Search results for "angst"
showing 10 items of 44 documents
Harvest Pressure on Coastal Atlantic Cod (Gadus morhua) from Recreational Fishing Relative to Commercial Fishing Assessed from Tag-Recovery Data
2016
- Marine recreational fishing is a popular outdoor activity. However, knowledge about the magnitude of recreational catches relative to commercial catches in coastal fisheries is generally sparse. Coastal Atlantic cod (Gadus morhua) is a target species for recreational fishers in the North Atlantic. In Norway, recreational fishers are allowed to use a variety of traps and nets as well as long-line and rod and line when fishing for cod. From 2005 to 2013, 9729 cod (mean size: 40 cm, range: 15–93 cm) were tagged and released in coastal Skagerrak, southeast Norway. Both high-reward (NOK 500) and low-reward tags (NOK 50) were used in this study. Because some harvested fish (even those posting h…
Values of broad band turbidity coefficients in a mediterranean coastal site
1999
Abstract The Angstrom turbidity coefficient, the Linke turbidity factor, and the Unsworth–Monteith coefficient have been determined and analysed based on measurements of normal direct irradiance and global horizontal irradiance taken in Valencia, Spain, between January 1990 and December 1996. The data, which were acquired automatically and continuously, have been filtered to select only those values corresponding to clear sky conditions. To determine the Angstrom turbidity coefficient the method proposed by Louche et al. has been used whilst the expression for δCDA proposed by Kasten was used to obtain the Linke turbidity coefficient. The Angstrom turbidity coefficient showed a minimum in w…
A study of the effect of molecular and aerosol conditions in the atmosphere on air fluorescence measurements at the Pierre Auger Observatory
2010
The air fluorescence detector of the Pierre Auger Observatory is designed to perforin calorimetric measurements of extensive air showers created by Cosmic rays of above 10(18) eV. To correct these measurements for the effects introduced by atmospheric fluctuations, the Observatory contains a group Of monitoring instruments to record atmospheric conditions across the detector site, ail area exceeding 3000 km(2). The atmospheric data are used extensively in the reconstruction of air showers, and are particularly important for the correct determination of shower energies and the depths of shower maxima. This paper contains a summary of the molecular and aerosol conditions measured at the Pierr…
Comparison of aerosol size distributions measured at ground level and calculated from inversion of solar radiances
2005
Ground-based sunphotometry measurements can be used to investigate atmospheric aerosol optical properties, such as the volume size distribution, an important parameter in the study of the effect of aerosol on atmospheric processes. Most inversion algorithms assume constant aerosol optical characteristics over the whole air column. In this work we present observational evidence of the limitations of this simplifying assumption in cases where the aerosol vertical structure is highly inhomogeneous. During the field campaign VELETA 2002, carried out in Granada (Spain), a quite complete characterization of the atmospheric aerosol was obtained by simultaneously measuring the columnar aerosol char…
Brown Carbon Aerosol in Urban Xi'an, Northwest China: The Composition and Light Absorption Properties.
2018
Light-absorbing organic carbon (i.e., brown carbon or BrC) in the atmospheric aerosol has significant contribution to light absorption and radiative forcing. However, the link between BrC optical properties and chemical composition remains poorly constrained. In this study, we combine spectrophotometric measurements and chemical analyses of BrC samples collected from July 2008 to June 2009 in urban Xi'an, Northwest China. Elevated BrC was observed in winter (5 times higher than in summer), largely due to increased emissions from wintertime domestic biomass burning. The light absorption coefficient of methanol-soluble BrC at 365 nm (on average approximately twice that of water-soluble BrC) w…
Analysis of a strong wildfire event over Valencia (Spain) during Summer 2012 – Part 1: Aerosol microphysics and optical properties
2013
Abstract. The most intense wildfire experienced in Eastern Spain since 2004 happened in Valencia during summer 2012. Although the fire was mostly active during days 29–30 June, a longer temporal period (from 24 June to 4 July) was selected for this analysis. Column-integrated, vertical resolved and surface aerosol observations were performed continuously at the Burjassot station throughout the studied period. The aerosol optical depth at 500 nm shows values larger than 2 for the most intense part of the wildfire and an extremely high maximum of 8 was detected on 29 June. The simultaneous increase of the Ångström exponent was also observed, indicating the important contribution of small part…
A more reliable relation between Angström and Linke atmospheric turbidity parameters
1989
Abstract This work analyses the correlation between Angstrom and Linke atmospheric turbidity parameters (β and T ) which are commonly used in studies about the atmosphere's behaviour since they efficaciously monitor a point turbidity state and model the aerosol attenuation of solar radiation. Starting from the usual linear relation β = a + bT , a more reliable one is here derived by hourly data of three coastal locations with typical Mediterranean meteoclimatic characteristics, for values of the experimental ratios of diffuse and global solar radiation ⩽0.3. The expression found notably differs from the starting one as shown by the time variable.
Spatial distribution of aerosol microphysical and optical properties and direct radiative effect from the China Aerosol Remote Sensing Network
2019
Multi-year observations of aerosol microphysical and optical properties, obtained through ground-based remote sensing at 50 China Aerosol Remote Sensing Network (CARSNET) sites, were used to characterize the aerosol climatology for representative remote, rural, and urban areas over China to assess effects on climate. The annual mean effective radii for total particles (ReffT) decreased from north to south and from rural to urban sites, and high total particle volumes were found at the urban sites. The aerosol optical depth at 440 nm (AOD440 nm) increased from remote and rural sites (0.12) to urban sites (0.79), and the extinction Ångström exponent (EAE440–870 nm) increased fro…
Contrast in column-integrated aerosol optical properties during heating and non-heating seasons at Urumqi — Its causes and implications
2017
Abstract Aerosol optical properties were retrieved from two years' worth of Sunphotometer measurements at Urumqi, an urban station in western China. Distinct seasonal variations of aerosol optical properties were revealed. During the heating season, mean aerosol optical depth at 550 nm (τ a ), Angstrom exponent calculated from aerosol optical depth at wavelength of 440 and 870 nm (α) as well as PM 2.5 concentration were 0.58 ± 0.33, 1.11 ± 0.34 and 79.5 ± 69.6 μg m − 3 , respectively, which contrasted their counterparts during the non-heating season of 0.32 ± 0.22, 0.79 ± 0.26, and 35.0 ± 20.1 μg m − 3 . Seasonal variations of τ a and PM 2.5 at Urumqi contrasted with corresponding values in…
Determination and analysis of in situ spectral aerosol optical properties by a multi-instrumental approach
2014
Continuous in situ measurements of aerosol optical properties were conducted from 29 June to 29 July 2012 in Granada (Spain) with a seven-wavelength Aethalometer, a Multi-Angle Absorption Photometer, and a three-wavelength integrating nephelometer. The aim of this work is to describe a methodology to obtain the absorption coefficients (babs) for the different Aethalometer wavelengths. In this way, data have been compensated using algorithms which best estimate the compensation factors needed. Two empirical factors are used to infer the absorption coefficients from the Aethalometer measurements: C – the parameter describing the enhancement of absorption by particles in the filter matrix due …