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Jozsef Szilagyi - One of the best experts on this subject based on the ideXlab platform.
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temperature corrections in the Priestley taylor equation of evaporation
Journal of Hydrology, 2014Co-Authors: Jozsef SzilagyiAbstract:Summary The Priestley–Taylor equation (PTE) is frequently applied in actual areal evapotranspiration (ET) estimation methods for obtaining the maximum daily rate of evaporation with data from sub-humid conditions. Since PTE was parameterized under humid conditions, a temperature correction is necessary to avoid overestimation of the maximum rate of ET. Wet-environment surface temperature (Tws), a proxy of the wet-environment air temperature (Twa), is estimated by the Szilagyi–Jozsa (SJ) approach as well as by a re-parameterized version of Monteith. The latter yields higher values but typically within 1 °C of the former. Tested by daily FLUXNET data, the estimates are only mildly sensitive to the mean daily wind velocity which thus can be replaced by a region-representative monthly average. From long-term simplified water-balances – plus monthly Moderate Resolution Imaging Spectroradiometer (MODIS) and ERA-Interim re-analysis data – the re-parameterized Monteith method appears to yield more accurate Tws estimates, while the PTE performs better with the SJ provided Tws values since they are closer to Twa, the PTE expects. Both methods require net radiation, air temperature, humidity and monthly mean wind velocity values plus ground heat fluxes when employed on a daily basis.
Jeanpaul Lhomme - One of the best experts on this subject based on the ideXlab platform.
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Matching the Budyko functions with the complementary evaporation relationship: consequences for the drying power of the air and the Priestley-Taylor coefficient
Hydrology and Earth System Sciences, 2016Co-Authors: Jeanpaul Lhomme, R. MoussaAbstract:The Budyko functions B-1(Phi(p))are dimensionless relationships relating the ratio E/P (actual evaporation over precipitation) to the aridity index Phi(p) = E-p/P (potential evaporation over precipitation). They are valid at catchment scale with E-p generally defined by Penman's equation. The complementary evaporation (CE) relationship stipulates that a decreasing actual evaporation enhances potential evaporation through the drying power of the air which becomes higher. The Turc-Mezentsev function with its shape parameter lambda, chosen as example among various Budyko functions, is matched with the CE relationship, implemented through a generalised form of the advection-aridity model. First, we show that there is a functional dependence between the Budyko curve and the drying power of the air. Then, we examine the case where potential evaporation is calculated by means of a Priestley-Taylor type equation (E-0) with a varying coefficient alpha(0). Matching the CE relationship with the Budyko function leads to a new transcendental form of the Budyko function B-1'(Phi(0)) linking E/P to Phi(0) = E-0/P. For the two functions B-1(Phi(p)) and B-1'(Phi(0) ) to be equivalent, the Priestley-Taylor coefficient alpha(0) should have a specified value as a function of the Turc-Mezentsev shape parameter and the aridity index. This functional relationship is specified and analysed.
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an examination of the Priestley taylor equation using a convective boundary layer model
Water Resources Research, 1997Co-Authors: Jeanpaul LhommeAbstract:The effect of large-scale parameters on the behavior of the Priestley-Taylor coefficient is addressed by means of a simple analytical model of the convective boundary layer (CBL). In this model, surface and aerodynamic resistances are maintained constant throughout daytime, and the diurnal course of available energy is parameterized in the form of a parabolic curve. To account for entrainment of overlying air, the height of the CBL is assumed to grow as square root of time, and the water vapor saturation deficit in the undisturbed atmosphere above the CBL is represented by a simple linear profile. The Priestley-Taylor coefficient is defined as the ratio of potential evaporation over equilibrium evaporation, and two different ways of defining potential evaporation are considered: (1) as the evaporation of an extensive saturated area (i.e., the whole region influencing the CBL) or (2) as the evaporation of a limited saturated area (small enough that the excess moisture does not modify the characteristics of the CBL). These two ways, called respectively Penman's and Morton's ways, are successively examined. Numerical simulations from the CBL model show that the Priestley-Taylor coefficient (α) does not have a fixed and universal value (1.26) as it has been suggested by these authors. When based on Penman's concept of potential evaporation, α varies as a function of the conditions in the undisturbed atmosphere above the CBL (inversion strength) but also as a function of the characteristics of the surface (aerodynamic resistance). The additional energy implied by a coefficient greater than 1 has to be ascribed only to the entrainment effect. When based on Morton's concept, α depends upon the areal surface resistance and the external conditions above the CBL: The daily mean value of α increases asymptotically with areal surface resistance towards a limit value which grows with inversion strength. In this case the additional energy (implied by α > 1) has a double origin: the feedback of areal evaporation on local potential evaporation and the entrainment effect.
