Are There Radio-quiet Solar Flares?

Some 15% of solar flares having a soft X-ray flux above GOES class C5 are reported to lack coherent radio emission in the 100 – 4000 MHz range (type I – V and decimetric emissions). A detailed study of 29 such events reveals that 22 (76%) of them occurred at a radial distance of more than 800″ from the disk center, indicating that radio waves from the limb may be completely absorbed in some flares. The remaining seven events have statistically significant trends to be weak in GOES class and to have a softer non-thermal X-ray spectrum. All of the non-limb flares that were radio-quiet above 100 MHz were accompanied by metric type III emission below 100 MHz. Out of 201 hard X-ray flares, there was no flare except near the limb (R>800″) without coherent radio emission in the entire meter and decimeter range. We suggest that flares above GOES class C5 generally emit coherent radio waves when observed radially above the source.     

Karst engineering studies at the Akköprü Reservoir area, southwest of Turkey

Akköprü Dam, which is under construction, is located at Dalaman Basin in the southwest of Turkey. The base rock at the Akköprü dam site and reservoir area is autochthon Akta? limestone and Gökseki flysch formation. Allochthon Cehennem Deresi limestone, a complex series of ferro- (melange) and peridotite–serpentine units, overlay this unit with tectonic contact. These units are covered by young sedimentary series. The outcrops of karstified Akta? limestone are observed at 2 km upstream of the dam site, at the right reservoir abutment. This unit is very permeable and the groundwater level is very deep, 100–116 m below the Dalaman riverbed. After impoundment, 250,000 m² of this unit will be submerged. Groundwater which percolates in this unit discharges at the coastal springs. This study analyzed the watertightness of Akköprü reservoir related to the karstified limestone in the left reservoir bank and discussed possible options of remedial works to reduce seepage.     

The Kyoto Protocol Emission Allocations: Windfall Surpluses for Russia and Ukraine

The emission targets adopted in the Kyoto Protocol¹ far exceed thelikely level of emissions from Russia and Ukraine. These countries could selltheir surplus if the Protocol is followedand industrialized countries establish an international emission tradingsystem. Critics have condemned the potentialsale and dubbed the surplus hot air because it does not represent anyreduction in emissions below the level thatwould have occurred anyway. Using the most recent, comprehensive regionalscenarios² for the emissions of carbon dioxide from the energysystem, we estimate that during the Protocol's2008–2012 budget period the surplus will range from 9 MtC (milliontons of carbon) to 900 MtC for Russia andfrom 3 MtC to 200 MtC for Ukraine. Even scenarios with high economic growthand carbon-intensive technologies donot exhaust the surplus before the budget period. In the central (middlecourse) scenario, the total carbon surplusexceeds 1000 MtC and is worth 22 to 170 billion U.S. dollars (4 to 34 billionU.S. dollars per year). This flow ofrevenues, which could exceed Russian earnings from natural gas exports($10 billion in 1997³), is comparable with the projectedtotal investmentsof the Russian energy system for 2008–2012. If directed towardslow-carbon infrastructure investments (e.g., gaspipelines), surplus transfers could reinforce and partially lock-indecarbonization of the world energy system.     

Formation of coronal MHD shock waves – II. The Pressure Pulse Mechanism

The ignition of coronal shock waves by flares is investigated. It is assumed that an explosive expansion of the source region caused by impulsive heating generates a fast-mode MHD blast wave which subsequently transforms into a shock wave. The solutions of 1-D MHD equations for the flaring region and for the external region are matched at their boundary. The obtained results show under what conditions flares can ignite shock waves that excite the metric type II bursts. The heat input rate per unit mass has to be sufficiently high and the preflare value of the plasma parameter in the flaring region has to be larger than ₀ ^crit. The critical values depend on the flare dimensions and impulsiveness. Larger and more impulsive flares are more effective in generating type II bursts. Shock waves of a higher Mach number require a higher preflare value of and a more powerful heating per unit mass. The results demonstrate why only a small fraction of flares is associated with type II bursts and why the association rate increases with the flare importance.     

