High-resolution methods for fluorescence retrieval from space

The retrieval from space of a very weak fluorescence signal was studied in the O2A and O2B oxygen atmospheric absorption bands. The accuracy of the method was tested for the retrieval of the chlorophyll fluorescence and reflectance terms contributing to the sensor signal. The radiance at the top of the atmosphere was simulated by means of a commercial radiative-transfer program at a high resolution (0.1 cm-1). A test data set was generated in order to simulate sun-induced chlorophyll fluorescence at the top of the canopy. Reflectance terms were spectrally modeled using cubic splines and fluorescence by means of the sum of two Voigt functions. Sensor radiance residual minimization was performed in the presence of a multiplicative noise, thus ensuring that the sensor simulations were realistic. The study, which focused on the possibility of retrieving fluorescence with an accuracy better than 10%, was performed for instrument resolutions ranging from about 0.4 cm-1 to 2 cm-1 in order to test the algorithm for the characteristics of existing and planned hyper-spectral sensors. The algorithm was also used to retrieve fluorescence in the single O2A band at the OCO and TANSO-FTS instrument spectral resolution

Increasing insightful thinking in analytic geometry

Elsewhere in this issue Ferdinand Verhulst described the discussion of the interaction of anal- ysis and geometry in the 19th century. In modern times such discussions come up again and again. As of 2014, synthetic geometry will not be part of the Dutch `vwo ¿ mathematics B¿ programme anymore. Instead, the focus will be more on analytic geometry. Mark Timmer and Nellie Verhoef explored possibilities to connect the two disciplines in order to have students look at analytical exercises from a more synthetic point of vie

Technique for validating remote sensing products of water quality

Remote sensing of water quality is initiated as an additional part of the on going activities of the EAGLE2006 project. Within this context intensive in-situ and airborne measurements campaigns were carried out over the Wolderwijd and Veluwemeer natural waters. However, in-situ measurements and image acquisitions were not simultaneous. This poses some constraints on validating air/space-borne remote sensing products of water quality. Nevertheless, the detailed insitu measurements and hydro-optical model simulations provide a bench mark for validating remote sensing products. That is realized through developing a stochastic technique to quantify the uncertainties on the retrieved aquatic inherent optical properties (IOP). The output of the proposed technique is applied to validate remote sensing products of water quality. In this processing phase, simulations of the radiative transfer in the coupled atmosphere-water system are performed to generate spectra at-sensor-level. The upper and the lower boundaries of perturbations, around each recorded spectrum, are then modelled as function of residuals between simulated and measured spectra. The perturbations are parameterized as a function of model approximations/inversion, sensor-noise and atmospheric residual signal. All error sources are treated as being of stochastic nature. Three scenarios are considered: spectrally correlated (i.e. wavelength dependent) perturbations, spectrally uncorrelated perturbations and a mixed scenario of the previous two with equal probability of occurrence. Uncertainties on the retrieved IOP are quantified with the relative contribution of each perturbation component to the total error budget of the IOP. This technique can be used to validate earth observation products of water quality in remote areas where few or no in– situ measurements are available

Scale, Scope and Cognition: Context Analysis of Multiple Stated Choice Experiments on the Values of Life and Limb

In this paper we use data from an SP study on flood safety in the Netherlands, and elicit individual preferences for reduction of risk to life and limb. We perform context analysis to test the robustness of fatality risk valuation throughout choice experiments. The main interest of this paper is VOSL sensitivity to the valuation of correlated risks (scope effect). Besides, we explore the role of cognition on the stability of valuation across choice experiments using age and education. We pool data from multiple choice experiments and apply nested and mixed logit models in our analysis. We confirm statistically significant sensitivity to scope, comparing VOSL estimates for the test group in a choice experiment where correlated risks were present (risks of fatality, injury and evacuation) to an experiment where only fatality risk is valued. We find that the origin of differences in VOSL valuations across the choice experiments lies in differences in age and educational attainment, and may therefore be related to cognitive abilities of respondents. In particular, we conclude that higher VOSL sensitivity to scope is most prominently present among respondents of senior age (65 and older) and respondents without college education. This finding has important implications for discrete choice modeling and the use of obtained values in cost-benefit analyses