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a theoretical basis for the Priestley taylor coefficient
Boundary-Layer Meteorology, 1997Co-Authors: Jeanpaul LhommeAbstract:The relationship between potential evaporation and arealevaporation is assessed using a closed-box model of the convectiveboundary layer (CBL). Potential evaporation is defined as theevaporation that would occur from a hypothetical saturated surface,with radiative properties similar to those of the whole area, and smallenough that the excess moisture flux does not modify thecharacteristics of the CBL. It is shown that the equilibrium rate ofpotential evaporation is given by Ep0=αE0,where E0 is the equilibrium evaporation (radiative termof the Penman formula), and α is a coefficient similar to thePriestley-Taylor coefficient. Its expression is $$\alpha = 1 + \left[ {1/(\varepsilon + 1)} \right]\left( {\left\langle {r_s } \right\rangle /r_a } \right)$$ , where $$\left\langle {r_s } \right\rangle $$ is the areal surface resistance, ra is the localaerodynamic resistance, and e is the dimensionless slope of thesaturation specific humidity at the temperature of the air. Itscalculated value is around 1 for any saturated surface surrounded bywater, about 1.3 for saturated grass surrounded by well-watered grassand can be greater than 3 over saturated forest surrounded by forest.The formulation obtained provides a theoretical basis to the overallmean value of 1.26, empirically found by Priestley and Taylor for thecoefficient α. Examining, at the light of this formulation, thecomplementary relationship between potential and actual evaporation(as proposed by Bouchet and Morton), it appears that the sum ofthese two magnitudes is not a constant at equilibrium, but depends onthe value of the areal surface resistance.
Guram Bezhanishvili - One of the best experts on this subject based on the ideXlab platform.
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Characterization of metrizable Esakia spaces via some forbidden configurations
Algebra universalis, 2019Co-Authors: Guram Bezhanishvili, Luca CaraiAbstract:By Priestley duality, each bounded distributive lattice is represented as the lattice of clopen upsets of a Priestley space, and by Esakia duality, each Heyting algebra is represented as the lattice of clopen upsets of an Esakia space. Esakia spaces are those Priestley spaces that satisfy the additional condition that the downset of each clopen is clopen. We show that in the metrizable case Esakia spaces can be singled out by forbidding three simple configurations. Since metrizability yields that the corresponding lattice of clopen upsets is countable, this provides a characterization of countable Heyting algebras. We show that this characterization no longer holds in the uncountable case. Our results have analogues for co-Heyting algebras and bi-Heyting algebras, and they easily generalize to the setting of p-algebras.
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lattice subordinations and Priestley duality
Algebra Universalis, 2013Co-Authors: Guram BezhanishviliAbstract:There is a well-known correspondence between Heyting algebras and S4-algebras. Our aim is to extend this correspondence to distributive lattices by defining analogues of S4-algebras for them. For this purpose, we introduce binary relations on Boolean algebras that resemble de Vries proximities. We term such binary relations lattice subordinations. We show that the correspondence between Heyting algebras and S4-algebras extends naturally to distributive lattices and Boolean algebras with a lattice subordination. We also introduce Heyting lattice subordinations and prove that the category of Boolean algebras with a Heyting lattice subordination is isomorphic to the category of S4-algebras, thus obtaining the correspondence between Heyting algebras and S4-algebras as a particular case of our approach.
