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Carlos Pires
University of Lisbon
StatisticsMathematical optimizationEconometricsMathematicsPrinciple of maximum entropy
36Publications
10H-index
496Citations
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Publications 37
Newest
#1Rui A. P. PerdigãoH-Index: 12
#2Carlos PiresH-Index: 10
Last. Julia HallH-Index: 10
view all 3 authors...
Source
#1Andreia F. S. Ribeiro (University of Lisbon)H-Index: 4
#2Ana Russo (University of Lisbon)H-Index: 12
Last. Carlos Pires (University of Lisbon)H-Index: 10
view all 5 authors...
Abstract. Extreme weather events, such as droughts, have been increasingly affecting the agricultural sector causing several socio-economic consequences. The growing economy requires improved assessments of drought-related impacts in agriculture, particularly under a climate that is getting drier and warmer. This work proposes a probabilistic model which intends to contribute to the agricultural drought risk management in rainfed cropping systems. Our methodology is based on a bivariate copula-a...
Source
#1Paula Paredes (IPN: Instituto Politécnico Nacional)H-Index: 19
#2Diogo S. Martins (Instituto Superior de Agronomia)H-Index: 7
Last. Carlos Pires (University of Lisbon)H-Index: 10
view all 5 authors...
Abstract This study aims at assessing the accuracy of estimating daily grass reference evapotranspiration (PM-ETo) computed with ERA-Interim reanalysis products, as well as to assess the quality of reanalysis products as predictors of daily maximum and minimum temperature, net radiation, dew point temperature and wind speed, which are used to compute PM-ETo. With this propose, ETo computed from local observations of weather variables in 24 weather stations distributed across Continental Portugal...
2 CitationsSource
#1Rui A. P. PerdigãoH-Index: 12
#2Julia HallH-Index: 10
Last. Günter BlöschlH-Index: 78
view all 4 authors...
#1Diogo S. Martins (Instituto Superior de Agronomia)H-Index: 7
#2Paula Paredes (Instituto Superior de Agronomia)H-Index: 19
Last. Luis S. Pereira (University of Lisbon)H-Index: 54
view all 6 authors...
Computing crop reference evapotranspiration (ETo) with the FAO Penman–Monteith method (PM-ETo) requires maximum and minimum air temperature, shortwave radiation, relative air humidity and wind speed. These data are often not available, thus requiring alternative computation procedures. Although some proposed approximations may provide ETo values with small estimation errors, the physics of the ET processes may then not be well described. The use of reanalysis data, which is common in climate stu...
8 CitationsSource
#1Carlos Pires (University of Lisbon)H-Index: 10
#2Andreia F. S. Ribeiro (University of Lisbon)H-Index: 4
We develop an expansion of space-distributed time series into statistically independent uncorrelated subspaces (statistical sources) of low-dimension and exhibiting enhanced non-Gaussian probability distributions with geometrically simple chosen shapes (projection pursuit rationale). The method relies upon a generalization of the principal component analysis that is optimal for Gaussian mixed signals and of the independent component analysis (ICA), optimized to split non-Gaussian scalar sources....
8 CitationsSource
We propose an expansion of multivariate time-series data into maximally independent source subspaces. The search is made among rotations of prewhitened data which maximize non-Gaussianity of candidate sources. We use a tensorial invariant approximation of the multivariate negentropy in terms of a linear combination of squared coskewness and cokurtosis. By solving a high-order singular value decomposition problem, we extract the axes associated with most non-Gaussianity. Moreover, an estimate of ...
4 CitationsSource
#1Rui A. P. PerdigãoH-Index: 12
#2Carlos PiresH-Index: 10
Last. Julia HallH-Index: 10
view all 3 authors...
We formulate a nonlinear synergistic theory of coevolutionary systems, disentangling and explaining dynamic complexity in terms of fundamental processes for optimised data analysis and dynamic model design: Dynamic Source Analysis (DSA). DSA provides a nonlinear dynamical basis for spatiotemporal datasets or dynamical models, eliminating redundancies and expressing the system in terms of the smallest number of fundamental processes and interactions without loss of information. This optimises mod...
2 Citations
#1Andreia F. S. Ribeiro (University of Lisbon)H-Index: 4
#2Carlos Pires (University of Lisbon)H-Index: 10
Abstract Atmospheric forecasting and predictability are important to promote adaption and mitigation measures in order to minimize drought impacts. This study estimates hybrid (statistical–dynamical) long-range forecasts of the regional drought index SPI (3-months) over homogeneous regions from mainland Portugal, based on forecasts from the UKMO operational forecasting system, with lead-times up to 6 months. ERA-Interim reanalysis data is used for the purpose of building a set of SPI predictors ...
7 CitationsSource
#1Carlos PiresH-Index: 10
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