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Huaraz, Peru

Rabatel A.,CNRS Laboratory for Glaciology and Environmental Geophysics | Francou B.,Grenoble Institute of Technology | Soruco A.,UMSA | Gomez J.,ANA | And 25 more authors.
Cryosphere | Year: 2013

The aim of this paper is to provide the community with a comprehensive overview of the studies of glaciers in the tropical Andes conducted in recent decades leading to the current status of the glaciers in the context of climate change. In terms of changes in surface area and length, we show that the glacier retreat in the tropical Andes over the last three decades is unprecedented since the maximum extension of the Little Ice Age (LIA, mid-17th-early 18th century). In terms of changes in mass balance, although there have been some sporadic gains on several glaciers, we show that the trend has been quite negative over the past 50 yr, with a mean mass balance deficit for glaciers in the tropical Andes that is slightly more negative than the one computed on a global scale. A break point in the trend appeared in the late 1970s with mean annual mass balance per year decreasing from -0.2 m w.e. in the period 1964-1975 to -0.76 m w.e. in the period 1976-2010. In addition, even if glaciers are currently retreating everywhere in the tropical Andes, it should be noted that this is much more pronounced on small glaciers at low altitudes that do not have a permanent accumulation zone, and which could disappear in the coming years/decades. Monthly mass balance measurements performed in Bolivia, Ecuador and Colombia show that variability of the surface temperature of the Pacific Ocean is the main factor governing variability of the mass balance at the decadal timescale. Precipitation did not display a significant trend in the tropical Andes in the 20th century, and consequently cannot explain the glacier recession. On the other hand, temperature increased at a significant rate of 0.10 C decade-1 in the last 70 yr. The higher frequency of El Niño events and changes in its spatial and temporal occurrence since the late 1970s together with a warming troposphere over the tropical Andes may thus explain much of the recent dramatic shrinkage of glaciers in this part of the world. © Author(s) 2013. CC Attribution 3.0 License. Source

Silk-Eglit G.M.,University at Albany | Stenclik J.H.,University at Albany | Miele A.S.,Brown University | Lynch J.K.,ANA | McCaffrey R.J.,University at Albany
Applied Neuropsychology:Adult | Year: 2015

Several studies have documented improvements in the classification accuracy of performance validity tests (PVTs) when they are combined to form aggregated models. Fewer studies have evaluated the impact of aggregating additional PVTs and changing the classification threshold within these models. A recent Monte Carlo simulation demonstrated that to maintain a false-positive rate (FPR) of ≤.10, only 1, 4, 8, 10, and 15 PVTs should be analyzed at classification thresholds of failing at least 1, at least 2, at least 3, at least 4, and at least 5 PVTs, respectively. The current study sought to evaluate these findings with embedded PVTs in a sample of real-life litigants and to highlight a potential danger in analytic flexibility with embedded PVTs. Results demonstrated that to maintain an FPR of ≤.10, only 3, 7, 10, 14, and 15 PVTs should be analyzed at classification thresholds of failing at least 1, at least 2, at least 3, at least 4, and at least 5 PVTs, respectively. Analyzing more than these numbers of PVTs resulted in a dramatic increase in the FPR. In addition, in the most extreme case, flexibility in analyzing and reporting embedded PVTs increased the FPR by 67%. Given these findings, a more objective approach to analyzing and reporting embedded PVTs should be introduced. Copyright © Taylor & Francis Group, LLC. Source

Callede J.,Brazilian Radiological Protection and Dosimetry Institute (IRD) | Cochonneau G.,University of Brasilia | Ronchail J.,French National Center for Scientific Research | Vieira Alves F.,ANA | And 3 more authors.
Revue des Sciences de l'Eau | Year: 2010

e mean interannual discharge of the River Amazon in the Atlantic Ocean has been estimated using two methods, independent but complementary After having de ned, in the most logical way, the eastern limit of the Amazon basin, the v\ater balance from Óbidos was established for the 1972-2003 period, e mean interannual discharge at the mouth wouldbe 205,000 m3s-1. A second method was based on ten sets of ow measurements done at the mouth from 1997 to 2008, which correlated very well with the corresponding discharge values observed in Óbidos, is method indicates an interannual ow at the mouth of 208,000 m3 s-1, including 6,000 m3 s -1 that represent the derivation from the Amazon River towards Rio Pará (and the Ocean) by the furos, channels that run in the River Amazon's old arm, With an uncertainty of ± 6%, the interannual contributions of the River Amazon to the Ocean, over the 1972-2003 period, would be 206,000 m3 s-1, and would represent 17% of the total volume of fresh water entering the oceans worldwide. Source

Schauwecker S.,Meteodat GmbH | Schauwecker S.,University of Zurich | Rohrer M.,Meteodat GmbH | Acuna D.,SENAMHI | And 11 more authors.
Global and Planetary Change | Year: 2014

The total glacial area of the Cordillera Blanca, Peru, has shrunk by more than 30% in the period of 1930 to the present with a marked glacier retreat also in the recent decades. The aim of this paper is to assess local air temperature and precipitation changes in the Cordillera Blanca and to discuss how these variables could have affected the observed glacier retreat between the 1980s and present. A unique data set from a large number of stations in the region of the Cordillera Blanca shows that after a strong air temperature rise of about 0.31. °C per decade between 1969 and 1998, a slowdown in the warming to about 0.13. °C per decade occurred for the 30. years from 1983 to 2012. Additionally, based on data from a long-term meteorological station, it was found that the freezing line altitude during precipitation days has probably not increased significantly in the last 30. years. We documented a cooling trend for maximum daily air temperatures and an increase in precipitation of about 60. mm/decade since the early 1980s. The strong increase in precipitation in the last 30. years probably did not balance the increase of temperature before the 1980s. It is suggested that recent changes in temperature and precipitation alone may not explain the glacial recession within the thirty years from the early 1980s to 2012. Glaciers in the Cordillera Blanca may be still reacting to the positive air temperature rise before 1980. Especially small and low-lying glaciers are characterised by a serious imbalance and may disappear in the near future. © 2014 Elsevier B.V. Source

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