Search results for "Exponent"
showing 10 items of 896 documents
Aerosol influence on radiative cooling
2011
Aerosol particles have a complex index of refraction and therefore contribute to atmospheric emission and radiative cooling rates. In this paper calculations of the longwave flux divergence within the atmosphere at different heights are presented including water vapour and aerosol particles as emitters and absorbers. The spectral region covered is 5 to 100 microns divided into 23 spectral intervals. The relevant properties of the aerosol particles, the single scattering albedo and the extinction coefficient, were first calculated by Mie-theory and later by an approximation formula with a complex index of refraction given by Volz. The particle growth with relative humidity is also incorporat…
Evaluation of the new ESR network software for the retrieval of direct sun products from CIMEL CE318 and PREDE POM01 sun-sky radiometers
2012
Abstract. The European Skynet Radiometers network (EuroSkyRad or ESR) has been recently established as a research network of European PREDE sun-sky radiometers. Moreover, ESR is federated with SKYNET, an international network of PREDE sun-sky radiometers mostly present in East Asia. In contrast to SKYNET, the European network also integrates users of the CIMEL CE318 sky–sun photometer. Keeping instrumental duality in mind, a set of open source algorithms has been developed consisting of two modules for (1) the retrieval of direct sun products (aerosol optical depth, wavelength exponent and water vapor) from the sun extinction measurements; and (2) the inversion of the sky radiance to derive…
Aerosol columnar properties retrieved from CIMEL radiometers during VELETA 2002
2008
During the 2002 summer, the VELETA 2002 field campaign has been carried out at the Sierra Nevada Massif, close to Granada in South-Eastern Spain. During the campaign, CIMEL CE-318 robotic radiometer has been one of the key instruments in the characterization of the atmospheric aerosol columnar properties. This kind of radiometers have been operated at Motril, a coastal location at sea level, Pitres (1200 m a.s.l.), located in the South slope of Sierra Nevada Massif, Las Sabinas (2200m a.s.l.), located on the north slope of the mountain range, and Armilla (680m a.s.l.), located in the valley. The principal feature of the locations is that they provide a strong altitudinal gradient. This work…
Columnar aerosol properties in a Northeastern Atlantic site (Plymouth, United Kingdom) by means of ground based skyradiometer data during years 2000-…
2012
Between 2000 and 2008, columnar optical and radiative properties were measured at the Plymouth Marine Laboratory (PML), UK (50° 21.95'N, 4° 8.85'W) using an automatic Prede POM01L sun-sky photometer. The database was analyzed for aerosol optical properties using the SKYRAD radiative inversion algorithm and calibrated using the in situ SKYIL calibration method. Retrievals include aerosol optical depth, ångström wavelength exponent, aerosol volume distribution, refractive index and single scattering albedo. The results show that the Plymouth site is characterized by low values of aerosol optical depth with low variability (0.18 ± 0.08 at 500 nm) and a mean annual ångström exponent of 1.03 ± 0…
Relationship between the effective cloud optical depth and different atmospheric transmission factors
2015
This study examines the sensitivity of cloud optical depth (COD) for overcast conditions to radiation transmission using data collected in Valencia, Spain. These relationships are provided as simple empirical functions, therefore avoiding the need to apply complex model minimisation schemes to obtain COD. Comparisons are presented between COD obtained by a minimization method and several radiation transmission factors comprising a clearness index (kt), a modified version (kt'), a cloud modification factor (CMF) and its modified version (CMF'). Additionally, a statistical model of COD proposed by J.C. Barnard and C.N. Long (2004) is tested with our data. Statistical relationships between COD…
Quantum localization and bound state formation in Bose-Einstein condensates
2010
We discuss the possibility of exponential quantum localization in systems of ultracold bosonic atoms with repulsive interactions in open optical lattices without disorder. We show that exponential localization occurs in the maximally excited state of the lowest energy band. We establish the conditions under which the presence of the upper energy bands can be neglected, determine the successive stages and the quantum phase boundaries at which localization occurs, and discuss schemes to detect it experimentally by visibility measurements. The discussed mechanism is a particular type of quantum localization that is intuitively understood in terms of the interplay between nonlinearity and a bou…
Meaning and magnitude of the reduced density matrix cumulants
2012
Abstract Within the framework of a generalized normal ordering (GNO), invented by Mukherjee [1] , the reduced density matrix cumulants of the (multiconfigurational) reference wave function play a central role, as they arise directly from the contraction rules. The extended Wick theorem allows contractions of an arbitrary number of active annihilators and creators through a cumulant of corresponding rank. Because the cumulant rank truncates naturally only at the number of active spin orbitals, practical applications of the GNO concept seem to rely on a fast convergence of the cumulant series, allowing one to neglect cumulants with high rank. By computing cumulant norms for selected systems (…
Robust H-Infinity Filter Design for Uncertain Linear Systems Over Network with Network-Induced Delays and Output Quantization
2009
This paper investigates a convex optimization approach to the problem of robust H-Infinity filtering for uncertain linear systems connected over a common digital communication network. We consider the case where quantizers are static and the parameter uncertainties are norm bounded. Firstly, we propose a new model to investigate the effect of both the output quantization levels and the network conditions. Secondly, by introducing a descriptor technique, using Lyapunov-Krasovskii functional and a suitable change of variables, new required sufficient conditions are established in terms of delay-dependent linear matrix inequalities (LMIs) for the existence of the desired network-based quantize…
Predicting soil loss in central and south Italy with a single USLE-MM model
2018
Purpose: The USLE-MM estimates event normalized plot soil loss, Ae,N, by an erosivity term given by the runoff coefficient, QR, times the single-storm erosion index, EI30, raised to an exponent b1> 1. This modeling scheme is based on an expected power relationship, with an exponent greater than one, between event sediment concentration, Ce, and the EI30/Pe(Pe= rainfall depth) term. In this investigation, carried out at the three experimental sites of Bagnara, Masse, and Sparacia, in Italy; the soundness of the USLE-MM scheme was tested. Materials and methods: A total of 1192 (Ae,N, QREI30) data pairs were used to parameterize the model both locally and considering all sites simultaneously. …
Bayesian Inference for the Exponential Power Function Parameters
2008
This paper addresses the problem of obtaining the marginal posterior distributions, via Gibbs Sampler, for the parameters of the well-known generalized error distribution called Exponential Power Function (E.P.F.). This density represents a family of unimodal symmetric distributions with shapes varying from leptokurtic to platikurtic.