Aspect controls the survival of ice cliffs on debris-covered glaciers

Supraglacial ice cliffs exist on debris-covered glaciers worldwide, but despite their importance as melt hot spots, their life cycle is little understood. Early field observations had advanced a hypothesis of survival of north-facing and disappearance of south-facing cliffs, which is central for predicting the contribution of cliffs to total glacier mass losses. Their role as windows of energy transfer suggests they may explain the anomalously high mass losses of debris-covered glaciers in High Mountain Asia (HMA) despite the insulating debris, currently at the center of a debated controversy. We use a 3D model of cliff evolution coupled to very high-resolution topographic data to demonstrate that ice cliffs facing south (in the Northern Hemisphere) disappear within a few months due to enhanced solar radiation receipts and that aspect is the key control on cliffs evolution. We reproduce continuous flattening of south-facing cliffs, a result of their vertical gradient of incoming solar radiation and sky view factor. Our results establish that only north-facing cliffs are recurrent features and thus stable contributors to the melting of debris-covered glaciers. Satellite observations and mass balance modeling confirms that few south-facing cliffs of small size exist on the glaciers of Langtang, and their contribution to the glacier volume losses is very small (∼1%). This has major implications for the mass balance of HMA debris-covered glaciers as it provides the basis for new parameterizations of cliff evolution and distribution to constrain volume losses in a region where glaciers are highly relevant as water sources for millions of people

Including debris cover effects in a distributed model of glacier ablation

Distributed glacier melt models generally assume that the glacier surface consists of bare exposed ice and snow. In reality, many glaciers are wholly or partially covered in layers of debris that tend to suppress ablation rates. In this paper, an existing physically based point model for the ablation of debris-covered ice is incorporated in a distributed melt model and applied to Haut Glacier d’Arolla, Switzerland, which has three large patches of debris cover on its surface. The model is based on a 10 m resolution digital elevation model (DEM) of the area; each glacier pixel in the DEM is defined as either bare or debris-covered ice, and may be covered in snow that must be melted off before ice ablation is assumed to occur. Each debris-covered pixel is assigned a debris thickness value using probability distributions based on over 1000 manual thickness measurements. Locally observed meteorological data are used to run energy balance calculations in every pixel, using an approach suitable for snow, bare ice or debris-covered ice as appropriate. The use of the debris model significantly reduces the total ablation in the debris-covered areas, however the precise reduction is sensitive to the temperature extrapolation used in the model distribution because air near the debris surface tends to be slightly warmer than over bare ice. Overall results suggest that the debris patches, which cover 10% of the glacierized area, reduce total runoff from the glacierized part of the basin by up to 7%

Suitability of a constant air temperature lapse rate over an Alpine glacier: testing the Greuell and Böhm model as an alternative

Near-surface air temperature, typically measured at a height of 2 m, is the most important control on the energy exchange and the melt rate at a snow or ice surface. It is distributed in a simplistic manner in most glacier melt models by using constant linear lapse rates, which poorly represent the actual spatial and temporal variability of air temperature. In this paper, we test a simple thermodynamic model proposed by Greuell and Böhm in 1998 as an alternative, using a new dataset of air temperature measurements from along the flowline of Haut Glacier d'Arolla, Switzerland. The unmodified model performs little better than assuming a constant linear lapse rate. When modified to allow the ratio of the boundary layer height to the bulk heat transfer coefficient to vary along the flowline, the model matches measured air temperatures better, and a further reduction of the root-mean-square error is obtained, although there is still considerable scope for improvement. The modified model is shown to perform best under conditions favourable to the development of katabatic winds – few clouds, positive ambient air temperature, limited influence of synoptic or valley winds and a long fetch – but its performance is poor under cloudy conditions

Heterogeneous glacier thinning patterns over the last 40 years in Langtang Himal

Himalayan glaciers are losing mass at rates similar to glaciers elsewhere, but heavily debris-covered glaciers are receding less than debris-free glaciers or even have stable fronts. There is a need for multi-temporal mass balance data to determine if glacier wastage of debris-covered glaciers is accelerating. Here, we present glacier volume and mass changes of seven glaciers (5 partially debris-covered, 2 debris-free) in the upper Langtang catchment in Nepal of 28 different periods between 1974 and 2015 based on 8 digital elevation models (DEMs) derived from high-resolution stereo satellite imagery. We show that glacier volume decreased during all periods between 2006 and 2015 (2006–2015: −0.60 ± 0.34 m a−1) and at higher rates than between 1974 and 2006 (−0.28 ± 0.42 m a−1). However, the behavior of glaciers in the study area was highly heterogeneous, and the presence of debris itself does not seem to be a good predictor for mass balance trends. Debris-covered tongues have highly non-linear thinning profiles, and we show that local accelerations in thinning correlate with complex thinning patterns characteristic of areas with a high concentration of supraglacial cliffs and lakes. At stagnating glacier area near the glacier front, on the other hand, thinning rates may even decrease over time. We conclude that trends of glacier mass loss rates in this part of the Himalaya cannot be generalized, neither for debris-covered nor for debris-free glaciers

