Determination of the Turbulent Temperature–Humidity Correlation from Scintillometric Measurements

We report on the investigation and successful application of the bichromatic correlation of optical and microwave signals for determining the area-averaged correlation of temperature–humidity fluctuations. The additional technical effort is marginal compared to the common ‘two-wavelength method’, which has (in contrast) the restriction that only two of the three relevant meteorological structure parameters can be deduced. Therefore, in the past, it was often assumed that the turbulent humidity and temperature fluctuations are perfectly positively or negatively correlated. However, as shown in this study, over non-homogeneous terrain when the flow conditions are not ideal, this assumption is questionable. The measurements were analysed statistically, and were compared to in situ measurements of the Bowen ratio Bo and the correlation of temperature–humidity fluctuations using eddy-covariance techniques. The latter is in good agreement to that derived by scintillometry. We found that the correlation is not ±1 but as low as −0.6 for Bo smaller than −2, and up to 0.8 for Bo larger than 1.     

Climatically induced lake level changes during the last two millennia as reflected in sediments of Laguna Potrok Aike,southern Patagonia (Santa Cruz,Argentina)

The volcanogenic lake Laguna Potrok Aike, Santa Cruz, Argentina, reveals an unprecedented continuous high resolution climatic record for the steppe regions of southern Patagonia. With the applied multi-proxy approach rapid climatic changes before the turn of the first millennium were detected followed by medieval droughts which are intersected by moist and/or cold periods of varying durations and intensities. The total inorganic carbon content was identified as a sensitive lake level indicator. This proxy suggests that during the late Middle Ages (ca. AD 1230–1410) the lake level was rather low representing a signal of the Medieval Climate Anomaly in southeastern Patagonia. At the beginning of the Little Ice Age the lake level rose considerably staying on a high level during the whole period. Subsequently, the lake level lowered again in the course of the 20th century.     

Investigations into a small fraction of volatile hydrocarbons: I. Contamination of Atlantic and Baltic Sea surface waters with C3-alkylated benzenes

A uniform pattern of alkylated benzenes was encountered in water samples from a transect through the Baltic Sea and the central Atlantic. The data resembled findings of others at a coastal sampling site. The distribution of alkylated benzenes appears to be dominated by large-scale transport in the atmosphere and in water masses.     

Total atmospheric ozone measured by ground based high resolution infrared spectra-comparison with dobson measurements

Total atmospheric ozone has been measured at the “Observatoire de Haute-Provence”, Chiran Station, 1905 m high with a ground based, high resolution i.r. spectrometer, using the Sun as a source. Results are compared with a Dobson spectrophotometer which has been calibrated and intercompared with a standard. Total ozone values found with Dobson are 4% lower than values given by i.r. measurements. In addition, a negative correlation between total ozone and tropopause height has been found.     

Trace element study of high- and low-refractive index Muong Nong-type tektites from Indochina

Abstract— Previous work indicates that Muong Nong-type tektites from Indochina with low refractive indices and high silica contents contain relict mineral grains while those with high refractive indices and low silica contents do not. Instrumental Neutron Activation Analysis (INAA) was used to determine selected trace element concentrations for four Muong Nong-type tektites with high refractive indices and no relict mineral inclusions and one with low refractive index and relict inclusions, to determine if there are any systematic differences in trace element compositions between the two groups. The data also were compared with published trace element data for sixteen Muong Nong-type tektites which have low refractive indices and, therefore, should contain relict inclusions. Except for Ta which had lower concentrations in the high refractive index group, there is no consistent difference in trace element compositions between the two groups. We interpret these results to indicate a single, slightly heterogeneous source for the Muong Nong-type tektites, rather than different source regions.     

New estimations of precipitation and surface sublimation in East Antarctica from snow accumulation measurements

Surface mass balance (SMB) distribution and its temporal and spatial variability is an essential input parameter in mass balance studies. Different methods were used, compared and integrated (stake farms, ice cores, snow radar, surface morphology, remote sensing) at eight sites along a transect from Terra Nova Bay (TNB) to Dome C (DC) (East Antarctica), to provide detailed information on the SMB. Spatial variability measurements show that the measured maximum snow accumulation (SA) in a 15 km area is well correlated to firn temperature. Wind-driven sublimation processes, controlled by the surface slope in the wind direction, have a huge impact (up to 85% of snow precipitation) on SMB and are significant in terms of past, present and future SMB evaluations. The snow redistribution process is local and has a strong impact on the annual variability of accumulation. The spatial variability of SMB at the kilometre scale is one order of magnitude higher than its temporal variability (20–30%) at the centennial time scale. This high spatial variability is due to wind-driven sublimation. Compared with our SMB calculations, previous compilations generally over-estimate SMB, up to 65% in some areas.     

Crustal attenuation for Jamaica, West Indies

The S and coda wave spectra of small earthquakes on the island of Jamaica were used to determine the near surface and coda Q attenuation, and Q _c,respectively. Q _c determined by the single-station method was found in the range of 1 to 10 Hertz to be given by the relationship, Q _c= 60 ± 5f ^0.87±0.05. This suggests that the Jamaican crust is highly attenuating which is further supported by the observation of rapid intensity fall-off with distance for earthquakes that have affected the island in the past. , determined from S-wave spectra with short travel times was found to be 0.058 ± 0.012 on the central crustal block, which makes up nearly two-thirds of the island, and 0.080 ± 0.014 in surrounding belt sub-regions. The pattern of values seems to fit with the surface geology in that the central block has areas of exposed outcrops of older and harder rock than the belts, which are characterized by thicker sedimentary sequences as well as intense fracturing and faulting.Atkinson and Boore (1998) and Atkinson(2001) presented an alternative method to stochastic modelling for ground motion in Eastern North America, whereby California attenuation relationships were modified to account for crustal differences invelocity-depth profile, Q and between both regions. Following their example, the California spectral attenuation relation of Boore, Joyner and Fumal (1997) was modified to account for differences between the California and Jamaica crust, resulting in an attenuation relation that is deemed to be more appropriate for Jamaica. Spectral accelerations for Jamaica when compared to California, are especially reduced beyond 20 km from the source and at high frequencies, f 1 hertz.The study concludes that the Jamaican crust, although having an oceanic composition is highly attenuating, which may be a result of intensive tectonic processes, whereas is consistent with near-rock conditions on the central block and soft rock conditions elsewhere on the island.     

Reconstruction of palaeohydrological conditions in a lagoon during the 2nd Zechstein cycle through simultaneous use of δD values of individual n-alkanes and δ<Superscript>18</Superscript>O and δ<Superscript>13</Superscript>C values of carbonates

For the first time ¹⁸O and ¹³C values from carbonates and D values of individual n-alkanes were used to reconstruct palaeohydrological conditions in a lagoon at the southern margin of the Central European Zechstein Basin (CEZB). A 12-m core covering the complete Ca2 interval and adjacent anhydrites (A1 and A2) was analyzed for ¹⁸O and ¹³C values of dolomitized carbonates and D values of individual n-alkanes. ¹⁸O_carb values (+2 to +5 vs. VPDB) were strongly influenced by evaporation and temporal freshwater input into the lagoon. The ¹³C_carb values (–1 to +4 vs. VPDB) were controlled mainly by changes in primary production. Both isotopic ratios show an inverse relationship throughout most of the core, contradicting diagenetic alteration, since ¹³C_carb values are not altered significantly during dolomitization. Assuming a temperature range of 35–40 °C in the lagoon, ¹⁸O_carb values of +2.5 to +8 (vs. VSMOW) for the lagoonal water can be reconstructed. The lagoon may have desiccated twice during the Ca2 interval, as indicated by very high ¹⁸O_carb and low ¹³C_carb values, coinciding with increasing amount of anhydrite in the analyzed sample. These events seem to reflect not just local but a regional intra-Ca2 cyclicity. Measured D values of the short-chain n-alkanes, namely n-C₁₆ and n-C₁₈ which are widely used as indicators for photosynthetic bacterial and algal input, reflect the isotopic composition of the lagoonal water. Assuming constant fractionation during incorporation of hydrogen into lipids of –160, an average D value of +70 (vs. VSMOW) can be reconstructed for the lagoonal water, accounting for very arid conditions. The long-chain n-alkanes n-C₂₇, n-C₂₈, n-C₂₉ and n-C₃₀, thought to be derived from the leaf waxes of terrestrial higher plants, were shown to be depleted in D relative to the short-chain alkanes, therefore indicating a different hydrogen source. Terrestrial plants in arid areas mainly use water supplied by precipitation. By using a smaller fractionation of –120 due to evaporation processes in the leaves, reconstructed values vary between –74 and –9 (vs. VSMOW). These values are not indicating extremely arid conditions, implying that the long-chain n-alkanes were transported trough wind and/or rivers into the lagoon at the Zechstein Sea coast. D_water values, reconstructed using the n-C₁₆ alkane and ¹⁸O _water values, independently reconstructed on the same sample using the temperature dependant fractionation for dolomites are good agreement and suggest high amounts of evaporation affecting the coastal lagoon. Altogether, our results indicate that hydrogen isotopic ratios of n-alkanes give information on their origin and are a useful proxy for palaeoclimatic reconstruction.     

Phthalate esters in the Kiel Bight

Phthalate plasticizers have been accumulated from filtered seawater by liquid—solid adsorption, and in suspended organic matter collected on glass-fibre filters. They were characterized by gas chromatographic retention indices and by their mass spectra. Single-ion detection, focused on m/e 149, was used as a selective and sensitive method to quantify different phthalate esters in Baltic seawater in the 1:10¹⁰–1:10¹¹ concentration range.