second season, reflecting the rate of spread between dekads. Vegetative drought objects close to rainfall deficit objects showed similar trajectories and sometimes regions overlapped. This indicated that the two events are related. We conclude that a spatiotemporal relationship existed between the two types of events and that this could be quantified.     

Using geographically weighted regression kriging for crop yield mapping in West Africa

Geographical information systems support the application of statistical techniques to map spatially referenced crop data. To do this in the optimal way, errors and uncertainties have to be minimized that are often associated with operations on the data. This paper applies a spatial statistical approach to upscale crop yields from the field level toward the scale of Burkina Faso. Observed yields were related to the Normalized Difference Vegetation Index derived from SPOT-VEGETATION. The objective was to quantify the uncertainties at the subsequent steps. First, we applied a point pattern analysis to examine uncertainties due to the sampling network of field surveys in the country. Second, geographically weighted regression kriging (GWRK) was applied to upscale the yield observations and to quantify the corresponding uncertainty. The proposed method was demonstrated with the mapping of sorghum yields in Burkina Faso and results were compared with those from regression kriging (RK) and kriging with external drift using a local kriging neighborhood (KEDLN). The proposed method was validated with independent yield observations obtained from field surveys. We observed that the lower uncertainty range value increased by 39%, and the upper uncertainty range value decreased by 51%, when comparing GWRK with RK and KEDLN. Moreover, GWRK reduced the prediction error variance as compared to RK (20 vs. 31) and to KEDLN (20 vs. 39). We found that climate and topography had a major impact on the country’s sorghum yields. Further, the financial ability of farmers influenced the crop management and, thus, the sorghum crop yields. We concluded that GWRK effectively utilized information present in the covariate datasets and improved the accuracies of both the regional-scale mapping of sorghum yields and was able to quantify the associated uncertainty.     

Observations and temperatures of Io's Pele Patera from Cassini and Galileo spacecraft images

Pele has been the most intense high-temperature hotspot on Io to be continuously active during the Galileo monitoring from 1996-2001. A suite of characteristics suggests that Pele is an active lava lake inside a volcanic depression. In 2000-2001, Pele was observed by two spacecraft, Cassini and Galileo. The Cassini observations revealed that Pele is variable in activity over timescales of minutes, typical of active lava lakes in Hawaii and Ethiopia. These observations also revealed that the short-wavelength thermal emission from Pele decreases with rotation of Io by a factor significantly greater than the cosine of the emission angle, and that the color temperature becomes more variable and hotter at high emission angles. This behavior suggests that a significant portion of the visible thermal emission from Pele comes from lava fountains within a topographically confined lava body. High spatial resolution, nightside images from a Galileo flyby in October 2001 revealed a large, relatively cool (<800 K) region, ringed by bright hotspots, and a central region of high thermal emission, which is hypothesized to be due to fountaining and convection in the lava lake. Images taken through different filters revealed color temperatures of 1500±80 K from Cassini ISS data and 1605±220 and 1420±100 K from small portions of Galileo SSI data. Such temperatures are near the upper limit for basaltic compositions. Given the limitations of deriving lava eruption temperature in the absence of in situ measurement, it is possible that Pele has lavas with ultramafic compositions. The long-lived, vigorous activity of what is most likely an actively overturning lava lake in Pele Patera indicates that there is a strong connection to a large, stable magma source region.     

Modelling of Shape Changes of the Nuclei of Comets C/1995 O1 Hale–Bopp and 46P/Wirtanen Caused by Water Ice Sublimation

The aim of this modelling work is to assess shape changes of cometary nuclei caused by sublimation of ices. The simplest possible model is assumed with the nucleus being initially spherical and its thermal conductivity being neglected. We have calculated the time-dependent sublimation flux versus cometographic latitude. If the rotation axis of the comet is inclined to the orbital plane, then sublimation leads to non-symmetrical changes of the nucleus shape. Calculations were performed for the nuclei of comets Hale–Bopp and Wirtanen.     

Vertical vibration of an elastic strip footing on saturated soil

Based on Biot's dynamic coupled equations, the vertical vibration of an elastic strip footing on the surface of saturated soil is studied. Utilizing the Fourier transform, the governing dynamic differential equations for saturated poroelastic medium are solved. Considering the mixed boundary value conditions at the bottom of the foundation, a pair of dual integral equations about the vertical vibration of an elastic strip footing is derived, which can be converted to a set of linear equations by means of infinite series of orthogonal functions. The relation between the dynamic compliance coefficients and the dimensionless frequency tends to be gentle with decreasing footing rigidity, while the dimensionless frequency has only small effect on the dynamic compliance coefficients. When the dynamic permeability is large, its effect on the dynamic compliance coefficients should be taken into consideration. Furthermore, the dynamic compliance coefficients are found to be not sensitive to Poisson's ratio of the soil for footing on saturated soil. Copyright © 2007 John Wiley & Sons, Ltd.     

Rays and secondary craters of Tycho

The large, fresh crater Tycho in the nearside lunar highlands has an extensive system of bright rays covering approximately 560,000 km², containing dense clusters of secondary craters. Examination of crater densities in several clusters shows that Tycho produced almost 10⁶ secondary craters larger than 63 m diameter. This is a lower limit, because small crater densities are reduced, most likely by mass wasting. We estimate a crater erasure rate of 2-6 cm/Myr, varying with crater size, and consistent with previous results. This process has removed many small craters, and it is probable that the original number of secondary craters formed by Tycho was higher. Also, we can only identify distant secondaries of Tycho where they occur in bright rays. Craters on Mars and Europa also formed large numbers of secondaries, but under possibly ideal conditions for spallation as a mechanism to produce high-velocity ejecta fragments. The results from Tycho show that large numbers of such fragments can be produced even from impact into a heavily fragmented target on which spallation is expected to be less important.