Reconstruction of MODIS total suspended matter time series maps by DINEOF and validation with autonomous platform data

In situ measurements of total suspended matter (TSM) over the period 2003–2006, collected with two autonomous platforms from the Centre for Environment, Fisheries and Aquatic Sciences (Cefas) measuring the optical backscatter (OBS) in the southern North Sea, are used to assess the accuracy of TSM time series extracted from satellite data. Since there are gaps in the remote sensing (RS) data, due mainly to cloud cover, the Data Interpolating Empirical Orthogonal Functions (DINEOF) is used to fill in the TSM time series and build a continuous daily “recoloured” dataset. The RS datasets consist of TSM maps derived from MODIS imagery using the bio-optical model of Nechad et al. (Rem Sens Environ 114: 854–866, 2010). In this study, the DINEOF time series are compared to the in situ OBS measured in moderately to very turbid waters respectively in West Gabbard and Warp Anchorage, in the southern North Sea. The discrepancies between instantaneous RS, DINEOF-filled RS data and Cefas data are analysed in terms of TSM algorithm uncertainties, space–time variability and DINEOF reconstruction uncertainty.     

A Location Aware Mobile Tool for Direct and Indirect Climate Data Sensors

Access to GIS data from mobile platforms continues to be a challenge and there is a wide range of fields where it is extremely useful. In this work, we combined three key aspects: climate data sensors, mobile platforms and spatial proximity operations. We published and made use of a web 2.0 network of climate data, where content is user‐collected, by means of their meteorological stations, and exposed as available information for the virtual community. Moreover, we enriched this data by giving the users the opportunity to directly inform the system with different climate measures. In general, management of this type of information from a mobile application could result in an important decision tool, as it enables us to provide climate‐related data according to a context and a geographical location. Therefore, we implemented a native mobile application for iPhone and iPad platforms by using ArcGIS SDK for iOS and by integrating a series of ArcGIS webmaps, which allows us to perform geospatial queries based on the user's location, offering, at the same time, access to all the data provided by the climate data sensor network and from direct users.     

Observations of Atmospheric Downward Radiation in the Tokyo Area

The size and variation of the urban increase of atmospheric downward radiation have been observed in the Tokyo area. Downward radiation flux, air temperature and humidity were observed by automobile traverses along the expressways across the greater Tokyo area from the Kanagawa (southwest) to the Chiba (east) sides. The observations were carried out on clear and rather calm nights in the winters of 1975–1978. The results show that Tokyo receives increased downward radiation in comparison with the amount received in the surrounding rural areas. The area of increased downward flux extends about 40 km at its widest along the observation route when the winds are weak, and the rural-urban increase of downward radiation becomes about 8% on the Kanagawa side and about 10% on the Chiba side. The area of increased downward flux is close to that of the urban heat island, where an urban decrease of water vapour content is also observed. The present analysis shows that the large urban increase of radiation flux is due to the difference between the vertical temperature profiles over the urban and rural regions. The development of a surface temperature inversion over the rural area and the urban decrease in water vapour content provide a rather smaller rural-urban difference in downward radiation compared with the development of a heat island.     

Urban albedo as a function of the urban structure — A model experiment

A model experiment has been carried out in order to examine the effect of surface irregularity of an urban structure on the anomalous absorption of incident solar radiation. Several models of an urban structure resembling buildings and canyons were constructed by using concrete blocks in cubic form. By building and dismantling the urban models, the albedo change as a function of solar zenith angle was observed throughout the year. The result shows that the absorption increment originating from the irregular urban structure amounts to about 20% as compared with the absorption by a flat surface of the same material. The amount of additional absorption depends on the relative area occupied by canyons in the model.     

Analysis of surface chlorophyll a associated with sea surface temperature and surface wind in the South China Sea

Ocean Dynamics - In this study, the spatial and temporal variability in surface chlorophyll a (Chl-a) in the whole South China Sea (SCS) was investigated in detail by using 8-day, 4-km, gap-free...     

Neogene sediment deformations and tectonic features of northeastern Tunisia: evidence for paleoseismicity

The Neogene stratigraphic series is characterized by predominant clayey facies alternated by other sand layers. The outcrop and subsurface studies show varied and complex styles of deformations and lead to relate the structures to paleoseismic events. The seismicity of eastern onshore and offshore Tunisian margin follows the master fault corridors oriented globally N–S, E–W, and NW–SE that correspond to the bordering faults of grabens and syncline corridors and associated faulted drag fold structures oriented NE–SW. Epicenters of magnitudes between 3 and 5 are located along these border fault corridors. The Neogene strata record brittle structures, including numerous and deep faults and fractures with straight and high-angle dipping planes. The structuring of NE–SW en echelon folds and synclines inside and outside NW–SE and E–W right lateral and N–S and NE–SW left lateral tectonic corridors indicates the strike-slip type of bordering faults and their seismogenic nature. Wrench fault movements that induce mud and salt diapirs, mud volcanoes, and intrusive ascensions are related to seismic shocks. Seismic waves caused by activity along one, or most likely, several tectonic structures would have propagated throughout the Quaternary cover producing seismites. The similarity of deposits, structuring, and seismites between the Tunis-Bizerte to the North and Hammamet-Mahdia to the South accredits the hypothesis that the seismic episodes might have affected sedimentation patterns along the Sahalian large geographic area. The paleoseismic events in northeastern Tunisia might be related to tectonic fault reactivations through time. This hypothesis is consistent with the geomorphologic context of the study area, characterized by several morphostructural lineaments with strong control on the sediment distribution, as well as uplifted and subsiding terrains. The estimated magnitude of the seismic events and the great regional tectonically affected areas demonstrate that the northeastern Tunisia experienced stress through the last geological episodes of its evolution. This Neogene kinematic reconstruction highlights the neotectonic system inducing the actual seismicity on this margin. Therefore, there is a straight relationship between deepseated faults and seismicity.     

Solitons and other solutions to the quantum Zakharov-Kuznetsov equation

In this paper, we present G′/G-expansion method, exp-function method, modified F-expansion method as well as the traveling wave hypothesis for finding the exact traveling wave solutions of the quantum Zakharov-Kuznetsov equation which arises in quantum magneto-plasmas. By these methods, rich families of exact solutions have been obtained, including soliton solutions. This work continues to reinforce the idea that the proposed methods, with the help of symbolic computation, provide a powerful mathematical tool for solving nonlinear partial differential equations.     

Local ensemble assimilation scheme with global constraints and conservation

Ensemble assimilation schemes applied in their original, global formulation respect linear conservation properties if the ensemble perturbations are set up accordingly. For realistic ocean systems, only a relatively small number of ensemble members can be calculated. A localization of the ensemble increment is therefore necessary to filter out spurious long-range correlations. The conservation of the global properties will be lost if the assimilation is performed locally, since the conservation requires a coupling between all model grid points which is removed by the localization. The distribution of ocean observations is often highly inhomogeneous. Systematic errors of the observed parts of the ocean state can lead to spurious adjustment of the non-observed parts via data assimilation and thus to a spurious increase or decrease in long-term simulations of global properties which should be conserved. In this paper, we propose a local assimilation scheme (with different variants and assumptions) which can satisfy global conservation properties. The proposed scheme can also be used for non-local observation operators. Different variants of the proposed scheme are tested in an idealized model and compared to the traditional covariance localization with an ad-hoc step enforcing conservation. It is shown that the inclusion of the conservation property reduces the total RMS error and that the presented stochastic and deterministic schemes avoiding error space rotation provide better results than the traditional covariance localization.