Area-Averaged Surface Fluxes Over the Litfass Region Based on Eddy-Covariance Measurements

Micrometeorological measurements (including eddy-covariance measurements of the surface fluxes of sensible and latent heat) were performed during the LITFASS-2003 experiment at 13 field sites over different types of land use (forest, lake, grassland, various agricultural crops) in a 20 × 20 km² area around the Meteorological Observatory Lindenberg (MOL) of the German Meteorological Service (Deutscher Wetterdienst, DWD). Significant differences in the energy fluxes could be found between the major land surface types (forest, farmland, water), but also between the different agricultural crops (cereals, rape, maize). Flux ratios between the different surfaces changed during the course of the experiment as a result of increased water temperature of the lake, changing soil moisture, and of the vegetation development at the farmland sites. The measurements over grass performed at the boundary-layer field site Falkenberg of the MOL were shown to be quite representative for the farmland part of the area. Measurements from the 13 sites were composed into a time series of the area-averaged surface flux by taking into account the data quality of the single flux values from the different sites and the relative occurrence of each surface type in the area. Such composite fluxes could be determined for about 80% of the whole measurement time during the LITFASS-2003 experiment. Comparison of these aggregated surface fluxes with area-averaged fluxes from long-range scintillometer measurements and from airborne measurements showed good agreement.     

Unusual transition in quartzite dislocation creep regimes and crystal slip systems in the aureole of the Eureka Valley–Joshua Flat–Beer Creek pluton, California: a case for anhydrous conditions created by decarbonation reactions

Microstructures and quartz c-axis fabrics were analyzed in five quartzite samples collected across the eastern aureole of the Eureka Valley–Joshua Flat–Beer Creek composite pluton. Temperatures of deformation are estimated to be 740±50 °C based on a modified c-axis opening angle thermometer of Kruhl (J. Metamorph. Geol. 16 (1998) 142). In quartzite layers located closest (140 m) to the pluton-wall rock contact, flattened detrital grains are plastically deformed and partially recrystallized. The dominant recrystallization process is subgrain rotation (dislocation creep regime 2 of Hirth and Tullis (J. Struct. Geol. 14 (1992) 145)), although grain boundary migration (dislocation creep regime 3) is also evident. Complete recrystallization occurs in quartzite layers located at a distance of 240 m from the contact, and coincides with recrystallization taking place dominantly through grain boundary migration (regime 3). Within the quartzites, strain is calculated to be lowest in the layers closest to the pluton margin based on the aspect ratios of flattened detrital grains.The c-axis fabrics indicate that a slip operated within the quartzites closest to the pluton-wall rock contact and that with distance from the contact the operative slip systems gradually switch to prism [c] slip. The spatial inversion in microstructures and slip systems (apparent “high temperature” deformation and recrystallization further from the pluton-contact and apparent “low temperature” deformation and recrystallization closer to the pluton-contact) coincides with a change in minor phase mineral content of quartzite samples and also in composition of the surrounding rock units. Marble and calc-silicate assemblages dominate close to the pluton-wall rock contact, whereas mixed quartzite and pelite assemblages are dominant further from the contact.We suggest that a thick marble unit located between the pluton and the quartzite layers acted as a barrier to fluids emanating from the pluton. Decarbonation reactions in marble layers interbedded with the inner aureole quartzites and calc-silicate assemblages in the inner aureole quartzites may have produced high X_CO2 (water absent) fluids during deformation. The presence of high X_CO2 fluid is inferred from the prograde assemblage of quartz+calcite (and not wollastonite)+diopside±K-feldspar in the inner aureole quartzites. We suggest that it was these “dry” conditions that suppressed prism [c] slip and regime 3 recrystallization in the inner aureole and resulted in a slip and regime 2 recrystallization, which would normally be associated with lower deformation temperatures. In contrast, the prograde assemblage in the pelite-dominated outer part of the aureole is biotite+K-feldspar. These “wet” pelitic assemblages indicate fluids dominated by water in the outer part of the aureole and promoted prism [c] slip and regime 3 recrystallization. Because other variables could also have caused the spatial inversion of c-axis fabrics and recrystallization mechanisms, we briefly review those variables known to cause a transition in slip systems and dislocation creep regimes in quartz. Our conclusions are based on a small number of samples, and therefore, the unusual development of crystal fabrics and microstructures in the aureole to the EJB pluton suggests that further study is needed on the effect of fluid composition on crystal slip system activity and recrystallization mechanisms in naturally deformed rocks.     