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generalized Priestley quasi orders
Order, 2011Co-Authors: Guram Bezhanishvili, Ramon JansanaAbstract:We introduce generalized Priestley quasi-orders and show that subalgebras of bounded distributive meet-semilattices are dually characterized by means of generalized Priestley quasi-orders. This generalizes the well-known characteriza- tion of subalgebras of bounded distributive lattices by means of Priestley quasi- orders (Adams, Algebra Univers 3:216-228, 1973; Cignoli et al., Order 8(3):299- 315, 1991; Schmid, Order 19(1):11-34, 2002). We also introduce Vietoris families and prove that homomorphic images of bounded distributive meet-semilattices are dually characterized by Vietoris families. We show that this generalizes the well- known characterization (Priestley, Proc Lond Math Soc 24(3):507-530, 1972 )o f homomorphic images of a bounded distributive lattice by means of closed subsets of its Priestley space. We also show how to modify the notions of generalized Priestley quasi-order and Vietoris family to obtain the dual characterizations of subalgebras and homomorphic images of bounded implicative semilattices, which generalize the well-known dual characterizations of subalgebras and homomorphic images of Heyting algebras (Esakia, Sov Math Dokl 15:147-151, 1974).
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Priestley style duality for distributive meet semilattices
Studia Logica, 2011Co-Authors: Guram Bezhanishvili, Ramon JansanaAbstract:We generalize Priestley duality for distributive lattices to a duality for distributive meet-semilattices. On the one hand, our generalized Priestley spaces are easier to work with than Celani's DS-spaces, and are similar to Hansoul's Priestley structures. On the other hand, our generalized Priestley morphisms are similar to Celani's meet-relations and are more general than Hansoul's morphisms. As a result, our duality extends Hansoul's duality and is an improvement of Celani's duality.
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Priestley Rings and Priestley Order-Compactifications
Order, 2010Co-Authors: Guram Bezhanishvili, Patrick J. MorandiAbstract:We introduce Priestley rings of upsets (of a poset) and prove that inequivalent Priestley ring representations of a bounded distributive lattice L are in 1-1 correspondence with dense subspaces of the Priestley space of L. This generalizes a 1955 result of Bauer that inequivalent reduced field representations of a Boolean algebra B are in 1-1 correspondence with dense subspaces of the Stone space of B. We also introduce Priestley order-compactifications and Priestley bases of an ordered topological space, and show that they are in 1-1 correspondence. This generalizes a 1961 result of Dwinger that zero-dimensional compactifications of a topological space are in 1-1 correspondence with its Boolean bases.
Lin Erda - One of the best experts on this subject based on the ideXlab platform.
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performance of the Priestley taylor equation in the semiarid climate of north china
Agricultural Water Management, 2005Co-Authors: Liu Xiaoying, Lin ErdaAbstract:Abstract The reference crop evapotranspiration is the most important component in the determination of agricultural water use. Since too many different methods are available in computing this value, the evaluation of these methods is the first step before using them. The objective of this paper is to assess the applicability of the Priestley–Taylor equation, widely used in many crop simulation models, by comparing its value with that of the Penman utilizing 46–50 years data series from six weather stations in the semiarid north china. The FAO Penman 1979 version is adopted because of its wide use in China. The input data includes monthly average sunshine duration, air temperature, relative humidity, air pressure and wind speed. Daily rate of monthly average is first obtained, and then multiplied by the days of each month to get the monthly total. During the calculation, the intermediate net radiation is estimated, and the soil heat flux is omitted. The required data, subjected to strict quality control before delivering and can make sure the accuracy of this study, is provided by the Climate Data Center, National Meteorological Bureau. The six locations are all national standard meteorological stations with long data record and are almost evenly distributed in the region. The evaluation was conducted at three time scales, annually, monthly and daily. The Priestley–Taylor equation underestimated the reference crop evapotranspiration significantly at yearly time scale, ranging from 128.6 to 364.1 mm, or 14–31% in terms of percentage. Spatially, it performed decreasingly according to Taiyuan > Shijiazhuang > Zhengzhou > Tianjin > Beijing > Jinan. At monthly time scale, the performance in most locations depends largely on month. In the humid months of July and August, it is comparable to the Penman equation. But when the wind speed is above certain level, the agreement decreased. In other months, its performance is unacceptable. At daily time scale in July and August in the best-performed year and the worst performed year, the Priestley–Taylor equation also performed well. At the latter two time scales, the spatial performing order varies from that at yearly time scale, and varies for different months and years. At all time scales considered, the performance of the Priestley–Taylor equation in the semiarid region is inversely affected by the ratio of aerodynamic term to radiation. This was supported by the correlations between this ratio and the ratio of the Priestley–Taylor value to the Penman value for annual, monthly and daily series. In addition, precipitation and wind speed also play a part in the performance. Years, months or days with higher precipitation or lower wind speed usually result in better performance, or vice versa. In summary, care should be taken when applying the Priestley–Taylor equation in the semiarid climate in north China. Temporally, it can be used in July and August and at daily time scale in these two months, but unsatisfactorily in other months and at yearly time scale. Spatially, except locations with wind speed higher than 2.61 and 2.36 m s −1 as Jinan in July and August, it is applicable in other locations in these two months. With the widespread use of this equation in crop simulation modeling, the possible modification to the coefficient α in the region deserves further investigation.
