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The performance of passive microwave sea-ice concentration products in the marginal ice zone and at the ice edge draws much attention in accuracy assessments. In this study, we generated 917 pseudo-ship observations from four Moderate Resolution Imaging Spectroradiometer (MODIS) images based on the Antarctic Sea Ice Processes and Climate (ASPeCt) protocol to assess the quality of the Advanced Microwave Scanning Radiometer for Earth Observing System (AMSR-E) ARTIST (Arctic Radiation and Turbulence Interaction STudy) Sea Ice (ASI) concentrations at the ice edge in Antarctica. The results indicate that the ASI pixels in the pseudo-ASPeCt observations have a mean ice concentration of 13% and are significantly different from the well-established 15% threshold. The average distance between the pseudo-ice edge and the 15% threshold contour is ~10 km. The correlation between the sea-ice concentration (SIC), SICASI and SICMODIS values at the ice edge was considerably lower than the high coefficients obtained from a transect analysis. Underestimation of SICASI occurred in summer, whereas no clear bias was observed in winter. The proposed method provides an opportunity to generate a new source of reference data in which the spatial coverage is wider and more flexible than in traditional in situ observations.
This study analyses the factors affecting tea productivity in Northeast India using a combined statistical and modelling approach. The effects of a number of genotypic, environmental and management factors on tea yield are quantified and modelled, using a three-year (2007–2009) field trial in Assam, Northeast India. Simulations of the potential tea yield are obtained using the Cranfield University Plantation Productivity Analysis (CUPPA) Tea model to find out how well the predicted and observed values for tea production match. This combined approach shows that plantation age has a significant negative (R2 = 0.77) effect on tea yield. Monthly rainfall had a significant positive effect on monthly yields (R2 = 0.43). Rainfall was more strongly associated with tea yield when rainfall in month x was related to the tea yield in month x + 1 (R2 = 0.49). When repeating the analysis for a hypothetical situation that the fields are fully planted, the correlation between monthly rainfall in month x and tea yield for month x + 1 increases (R2 = 0.58). Adjusted yields show a higher correlation than actual yields. The results obtained show a close correspondence between predicted and observed yields, indicating that the model could be used on contrasting soil types, genotypes and also on daily, weekly and monthly weather data. It can be further calibrated and validated for Northeast Indian conditions if more required input parameters are collected in a series of plantations. Tea research might benefit from developing new versions of the CUPPA Tea model for the major clonal tea cultivars, with a more flexible module for fertiliser application as is currently the case.
The red fox Vulpes vulpes is usually classified as being territorial, dispersing or transient. Past studies have focused almost exclusively on territorial or dispersing foxes, leaving transient foxes out of the analysis. In this paper, we present spatial-statistical methods for the classification of free-ranging foxes, using 95% fixed kernels and 100% minimum convex polygons. By means of these procedures we classify individual foxes on the basis of their spatial behaviour, using home-range size and home range shift. Also, we make a methodological comparison between these classification procedures and interpret the composition of these classes ethologically. The procedures apply to a sample of 24 foxes, radio-tracked in the dune area of the Netherlands from January 1997 to June 1999. We analysed size of home range and successive 3-month overlap using a geographical information system (GIS). Classifying the sample using 95% fixed kernel home ranges resulted in two classes of foxes: a class of 20 territorial foxes with relatively small home ranges (<250 ha), and a class of four dispersing and transient foxes with relatively large home ranges (400–600 ha). This study shows that a fox population can be divided into different classes of individuals in a quantitative statistical way, honouring measured characteristics. This is a clear extension of more informal ways relying on expert judgement applied so far.
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