The fine structure of the normal incidence synthetic seismogram

Summary . The spectral function of a perfectly elastic, horizontally stratified medium has been demonstrated previously to provide an attractive formulation to describe the properties of the one-dimensional synthetic seismogram (Robinson & Treitel). Here we examine the mathematical framework of the Model in still greater detail. Knowledge of this fine structure of the synthetic seismogram leads to the solution of two particular seismic inverse problems. First, we consider a layered medium with an arbitrary surface reflection coefficient c _o, where | c _o|<1, and which contains an impulsive source immediately above the surface. Given the corresponding synthetic seismogram, we develop an inverse, or backward recursion formalism which recovers the entire series of original reflection coefficients. Second, we consider a similar problem for an impulsive source located just below the surface. Both inversion procedures constitute a continuation of the work of Goupillaud and of Sherwood & Trorey, and represent a generalization of the classical technique originally proposed by Kunetz which, however, only holds for the marine case, c_o =±1. The present approach is not so constrained and thereby becomes applicable to land seismograms as well.
If products of third or higher order in the reflection coefficients can be neglected, significant simplifications arise in the theory. In that event the usual representation of the synthetic seismogram as a ratio of two polynomials in the complex variable z becomes particularly revealing. The numerator polynomial is then approximately equal to the z transform of the reflection coefficient series, while the denominator polynomial is approximately equal to the z transform of the autocorrelation of these reflection coefficients. The resulting simplified theory affords important computational savings in the appropriate backward recursion algorithms.     

Damage Potential and Losses Resulting from Snow Avalanches in Settlements of the Canton of Grisons,Switzerland

In the field of natural hazards, risk is usually expressed as a function of probability of occurrence and damage potential. A key factor in the development of avalanche risk is a change in damage potential. In this paper, the development of damage potential and losses is analysed for settlements in the canton of Grisons, Switzerland for the period between 1950 and 2000. The spatial development patterns of the residential population and the insured value of buildings on a municipal level are described. These patterns are overlain by an accentuated occurrence of avalanches that caused damage to buildings. Extensive results from areas threatened by avalanches in the municipality of Davos are presented. Although the natural avalanche activity remained constant during the last decades, the total amount of damage decreased due to mitigation measures. The example of the municipality of Davos shows that mitigation measures are able to compensate an increase of tangible assets which leads to a reduced avalanche risk compared to earlier decades.     

Acclimations of macroalgae as reflected in photosynthetic parameters derived from PAM fluorometry, and possible implications for abundance patterns

The presences of the common macroalgae Ulva sp. and Jania rubens vary between seasons along the Israeli Mediterranean intertidal zone. To reveal some of the potential acclimation mechanisms of these algae, we examined their photosynthetic traits during the year using rapid light curves (RLC) derived from pulse amplitude modulated (PAM) fluorometry. In addition, the relationships between those photosynthetic traits and the relative abundances of the two algae were investigated. Ulva sp. showed high maximal electron transport rates (ETR_max) (49.7–68.8 μmol electrons m⁻² s⁻¹) and onsets of light saturation values (E_k) (75.8–85.6 μmol photons m⁻² s⁻¹) in the winter months of December–February, while low values were found in the summer months of June–July (5.2–20.6 μmol electrons m⁻² s⁻¹ and 6.0–23.7 μmol photons m⁻² s⁻¹, respectively). At noon time (during the highest irradiance of the day), the maximal effective quantum yield (Y₀) did not vary significantly during the year. These results indicate that seasonal irradiance influences the number of reaction centres per thallus area. Both algae showed depressions in Y₀ at noon (23.8% for Ulva sp. and 20.3% for Jania rubens), indicating an efficient non‐photochemical quenching mechanism. A positive correlation between the relative abundance and the photosynthetic parameter Y₀ was found for Jania rubens when Y₀ was sampled in the morning or noon, indicating that growth rate and primary production for this alga can be estimated from RLCs. No such correlation was found for Ulva sp., indicating that, in addition to photosynthetic traits, the relative seasonal abundance of this alga is influenced by other factors such as grazing and/or catastrophic events.     

