Kalman filtering for nonlinear atmospheric chemistry models : first experiences

The aim of the {sc eu project {sc riftoz is to analyse regional differences in tropospheric ozone over Europe. One of the key activities within {sc riftoz therefore involves recovering ozone concentrations from available measurements. This will be done by running the atmospheric chemistry model {sc lotos over the selected period using a data assimilation technique to incorporate the measurements. A commonly used data assimilation technique is the (extended) Kalman filter. This filter has proved to be very useful in many applications. However, the models involved in these applications are usually only weakly nonlinear, whereas atmospheric models, like {sc lotos, are often highly nonlinear. The paper presents first results on data assimilation with a highly nonlinear test model using the (extended) Kalman filter algorithm. The test model has been designed such that the essential characteristics of the {sc lotos model, including stiff (photo-)chemistry, have been retained. Application of the standard algorithm for Kalman filtering is infeasible because of the huge computational and storage requirements. Instead, a reduced rank approximation of the covariance matrix is used, which reduces the computational burden to an acceptable amount of CPU time. Also attention is paid to reducing the number of noise parameters in the filter algorithm in order to further restrict the number of model evaluations that is required to solve the filtering problem. The results of the tests are very promising and show that Kalman filtering may be successfully applied to atmospheric chemistry models

Numerical smog prediction

This paper describes a finite-volume grid refinement technique and its application to the Dutch Smog Prediction Model. This technique is used to improve the numerical quality of the model calculations, especially in areas with large spatial gradients (for example in regions with strong emissions) and areas of interest (to be specified by the user). To illustrate the effect of the refinement strategy, results of model computations and comparisons with measurements are presented

Fast and efficient solution methods for ozone chemistry

Two special-purpose solvers for chemical kinetics problems, a QSSA method and TWOSTEP, together with the state-of-the-art stiff solver VODE, provided with sparse matrix routines, are considered for application in an atmospheric model. Of all three methods a short description is given. A comparison is made for a chemical model describing (parametrized) ozone chemistry. The code TWOSTEP turns out to be a good alternative for the QSSA solver as regards accuracy and to outperform VODE with respect to computation time for accuracies near 1

Fertiliser use and soil carbon sequestration: Key messages for climate change mitigation strategies

Reducing greenhouse gas (GHG) emissions and increasing soil or biomass carbon stocks are the main agricultural pathways to mitigate climate change. Scientific and policy attention has recently turned to evaluating the potential of practices that can increase soil carbon sequestration. Forty percent of the world’s soils are used as cropland and grassland, therefore agricultural policies and practices are critical to maintaining or increasing the global soil carbon pool. This info note explains the current understanding of the impact of mineral fertiliser use on soil carbon sequestration as a mitigation strategy in agriculture. The science and understanding on soil carbon sequestration and mitigation is still emerging, especially in tropical regions. Taking this into consideration, this info note discusses related effects of fertiliser use on climate change mitigation, such as nitrous oxide (N2O) and carbon dioxide (CO2) emissions from nitrogen fertiliser use and production, and the potential effects of mineral fertiliser use on land use change

A dearth of OH/IR stars in the Small Magellanic Cloud

We present the results of targeted observations and a survey of 1612-, 1665-, and 1667-MHz circumstellar OH maser emission from asymptotic giant branch (AGB) stars and red supergiants (RSGs) in the Small Magellanic Cloud (SMC), using the Parkes and Australia Telescope Compact Array radio telescopes. No clear OH maser emission has been detected in any of our observations targeting luminous, long-period, large-amplitude variable stars, which have been confirmed spectroscopically and photometrically to be mid- to late-M spectral type. These observations have probed 3 - 4 times deeper than any OH maser survey in the SMC. Using a bootstrapping method with LMC and Galactic OH/IR star samples and our SMC observation upper limits, we have calculated the likelihood of not detecting maser emission in any of the two sources considered to be the top maser candidates to be less than 0.05%, assuming a similar pumping mechanism as the LMC and Galactic OH/IR sources. We have performed a population comparison of the Magellanic Clouds and used Spitzer IRAC and MIPS photometry to confirm that we have observed all high luminosity SMC sources that are expected to exhibit maser emission. We suspect that, compared to the OH/IR stars in the Galaxy and LMC, the reduction in metallicity may curtail the dusty wind phase at the end of the evolution of the most massive cool stars. We also suspect that the conditions in the circumstellar envelope change beyond a simple scaling of abundances and wind speed with metallicity

Balancing food and density-dependence in the spatial distribution of an interference-prone forager

Foraging distributions are thought to be density-dependent, because animals not only select for a high availability and quality of resources, but also avoid conspecific interference. Since these processes are confounded, their relative importance in shaping foraging distributions remains poorly understood. Here we aimed to rank the contribution of density-dependent and density-independent effects on the spatio-temporal foraging patterns of eurasian oystercatchers. In our intertidal study area, tides caused continuous variation in oystercatcher density, providing an opportunity to disentangle conspecific interference and density-independent interactions with the food landscape. Spatial distributions were quantified using high-resolution individual tracking of foraging activity and location. In a model environment that included a realistic reconstruction of both the tides and the benthic food, we tested a family of behaviour-based optimality models against these tracking data. Density-independent interactions affected spatial distributions much more strongly than conspecific interference, even in an interference-prone species like oystercatchers. Spatial distributions were governed by avoidance of bill injury costs, selection for high interference-free intake rates and a decreasing availability of benthic bivalve prey after their exposure. These density-independent interactions outweighed interference competition in terms of effect size. We suggest that the bottleneck in our mechanistic understanding of foraging distributions may be primarily the role of density-independent prey attributes unrelated to intake rates, like damage costs in the case of oystercatchers foraging on perilous prey. At a landscape scale, above the finest inter-individual distances, effects of conspecific interaction on spatial distributions may have been overemphasised

THE INFLUENCE OF FINANCIAL LITERACY, THE IMAGE OF DESTINATION, THE SOCIAL MEDIA AGAINST THE INTEREST OF VISITING LOCAL TOURISTS THROUGH THE MEDIATION OF THE EMOTIONAL EXPERIENCE

This study aims to determine the influence of financial literacy, the image of destination, the social media against the interest of visiting local tourists through the mediation of the emotional experience of visitors. The population in this study is all domestic visitors of Telaga Sarangan Natural Attraction with purposive sampling technique as many as 120 respondents. The tool of analysis used is path analysis to test each of the relationships between the research variables. The results showed that the visitor’s financial literation, the image of destination, and the social media significantly influence the emotional experience of visitors. In addition, the visitor’s financial literation, the image of destination and the social media also directly affects the increase of interest to revisit the destination in the future. On the other hand, the emotional experience has a significant effect on the interest to revisit the destination in the future, so the relationship between the emotional experiences in a positive manner can increase the visitor’s interest to revisit Telaga Sarangan Natural Attraction.  Article visualizations