Satellite-based analysis of recent trends in the ecohydrology of a semi-arid region

We present a regional framework for an integrated and spatiotemporally distributed assessment of human-induced trends in the hydrology and the associated ecological health of a semi-arid basin where both human activities (i.e. agriculture) and natural ecosystems are highly groundwater dependent. To achieve this, we analysed the recent trends (from year 2000 to 2010) in precipitation, evapotranspiration (actual and potential) and vegetation greenness (i.e. NDVI) using a combination of satellite and ground-based observations. The trend assessment was applied for the semi-arid Konya Basin (Turkey), one of the largest endorheic basins in the world. The results revealed a consistent increasing trend of both yearly evapotranspiration (totally 63 MCM yr−1 from croplands) and mean NDVI (about 0.004 NDVI yr−1 in irrigated croplands), especially concentrating in the plain part of the basin, while no significant trends were observed for the precipitation and potential evapotranspiration variables. On the contrary, a consistent decreasing trend of both yearly evapotranspiration (totally −2.1 MCM yr−1) and mean NDVI (−0.001 NDVI yr−1) was observed in the wetlands, which also cannot be explained by trends in precipitation and potential evapotranspiration. The emerging picture suggest that the greening trend of the vegetation and increasing of evapotranspiration in the plain are related to land cover changes (i.e. conversion into irrigated croplands) and to the intensification of the supplementary irrigation for agriculture, which in turn caused drying out of some wetlands and the natural vegetation which mostly depend on the groundwater, the main source of irrigation water as well. Our study presented an example of the utility of spatially and temporally continuous RS data in assessing the regional trends in hydrological and ecological variables and their interactions in a spatially distributed manner in a semi-arid region, which can also be adapted to other regions. Such spatiotemporally distributed analysis at the basin level is particularly important considering that most of the water management interventions also take place at this scale

Composite Valuation of Immaterial Damage in Flooding: Value of Statistical Life, Value of Statistical Evacuation and Value of Statistical Injury

This paper enriches existing valuation literature in a number of ways by presenting context-specific estimates of immaterial damage. First, it offers an estimation of value of statistical life (VOSL) in the context of a natural hazard (flooding). Next, as one of the contributions, alongside with less biased estimate of VOSL (euro 6.8 mln) it also provides estimates of the value of statistical injury (VOSI, euro 92,000), and of the value of statistical evacuation (VOSE, euro 2,400). Our estimated indicators are plausible and stay robust throughout various estimations. For flood protection policy in the Netherlands, a higher value of VOSL forthcoming from this research would imply 'underprotection' under current conditions. Another important finding concerns the composition of the total value of immaterial damages, where value of fatalities or value of evacuation may dominate depending on the prevailing floor risk circumstances. This implies that, first, VOSL is not an adequate proxy for immaterial damages since it understates prospective benefits of designated protective measures. Second, spatially differentiated composition of immaterial damages should be explicitly considered to guide policy decisions

Biomass stocks in Ghanaian cocoa ecosystems: the effects of region, management and stand age of cocoa trees

Determination of biomass produced in cocoa ecosystems is an important step towards quantifying the carbon sequestration potential of cocoa production systems. This study provides data on the biomass of cocoa systems being influenced by management, cocoa stand ages and region. Eight cocoa farms were sampled on the basis of three variables: region (Eastern, Western region), shade management (shaded, unshaded) and stand age (15 years). Allometric equations (R2 > 0.94) were developed to estimate the biomass of live cocoa trees, while the biomass of non-cocoa trees was estimated using an existing equation by FAO. Generally, biomass stocks were higher in the Eastern than Western region, shaded than unshaded, and in stands >15 years than those <15 years. The total cocoa ecosystem biomass range was, 48.1 ± 6.5 to 101.6 ± 12.6 Mg/ha. The high biomass estimates reveals a potential of system to restore appreciable biomass losses resulting from deforestation and forest degradation in Ghana