Contrasting climate change impact on river flows from high altitude catchments in the Himalayan and Andes Mountains

Mountain ranges are world’s natural water towers and provide water resources for millions of people. Yet, their hydrological balance and possible future changes in river flow remain poorly understood because of high meteorological variability, physical inaccessibility and the complex interplay between climate, cryosphere and hydrological processes. Here we use a state-of-the art glacio-hydrological model informed by data from high altitude observations and CMIP5 climate change scenarios to quantify the climate change impact on water resources of two contrasting catchments vulnerable to changes in the cryosphere. The two study catchments are located in the Central Andes of Chile and in the Nepalese Himalaya in close vicinity of densely populated areas. Although both sites reveal a strong decrease in glacier area, they show a remarkably different hydrological response to projected climate change. In the Juncal catchment in Chile runoff is likely to sharply decrease in the future and the runoff seasonality is sensitive to projected climatic changes. In the Langtang catchment in Nepal, future water availability is on the rise for decades to come with limited shifts between seasons. Owing to the high spatio-temporal resolution of the simulations and process complexity included in the modelling the response times and the mechanisms underlying the variations in glacier area and river flow can be well constrained. The projections indicate that climate change adaptation in Central Chile should focus on dealing with a reduction in water availability, whereas in Nepal preparedness for flood extremes should be the policy priority

Primeira ocorrência de Hypsipyla ferrealis (Lepidoptera: Pyralidae) em andiroba (Carapa guianensis) no Estado do Acre.

O óleo extraído das sementes de C. guianensis é um dos produtos florestais não madeireiros mais conhecidos da Amazônia e, com grande potencial de promover a valorização e o uso econômico da floresta. Este produto tem demanda internacional e é utilizado para iluminação, confecção de sabão e velas, na indústria de cosméticos, como repelente de insetos e na medicina popular. Dentre os principais insetos-praga associados à andirobeira no Brasil, estão os lepidópteros do gênero Hypsipyla, que podem atacar os ponteiros e frutos das árvores, comprometendo a dispersão de sementes e a qualidade do óleo produzido

Design, Development and Testing of the GMI Launch Locks

Ball Aerospace will deliver the GPM Microwave Imager (GMI), to NASA as one of the 3 instruments to fly on the Global Precipitation Measurement (GPM) mission, for launch in 2013. The radiometer, when deployed, is over 8 feet tall and rotates at 32 revolutions per minute (RPM) can be described as a collection of mechanisms working to achieve its scientific objectives. This collection precisely positions a 1.2 meter reflector to a 48.5 degree off nadir angle while rotating, transferring electrical power and signals to and from the RF receivers, designs two very stable calibration sources, and provides the structural integrity of all the components. There are a total of 7 launch restraints coupling across the moving and stationary elements of the structure,. Getting from design to integration will be the focus of this paper

Trabalho Feminino no Setor de Call Center

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Sócio-Econômico. Economia.Nas últimas décadas as relações de trabalho sofreram e estão sofrendo alterações que se refere à inserção da mulher no mercado de trabalho. O trabalho feminino que é majoritariamente utilizado no setor de serviços por se tratar de urna mão-de-obra mais qualificada e por possuir competências diferentes da mão-de-obra masculina, como as competências voltadas para o gerenciamento de pessoas. Um ramo do setor de serviços que utiliza basicamente mão-de-obra feminina para a maioria das funções é o setor de Call Center. 0 presente estudo tem como objetivo caracterizar o trabalho feminino no setor de Call Center, para isso, foi realizada uma revisão na literatura sobre as transformações no mundo do trabalho; foi analisada a evolução da participação feminina no mercado de trabalho brasileiro de 2001 a 2005; foi feita uma caracterização do setor de Call Center: e foi realizado um estudo de caso em uma empresa de Call Center de Florianópolis, visando caracterizar o perfil dos operadores de telemarketing, verificando as possibilidades de crescimento profissional que o setor possibilita. A pesquisa caracteriza-se como descritiva na medida em que busca levantar dados sobre o trabalho feminino no setor de Call Center e assume a forma de estudo de caso. 0 universo da pesquisa limitou-se a uma grande empresa de Call Center de Florianópolis a Softway Contact Center, Unidade Praça XV, com aproximadamente 1228 funcionários. levantamento de dados permitiu caracterizar o perfil dos operadores de Call Center que é na maioria formado por mulheres (70% dos funcionários do Call Center são do sexo feminino), muito jovens com menos de 24 anos, e com segundo grau completo, a maior parte das entrevistadas estão satisfeitas com o trabalho que realizam e com a possibilidade de crescimento profissional que o setor possibilita, por se tratar de pessoas muito jovens, utilizam o setor de Call Center como porta de entrada para o mercado de trabalho. Este setor permite um grande crescimento profissional através da possibilidade de estudar, por se tratar de um emprego de 6 horas e no caso da Softway por possuir a Universidade Corporativa e adquirindo experiência profissional que o mercado de trabalho exige