Suchergebnisse

CH4 is the second most potent anthropogenic greenhouse gas, after CO2, and is directly responsible for approximately 20% of the human-induced greenhouse effect. To improve our understanding of the global CH4budget, high quality measurements of its atmosphericmole fraction are needed with good resolution in space and time. They provide constraints to the so-called inverse models, which are used to convert the mole fraction gradients into surface fluxes. Unfortunately, it is difficult to take continuous measurements on the ground in many regions of the world due to political or geographical limitations, leaving the models incapable of estimating the fluxes in these regions. Measurements made by sensors onboard a satellite platform can be a suitable source of information as they provide near global coverage. However, satellite retrievals often suffer from errors due to scattering of light by aerosol and cirrus. Such errors, if unaccounted, can be wrongly attributed to the flux estimates of inverse models. One way to dodge this problem is to use the ratio between the retrievals of two tracers, so that the retrieval errors cancel out in the ratio. The traditional 'proxy' method achieves this goal by multiplying the ratio of satellite retrieval of CH4 and CO2 with numerically modeled CO2 mole fractions to obtain CH4 mole fraction estimates. The method assumes that the errors in modeled CO2 are negligible compared to residual errors in the ratio of satellite retrievals. However, the retrieval errors are becoming smaller with new and more advanced satellite data becoming available and CO2 model errors are becoming the performance limiting factor in inverse modelling. In this thesis, I present the ratio inversion method, which avoids the use of modeled CO2 by assimilating the ratio of satellite retrievals of CH4 and CO2 to constrain surface emissions. I tested the method with synthetic numerical experiments, where the satellite retrievals were simulated numerically with predefined 'true' fluxes. These experiments ...

This article describes the development of a measure of role conflict. Role conflict was conceptualized as consisting of four dimensions: intrasender, intersender, interrotle, and person‐role conflict respectively. Study 1 (N = 65), which was conducted to pilot test the 96 item questionnaire (reduced from 224 items after expert rating), resulted in the reduction of the questionnaire to 43 items with three interpretable dimensions. Study 2 (N = 100) was carried out to examine the construct validity of the scale and confirm the factor structure. There was convergence with the findings of Study 1. Cronbach alpha for each subscale was adequate, and evidence of concurrent, convergent, and discriminant validities was found. Study 3 (N = 242) attempted to provide some normative data for the measure, in addition to carrying out a confirmatory factor analysis (CFA) using LISREL. The findings of Study 2 were almost duplicated, and the CFA results lent greater support to a three‐factor structure of role conflict.