Coastal lagoons and beach ridges as complementary sedimentary archives for the reconstruction of Holocene relative sea‐level changes

Coastal lagoons and beach ridges are genetically independent, though non‐continuous, sedimentary archives. We here combine the results from two recently published studies in order to produce an 8000‐year‐long record of Holocene relative sea‐level changes on the island of Samsø, southern Kattegat, Denmark. The reconstruction of the initial mid‐Holocene sea‐level rise is based on the sedimentary infill from topography‐confined coastal lagoons (Sander et al., Boreas, 2015b). Sea‐level index points over the mid‐ to late Holocene period of sea‐level stability and fall are retrieved from the internal structures of a wide beach‐ridge system (Hede et al., The Holocene, 2015). Data from sediment coring, georadar and absolute dating are thus combined in an inter‐disciplinary approach that is highly reproducible in micro‐tidal environments characterised by high sediment supply. We show here that the commonly proximate occurrence of coastal lagoons and beach ridges allows us to produce seamless time series of relative sea‐level changes from field sites in SW Scandinavia and in similar coastal environments.     

Early‐middle Holocene land snail shell stable isotope record from Grotta di Latronico 3 (southern Italy)

This paper compares stable isotope (δ¹⁸O and δ¹³C) records of early–middle Holocene land snail shells from the archaeological deposits of Grotta di Latronico 3 (LTR3; southern Italy) with modern shell isotopic data. No substantial interspecific variability was observed in shell δ¹⁸O (δ¹⁸Os) of modern specimens (Pomatias elegans, Cornu aspersum, Eobania vermiculata, Helix ligata and Marmorana fuscolabiata). In contrast, interspecific shell δ¹³C (δ¹³Cs) variability was significant, probably due to different feeding behaviour among species. The δ¹⁸Os values of living land snails suggest that species hibernate for a long period during colder months, so that the signal of ¹⁸O‐depleted winter rainfall in their δ¹⁸Os is lost. This suggests that δ¹⁸Os and δ¹³Cs values of Pomatias elegans from this archaeological succession provide valuable clues for seasonal (spring–autumn) climatic conditions during the early–middle Holocene. The δ¹⁸Os values of fossil specimens are significantly lower than in modern shells and in agreement with other palaeoclimatic records, suggesting a substantial increase of precipitation and/or persistent changes in air mass source trajectories over this region between ca. 8.8 cal ka BP and 6.2–6.7 ka ago. The δ¹³Cs trend suggests a transition from a slightly ¹³C‐enriched to a ¹³C‐depleted diet between early and middle Holocene compared to present conditions. We postulate that this δ¹³Cs trend might reflect changes in the C3 vegetation community, potentially combined with other environmental factors such as regional moisture increase and the progressive decrease of atmospheric CO₂ concentration. Copyright © 2010 John Wiley & Sons, Ltd.     

Long-term variability of UV radiation in the spectral range of 300–380 nm in Moscow

The seasonal and interannual variability of global ultraviolet (UV) radiation in the spectral range of 300-380 nm (0380) in Moscow in 1968-2014 is analyzed. The effect of cloudiness on the magnitude of 0380 is assessed. The smallest (-22...-26%) losses due to cloudiness are registered in May-August, and the highest ones (to -45%) are observed in October-November. According to the UV radiation reconstruction model and measurement data, the long-term deviations of 0380 from the average (for 1968-1997) due to clouds can reach + (11-12)%. The statistically significant positive linear trend in total annual 0380 is revealed from the data of both the reconstruction model and observations (about 1.5% per decade for 1968-2014 and 3% per decade for 1979-2014).     

Some observations and characteristics of lightning ground discharges in southern Ontario

Abstract

Lightning ground flash and stroke observations were made with a single‐station gated, wideband magnetic direction‐finding system with a nominal range of 180 km located in Southern Ontario during the May‐September lightning‐active seasons of 1982 and 1983. Information was recorded on the azimuth of arrival, time, amplitude, stroke multiplicity and order, and polarity. The local climatology and seasonal statistics of lightning are analysed and summarized, and compared with standard observations of thunderstorm days and hours. Regional daily flashing rates and extremes for periods of 5 to 60 min were found to have a good empirical relationship. About 15% of the flashes had multiple strokes, generally less than 10 but with as many as 14 strokes. About 8% of the flashes were positive discharges; 3% of these were multistroke with no more than 2 strokes.

The lightning activity exhibits well defined diurnal peaks in the afternoon and at night 1–3 h before sunrise. The time interval between strokes was found to have a lognormal distribution with modal and median values of 60 and 75 ms, respectively, and no significant dependence on the order of stroke. The stroke‐to‐stroke amplitude changes within the same flash show that subsequent stroke amplitudes are often greater than the first. Subsequent strokes follow many patterns of change, the most common being an amplitude oscillating with ascending stroke order. The multistroke flash duration median values rose from about 80 ms for 2‐stroke flashes to about 650 ms for 8‐stroke flashes.

Under certain assumptions of system detection efficiency and range limits a regional ground flash density of 1.62 and 2.44 km^?2 a^?1 was estimated for the two years.     

The effect of the atmosphere on the propagation of high-power ultrabroadband microwave emission pulses

The effect of the atmosphere on the propagation of single successive pulses of the ultrabroadband microwave emission has been calculated in detail. It has been indicated that nonlinear effects mainly influence the propagation of the LF pulse part in the absence of divergence, which substantially affects the propagation of the following pulses.     

A laboratory study of the turbulent ekman layer

Abstract

Comparing characteristics of a turbulent Ekman boundary layer in a rotating apparatus with atmospheric observations and theories, we find that the similarity relations derived by Kazanski and Monin, and others, scale both laboratory and field data quite well, especially considering that the Coriolis parameter is larger by a factor of 10⁵ in the experiment than it is in the atmosphere. Eddy viscosity models and Deardorff's numerical model predict the properties of both with varying degrees of success. High frequency spectra of velocity fluctuations scale with the Kolmogoroff length and time scales. Both magnitude and direction of the surface shear stress were measured directly, with a heated film stress gauge.     

Statutes and Bye-laws of the International Association of Hydrological Sciences

Abstract

A baseflow recession constant, which can be derived from a simple exponential equation, is used to characterize the behaviour of low flows. Its derivation and quantification is important to the water industry. The use of a computer statistical package that speeds up its derivation has been tried and found to be more effective than the present tedious manual and subjective techniques. It is therefore advocated in this paper.     

Selection and quality assessment of Landsat data for the North American forest dynamics forest history maps of the US

Using the NASA Earth Exchange platform, the North American Forest Dynamics (NAFD) project mapped forest history wall-to-wall, annually for the contiguous US (1986–2010) using the Vegetation Change Tracker algorithm. As with any effort to identify real changes in remotely sensed time-series, data gaps, shifts in seasonality, misregistration, inconsistent radiometry and cloud contamination can be sources of error. We discuss the NAFD image selection and processing stream (NISPS) that was designed to minimize these sources of error. The NISPS image quality assessments highlighted issues with the Landsat archive and metadata including inadequate georegistration, unreliability of the pre-2009 L5 cloud cover assessments algorithm, missing growing-season imagery and paucity of clear views. Assessment maps of Landsat 5–7 image quantities and qualities are presented that offer novel perspectives on the growing-season archive considered for this study. Over 150,000+ Landsat images were considered for the NAFD project. Optimally, one high quality cloud-free image in each year or a total of 12,152 images would be used. However, to accommodate data gaps and cloud/shadow contamination 23,338 images were needed. In 220 specific path-row image years no acceptable images were found resulting in data gaps in the annual national map products.