@article{RitterAngelesBurgosBoeckmannetal.2018, author = {Ritter, Christoph and {\´A}ngeles Burgos, Mar{\´i}a and B{\"o}ckmann, Christine and Mateos, David and Lisok, Justyna and Markowicz, Krzysztof M. and Moroni, Beatrice and Cappelletti, David and Udisti, Roberto and Maturilli, Marion and Neuber, Roland}, title = {Microphysical properties and radiative impact of an intense biomass burning aerosol event measured over Ny-angstrom lesund, Spitsbergen in July 2015}, series = {Tellus - Series B, Chemical and Physical Meteorology}, volume = {70}, journal = {Tellus - Series B, Chemical and Physical Meteorology}, publisher = {Routledge, Taylor \& Francis Group}, address = {Abingdon}, issn = {1600-0889}, doi = {10.1080/16000889.2018.1539618}, pages = {23}, year = {2018}, abstract = {In this work, an evaluation of an intense biomass burning event observed over Ny-angstrom lesund (Spitsbergen, European Arctic) in July 2015 is presented. Data from the multi-wavelengths Raman-lidar KARL, a sun photometer and radiosonde measurements are used to derive some microphysical properties of the biomass burning aerosol as size distribution, refractive index and single scattering albedo at different relative humidities. Predominantly particles in the accumulation mode have been found with a bi-modal distribution and dominance of the smaller mode. Above 80\% relative humidity, hygroscopic growth in terms of an increase of particle diameter and a slight decrease of the index of refraction (real and imaginary part) has been found. Values of the single scattering albedo around 0.9 both at 355nm and 532nm indicate some absorption by the aerosol. Values of the lidar ratio are around 26sr for 355nm and around 50sr for 532nm, almost independent of the relative humidity. Further, data from the photometer and surface radiation values from the local baseline surface radiation network (BSRN) have been applied to derive the radiative impact of the biomass burning event purely from observational data by comparison with a clear background day. We found a strong cooling for the visible radiation and a slight warming in the infra-red. The net aerosol forcing, derived by comparison with a clear background day purely from observational data, obtained a value of -95 W/m(2) per unit AOD500.}, language = {en} } @article{GrieveHalesParkeretal.2018, author = {Grieve, Stuart W. D. and Hales, Tristram C. and Parker, Robert N. and Mudd, Simon M. and Clubb, Fiona J.}, title = {Controls on Zero-Order Basin Morphology}, series = {Journal of geophysical research : Earth surface}, volume = {123}, journal = {Journal of geophysical research : Earth surface}, number = {12}, publisher = {American Geophysical Union}, address = {Washington}, issn = {2169-9003}, doi = {10.1029/2017JF004453}, pages = {3269 -- 3291}, year = {2018}, abstract = {Zero-order basins are common features of soil-mantled landscapes, defined as unchanneled basins at the head of a drainage network. Their geometry and volume control how quickly sediment may reaccumulate after landslide evacuation and, more broadly, zero order basins govern the movement of water and sediment from hillslopes to the fluvial network. They also deliver water and sediment to the uppermost portions of the fluvial network. Despite this role as the moderator between hillslope and fluvial processes, little analysis on their morphology has been conducted at the landscape scale. We present a method to identify zero-order basins in landscapes and subsequently quantify their geometric properties using elliptical Fourier analysis. We deploy this method across the Coweeta Hydrologic Laboratory, USA. Properties such as length, relief, width, and concavity follow distinct probability distributions, which may serve as a basis for testing predictions of future landscape evolution models. Surprisingly, in a landscape with an orographic precipitation gradient and large hillslope to channel relief, we observe no correlation between elevation or spatial location and basin geometry. However, we find that two physiographic units in Coweeta have distinct zero-order basin morphologies. These are the steep, thin soiled, high-elevation Nantahala Escarpment and the lower-gradient, lower-elevation, thick soiled remainder of the basin. Our results indicate that basin slope and area negatively covary, producing the distinct forms observed between the two physiographic units, which we suggest arise through competition between spatially variable soil creep and stochastic landsliding.}, language = {en} }