Calculation of rainfall from satellite data in and around Bangladesh

We calculated GMS Precipitation Index (GPI, satellite rainfall) using three hourly IR data from GMS-5 over Bangladesh and adjoining areas for spatial resolution of 0.5° × 0.5°, l° × 1°, 2° × 2° and temporal scales of 1-day, 3-day and 7-day and monthly averages. There was no special difference between the spatial averaging scale of 0.5° or 1° mesh on land. The GPI contours were closely spaced in 0.5° mesh and better to comprehend the GPI fluctuation. From the monsoon month of June to July the GPI maxima and minima shift from their original (starting) location. Both the GPI maxima and minima shifted toward north. There was an increase in GPI as one moved from north to south. Sea and offshore areas received almost uniform GPI compared to land areas where rain fluctuations occurred with little horizontal distance. It was found that actual rainfall was 88% of the GPI in this study.

Stress-weighted spatial averaging of random fields in geotechnical risk assessment

Effects of spatial fluctuations of soil parameters are considered in a new context – considering variability of soil parameters in conjunction with non-uniform stress fields, which can locally amplify (or suppress) subsoil inhomogeneities. In this way, several design situations for the Coulomb frictional material with random tan(φ(x)) reveal a reduction of variance, which is less significant than for the standard volume averaging. When looking for an ‘effective’ random variable [tan(φ)]a – that is, a random variable, which is equivalent to the random field tan(φ( x )) – the Vanmarcke averaging by simple volume integrals is insufficient; it systematically overestimates effects of variance reduction, thus causing potentially unsafe situations. The new proposed approach is coherent, formally defined and more realistic.

On the Low Frequency Impact Noise Measurement in Residential Buildings

We commonly encounter cases that, despite the fact that buildings meet normative requirements, people are disturbed by unwanted noise generated by walking and other sources of impact noise. It is not unusual that in practice the designer often moves on the edge of the required criteria in order to reduce the cost of constructions and its parts. In this article, we selected 4 blindly chosen cases of flats where complaints from residents about high levels of impact noise were recorded although the construction meets the requirements set out in the standard. Based on the obtained documentation of in-situ performed measurements by different consulting companies, BEM and FEM models were created, and the distribution of acoustic pressure in an enclosed space and compared different methods of spatial averaging of the resulting acoustic pressure were simulated. The aim of this analysis is to point some of the reasons for possible user complaints about the impact noise despite normative requirements. The usual problems are benevolent national requirements and the issue of measuring noise in the low frequency range and underestimating its significance. The article also discusses the currently set requirements for the evaluation of floor structures in selected countries.

Sedimentary microplankton distributions are shaped by oceanographically connected areas

Having descended through the water column, microplankton in ocean sediments are representative for the ocean surface environment, where they originated from. Sedimentary microplankton is therefore used as an archive of past and present surface oceanographic conditions. However, these particles are advected by turbulent ocean currents during their sinking journey. So far, it is unknown to what extent this particle advection shapes the microplankton composition in sediments. Here we use global simulations of sinking particles in a strongly eddying global ocean model, and define ocean bottom provinces based on the particle surface origin locations. We find that these provinces can be detected in global datasets of sedimentary microplankton assemblages, demonstrating the effect provincialism has on the composition of sedimentary remains of surface plankton. These provinces explain the microplankton composition, together with e.g. ocean surface environment. Connected provinces have implications on the optimal spatial extent of microplankton sediment sample datasets that are used for palaeoceanographic reconstructions, and on the optimal spatial averaging of sediment samples over global datasets.