Ramon Jansana - One of the best experts on this subject based on the ideXlab platform.
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Priestley duality for modal n4 lattices
Transactions of the Association for Computational Linguistics, 2013Co-Authors: Ramon Jansana, Umberto RivieccioAbstract:N4-lattices are the algebraic semantics of paraconsistent Nelson logic, which was introduced in [1] as an inconsistency-tolerant counterpart of the better-known logic of Nelson [7, 13]. Paraconsistent Nelson logic combines interesting features of intuitionistic, classical and many-valued logics (e.g., Belnap-Dunn four-valued logic); recent work has shown that it can also be seen as one member of the wide family of substructural logics [15]. The work we present here is a contribution towards a better topological understanding of the algebraic counterpart of paraconsistent Nelson logic, namely a variety of involutive lattices called N4-lattices in [8]. A Priestley-style duality for these algebras has already been introduced by Odintsov [10]. The main difference between his approach and ours is that we only rely on Esakia duality for Heyting algebras [4], whereas [10] uses both Esakia duality and the duality for De Morgan algebras [2, 3]; as a consequence, the description of dual spaces that we obtain is, in our opinion, much simpler. Moreover, [10] only deals with N4-lattices whose lattice reduct is bounded, whereas we show that our treatment extends to the non-bounded case as well. We also consider N4-lattices expanded with a monotone modal operator, which have been recently introduced in the algebraic investigation of modal expansions of Belnap-Dunn logic [12, 11, 14]. Building on duality theory for distributive lattices with modal operators [5, 6], we introduce a duality for these modal N4-lattices, which can moreover be employed to provide a neighborhood semantics for the logic of [14].
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Priestley style duality for distributive meet semilattices
Studia Logica, 2011Co-Authors: Guram Bezhanishvili, Ramon JansanaAbstract:We generalize Priestley duality for distributive lattices to a duality for distributive meet-semilattices. On the one hand, our generalized Priestley spaces are easier to work with than Celani's DS-spaces, and are similar to Hansoul's Priestley structures. On the other hand, our generalized Priestley morphisms are similar to Celani's meet-relations and are more general than Hansoul's morphisms. As a result, our duality extends Hansoul's duality and is an improvement of Celani's duality.
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generalized Priestley quasi orders
Order, 2011Co-Authors: Guram Bezhanishvili, Ramon JansanaAbstract:We introduce generalized Priestley quasi-orders and show that subalgebras of bounded distributive meet-semilattices are dually characterized by means of generalized Priestley quasi-orders. This generalizes the well-known characteriza- tion of subalgebras of bounded distributive lattices by means of Priestley quasi- orders (Adams, Algebra Univers 3:216-228, 1973; Cignoli et al., Order 8(3):299- 315, 1991; Schmid, Order 19(1):11-34, 2002). We also introduce Vietoris families and prove that homomorphic images of bounded distributive meet-semilattices are dually characterized by Vietoris families. We show that this generalizes the well- known characterization (Priestley, Proc Lond Math Soc 24(3):507-530, 1972 )o f homomorphic images of a bounded distributive lattice by means of closed subsets of its Priestley space. We also show how to modify the notions of generalized Priestley quasi-order and Vietoris family to obtain the dual characterizations of subalgebras and homomorphic images of bounded implicative semilattices, which generalize the well-known dual characterizations of subalgebras and homomorphic images of Heyting algebras (Esakia, Sov Math Dokl 15:147-151, 1974).