“Initialization” using an iterative Matsuno style scheme in the Eta Model adjustment stage

Summary  Following a recent approach of Fox-Rabinovitz an iterative Matsuno or a “Super-Matsuno” style scheme is applied as a filter in the Eta Model. In contrast to Fox-Rabinovitz, we however apply the scheme not for all of the model’s time-differencing but for its adjustment terms only. These distinctions compared to the original Fox-Rabinovitz’-method are made easy to implement by the split time differencing approach of the Eta, and at the same time would appear clearly appropriate for the “initialization” purpose. In addition, while Fox-Rabinovitz emphasizes the use of the method within a long time-scale data assimilation framework, we are focusing on the impact of the method in a short-range forecasting environment/time-scale. After a short one hour “initialization” procedure is completed, standard model integration is continued, now very much free of noise. The Super-Matsuno style scheme is found to balance initially unbalanced external and internal modes and to significantly reduce the high-frequency noise during the first 6 time steps. In a control case noise also reduces in amplitude as integration proceeds, but at a much slower rate. The model integration results with and without “initialization” after 6 hours are however very similar. Even so, it is to be expected that small differences, given that they have resulted from the removal of spurious initial noise, have to be beneficial. Received July 5, 1999/Revised January 11, 2000     

Water flow and solute transport model of potentially toxic elements through unsaturated zone at regional wellfield Kosnica

The objective of this work was to build a prognostic water flow model and potentially toxic elements (lead, cadmium, zinc) transport model in the unsaturated zone. Research was conducted in the catchment area of Kosnica regional wellfield, where the unsaturated zone is characterised by Fluvisol. Lower sorption capacities were determined in the first horizons for all three potentially toxic elements. Correlation coefficient of the measured and simulated values of tracer concentration is 0.58 for the AC horizon and 0.84 for the 2C/C1 horizon. Based on calibrated water flow and transport parameters, a prognostic water flow model and potentially toxic elements (lead, cadmium, zinc) transport model in the unsaturated zone was built. In case of an accidental spill of potentially toxic elements with concentrations of 1000 mg/l, the risk of contamination of the aquifer is present. Copyright © 2016 John Wiley & Sons, Ltd.     

Towards a spatio-temporal multicriteria evaluation method: A suitability analysis of residential units in a 3D urban environment

Spatial multi-criteria evaluation (MCE) techniques aid urban planning management by analyzing decision problem alternatives for solutions to help inform decision-making. However, there is a lack of such methods that incorporate the temporal dimension, an important factor when analyzing the dynamic urban landscape and decisions surrounding its changes. A novel spatio-temporal MCE approach is proposed that operates in three-dimensional (3D) space and time to identify changing suitability values of decision alternatives. This space–time method is implemented to evaluate the suitability of residential units over a 15-year period in part of downtown City of Vancouver, Canada. The results indicate that the majority of units exhibit a decrease in suitability with time due to depreciation and reduction of assets like view and privacy from the construction of new buildings. The proposed method can be used by urban planners and developers to assist in long-term assessments of proposed development scenarios and their impact on existing urban infrastructure.     

Coastal cliff geometry derived from structure-from-motion photogrammetry at Stara Baška,Krk Island,Croatia

The aim of this study was to examine the capability of structure-from-motion photogrammetry in defining the geometry of cliffs and undercuts in rocks of complex geomorphology. A case site was chosen along pocket beaches near the village of Stara Ba?ka on the Adriatic Sea island of Krk, Gulf of Kvarner, Croatia, where cliff erosion of 5 m in breccias was identified by comparison of aerial photographs from 1960 and 2004. The 3D point cloud was derived from approx. 800 photos taken on 9 January 2014 by a single camera from various elevations and angles, and processed using the online software ReCap (Autodesk). Data acquisition was found to be quick and the method easy to implement. The difference between the georeferenced 3D cloud points and an RTK-GPS survey was 7 cm, i.e. within the limits of RTK-GPS precision. Quantifying the spatial variation in undercut geometries revealed that the deepest and largest (17 m³) undercut was in the south-eastern sector of the beach. Reconstructing the detailed geomorphology of this 3.8-m-deep undercut convincingly demonstrates the high efficiency of the method. Such assessments of spatiotemporal changes in undercut and overhang volumes can prove useful for evaluations of cliff erosion risk. Coupled with the low cost and relatively simple application, this is evidently an attractive technique for meaningful geotechnical and coastal engineering monitoring in the future on the island of Krk and, for that matter, also on other Adriatic islands and in similar settings worldwide.