(Table 3) Air temperatures, and snow and ice characteristics of fresh and brackish water lakes in the Northwest Territories, Canada

The algorithms designed to estimate snow water equivalent (SWE) using passive microwave measurements falter in lake-rich high-latitude environments due to the emission properties of ice covered lakes on low frequency measurements. Microwave emission models have been used to simulate brightness temperatures (Tbs) for snowpack characteristics in terrestrial environments but cannot be applied to snow on lakes because of the differing subsurface emissivities and scattering matrices present in ice. This paper examines the performance of a modified version of the Helsinki University of Technology (HUT) snow emission model that incorporates microwave emission from lake ice and sub-ice water. Inputs to the HUT model include measurements collected over brackish and freshwater lakes north of Inuvik, Northwest Territories, Canada in April 2008, consisting of snowpack (depth, density, and snow water equivalent) and lake ice (thickness and ice type). Coincident airborne radiometer measurements at a resolution of 80x100 m were used as ground-truth to evaluate the simulations. The results indicate that subsurface media are simulated best when utilizing a modeled effective grain size and a 1 mm RMS surface roughness at the ice/water interface compared to using measured grain size and a flat Fresnel reflective surface as input. Simulations at 37 GHz (vertical polarization) produce the best results compared to airborne Tbs, with a Root Mean Square Error (RMSE) of 6.2 K and 7.9 K, as well as Mean Bias Errors (MBEs) of -8.4 K and -8.8 K for brackish and freshwater sites respectively. Freshwater simulations at 6.9 and 19 GHz H exhibited low RMSE (10.53 and 6.15 K respectively) and MBE (-5.37 and 8.36 K respectively) but did not accurately simulate Tb variability (R= -0.15 and 0.01 respectively). Over brackish water, 6.9 GHz simulations had poor agreement with airborne Tbs, while 19 GHz V exhibited a low RMSE (6.15 K), MBE (-4.52 K) and improved relative agreement to airborne measurements (R = 0.47). Salinity considerations reduced 6.9 GHz errors substantially, with a drop in RMSE from 51.48 K and 57.18 K for H and V polarizations respectively, to 26.2 K and 31.6 K, although Tb variability was not well simulated. With best results at 37 GHz, HUT simulations exhibit the potential to track Tb evolution, and therefore SWE through the winter season.

GPS raw data (control points and ground control points) from the Liguria Region, Borghetto Santo Spirito, Italy

Monitoring the impact of sea storms on coastal areas is fundamental to study beach evolution and the vulnerability of low-lying coasts to erosion and flooding. Modelling wave runup on a beach is possible, but it requires accurate topographic data and model tuning, that can be done comparing observed and modeled runup. In this study we collected aerial photos using an Unmanned Aerial Vehicle after two different swells on the same study area. We merged the point cloud obtained with photogrammetry with multibeam data, in order to obtain a complete beach topography. Then, on each set of rectified and georeferenced UAV orthophotos, we identified the maximum wave runup for both events recognizing the wet area left by the waves. We then used our topography and numerical models to simulate the wave runup and compare the model results to observed values during the two events. Our results highlight the potential of the methodology presented, which integrates UAV platforms, photogrammetry and Geographic Information Systems to provide faster and cheaper information on beach topography and geomorphology compared with traditional techniques without losing in accuracy. We use the results obtained from this technique as a topographic base for a model that calculates runup for the two swells. The observed and modeled runups are consistent, and open new directions for future research.

Geochemical studies of the Cretaceous-Tertiary boundary in ODP Holes 113-689B and 113-690C

In a study of ODP Hole 689B no iridium (Ir) anomaly was found in Sections 1 through 6 of Core 25X or in Core 26X from the top down to section 2, 3-12 cm. The background Ir abundance averaged 11 parts per trillion (ppt) and a clay-enriched region had nearly the same average, 26 ± 12 ppt. If the Cretaceous-Tertiary (K-T) contact is in the region studied, then sedimentation was not continuous, and the K-T boundary was probably either not deposited or it was eroded away. In a study of Cores 15X and 16X of ODP Hole 690C, an iridium peak with a maximum abundance of 1566 ± 222 ppt was found in Section 4 of Core 15X at 39-40 cm with a half-width of 6.6 cm. Background abundances were ~15 ppt and distinctly higher Ir abundances were observed from 119 cm below to 72 cm above the main peak. The Ir distribution below the main peak is attributed to bioturbation by organisms with burrows extending at least 0.4 m. The Ir distribution above the main peak may be due to the same cause but other explanations may be significant. There are variable enrichments of clay in the mainly CaCO3 sediment of Core 15X, and the stratigraphically lowest part of the most abundant clay deposits is found (within 2 cm) in the same position as the main Ir peak. The clay deposit, which is estimated to be about 50% of the sediment, extends upward ~19 cm and then slowly decreases to a background level of 10% over 1 m. The degree of homogeneity of the clay-rich interval suggests it was not due to episodic volcanism but may have been due to a decrease of the CaCO3 deposition rate which was possibly triggered by the impact of a large asteroid or comet on the Earth.