Regional maximum rainfall analysis using L-moments at the Titicaca Lake drainage,Peru

Theoretical and Applied Climatology - The present study investigates the application of the index flood L-moments-based regional frequency analysis procedure (RFA-LM) to the annual maximum 24-h...     

The role of iron in tetrahedrite and tennantite determined by Rietveld refinement of neutron powder diffraction data

Rietveld refinement of neutron powder diffraction data on four samples of synthetic, iron-bearing tetrahedrite (Cu_12?xFe_xSb₄S₁₃) with x = 0.28, 0.69, 0.91, 2.19 and four samples of synthetic tennantite (Cu_12?xFe_xAs₄S₁₃) with x = 0.33, 0.38, 0.86, 1.5 indicate unambiguously that iron is incorporated into tetrahedral M1 (12d) sites and not into triangular M2 (12e) sites in the cubic crystal structure (space group I $ \ifmmode\expandafter\bar\else\expandafter\=\fi{4} Rietveld refinement of neutron powder diffraction data on four samples of synthetic, iron-bearing tetrahedrite (Cu_12−xFe_xSb₄S₁₃) with x = 0.28, 0.69, 0.91, 2.19 and four samples of synthetic tennantite (Cu_12−xFe_xAs₄S₁₃) with x = 0.33, 0.38, 0.86, 1.5 indicate unambiguously that iron is incorporated into tetrahedral M1 (12d) sites and not into triangular M2 (12e) sites in the cubic crystal structure (space group I 3 m). The refinement results also confirm that M2 is a split (24g), flat-pyramidal site situated statistically on both sides of the S1−S1–S2 triangle. In tetrahedrite, this split is about 0.6 ?, in tennantite about 0.7 ?. Trends in bond lengths and magnitude of the M2 split were evaluated by means of linear regression with Fe concentration as the independent variable.     

Joint atmospheric-terrestrial water balances for East Africa: a WRF-Hydro case study for the upper Tana River basin

Theoretical and Applied Climatology - For an improved understanding of the hydrometeorological conditions of the Tana River basin of Kenya, East Africa, its joint atmospheric-terrestrial water...     

Dealing with climate science denialism: experiences from confrontations with other forms of pseudoscience

Climate science denialism is a form of pseudoscience. This contribution provides proposals for how to counter it, based on previous research on the demarcation between science and pseudoscience and on the author’s experience of tackling other forms of pseudoscience. Science denialism has much in common with other variants of pseudoscience, but it also has characteristics of its own. In particular, it is much more prone than other forms of pseudoscience to seek conflicts with genuine science. Like other science denialists, those attacking climate science have fabricated a large number of fake controversies in issues where there is no authentic scientific controversy. The defence of climate science against science denial has to take this into account. There is no reason to accept the denialists’ agenda or to treat their claims as legitimate alternatives to science. Climate science should primarily be presented to the public in ways that are independent of denialist activities, rather than reactively in response to those activities. Disclosures of the strategies, motives and funding of denialism are important contributions to the public understanding of the fake controversies. It is also important to document the scientific consensus and make it known. The public defence of climate science is an important and urgent undertaking, and active contributions by as many scientists as possible are needed.

Key policy insights

• Climate science denialism is a form of pseudoscience, and much can be learned from confrontations with other types of pseudoscience.

• The creation of fake controversies is a key strategy of climate science denialism. It is important to expose this strategy and not to accept denialists’ choice of an agenda.

• ‘Equal time’ arrangements should be rejected since they put the truthful side at a disadvantage. It takes more time to refute a single lie than to deliver ten new ones.

• The experience from fighting tobacco science denialism shows that it is highly efficient to expose the hidden operations, funding and motives behind denialism.

• As many scientists as possible should take part in the public defence of climate science. This is one of the best ways to show our consensus.