34 research outputs found
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Longwave radiation at the ground: IV. Comparison of measurement and calculation of radiation from cloudless skies
On cloudless days in summer, longwave irradiance was measured with a radiometer and was calculated
from a radiation chart using records from radiosondes released at regular intervals. The results show that
the chart underestimated the longwave flux density at the ground by up to 40W/m^(-2), corresponding to
an extra atmospheric emissivity of up to 0.12. The extra emissivity was correlated with turbidity during the
day, and on turbid days it showed a diurnal variation with a maximum at noon. It is suggested that
emission in the atmospheric window from dust, pollen and spores may account for some of the observed
excess
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Longwave radiation at the ground: III. A radiometer for the 'representative angle'
The construction of a directional radiometer for measuring longwave radiation from the atmosphere is
described. The instrument had a filter of black polyethylene to exclude solar radiation, and the detector was
a thermopile. By analysis of the radiation and heat balances of the thermopile, correction terms are derived
for (i) the flux density of radiation received by the thermopile from the filter, and (ii) the dependence of
instrument sensitivity on temperature. Measurements with the new instrument of the equivalent flux density
below cloudless skies at zenith angle 52.5° agree well with measurements of hemispheric flux density derived
from simultaneous measurements with a Linke-Feussner actinometer
Compositional data analysis of Holocene sediments from the West Bengal Sundarbans, India: Geochemical proxies for grain-size variability in a delta environment
© 2016 Elsevier Ltd This paper is part of a special issue of Applied Geochemistry focusing on reliable applications of compositional multivariate statistical methods. This study outlines the application of compositional data analysis (CoDa) to calibration of geochemical data and multivariate statistical modelling of geochemistry and grain-size data from a set of Holocene sedimentary cores from the Ganges- Brahmaputra (G-B) delta. Over the last two decades, understanding near-continuous records of sedimentary sequences has required the use of core-scanning X-ray fluorescence (XRF) spectrometry, for both terrestrial and marine sedimentary sequences. Initial XRF data are generally unusable in ‘raw-format’, requiring data processing in order to remove instrument bias, as well as informed sequence interpretation. The applicability of these conventional calibration equations to core-scanning XRF data are further limited by the constraints posed by unknown measurement geometry and specimen homogeneity, as well as matrix effects. Log-ratio based calibration schemes have been developed and applied to clastic sedimentary sequences focusing mainly on energy dispersive-XRF (ED-XRF) core-scanning. This study has applied high resolution core-scanning XRF to Holocene sedimentary sequences from the tidal-dominated Indian Sundarbans, (Ganges-Brahmaputra delta plain). The Log-Ratio Calibration Equation (LRCE) was applied to a sub-set of core-scan and conventional ED-XRF data to quantify elemental composition. This provides a robust calibration scheme using reduced major axis regression of log-ratio transformed geochemical data. Through partial least squares (PLS) modelling of geochemical and grain-size data, it is possible to derive robust proxy information for the Sundarbans depositional environment. The application of these techniques to Holocene sedimentary data offers an improved methodological framework for unravelling Holocene sedimentation patterns
A review of techniques for parameter sensitivity analysis of environmental models
Mathematical models are utilized to approximate various highly complex engineering, physical, environmental, social, and economic phenomena. Model parameters exerting the most influence on model results are identified through a ‘sensitivity analysis’. A comprehensive review is presented of more than a dozen sensitivity analysis methods. This review is intended for those not intimately familiar with statistics or the techniques utilized for sensitivity analysis of computer models. The most fundamental of sensitivity techniques utilizes partial differentiation whereas the simplest approach requires varying parameter values one-at-a-time. Correlation analysis is used to determine relationships between independent and dependent variables. Regression analysis provides the most comprehensive sensitivity measure and is commonly utilized to build response surfaces that approximate complex models.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42691/1/10661_2004_Article_BF00547132.pd
Using a structured approach to the acquisition of probabilistic data from expert opinion
SIGLEAvailable from British Library Document Supply Centre- DSC:3614.604(DOE/RW--88.007) / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Development of SYVAC sampling techniques
SIGLEAvailable from British Library Lending Division - LD:3614.604(DOE/RW--85.072) / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Testing of a method of importance sampling for use with SYVAC
DOE SYVAC Technical Report TR-STH--15 1. edAvailable from British Library Document Supply Centre- DSC:3614.604(DOE/RW--86.059) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
Optimisation of radioactive waste Management systems using weighted measures of economic and radiological impact
SIGLEAvailable from British Library Document Supply Centre- DSC:3614.604(DOE/RW--85.159) / BLDSC - British Library Document Supply CentreGBUnited Kingdo
Final report on the acquisition of data for use in the probabilistic risk assessment of underground disposal of radioactive wastes
DOE SYVAC Technical Report TR-STH--19 2. edAvailable from British Library Document Supply Centre- DSC:3614.604(DOE/RW--86.071) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo